View Full Version : DSP active crossover
So I'm mulling over doing a new project. Specifically a 3-way active DSP crossover. Was wondering if someone has done something similar or can provide any hints/warnings etc.
I already have most of the main items, the balance are relatively cheap to get.
Idea is to use Magnum K2s I have lurking here (given to me by Tom of this parish) driven by a Sony 7.1 AV amp (another item that is lurking). DSP will be via JRiver's parametric equaliser.
So this 3-way digital crossover signal path will be something like this:
Digital source (flac etc) > Windows 10 machine > JRiver > Parametric EQ > USB > multi-channel DAC (e.g. Xonar) using 6 of the available channels > Sony AV amp (6 ch. in > 6 ch. out) > Magnum K2.
In terms of the Magnum's I would simply take the existing passive crossovers offline and connect up each driver (bass, mid and HF) to the corresponding speaker output of the AV amp. I would protect the tweeters and probably also the midrange drivers with capacitors (just in case I muck up the DSP/DAC mappings). What I'm not sure of yet is how I place such caps (serial or parallel?) and what capacity caps I should use?
In terms of the parametric EQ I would create suitable low and high pass filters and map those to the relevant DAC ports. What I'm not clear about is where I would set the low and high pass points. I guess I could start with whatever cross over points are already used in the passive setup? Or perhaps it does not matter as long as I'm in the general area and get the roll off slopes correct?
Later on, assuming this all works, I could do some room correction I guess. Using something like REW and implementing a filter within JRiver?
This is just a 'fun' project. Not sure what the eventual SQ will be like, but judging from other forums could be quite nice. Certainly the Magnum K2 12 inch bass drivers can move vast amounts of air. :lol:
I have done similar. Best crossing points to start are the ones in the passive crossover. Then adjust as suits. It is worth working out the passive crossover schematic and modelling it to see what eq was built into it and slopes used.
You only really need a cap on the hf unit as it is easily wrecked by bass energy, the mid and bass units will just sound rubbish if the crossovers are wrong. So saying, it would be easy to run a frequency sweep through the active crossover and check it on a 'scope before connecting up. I think a common value such as 2.2uF would be fine, depending on crossover point and impedances and placed in series with the tweeter to block bass energy.
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I have done similar. Best crossing points to start are the ones in the passive crossover. Then adjust as suits. It is worth working out the passive crossover schematic and modelling it to see what eq was built into it and slopes used.
You only really need a cap on the hf unit as it is easily wrecked by bass energy, the mid and bass units will just sound rubbish if the crossovers are wrong. So saying, it would be easy to run a frequency sweep through the active crossover and check it on a 'scope before connecting up. I think a common value such as 2.2uF would be fine, depending on crossover point and impedances and placed in series with the tweeter to block bass energy.
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Cheers James. Really helpful getting confirmation I'm heading in the right direction. But I hasten to add I'm not very experienced in electronic engineering. I would not know what to do with a schematic. Having said that I could not find any schematic for the Magnum K2s. The only info I found was that the crossover points appear to be at 800hz and 5khz. But perhaps 950hz and 5khz.
At what point do I need to place the 2.2uF cap? on the +ve or -ve?
Good idea to run a freq. sweep through the active crossover. Trouble is I don't have an oscilloscope and never used one. Would a pc based 'scope such as the pico be ok? Perhaps you have a cheaper suggestion please? Not really looking to spend lots of money on this project really.
As mentioned I already have the main items (3 way speaker, AV amp giving me 6 channels and JRiver software). Remaining items to get is a xonar 7.1 dac (about £60) and speaker binding posts, cable etc. Down the road I may get a calibrated mic for room measurement and creation of a suitable filter. One idea is to also use some coral 10 inch bass drivers I have instead of the 12 inch drivers already in the Magnums. Just for fun.
Come to think of it I could possibly use Roon software for the parametric EQ and room correction instead of JRiver.
Interested to know what you did on your project.
WESTLOWER
14-06-2018, 16:20
Come to think of it I could possibly use Roon software for the parametric EQ and room correction instead of JRiver.
Interested to know what you did on your project.
interesting!
Cheers James. Really helpful getting confirmation I'm heading in the right direction. But I hasten to add I'm not very experienced in electronic engineering. I would not know what to do with a schematic. Having said that I could not find any schematic for the Magnum K2s. The only info I found was that the crossover points appear to be at 800hz and 5khz. But perhaps 950hz and 5khz.
At what point do I need to place the 2.2uF cap? on the +ve or -ve?
Good idea to run a freq. sweep through the active crossover. Trouble is I don't have an oscilloscope and never used one. Would a pc based 'scope such as the pico be ok? Perhaps you have a cheaper suggestion please? Not really looking to spend lots of money on this project really.
As mentioned I already have the main items (3 way speaker, AV amp giving me 6 channels and JRiver software). Remaining items to get is a xonar 7.1 dac (about £60) and speaker binding posts, cable etc. Down the road I may get a calibrated mic for room measurement and creation of a suitable filter. One idea is to also use some coral 10 inch bass drivers I have instead of the 12 inch drivers already in the Magnums. Just for fun.
Come to think of it I could possibly use Roon software for the parametric EQ and room correction instead of JRiver.
Interested to know what you did on your project.I'm no engineer either sadly, just a happy amateur [emoji4]
I was working on a pair of Tannoys.I love everything about them except the sound in my room dammit. So I attempted a fix. It sort of worked but I came to the conclusion that it was the cone/ horn interface that I didnt like.
Whatever, I have a DEQX 3.0 that is the only item that hasn't changed in the last 5 or 6 years, in and (occasionally) out of the system. I am becoming wedded to it. Extraordinary what it can do. Get stuck in, you won't regret it I think!
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Yes I've heard great things about the deqx stuff. Lovely stuff, bit expensive for my tastes. I did try out their software at some point but that was a fail as I did not have a good enough mic.
I will need a mic at some point in this project to do room correction. Was thinking of using REW for that.
Once I start this project I may have a question or two. I'll put them up in this thread.
Were the Tannoys dual concentrics that you tried to drive via the DEQX?
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I did some reading on this subject some time ago. From what I remember, they used a pro digital crossover, and 3 amps. Like a DBX digital crossover, you feed the output of your preamp to it, and it distributes it into 3 parts to drive 3 amps, one for each part of your speaker. Then they used a software package with calibration microphones to adjust it. Something like this maybe?
https://www.roomeqwizard.com/
And the DBX crossover allowed adjustment of the crossover points and individual volumes to each amp, and you used the calibration microphone and the software to adjust it to get the best looking response in your room.
I have done (helped a guy do) this for a live performance hall, (bar) but never for a home audio system, but I assume it’s about the same? Set the mic at your listening position and calibrate the system for the flattest curve. And the digital DBX even has time delays to help reduce reflections, if you are running surround sound.
A friend has a huge Onkyo surround sound receiver that comes with a calibration mic, and a built in system to create a flat response at the listening position, it came with a book to figure it out, but he never read it, and instead just used the “auto-adjust”, and let it do its thing. This doesn’t adjust the levels of each speaker, but just works an internal EQ.
This is all probably a mile from what you are trying to accomplish? But just showing there is more than one way to skin a cat.
Russell
Thanks Russell
Certainly not a mile away, it is precisely what I'm trying to achieve. The big difference in my plan is it is just for fun but primarily I will be doing it on the cheap. Essentially I will take a USB feed from a computer and go into a cheap multi-channel DAC (stuff they use everyday in gaming rigs) and from there to a multi-channel amp. From there I will take 3 stereo pairs and drive the 3-way drivers in Goodmans Magnum K2s. Within the computer there will be a digital cross-over such that the feed to the DAC will have 3 stereo pairs. That is the first step.
As a second step, assuming the first step is fine, I will do room correction via REW (as per your link) and a mic. As I understand it REW will create a FIR filter which I can inject into my software.
Looking at my costs (I consider the computer, software, multi-channel amp, cabling and speakers free as I already have them) the biggest cost will actually be the banana plugs, binding posts and DAC. That should be about £100 - so a cheap(ish) experiment. Not sure what I will do with it all once I have done it as my main system are more than adequate. :)
You can do it on the cheap just fine. When I bought the DEQX you couldn't do it cheap. Now I would buy a mini DSP and a UMic. They aren't as feature rich but they're a damn sight cheaper, and within their limits more flexible as well.
Capacitor best across the positive terminal of the speaker for lower PD between wiring and ground. Not essential and I suspect there's no difference in SQ.
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Thanks Russell
Certainly not a mile away, it is precisely what I'm trying to achieve. The big difference in my plan is it is just for fun but primarily I will be doing it on the cheap. Essentially I will take a USB feed from a computer and go into a cheap multi-channel DAC (stuff they use everyday in gaming rigs) and from there to a multi-channel amp. From there I will take 3 stereo pairs and drive the 3-way drivers in Goodmans Magnum K2s. Within the computer there will be a digital cross-over such that the feed to the DAC will have 3 stereo pairs. That is the first step.
As a second step, assuming the first step is fine, I will do room correction via REW (as per your link) and a mic. As I understand it REW will create a FIR filter which I can inject into my software.
Looking at my costs (I consider the computer, software, multi-channel amp, cabling and speakers free as I already have them) the biggest cost will actually be the banana plugs, binding posts and DAC. That should be about £100 - so a cheap(ish) experiment. Not sure what I will do with it all once I have done it as my main system are more than adequate. :)
So, if you’ve got the multi channel amp, and a computer, that’s a major head start!
You could get by cheaper with my scenario by buying a Behringer digital crossover, used. And a calibration mic, you may even find one used? But I’ve seen new ones for $35. And as I was searching for the software, like the one I referred to, I see a lot of versions that were free for download. How much they will do? I guess you’d have to try a few. So, a used Behringer digital crossover may not be more than $100? These digital DSP’s have 24bit processing and run exceedingly quiet. The DBX brand is more feature rich, but one of the articles I read about used the Behringer with great success.
But you sound like you’ve got a handle on it! I was not aware that there were DAC’s that you could control with a computer to create crossover points? It sounds very interesting!
Of course, you will have to keep us updated as you go, with photos and listening impressions. To educate the masses!
Russ
Thanks Russell
Certainly not a mile away, it is precisely what I'm trying to achieve. The big difference in my plan is it is just for fun but primarily I will be doing it on the cheap. Essentially I will take a USB feed from a computer and go into a cheap multi-channel DAC (stuff they use everyday in gaming rigs) and from there to a multi-channel amp. From there I will take 3 stereo pairs and drive the 3-way drivers in Goodmans Magnum K2s. Within the computer there will be a digital cross-over such that the feed to the DAC will have 3 stereo pairs. That is the first step.
As a second step, assuming the first step is fine, I will do room correction via REW (as per your link) and a mic. As I understand it REW will create a FIR filter which I can inject into my software.
Looking at my costs (I consider the computer, software, multi-channel amp, cabling and speakers free as I already have them) the biggest cost will actually be the banana plugs, binding posts and DAC. That should be about £100 - so a cheap(ish) experiment. Not sure what I will do with it all once I have done it as my main system are more than adequate. :)
So, if you’ve got the multi channel amp, and a computer, that’s a major head start!
You could get by cheaper with my scenario by buying a Behringer digital crossover, used. And a calibration mic, you may even find one used? But I’ve seen new ones for $35. And as I was searching for the software, like the one I referred to, I see a lot of versions that were free for download. How much they will do? I guess you’d have to try a few. So, a used Behringer digital crossover may not be more than $100? These digital DSP’s have 24bit processing and run exceedingly quiet. The DBX brand is more feature rich, but one of the articles I read about used the Behringer with great success.
But you sound like you’ve got a handle on it! I was not aware that there were DAC’s that you could control with a computer to create crossover points? It sounds very interesting!
Of course, you will have to keep us updated as you go, with photos and listening impressions. To educate the masses!
Russ
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So, if you’ve got the multi channel amp, and a computer, that’s a major head start!
You could get by cheaper with my scenario by buying a Behringer digital crossover, used. And a calibration mic, you may even find one used? But I’ve seen new ones for $35. And as I was searching for the software, like the one I referred to, I see a lot of versions that were free for download. How much they will do? I guess you’d have to try a few. So, a used Behringer digital crossover may not be more than $100? These digital DSP’s have 24bit processing and run exceedingly quiet. The DBX brand is more feature rich, but one of the articles I read about used the Behringer with great success.
But you sound like you’ve got a handle on it! I was not aware that there were DAC’s that you could control with a computer to create crossover points? It sounds very interesting!
Of course, you will have to keep us updated as you go, with photos and listening impressions. To educate the masses!
Russ
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Oh I'm just part of the masses Russell, learning as I go along. Mostly making mistakes. :doh:
Speaking of Behringers a mate has one to semi-actively drive his speakers. In his case he is driving the bass of his XTZ Divine Alphas (costing thousands) with a cheap Beheringer. So what with the addition of another stereo amp and tuning of the xover point the bass has vastly improved. In fact it is this improvement that is part of what inspires me to try things out - but in my case focusing on lower end stuff and full digital xovers.
Got to pull the trigger on the remaining bits of pieces. Just deciding if I go with spades or bananas. :confused: Probably just bare wire and cable couplings for now.
paulf-2007
15-06-2018, 13:02
I had one of the early deqx units pdc 2.6, bought it ex demo £600 and sold it later for £700, a rare occasion where I didn't lose money. Great bit of kit. I now use Najda dsp, bought for future projects but used in my office set up as a Dac, very good Dac it has too.
I have some behringer analogue crossovers you could try, one is a 3 way the other a 2 way. I used them early on in my horn build. Easy to use, just twiddle the knobs to the desired crossover point.
You’ve got me curious to try one of these software packages. I’m not planning any digital crossovers, but I just want to see what the sound looks like at my listening position. Get me a cheap calibration mic with USB, and download a free app, and perhaps help me get the speakers into the best position? I don’t have a lot of leeway, but some, I’ve pulled them way out into the room recently, they are majorly in the way but sound much better. The woofer in the rear really creates tons of bass in the room and it gets hard to tame. Perhaps some sound treatments behind the speaker would help?
Anyway, I find your project most interesting and would love to hear how it goes, and what you learn as you go along.
Russell
I've stalled a bit as other things like work has got in the way. Also when firing up the AV receiver (a Sony) I found one channel is down. So I need to get another 7.1 AVR but they are cheap as chips when bought used . Just have to ensure the 7.1 channels are accessible via RCA inputs rather than just HDMI which many newer AVRs have. Got my eye on several in eBay. HDMI alone may work but, judging from other forums, there may be an issue with needing an attached video - which in my implementation I don't want/need.
I feel confident that it will all work out - based on many other people doing the same via JRiver in particular.
But turning to your situation I'm not clear if active dsp crossovers alone will cure your bass issues. Physical room treatment (bass traps, speaker placement etc) will I'm sure go some way and probably digital room correction (via creation of a filter after mic measurement) will also have some improvement. As mentioned all I'm seeking to do at this stage is create a 3-way active digital crossover. Later on I may create a room correcting filter with a mic and REW).
I had one of the early deqx units pdc 2.6, bought it ex demo £600 and sold it later for £700, a rare occasion where I didn't lose money. Great bit of kit. I now use Najda dsp, bought for future projects but used in my office set up as a Dac, very good Dac it has too.
I have some behringer analogue crossovers you could try, one is a 3 way the other a 2 way. I used them early on in my horn build. Easy to use, just twiddle the knobs to the desired crossover point.
Hi Paul, that is very generous of you. This may also be very interesting indeed. I'm inclined to try the full digital idea as a priority but perhaps I can try the Behringer's as well. After all I will have sufficient multi amp channels so it would be simply taking the computer and DAC offline and rerouting as required. What model Behringers are they and whereabouts are you? Feel free to use PM.
I have a friend who uses Behringer's in a semi active form (I think I mentioned this in this thread already) to great effect.
Magna Audio
21-06-2018, 19:41
Interesting using JRiver to do the X/O stuff.
Had that existed / been on my horizon 5 years ago I'd have been interested in it.
The Berhringer DEQ 24/96 is in my opinion not sufficiently Hifi.
I tried them even modded.
They would work on bass frequency duty though.
I use a WAF Najda DSP X/O in my 5 way horn system.
The flexibility and SQ are amazing.
There's a wealth of info on Diyaudio. The part 1 thread is all about the Reqs, part 2 is about the creation, manufacture and folk using this very high quality solution. They even do a complete turn key option now too.
Several of us HQ multi way horn addicts use them to stunning affect.
I use room correction on my tapped horn subs only (18Hz to 90Hz) and 4th order X/O. I've tried 8th order but it's a bit too constrained somehow..
Without DSP room correction you would not want to listen to it :) with it the results are stunning.
Going active with Tannoys with a big PP or Silicon amp on bass and a sweet SET on the treble is the way to go. L-pads, Zobels etc sap clarity and dynamics terribly.
Be interesting to see how you get on.
I have heard several hardware solutions from miniDSP and own the Hypex DLCP.
They are all pretty good with digital sources, but the ADC on any of these is not up to the standard required for vinyl reproduction.
If I was going Digital Active (I am Analogue Active now) I would go the software route on a PC. Waiting on delivery (this morning) of the power amps for my set up.
Halfwaytree of this parish uses JRiver and "Accurate" for the filter/room correction, in his superb sounding Linkwitz LX521 set up, try dropping him a PM.
Going active with Tannoys with a big PP or Silicon amp on bass and a sweet SET on the treble is the way to go. L-pads, Zobels etc sap clarity and dynamics terribly.
Thanks Steve. For simplicity and 'proof of concept' just planning on using an AV amp for its multi-channel audio amps and one volume control for all channels. But certainly the idea of using PP for the bass and SET for the highs is very attractive. The amps in an AV unit I suspect are not really high end. Probably cheap class D boards.
I have heard several hardware solutions from miniDSP and own the Hypex DLCP.
They are all pretty good with digital sources, but the ADC on any of these is not up to the standard required for vinyl reproduction.
If I was going Digital Active (I am Analogue Active now) I would go the software route on a PC. Waiting on delivery (this morning) of the power amps for my set up.
Halfwaytree of this parish uses JRiver and "Accurate" for the filter/room correction, in his superb sounding Linkwitz LX521 set up, try dropping him a PM.
Thanks Ken.
On the vinyl side of things have you considered using a pro ADC? Something like that RME does. Their ADI-2 Pro will sample at 192/24 with, I understand, great results. But I'm sure most people with great vinyl rigs will want to stay in the analog domain from the black circle all the way to the speakers. Purism rules ok! :)
Between other things I've been mucking around with JRiver Parametric EQ (https://wiki.jriver.com/index.php/Parametric_Equalizer) and trying to get my head around stuff like Linkwitz Transforms and the like. All very interesting.
Still waiting for an AV amp to come up. I may, assuming I get to grips with the parametric eq soon, just go for a 2 way stereo idea using a different (sacrificial) speaker and the existing AV amp I have.
Thanks for the tip on Halfwaytree (Gordon) - I may well drop him a message.
What power amps you getting?
Thanks Steve. For simplicity and 'proof of concept' just planning on using an AV amp for its multi-channel audio amps and one volume control for all channels. But certainly the idea of using PP for the bass and SET for the highs is very attractive. The amps in an AV unit I suspect are not really high end. Probably cheap class D boards.
Thanks Ken.
On the vinyl side of things have you considered using a pro ADC? Something like that RME does. Their ADI-2 Pro will sample at 192/24 with, I understand, great results. But I'm sure most people with great vinyl rigs will want to stay in the analog domain from the black circle all the way to the speakers. Purism rules ok! :)
Between other things I've been mucking around with JRiver Parametric EQ (https://wiki.jriver.com/index.php/Parametric_Equalizer) and trying to get my head around stuff like Linkwitz Transforms and the like. All very interesting.
Still waiting for an AV amp to come up. I may, assuming I get to grips with the parametric eq soon, just go for a 2 way stereo idea using a different (sacrificial) speaker and the existing AV amp I have.
Thanks for the tip on Halfwaytree (Gordon) - I may well drop him a message.
What power amps you getting?
I considered getting the Burl Audio B2 Bomber ADC which plenty of producers swear by for an "Analogue sound", the cost of the overall set up including 6 channels of power amp was getting a bit much though.
I decided to stick with an Analogue active solution, from which I was getting good results with my vinyl set up. This was using a two way active crossover (Rod Elliott's boards) to cross at 500Hz and feed the <500hz direct to the bass via amps and the >500 to the amps then to a passive cross over further splitting at 6kHz for mid/tweeter. So the mid still only sees 500Hz to 6kHz. This semi active set up works great and avoids a big bank of caps which were in series with the mid driver in the original passive crossover. My op-amp choice in the active crossover tames the previously forward treble (Yam NS1000M) and by using an alternative 12" Scanspeak bass driver I have taken the bass f3 point from 52Hz to about 29Hz. It doesn't start to roll off till 35Hz and in a similar sized closed box to the NS1000m, both were measured in my room, which does give some bass lift.
I also considered a Linkwitz transform and Rod Elliott produces a board to achieve this, Rod steered me clear, his crossover is phase coherent and adding a transform circuit would alter the phase. So unless I wanted to get into sorting that can of worms, he suggested I leave it out. If your doing it in the digital domain, then things may well be different.
I'm getting a pair of Nord One UP NC500DM (Dual Mono) so 4 Channels of amplification.
These use the Hypex NC500 modules providing 700w each channel for my two 4ohm woofers and 400w each channel shared between a 8ohm Mid/Twtr. It's the model with their own discrete input buffer and regulators which is supposed to give an improvement over the stock Hypex input which uses a chip op-amp.
I have a Nakamichi 7 channel Amp 110w/channel I may be moving on, its an absolute cracker. I promised someone first refusal if I ever sold it, so it would depend on whether he is still interested. It weighs 32kg, the pair of Nord class D weigh 18kg and take up less space, which is the only reason I am replacing the Nakamichi. I'll let you know if it's available. ;)
4 O'clock and no sign of UPS yet :steam:
Five past four, they arrived :carrot:
Ah yes I know the frustration of having to wait in. We have friendly neighbours so usually something can be arranged. Once I had a neighbour sign for a car that was being delivered. Lol
Going the avr route at this stage is the cheaper option. Assuming things go swimmingly I may consider going up the chain in terms of quality. What I don't have my head around on a multi channel power amp set up (say using your 7ch nak) is how I would incorporate a simple attenuation box without having to go down an expensive multichannel preamp road.
Yes I know the naks can be very heavy. A mate has a PA Nelson pass one. That is a two man lift.
Good luck with your new toys.
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I attenuate the mid/tweeter signal at line level on my active crossover, before the power amps. The Woofer demands more but is 4ohm so its the 8ohm Mid/Twt that needs slight attenuation. (My power amp channels all have the same gain).
Gordon has a MYTEK eight channel DAC and I think it has variable output on each channel, plus DSP software adjustment.
I think that's right but he would explain it better than me.
Thanks. Interesting.
My cunning plan (!?) is to attenuate via the parametric eq each channel to take account of different driver's sensitivities (so instead of resistors in a passive xover).
I could do overall volume control in the digital domain (and given that all the math is in 64 bit there will be negligible loss) but I'm scared of that as for sure I will at some point drive the speakers at full tilt. Been there and got the T shirt.
Need to find a minute to pm Gordon.
Did you get your new toys wired up?
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I did a basic test on the amps to make sure they were working, with a cheap passive pair of speakers.
I'm making a matching case for the active crossover about 2/3 the width of an amp and Using the same illuminated switch, which I need to match for brightness using the voltage I have available. 9k1 seems to be the resistor I need, so just ordered those. Got some feet to fit, I'm almost there. This is my build thread if you've not seen it:
http://theartofsound.net/forum/showthread.php?56378-Yamaha-NS-1000M-A-Fresh-Start/page4
Ah yes I've been following that thread. Quality!
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Halfway Tree
02-07-2018, 14:02
Thanks. Interesting.
My cunning plan (!?) is to attenuate via the parametric eq each channel to take account of different driver's sensitivities (so instead of resistors in a passive xover).
I could do overall volume control in the digital domain (and given that all the math is in 64 bit there will be negligible loss) but I'm scared of that as for sure I will at some point drive the speakers at full tilt. Been there and got the T shirt.
Need to find a minute to pm Gordon.
Did you get your new toys wired up?
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Spot on with your cunning plan! It's a good idea to provide a bit of headroom in each channel - so dropping each input by a few db (on top of what you may need for driver sensitivities) will be beneficial - digital clipping is not nice! Don't worry about digital volume control either - you're working inside a 64 bit environment in JRiver which is dithered down to 24bit at the output. 6db attenuation = 1bit less so you have plenty to play with.
If you are looking for an 8 channel DAC I'd suggest the Motu 8A - an excellent piece of pro gear at about £750 and compact to boot. I love my Mytek 8x192ADDA and it's not going anywhere, but it's a big piece of gear and at more than £2k, not cheap. The Motu is a bargain by comparison and it's what I would choose if I was doing this now.
I went the software dsp route about 4 years ago now and don't regret it one bit (sorry for the pun).
There's been some good input from others on this thread so I'd just say go for it - you won't regret it. DSP controlled speakers is the way forward IMO. I've heard both the Kii3 and the Dutch & Dutch 8Cs (way ahead of anything else at the recent Cranage show for me) and they are both outstanding speakers.
Hi Gordon
Thanks for the very helpful response. Yes I will create a few db headroom but I was guessing the JRivers clipping control will save my bacon in extreme.
I've moved ahead a bit on this cunning plan (hope it is not a Baldrick failure mind you!) and got various additional bits - or they are on their way. A Sony 7.1 AVR is heading over. This AVR, I'm reliably informed, has top notch amps (relative to other AVRs that is). Extra speaker cable on its way (will need 6 x 2m + internal cab wiring) and a dozen speaker posts. Plus various line level cabling. Oh and a xonar 7.1 dac (nice and cheap).
Still need to get some caps (to protect the tweeters from user error). The sacrificial speakers I will be using have their passive crossovers set at 800hz and 5khz so I will start from there.
Also sussed out fully how to set things up in JRiver - routing of channels and crossovers etc.
As this is just a fun learning project my focus is simply to do things cheaply. I'll need to get a decent mic at some point to create a room correction filter.
Maybe later on I can go up the tree in terms of quality. The Moto or Mytek or MiniDSP comes to mind. Or just plagiarise what Ken is doing with his build. :lol:
Just had a skim at the Motu-8 unit. Yummy. :drool:
I'm confused on what value capacitor I need to get to protect the tweeters in this project. In post #2 of this thread James/Jazid suggests 2.2 uf but in various other places I see differing values being mentioned. For example in this post (https://www.audiofrog.com/community/tech-tips/to-cap-or-not-to-cap-tweeters-in-systems-with-active-crossovers/) a value of 68uf is mentioned.
Given that the passive mid-range/tweeter crossover point in my speaker is currently at 5kz what value cap do I need to get to protect the tweeter? In my simple way of thinking I need a cap that provides a basic high pass filter at somewhere below 5kz (say4.khz) such that any stuff below 4.5kz does not get transmitted.
Clearly I'm missing something in my understanding. :confused:
walpurgis
02-07-2018, 22:34
68uF is far too big. 3uF or smaller will do the trick.
3uF in a 1st order crossover will roll an 8 ohm tweeter in at 6db/oct to near enough level (full) output at around 3kHz.
If you need to attenuate the tweeter level in comparison to the mid driver using a two way active crossover, an 'L' pad will do this.
Thanks Geoff.
I'll pop over to Cricklewood to get some.
I need to open up the Magnum K2s by breaking the rear seals. I think somewhere you mentioned you did similar. Any hints?
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Capacitive reactance formula is pretty standard.
Xc=1/2(pi)fC.
That is impedance of the capacitor is determined by the reciprocal of approx 6.3 times the capacitance in farads times the frequency. So If you know the impedance of the tweeter and the crossover frequency you can find a capacitance of equal value at that frequency and it will cross over at the - 3dB point there. Assuming 6.3 ohms tweeter impedance and 5 kHz crossover the cap would be around 5uF.
If you are using the cap as a circuit protector then you might want to be prudent and lower the value a little to increase the impedance at low frequencies, after all there is already a crossover in place!
Sent from my BLA-L09 using Tapatalk
walpurgis
02-07-2018, 23:03
The Magnum K2 used the DT3 tweeter. Goodmans recommended a series 3uF capacitor filter with this if I recall for system builders. I have the relevant literature somewhere. The DT3 was also marketed as the Axent tweeter for home build users and I'm fairly sure had a built in 3uF filter.
What Walpurgis said.
Just work out the frequency you want to use as your limiting factor (protection), without interfering with driver output/crossover. Remember the crossover point is not a cliff so you need to take roll off into account. So a value at least an octave, maybe more, below the crossover frequency.
Thanks guys (James, Geoff and Ken)
I had a quick looksee at the tweeter and mine does not seem to have the inbuilt filter. See pic later here.
So I will just split the difference and put a 4uF cap in and keep 3 and 5 caps spare. And also use that other well know hifi tweak of crossing my fingers. [emoji41]
Pics of the tweeter, mid and bass https://uploads.tapatalk-cdn.com/20180703/1bc12fe779a9f00488b8321ee31bd9bb.jpghttps://uploads.tapatalk-cdn.com/20180703/10c17b7b1ef627c667920049f0d78051.jpghttps://uploads.tapatalk-cdn.com/20180703/77c0a254ff4d6abf55f6ccbd0c46171c.jpghttps://uploads.tapatalk-cdn.com/20180703/4b73251b4ac5246e4a27090126b4cd27.jpg
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Well if the driver is 8 ohms as it claims the 4uF is perfect fit. I believe impedance usually rises near crossover point as its a resonant frequency and if so this should deliver minimal interference with the x-over and maximum protection against whoopsies from the amp/DSP end. If you wanted to go an octave lower (I wouldn't unless it sounded wrong) then use the 5 and 3 in series and you've got the 8uF required. Less protection though. Don't worry, its neither exact nor critical :)
Halfway Tree
03-07-2018, 10:56
You may already know this, so apologies in advance if you do, but when you build your x-over/eq in JRiver DSP Studio add a Mute checkbox at the beginning of each channel configuration. Then when you fire up for the first time you can mute all channels except the woofers and that enables you to be sure you have the channel routing correct and you are not sending the woofer signal to the tweeter. It's also useful just to be able to mute any channel during listening tests etc. That mute checkbox has saved my tweeters a few times! Together with the suggested cap you'll have double protection. About the only weakness of JRiver's DSP Studio IMO is that it doesn't graph the x-over/eq - that visualisation would help to eliminate mistakes. MiniDSP is very good in that regard.
Thanks Gordon. I use the checkboxes for other features in JRiver and good idea to use them at the individual filter level to check routing etc as you mention.
Yes it would be great if JRiver had similar graphs that MiniDSP has. And it would be good if JRiver's 'analyzer' in their DSP studio also had a toggle to show the effects of how the channels are being processed by the various settings. The only toggle is with/without JRiver's internal attenuation.
Currently I'm being distracted on this most important audio project by tennis, footie and work. :)
Hi Gordon
Appreciate if you could have a look at the following screenshots and let me know if I have got it right.
My plan is to have the normal L/R channels mapped to the bass drivers, the surround L/R channels mapped to the midrangers and the Rear L/R mapped to the tweeters. I have used the passive crossover points of 800hz and 5,000hz. Will start with a 4th order (24db) slope. Once I plug things in I can adjust from this baseline.
What I'm not clear about at this stage is what negative or positive gain I need to apply to each channel to start with? Or will I just derive this by trial and error later on? What did you do?
Cheers
Output Format
http://imapnet.com/aos/jriver/output_format.JPG
Copy Channels
http://imapnet.com/aos/jriver/PEQ_copy.JPG
High Pass Filter
http://imapnet.com/aos/jriver/PEQ_HighPass.JPG
Low Pass Filter
http://imapnet.com/aos/jriver/PEQ_LowPass.JPG
Magna Audio
04-07-2018, 18:13
Won't comment on the Jriver side of things not used it as X/O, do try lower than 4 order though.
I've found 4th order okay on sub horns and mid bass but further up the frequencies it kills feeling / mood - very driver dependant I guess. If they are good quality you want to let the loveliness play on a bit.
Won't comment on the Jriver side of things not used it as X/O, do try lower than 4 order though.
I've found 4th order okay on sub horns and mid bass but further up the frequencies it kills feeling / mood - very driver dependant I guess. If they are good quality you want to let the loveliness play on a bit.
Thanks Steve. This is precisely why I'm attracted to try active dsp, the ability of being able to adjust things easily and immediately hear the differences. In addition to trying different slopes I will be trying out different crossover points starting at what the passive crossovers are.
Room correction will add another dimension.
My fear is that this will all become too good leading me to having to get high end and expensive multichannel amps such as what Ken is currently doing.
At a recent show I went to there were some 3 way Kudos Titan speakers being actively driven with multiple Linn amps. Shockingly good.
But I dare say not as good as your Tannoy GRF recipes. :cool: When I win the lottery I will be over to you and Paul's (RFC) to discuss a bespoke Tannoy system. Until then I will have to slum it with the Eatons. :)
Magna Audio
05-07-2018, 07:22
Hehe, you haven't heard my 5 way system yet ;)
Hehe, you haven't heard my 5 way system yet ;)
No indeed I have not heard them but I have heard of people who have heard your 5-way horn system. (there I got 'heard' in 3 times :)).
Did dip into your WAM thread and could only dream of having your skills - particularly your woodworking skills.
What are the dimensions of the room you have your 5-way system is btw?
Magna Audio
05-07-2018, 10:12
It's a loft room.
5m wide and longer than needed.
I sit about 3.5m away.
They've come on a lot since the Wam thread ;)
DSP is great for that flexibility. So easy to try different settings and if you change driver impedance no problems ;)
My wife and friends keep bugging me to convert a dead space I have. If I did the space would be about 6.4m by 3.1m with 2.3m height. Seems ideal ... :eyebrows:
Halfway Tree
05-07-2018, 19:52
Hi Gordon
Appreciate if you could have a look at the following screenshots and let me know if I have got it right.
My plan is to have the normal L/R channels mapped to the bass drivers, the surround L/R channels mapped to the midrangers and the Rear L/R mapped to the tweeters. I have used the passive crossover points of 800hz and 5,000hz. Will start with a 4th order (24db) slope. Once I plug things in I can adjust from this baseline.
What I'm not clear about at this stage is what negative or positive gain I need to apply to each channel to start with? Or will I just derive this by trial and error later on? What did you do?
Cheers
Output Format
http://imapnet.com/aos/jriver/output_format.JPG
Copy Channels
http://imapnet.com/aos/jriver/PEQ_copy.JPG
High Pass Filter
http://imapnet.com/aos/jriver/PEQ_HighPass.JPG
Low Pass Filter
http://imapnet.com/aos/jriver/PEQ_LowPass.JPG
Sorry about the late response - been busy with watching footie too, plus my son is on a charity trip to Peru - he spent the evening in a bar in Lima airport watching the England/Colombia game - in a bar full of Colombian's :eek: everyone very friendly so no problems...:D he's finally got to his destination up in the mountains safely, so all is good.
Anyway, looking at your screenshots my first question is regarding your output format - is there a reason you are using 2 channels in a 7.1 container rather than using 5.1 channels as you have 3-way speakers?
The x-overs look fine, although I would have routed Left,Right for bass, Centre,Sub for mids and SL, SR for highs. However if what you have setup works for your routing it doesn't really matter. Like Steve (Magna Audio) I wouldn't recomment a 24db/oct Butterworth either. But I would use a 24db/oct Linkwitz-Riley which sums flat. JRiver can't do Linkwitz-Riley filters natively, but as they are just cascaded Butterworths all you need to do is create two 12db/oct Butterworths and you have your 24db/oct Linkwitz-Riley.
If you know the driver sensitivities then I would just take a rough guess at setting the most sensitive ones down a few db.
I may have missed it in your earlier posts but what DAC are you using to get the signal from JRiver to your amps?
Hope this helps.
Sorry about the late response - been busy with watching footie too, plus my son is on a charity trip to Peru - he spent the evening in a bar in Lima airport watching the England/Colombia game - in a bar full of Colombian's :eek: everyone very friendly so no problems...:D he's finally got to his destination up in the mountains safely, so all is good.
Ah yes I know Lima and Cusco well. We went there about 3 years ago to visit our daughter who was spending 6 months there. Very friendly people and great food (not the guinea pig though!)
Anyway, looking at your screenshots my first question is regarding your output format - is there a reason you are using 2 channels in a 7.1 container rather than using 5.1 channels as you have 3-way speakers?
Just going with JRiver's recommendation. Don't want anyway to get confused with the sub (as per in x.1) so aiming to just use 6 of the normal 7 channels.
The x-overs look fine, although I would have routed Left,Right for bass, Centre,Sub for mids and SL, SR for highs. However if what you have setup works for your routing it doesn't really matter. Like Steve (Magna Audio) I wouldn't recomment a 24db/oct Butterworth either. But I would use a 24db/oct Linkwitz-Riley which sums flat. JRiver can't do Linkwitz-Riley filters natively, but as they are just cascaded Butterworths all you need to do is create two 12db/oct Butterworths and you have your 24db/oct Linkwitz-Riley.
Any particular reason you would route things in that way? My rationale is just to skip centre and sub due to them not being L or R. And anyway surely the sub on an AVR is pure line level without ability for filtering, attenuation etc? Naturally I will have to actually map what I've set in JRiver to the actual channels on the amp.
How do I cascade the Butterworths by creating another filter?
If you know the driver sensitivities then I would just take a rough guess at setting the most sensitive ones down a few db.
I'll give the tweeter -4db, mid -2db and go from there. I imagine that later on when/if I do a room correction filter then that filter will adjust things appropriately.
I may have missed it in your earlier posts but what DAC are you using to get the signal from JRiver to your amps?
To start with I will be using a Xonar 7.1 dac (https://www.amazon.co.uk/gp/product/B06ZZNR4HQ). Not the state of the art, but remember this is just a 'proof of concept' project.
Hope this helps.
Yes it really does Gordon and I very much appreciate your time/help.
The AVR amp was meant to arrive today but no sign of it. I hate having to wait around or depend on neighbours.
Halfway Tree
06-07-2018, 09:36
Ah yes I know Lima and Cusco well. We went there about 3 years ago to visit our daughter who was spending 6 months there. Very friendly people and great food (not the guinea pig though!)
Just going with JRiver's recommendation. Don't want anyway to get confused with the sub (as per in x.1) so aiming to just use 6 of the normal 7 channels.
Any particular reason you would route things in that way? My rationale is just to skip centre and sub due to them not being L or R. And anyway surely the sub on an AVR is pure line level without ability for filtering, attenuation etc? Naturally I will have to actually map what I've set in JRiver to the actual channels on the amp.
How do I cascade the Butterworths by creating another filter?
I'll give the tweeter -4db, mid -2db and go from there. I imagine that later on when/if I do a room correction filter then that filter will adjust things appropriately.
To start with I will be using a Xonar 7.1 dac (https://www.amazon.co.uk/gp/product/B06ZZNR4HQ). Not the state of the art, but remember this is just a 'proof of concept' project.
Yes it really does Gordon and I very much appreciate your time/help.
The AVR amp was meant to arrive today but no sign of it. I hate having to wait around or depend on neighbours.
Just been looking at the Xonar 7.1 Dac - it seems to have 5 analogue outputs - Front L, Front R, Side, Centre and Rear - I'm probably missing something here, but how do you get the 6 channels you need out of it?
I'll grab a screenshot of Linkwitz-Riley crossover in JRiver.
Halfway Tree
06-07-2018, 10:39
Here's a screenshot of a 120Hz L-R 4th order (24db/oct) using cascaded Butterworth's in JRiver. The 12Hz high pass which is also a L-R 4th order is simply there to provide some protection for the bass drivers. You can create a L-R 2nd order simply by cascading two 6db/oct Butterworth filters. I use a 2nd order in my Linkwitz LX521s between the lower and upper mid drivers.
23795
Cheers Gordon
I think I see the logic of how you cascaded things. Thanks.
The Xonar outputs of Side and Rear are 3.5mm stereo pairs so with the FR and FL plus mono CTR you get to 7 channels.
AVR arrived. Yet to check operation. Huge transformers so quite weighty.
Next thing to do is to break the rear seals on the speakers and then rewire to 6 speaker posts (3 x 2) each speaker. I was thinking of having 8 posts each speaker with a suitable switch so I can readily go from active to passive. May do that later on. I'll leave the passive crossovers in-situ for now.
Small problem. How do I get into my Goodman Magnum K2s?
Obviously I can from the front via the drivers but no room to work that way.
The rear is locked down with glue and stuff. Should I just go for it with a Stanley knife and lever the rear off with force? I'd rather do this neatly. After all the speakers are super valuable. Got them for £20 I think. :)
https://uploads.tapatalk-cdn.com/20180707/1750740a935f5e096dee74a21ed799d1.jpg
Via Tapatalk
Based on some personal feedback and helpful tuition from Lawrence he says I should not open the rear but instead do all necessary work via the driver holes. So that is what I will do, firstly remove/desolder all the drivers and then the wadding. Need to find some time.
Watch this space. :)
Some progress
Removed old crossovers and wired up speaker drivers for direct input.
http://imapnet.com/aos/jriver/k2/rear_small.jpg
Some more pics of the Magnum K2 revision here (https://1drv.ms/a/s!Arf68P30ulKQgYJhpUqZFyQfzZLIGw).
Magna Audio
12-07-2018, 15:22
Looking good :)
Lawrence001
12-07-2018, 22:50
Yep good work Edward.
Sent from my BLN-L21 using Tapatalk
All working! :eek: :cool:
Managed to find some time to wire and plug it all in. (takes ages stripping 24 speaker wires you know).
Incredible change in sound. Fresh, open, natural sound - very coherent with lots of scale. Good texture.
So going active from passive presents lots of nice opportunities to try things out.
Just as a reminder I rewired a pair of old Goodman Magnum K2s (3 drivers each) to accept direct feeds to each driver from the amp channels. The active crossovers done within JRiver using various parametric equalizer functions. Amp duties done via 6 channels of a Sony AV amp. DAC is an Asus Xonar. The speakers are old (late 70s probably) with original caps so the active xovers replaces and freshens up things nicely.
So started with xovers points at 800hz/5000hz and played around (e.g. 300hz/4000hz, 1500/4500). Subtle differences in presentation. Need to spend more time to verbalise what differences these give.
Next steps: Find a calibrated microphone to create a room correction filter. Research trying all this via Roon.
Ultimately of course the sound is held back by the speakers - whilst great the K2s were never start of the art in the first place.
Still, all very interesting and educational. :)
http://imapnet.com/aos/active.jpg
walpurgis
19-07-2018, 21:54
Looks like you're having fun. :)
Those tweeters are OK down to 3kHz by the way, as long as the slope is steep and you don't go bonkers with power.
Yes tis good fun Geoff. This whole project forces me to understand new interesting stuff. Room correction via FIR filters will be another deep dive.
Re the tweeters. Did not know they went down to 3kHz. Currently protecting them with 4.7uF caps so protected at about 4kHz. I could easily change the caps to protect them at say 2.5kHz.
I may swap out the K2 bass drivers with the Coral ones I have. Need to work out how to easily reduce the baffles from 12 inch to 10 inch. Probably just get some MDF and mount that on the existing 12 inch bolts so easily reversible.
But I don't reckon I will be using this project on a permanent basis - the Eatons driven by the Sugden still takes a hell of a lot to beat for sheer utter enjoyment.
walpurgis
19-07-2018, 22:17
The Corals are best in ported cabinets. That's what they were designed for. I think you'd find the bass extension curtailed in the Magnum cabinets. They would probably give good enough results in big sealed boxes, but those would have to be maybe twice the size of the Magnums.
paulf-2007
20-07-2018, 12:07
Hi Paul, that is very generous of you. This may also be very interesting indeed. I'm inclined to try the full digital idea as a priority but perhaps I can try the Behringer's as well. After all I will have sufficient multi amp channels so it would be simply taking the computer and DAC offline and rerouting as required. What model Behringers are they and whereabouts are you? Feel free to use PM.
I have a friend who uses Behringer's in a semi active form (I think I mentioned this in this thread already) to grewat effect.i seem to have missed your reply until now.
They are super X pro cx3400 2way 3 way stereo and 4 way mono and cx2310 2way and 3way , xlr inputs and outputs but I have xlr adaptors. I'm in Gravesend
i seem to have missed your reply until now.
They are super X pro cx3400 2way 3 way stereo and 4 way mono and cx2310 2way and 3way , xlr inputs and outputs but I have xlr adaptors. I'm in Gravesend
Cheers Paul. Let me keep this in mind please, in particular the cx3400. For now still playing around in the all digital domain and want to explore room correction filters next. Clearly the main advantage of the Behringers is that no computer required and a much more intuitive way of doing things.
There was a guy at the last Scalford show (in 2017) that used 3-way Behringers in an active setup which sounded brilliant. Was that you?
Magna Audio
20-07-2018, 13:01
Was that the raving louny monster horn project at Scalford? Perhaps that was earlier though.
I took my S2 Vitavox and Raal tweeters as my contribution.
I had lugged all my gear there before so didn't feel like any more
Pete who had the modded 2 Berhringers for 5way, for that setup ditched them in favour of Najda very shortly after ;)
Cheers Paul. Let me keep this in mind please, in particular the cx3400. For now still playing around in the all digital domain and want to explore room correction filters next. Clearly the main advantage of the Behringers is that no computer required and a much more intuitive way of doing things.
There was a guy at the last Scalford show (in 2017) that used 3-way Behringers in an active setup which sounded brilliant. Was that you?
Was that the raving louny monster horn project at Scalford? Perhaps that was earlier though.
I took my S2 Vitavox and Raal tweeters as my contribution.
I had lugged all my gear there before so didn't feel like any more
Pete who had the modded 2 Berhringers for 5way, for that setup ditched them in favour of Najda very shortly after ;)Yes I think it was a guy called Pete. If memory serves he was using multiple Quad amps driving some English speakers (Graham Audio?). Don't recall your multiple horn set up. Perhaps it was an earlier year.
§
paulf-2007
20-07-2018, 18:23
Cheers Paul. Let me keep this in mind please, in particular the cx3400. For now still playing around in the all digital domain and want to explore room correction filters next. Clearly the main advantage of the Behringers is that no computer required and a much more intuitive way of doing things.
There was a guy at the last Scalford show (in 2017) that used 3-way Behringers in an active setup which sounded brilliant. Was that you?no, haven't been to scalford for a few years now. All the original horn guys, Steve included, were in the early days of scalford. I think you need to be careful with room correction, it can take the life out of the music. All this transparent accurate bollocks doesn't always work best.
I got the behringers out earlier and they are mint, only used them briefly before getting the deqx. Still in the plastic bags in the boxes.
Yes someone warned me about the dastardly impact room correction can have. Also a warning that the filters created can try correct things that speakers simply are not able to correct possibly damaging them.
But its all enjoyment and learning for me. I ain't going to rewire the Tannoys or other better speakers I have (for now :eyebrows: )
I agree with Paul to the extent that rather small changes in DSP can be surprisingly large in terms of presentation and enjoyment.
Never the less the only component that doesn't leave my system is a DEQX 3.0.
I think the best thing is to make small incremental changes, document them rigorously so you can undo/revisit them, and give any changes a few hours to settle in at first (a few days as you get closer to what you're after) .
There's a strong tendency to tweak and fiddle non stop, it's so easy to do, but there lies madness and frustration. .
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Thanks James. Good advice. Certainly the presentation differs markedly even with small changes - for example crossing over at 500Hz instead of 800Hz (which is what the passive crossover is set for on the bass). The software allows one to save DSP profiles which comes in handy.
Not had much playing around so far. Experienced a bit of distortion earlier which I need to track down. Have plenty of DSP headroom and clipping controls all turned on so I suspect a connection somewhere. Will troubleshoot by switching off all channels and working forward one at a time. All good learning.
Did a bit of digging around Roon and all of this is doable there. In fact seems more intuitive and a big bonus is that the crossovers and slopes are graphically shown with the points and slopes 'draggable' to change values. So I may transfer over to Roon first before doing more experimenting.
walpurgis
20-07-2018, 22:59
Are you experimenting with the phase relationship between the drivers at all Edward? It varies with frequency.
Are you experimenting with the phase relationship between the drivers at all Edward? It varies with frequency.
Well I understand the concept broadly and obviously would like to mitigate/minimise the smearing effect due to phase shifting. However I have yet to establish how to measure and then change timing within the software. I guess I could do it simply by hearing using an audio track which contains short sharp full frequency sounds and tuning each driver with positive or negative timings to get to an in-focus sound. But always keen/receptive to to get tips. :)
This is a Roon view of an active crossover (here 12Hz, 800Hz and 5000Hz). The actual implementation will be slightly different as it needs to be done per channel.
https://i.imgur.com/7Ob9DAP.png
Magna Audio
21-07-2018, 13:10
I've always found room eq below 100Hz or so it's fine. Above that with my horns there's no eq needed.
If you can measure the real room responses. Won't look quite like your roon schematic :)
Steve
I have a wanted post in exhibitions for a minidsp mic as I read that REW suggests only this mic for measuring stuff. However is this true, perhaps you could suggest an alternative mic etc to create a room correction filter?
§
For the price I'd just buy one, it's a tool you will use A LOT, in fact the minidsp is verge pointless without it and it is programmed to work seamlessly with this mic.
There are alternative eg. behringer mics but you'll have to faff about with loading calibration files. IIRC umics cost no more anyway, and they have different field responses: the umic is semi-omnidirectional for room correction, the behringers are directional for driver analysis, so the minidsp help files will have to be interpreted accordingly to deliver what the program and mic can offer. Horses for courses.
I personally find the phase relationships between drivers are better tuned by ear to real music. I have not come across a silver bullet for driver integration with crossovers, even in the digi domain, Speaker voicing still remains an art rather than a science IMHO, YMMV, etc.
Sent from my BLA-L09 using Tapatalk
Magna Audio
22-07-2018, 19:25
Agree with all of that.
Mic is a tool to get you near. Tune by ear.
Moving my gear from one room to another, I tuned the new room's bass responses to give me the same wow factor I heard / felt in the new room..
For the price I'd just buy one, it's a tool you will use A LOT, in fact the minidsp is verge pointless without it and it is programmed to work seamlessly with this mic.
There are alternative eg. behringer mics but you'll have to faff about with loading calibration files. IIRC umics cost no more anyway, and they have different field responses: the umic is semi-omnidirectional for room correction, the behringers are directional for driver analysis, so the minidsp help files will have to be interpreted accordingly to deliver what the program and mic can offer. Horses for courses.
I personally find the phase relationships between drivers are better tuned by ear to real music. I have not come across a silver bullet for driver integration with crossovers, even in the digi domain, Speaker voicing still remains an art rather than a science IMHO, YMMV, etc.
Sent from my BLA-L09 using Tapatalk
For the price I'd just buy one, it's a tool you will use A LOT, in fact the minidsp is verge pointless without it and it is programmed to work seamlessly with this mic.
There are alternative eg. behringer mics but you'll have to faff about with loading calibration files. IIRC umics cost no more anyway, and they have different field responses: the umic is semi-omnidirectional for room correction, the behringers are directional for driver analysis, so the minidsp help files will have to be interpreted accordingly to deliver what the program and mic can offer. Horses for courses.
I personally find the phase relationships between drivers are better tuned by ear to real music. I have not come across a silver bullet for driver integration with crossovers, even in the digi domain, Speaker voicing still remains an art rather than a science IMHO, YMMV, etc.
Sent from my BLA-L09 using Tapatalk
Cheers James. I'll wait a short while to see if anyone has a minidsp mic and if not get one from HK. Other than the minidsp mic I'm not planning on using other minidsp products for now.
Halfway Tree
23-07-2018, 09:16
Great to see that you've moved forward with this Edward - great stuff.
Once again, lots of sage advice from others who have travelled down this road. Making DSP corrections in the lower frequencies (under about 200Hz - essentially the transition frequency of your room) is good advice.
The MinisDSP Umik mic (I have one and they are available from Amazon) is the best and easiest way to get decent measurements using REW. However, if you want to get into some of the more advanced room correction using something like Acourate (https://www.audiovero.de/en/acourate.php), for example, the Umik is unfortunately not the best choice and something like the Behringer ECM8000 (I have one these also) is better suited. Ideally the ECM8000 should be calibrated, but it's not a must as you are dealing with relative measurements, not absolutes. You'll also need a mic pre-amp unless your interface has one. I bought an inexpensive used Alice Mik Pak which does the job fine.
Acourate is not cheap, is complex, doesn't have a particularly easy interface, but is very powerful and flexible. If you are thinking of going down that route I would highly recommend Accurate Sound Reproduction Using DSP by Mitch Barnett (https://www.amazon.co.uk/Accurate-Sound-Reproduction-Using-DSP-ebook/dp/B01FURPS40/ref=sr_1_1?ie=UTF8&qid=1532253216&sr=8-1&keywords=mitch+barnett)- the Kindle version is less than £7 - it's a good walkthrough using Acourate and highly informatiive about driver phase relationships, even if you never intend to purchase Acourate. BTW, correction files created with Acourate can be used in both JRiver and Roon.
I've been using Acourate for about 3 years now and I still find myself experimenting with it. It can make some music sound very, very good - especially vocals, but sometimes it can sound a little too laid back IMO if I want to listen to some loud compressed rock. But it only takes 2 mouse clicks to switch it in or out in JRiver so easy to do a comparison on the fly.
Gordon
Many thanks indeed for the most comprehensive post and all the highly useful tips. One thing I have to guard against is running before I can walk. I'm already imagining (after winning the lottery that is :)) of building myself a studio room optimised for sound, getting customised class a amps (3 stereo pairs or more) and building a 3 way (or more) speaker system using world-class drivers all driven by an Acourate optimised DSP setup. Then sitting back and enjoying the music. :cool:
For now I need to just play around with the free speakers I have (actually I think they cost me £20!), the cheap gaming dac (which has mic input), the AVR and a spare computer lying around. Actually quite pleased with the steps taken so far. I'm now using Roon instead of JRiver to do the crossovers - generally much easier.
Still buying lottery tickets though!
Thanks for the tip on the Behringer ECM8000 mics. Will investigate further but certainly they are cheaper and more easily available than the UMIK mic.
I've been reading this article (https://www.computeraudiophile.com/ca/ca-academy/advanced-acourate-digital-xo-time-alignment-driver-linearization-walkthrough/) and (embarrassingly) understand about 80% of it - well the concepts behind it that is. Is this the same author that you mention? I have free kindle via Amazon Prime so will download in a short while and have a read.
cheers
Magna Audio
24-07-2018, 05:55
Gordon
Many thanks indeed for the most comprehensive post and all the highly useful tips. One thing I have to guard against is running before I can walk. I'm already imagining (after winning the lottery that is :)) of building myself a studio room optimised for sound, getting customised class a amps (3 stereo pairs or more) and building a 3 way (or more) speaker system using world-class drivers all driven by an Acourate optimised DSP setup. Then sitting back and enjoying the music. :cool:
For now I need to just play around with the free speakers I have (actually I think they cost me £20!), the cheap gaming dac (which has mic input), the AVR and a spare computer lying around. Actually quite pleased with the steps taken so far. I'm now using Roon instead of JRiver to do the crossovers - generally much easier.
Still buying lottery tickets though!
Thanks for the tip on the Behringer ECM8000 mics. Will investigate further but certainly they are cheaper and more easily available than the UMIK mic.
I've been reading this article (https://www.computeraudiophile.com/ca/ca-academy/advanced-acourate-digital-xo-time-alignment-driver-linearization-walkthrough/) and (embarrassingly) understand about 80% of it - well the concepts behind it that is. Is this the same author that you mention? I have free kindle via Amazon Prime so will download in a short while and have a read.
cheersThat's a very good looking article for anyone considering DSP X/O's.
I only skimmed it but the time alignment result evaluation is spot on.
It's amazing how small DSP changes can dramatically change the sound. Managed to grab some time (as well as unplug the main speakers as I'm using the same stands).
Couple of small changes and the sound suddenly gains focus and comes forward. The small changes were a delay of 8ms on the HF and delay of 5ms on the MF. Also +2db on the MF and HF.
Easy to get confused on channel mapping though. At one point I had one of the left channels mapping to the right. Very muddled sound.
Lots of more experimenting to do ...
Magna Audio
29-07-2018, 20:28
Have you tried time aligning left and right channels as well?
No not yet. I did change the gain a bit on one side. I'll try timings and see how I go.
But the major constraints I have are the relative low quality of the Magnum drivers. But not yet prepared to step into the big time. Still learning and playing.
§
Magna Audio
31-07-2018, 18:09
No not yet. I did change the gain a bit on one side. I'll try timings and see how I go.
But the major constraints I have are the relative low quality of the Magnum drivers. But not yet prepared to step into the big time. Still learning and playing.
§Hehe, slippery slope to Vitavox, TAD, Raal Ribbon tweeters etc etc :)
Every time I go to a show I always look out for the TAD room. First time I heard a pair I was bowled over. The experience still lingers. Can't recall having heard Vitavox or Raal at shows but certainly both high pedigrees. For me the litmus test for a speaker is if it makes my spine tingle. I get that with a few speakers - TAD, Harbeth, MBL, Avantgarde and of course Tannoys. To name a few.
Wish I had the space for some horns.
Very interesting thread I started a thread on another forum asking for advice on building a Reggae soundsytem type valve pre amp that incorporates a 3 way active cross over with kill switches for all three so I’m wondering if your dsp could be incorporated perhaps with a valve output stage similar to those used within a dac.
Your work on your speaker is also very helpful as I would need to do the same.
paulf-2007
01-08-2018, 15:44
Hehe, slippery slope to Vitavox, TAD, Raal Ribbon tweeters etc etc :)
Raal are a no brainer. What I liked about deqx was three different set ups available on the fly. Finding best crossover points is instantaneous by ear. Maybe not for the purist, but different set ups for different music genre.
Very interesting thread I started a thread on another forum asking for advice on building a Reggae soundsytem type valve pre amp that incorporates a 3 way active cross over with kill switches for all three so I’m wondering if your dsp could be incorporated perhaps with a valve output stage similar to those used within a dac.
Your work on your speaker is also very helpful as I would need to do the same.
Hi Nat
Well I'm just learning. But perhaps describe in more detail what you have and what you are trying to achieve so other in this thread may offer some hints.
Removing a crossover from a speaker and wiring each driver up directly is relatively easy. A bit of desoldering and new soldering is as complicated as it gets. Just have to be methodical.
Edward
Raal are a no brainer. What I liked about deqx was three different set ups available on the fly. Finding best crossover points is instantaneous by ear. Maybe not for the purist, but different set ups for different music genre.
There is someone not far away from me (:)) who has a 3 way custom speaker system gathering shed dust. Maybe I will ask him if I can play around with it and find the optimum crossover points.
Was your 3 different set ups one speaker system with 3 different DSP profiles or 3 different speaker systems?
It's three per speaker setup, plus an uncorrected reference. Unlimited speakers.
Sent from my BLA-L09 using Tapatalk
paulf-2007
05-08-2018, 13:44
There is someone not far away from me (:)) who has a 3 way custom speaker system gathering shed dust. Maybe I will ask him if I can play around with it and find the optimum crossover points.
Was your 3 different set ups one speaker system with 3 different DSP profiles or 3 different speaker systems?
I used the three profiles with one speaker multi amp set up. It's possible to have one profile for different speaker set ups I guess, but not connected at the same time.
I've started to play with active crossovers and DSP with my UMIK-1 and miniDSP. I have removed the crossovers from my 3-way Heybrook Sextets and by using two miniDSP 2x4HD reproduced the original crossover parameters. The next stage was to use REW (Room Equalisation Wizard, an amazing piece of free software) to analyse my room to see the peaks and troughs.
By taking this curve and applying the required profile (ie. slight bass rise, flat mid, gentle treble rolloff) REW will create the necessary filters to apply to miniDSP, once applied you can sit back and listen to your results.
My next stage will be profile each drive unit to create the 'perfect' response for each unit and then bring them all together.
I'm very impressed with the results so far, just got to sort out my amplification....but that's a big can of worms.
Hi Damien
Sounds like you are taking a similar path to mine - the difference being that you are using minidsp to do the crossovers whilst I'm using Roon to do that. And you have built REW profiles.
But I'm confused. You say you are very impressed with the results so far but you still need to sort out the amplification. What amps are you using so far and why is that not good enough?
In my experiments I've used a multi-channel Sony AV amp and whilst not state of art gives very acceptable results.
Hi Damien
Sounds like you are taking a similar path to mine - the difference being that you are using minidsp to do the crossovers whilst I'm using Roon to do that. And you have built REW profiles.
But I'm confused. You say you are very impressed with the results so far but you still need to sort out the amplification. What amps are you using so far and why is that not good enough?
In my experiments I've used a multi-channel Sony AV amp and whilst not state of art gives very acceptable results.
Hi Edward,
Yes, I'm currently using my Marantz 2285B receiver to provide the highs, Quad 405 low, Marantz MA22s mid. The 2285B isn't ideal for many reasons, so I'm on the lookout for something low powered, high quality for the highs. I've got a Rotel RB-970BXII coming as a makeshift solution.
Hi Edward,
Yes, I'm currently using my Marantz 2285B receiver to provide the highs, Quad 405 low, Marantz MA22s mid. The 2285B isn't ideal for many reasons, so I'm on the lookout for something low powered, high quality for the highs. I've got a Rotel RB-970BXII coming as a makeshift solution.
How are you controlling volume?
My Marantz SC22 preamp, one DSP per channel, split 3 ways. The miniDSP can attenuate but I haven't needed to alter the volume to cater for amp differences.
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