Subwoofers & DSP or nearly bye bye room

[Reid Malenfant]

Ebay very kindly supplied me with some vouchers recently that gave me 15% off of anything over £100 & up to a maximum of £100 reduction :cool:

This happened to cover six categorys & luckily for me one of them was "consumer electronics" :eyebrows: So naturally i went looking about on the off chance that i might see something interesting & oh boy did i just...

Cutting a not too long story down to the bone i found a DSP device that is designed to be connected between a pre amp & subwoofer. This device feeds the sub with swept test tones & listens to the results & then modifies the output to the sub to get rid of room modes & tighten up the transient response. Or if you like it near as damn it gets rid of the room :) Now this is only suitable for active or if you like powered subwoofers which operate below 150Hz.

It can't be used with a standard pair of passive speakers, though it could be used with a passive sub if you found a suitable power amplifier or plate amp if building your own...

Introducing the Antimode 8033c Subwoofer EQ (http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=320671609501&ssPageName=STRK:MEWNX:IT)...

Now while i haven't installed the pair of them yet (yes Mark needs two of them with two active bass units) i have absolutely no doubt that these are going to make a real difference to proceedings. These things do not boost output at any frequency (though they have an overall 3Db of gain), they only cut & cut out room boom by EQing in the digital domain where a lot more can be done than with any analogue filter ;)

As soon as i'm strong enough to change out the Behringer CX3400 for the pair of DCX2496 i'll install these as well & see what they do, they should eliminate the room mode i have at about 40Hz & tighten things up nicely :eyebrows:

Here are few reviews just incase you are interested..

http://www.hometheatershack.com/forums/bfd-electronic-equalization-devices/11699-testing-dspeaker-anti-mode-8033-a.html

http://www.avforums.com/reviews/DSPeaker-Anti-mode-8033-Subwoofer-EQ-Review.html

Oh, cheers ebay for saving me over £64 :cool:

[HighFidelityGuy]

Nice one Mark. I'll follow this with interest as I've fancied trying one of the Antimode EQ's. I'm also planning on experimenting with a sub-harmonic synthesizer soon. It adds in extra harmonics below those already present in the music to add that extra infra-sonic feeling you get at gigs. :eyebrows: I'm guessing that sort of thing is up your street. ;) I'll start a new thread once I've got all the equipment together. :cool:

[Reid Malenfant]

Hi Dave, i'm not too sure about that in all honesty, the added (sub) harmonics thing i mean :eyebrows: Not sure i'd need anything like that in all honesty as i have quite a bit of music with heavy sub 25Hz content & a lot of that is sub 20Hz, so in certain respects i don't need to make what isn't there as it already is ;)

Besides which if you are going to try this thing out you'll need to use a speaker that can actually reproduce whatever frequency it is producing. If you are going to run some kind of reflex speaker then make sure it's tuned really low (like an LLT) or you may find that you are just moving the cone & cancelling via the port.

More on LLTs (large low tune) in the future :cool:

More on the 8033 as well once i feel up to pulling a load of kit out of my rack & fitting them in...

[HighFidelityGuy]

I know what you mean, I too have a lot of music with a lot of very low bass. The sub harmonic synthesizer is more for the music that doesn't have it on the recording but probably would have it live. I have a pair of sealed 10" subs that I already run with a crossover at 35Hz. They're 250W each but I have a spare pair of 550W mono blocks to play with too. :eyebrows: It's just something I've fancied trying out for a while as a daft experiment.

If it works out my subs will be getting more signal more often, so that got me wondering if I would then need to add some finer EQ control over the sub frequency band to keep things under control. I'll see how it works out. :)

[Reid Malenfant]

Well i guess most depends on the room, but to a certain extent on the bass drivers you are using. If they are something like the 10" Peerless XLS then they are very low Q & room modes will predominate. drivers with a higher Q that result in a closed box Q of more than 0.6 (definately over 0.7) may well benefit.

What i'm interested in is getting rid of the room modes & speeding up the bass due to much faster decay, which is exactly what it appears to do. Bass this way is no slouch either so it should be very interesting indeed :)

[Reid Malenfant]

Dave, you'll be interested to know that i have have the pair of these installed, working & calibrated :)

I'm not going to give too much of an opinion right now as i have literally just settled down, i hurt rather a lot & i have only spun a couple of tracks so far...

What i can say so far is that the difference is in no way subtle & the reviews appear to be dead accurate :eyebrows: The room modes appear to have gone, i can hear clearer differences in bass tones & things are even faster & less ponderous in the bottom end.

That's it for now :cool: I'll be back ;)

[Reid Malenfant]

Ok, i'm beginning to get a real handle on what these things are doing now so time to spill the beans a bit :)

One thing i can say with utter conviction is that room modes are eliminated! I have spun so many discs since installing them that it must be statistically nigh on impossible that i haven't spun something with approximately 40Hz output (which is where i had problems previously). Lets say it is very conspicuous by it's absence ;)

While these little boxes only have the ability to cut certain frequencies (they can't boost anything to equalise) there is a rather surprising increase in deep bass right down to the cutoff of my Paradigm DSP-3400 sub. Actually it's not an increase at all, it was just that the room interaction was masking the deep bass notes, now every note is clean & easily heard :)

I'd go so far as to say that i'm quite frankly astonished at the difference these things have made considering the type of loading that the drivers are under, no reflex here - a 4th order coupled cavity gives a similar response to a sealed box :eyebrows:

I find myself listening at a generally slightly higher level simply because there is not a tad of muddiness in the bass, in my system this is below 110Hz. One positive side effect of this is that i can clearly hear when one of the 12" drivers inside the enclosures runs out of excursion! Normally this would be masked by the overall volume/room effects etc. Now it's as plain as day, no way is it down to the amplifier clipping as i can feed the 12" Yamaha drivers with over 600W RMS of power each if called for from the Mackie amplifier :eek: They'll happily go with 300W RMS on peaks without complaining :eyebrows:

There is no two ways about it, this is the cleanest bass i have ever heard fullstop!

I only put this thread in the AV section as the 8033 is only effective below 150Hz which is generally going to restrict there use to subwoofers. As i happen to run four way active speakers the opportunity was there for me to use a pair of them below 110Hz. I calibrated each one (one per channel) which is simply a case of positioning a microphone in what would be the centre of your head at ear level & pushing two buttons at once for a few seconds. The 8033s did the rest, oh boy did they :)

I'd more than happily recommend these things to anyone - in a big way! Perhaps anybody that is considering small stand mounted speakers might think about adding a sub & one of these or two subs (in a way similar to my system) & a pair of them. It might not appear cheap, but even if purchasing a pair you'll likely end up with deeper (only as deep as the sub can perform) cleaner bass than is possible with any loudspeakers without the same kind of DSP...

Or do you own the Albert Hall? ;)

[Clive]

Some of my DSP journey can be seen here:

http://theartofsound.net/forum/showthread.php?t=3970&highlight=system&page=2

Since then I've damped the corner of the room beside the left speakers, this dramatically cut the decay time. I've also suspected that my bass is better with the door to the room open and I now have the graphs to prove it!

I'm not too sure how well the Antinode auto setup does and whether you can tweak the results. The initial results with my XTZ room measurement kit are good but can be significantly improved on with some manual tweaking once a rough setup is done. I also had good results with a DEQ2496.

For those with less problematic rooms an analogue option look interesting, there's a kit http://sound.westhost.com/project84.htm

[Reid Malenfant]

Hi Clive, cheers for popping in ;) The only way of tweeking the Antimode is to do a second "wide" area response. Frankly i'm not bothered though as this is very good indeed.

I can't measure it as i don't have a PC program etc but the response in room here should now match what the Paradigm sub is capable of, IE 15Hz -6Db & it's all clean :eyebrows:

The Antimode starts off it's calibration at 16Hz, it's a pure sine wave but it's interupted/pulsed so that it can listen to how it decays in the room. I guess this is how come the waterfall images & sound decays so much faster than standard after the 8033 is calibrated. It runs a 16Hz to 150Hz pattern 4 times before it's happy, all these are at differeing volume levels & stuttering as i call it ;)

I reckon it takes about 3 minutes to run through the lot, but at the end of it it's a new world of clean, deep bass reproduction!

[Clive]

That's fairly similar to how the XTZ combination works, though it's not quite automatic in that you have to upload the parameters from a PC to the DSP. My room is especially tough as it's 15' square with a bay tacked on at the rear. The ceiling is low at about 6' 9". The room modes are horrible hence my needing to tweak settings. DSP is great for the bass, I'm very much a believer in it!

[Reid Malenfant]

DSP is great for the bass, I'm very much a believer in it!
Me to now :eyebrows: My room is 4.5 x 4.5M but with a 9ft ceiling (whats that, just under 3M? lol).. I bypassed the pair of 8033 the other day & immediately switched them back on.

It wasn't bad in here before as i only appeared to have a problem at one frequency (around 40Hz), but until you try these things you have absolutely no idea of how the room effects every bass frequency!

DSP for me, i'm never going back!

[Macca]

Hi Mark good to see you about again:)

I guess as the filters only cut rather than boost that they are reducing output at the specific frequencies at which the dimensions of your room are causing reinforcement in the signal. As I recall your room is on the small side?

So essentially you are flattening the bass response out right down to the low hertz. One thing I would say is that whilst this may suit the sort of electronic music you listen to would it necessarily work with more mainstream rock or pop with a lot of bass around 80-120 hz but little lower down - would it result in a bass light effect is what I wonder?

[Reid Malenfant]

Hi Martin, no, i have tried all sorts chap & the results are good on anything up to 110Hz which is the limit of the bass speakers in my system.

As i said somewhere i'll try it on deep, rhythmic & punchy bass (which should cover the lot) & on everthing i have heard there is a definate increase in bass clarity (no kidding :eyebrows:) as well as no room modes...

It's like the room is no longer here. Bass at any frequency that comes under the control of the 8033 is also much faster, decays very fast indeed, which makes every note at any frequency stand out...

Simply put it's a revelation :)

[Clive]

The DSP will cut the peaks in the bass, that bit is easy. It may try to fill in some troughs but that is much less likely to work, that's the area where I do my manual tweaking but filling in troughs fully is nigh on impossible. Sorting the room and sub placement is more effective. The chances are that the resulting sound will seem bass light as resonances are removed but just turn the bass up a little to get the true bass!

[Reid Malenfant]

The DSP will cut the peaks in the bass, that bit is easy. It may try to fill in some troughs but that is much less likely to work, that's the area where I do my manual tweaking but filling in troughs fully is nigh on impossible. Sorting the room and sub placement is more effective. The chances are that the resulting sound will seem bass light as resonances are removed but just turn the bass up a little to get the true bass!
Yes, i lifted the bass 3Db to sort it... As you say there is no boosting with these ;) They only cut, but also make things decay much faster so it sounds like there is no room at all :)

[Macca]

I've had a listen to an REL sub that did it's own DSP, which was interesting but in a 9' by 8' very cluttered room it was hard to judge the quality. It made the door rattle though:) Seems like these units will do the same for any active sub. Very intersting...:eyebrows:

[Reid Malenfant]

Yes, they only control below 150Hz so unfortunately they aren't much good for most people. Even at a moderate volume i have doors rattling 40ft away :eyebrows: Upstairs, downstairs it dosn't matter...

It's like a rather large lorry outside, there isn't much difference except this goes louder when turned up :cool:

[Macca]

Yes, they only control below 150Hz so unfortunately they aren't much good for most people. Even at a moderate volume i have doors rattling 40ft away :eyebrows: Upstairs, downstairs it dosn't matter...

It's like a rather large lorry outside, there isn't much difference except this goes louder when turned up :cool:

Yep - close neighbours are the enemy of good SQ...

[Reid Malenfant]

Detached here :eyebrows: Anything goes Martin... Never a single complaint, or is that because i can't hear then hammering at the door with the music up?

:lolsign:

I have been outside myself when i have turned it up to silly levels & it's just about noticeable on the footpath 12ft from my front door...

I guess i'm in a good place :cool:

ATB m8 ;)

[electric beach]

Thanks for posting your experience with this device Mark, it's very interesting. I use a 2.1 set up for my system, for both films and music - well not really 2.1 I guess as that implies a dedicated, filtered bass channel, so I should really say I use 2 channel with bass augmentation.

The single sub is only set to very minimum output and a low cut-off point for music, just enough to excite the room. At this point the effect on presence and soundstage is huge and the projection into the room is a great contributor to the very live sound that I get. I turn the wick up a bit for movies but in either case, just tipping past this point gives me boomy bass, so there I stop.

I believe the reproduction of the lowest frequencies is essential to achieve "real" sounds. Even sounds that appear to have NO relationship with bass, say a triangle or cymbal. I'm sure it's just that our perception of "real" is based on the relationship to the full (or at least wide) frequency range and that deep bass does for high frequencies and imaging clues what a supertweeter does for tighter bass :confused:

I just recently found this unit on the BK site at the end of a surf run about subs, but I hadn't realised that you were in fact talking about the same bit of kit. I've heard Velodyne subs with DSP/ microphone compensation and the resulting effect was very clean, clear and desirable. As I'm commited to "2.1" I think one of these is going to be a finger slip away. :rolleyes:



PS. Val has gotten to the stage where she sees me on AOS and immediately asks "so what are we getting now then?"

[HighFidelityGuy]

Thanks for the mini review Mark. Your findings seem to tally with others I've read on these particular DSP boxes.

Just out of interest, would you be able to list the crossover points you use with all your speakers and subs and where in all that you've put the DSP boxes? It would just help me to understand your setup a bit better. Cheers. :cool:

[Reid Malenfant]

Thanks for posting your experience with this device Mark, it's very interesting. I use a 2.1 set up for my system, for both films and music - well not really 2.1 I guess as that implies a dedicated, filtered bass channel, so I should really say I use 2 channel with bass augmentation.

The single sub is only set to very minimum output and a low cut-off point for music, just enough to excite the room. At this point the effect on presence and soundstage is huge and the projection into the room is a great contributor to the very live sound that I get. I turn the wick up a bit for movies but in either case, just tipping past this point gives me boomy bass, so there I stop.

I believe the reproduction of the lowest frequencies is essential to achieve "real" sounds. Even sounds that appear to have NO relationship with bass, say a triangle or cymbal. I'm sure it's just that our perception of "real" is based on the relationship to the full (or at least wide) frequency range and that deep bass does for high frequencies and imaging clues what a supertweeter does for tighter bass :confused:

I just recently found this unit on the BK site at the end of a surf run about subs, but I hadn't realised that you were in fact talking about the same bit of kit. I've heard Velodyne subs with DSP/ microphone compensation and the resulting effect was very clean, clear and desirable. As I'm commited to "2.1" I think one of these is going to be a finger slip away. :rolleyes:



PS. Val has gotten to the stage where she sees me on AOS and immediately asks "so what are we getting now then?"
:lol: @ the last bit! If your output that you feed the sub amp with is line level & you then connect to a power amp & the speaker, or if you are using a commercial sub & the line level input - then yes you can connect up one of these ;)

Thanks for the mini review Mark. Your findings seem to tally with others I've read on these particular DSP boxes.

Just out of interest, would you be able to list the crossover points you use with all your speakers and subs and where in all that you've put the DSP boxes? It would just help me to understand your setup a bit better. Cheers. :cool:
Dave, the 8033 is connected to the (what is called) bass output of the DC2496. I have these set to 6 way mono but i have 2 channels muted. So i have bass, low mid, upper mid & high. The bass output is set to roll off above 110Hz, so the 8033 is fed signals up to 110Hz & then the output of the 8033 connects to the power amp. It could be up to 150Hz but no higher ;)

If i connected it prior to the DCX i'd get no mid or treble or anything over 150Hz..

So ARC MP1 pre amp - DCX2496 - 8033 on bass & then to pwr amp & from 2496 to pwr amps on all other channels.

Hope that helps m8 :)

[Reid Malenfant]

I had a friend over earlier who is always keen to listen to any changes on my system just to hear the differences ;)

As i have been living with these two devices for a while i decided to bypass them just to have a brief listen to how things used to be... So i pressed the bypass buttons on both units & the bass got louder & the room boom was overwhelming :eek:

It's simply stunning what these little boxes actually do, they eliminate the room effects below 110Hz in my case & the difference is absolutely astonishing! If i had known about these things previously & known what they would do i'd have happily payed full price for them & then some!

I know most people on this site don't happen to run active subs, that's a shame really as i in no way could live without what these things do now (you just have no idea of what you are missing!) ;) I can't recommend them highly enough. You want natural sounding deep bass, these are the answer & you'll no doubt have to pay a good bit to better these :eyebrows:

[John]

Its great to hear this works for you Mark
I now think for box speakers you have to go DSP to get the best out of the bass

[Reid Malenfant]

Its great to hear this works for you Mark
I now think for box speakers you have to go DSP to get the best out of the bass
You think, i know! :lol:

You just would not believe the difference John. I'm not going to say night & day but in all honesty if a lorry ran over your foot i think you'd notice it - a bit like this, it just can't be ignored as it's just immediately obvious :eyebrows:

[John]

Nothing like clean bass I am pretty sure I do not need one due to the open back nature of my speakers. When Vic tried this approach he no longer had to use the DSP for room modes but still uses it to control sub-sonic frequencies
Anyway great to hear it works the bass you getting now must be awesome Mark

[Reid Malenfant]

It's clean & at the right level. Never heard such clean bass i'll be honest :)

What was masked by the room due to decay & reflections is now crystal clear, i don't know how to explain it other than i seem to not be in a room as far as the bass is concerned. There are no reflections, no long decays, it all happens so fast & clean. Every different note is easily discernable & the whole rig appears to make even deeper bass notes more easily heard, i guess that is once again due to them effectively getting rid of the room effects :scratch:

Put it like this, when i first ran the calibration routine i turned the power amp way down. As the bass volume level was low i upped it some & recalibrated figuring it'd be more accurate. I did the same again as it was still in no way too loud. Each time i re-calibrated the initial 16Hz tone was heard as clear as if i was listening to you standing next to me whilst talking ;)

[John]

Yeah I know what you mean its such an addictive listen having clean bass and also allows everything up top to shine through more

[Reid Malenfant]

Yeah I know what you mean its such an addictive listen having clean bass and also allows everything up top to shine through more
I'd go along with that :) Another thing i have found is that i tend to listen at higher levels than i used to. Not that much higher but higher none the less! The clean bass rather than the added room artefacts makes everything so much clearer (as you rightly point out), it's kind of difficult to describe actually without actually hearing it :scratch:

I'm looking forward to Dave (Synsei) popping over & having a listen as you'll get a non biased second opinion. However, i'm sure he'll be as gobsmacked as i was earlier when i bypassed both units & listened to what the room adds :eek:

DSP4ME :lolsign:

Enjoy the rest of your weekend John, all the best m8 :)

[synsei]

Firstly, I need to declare here and now that I don't understand the technical niceties of how all this works, which is probably a good thing if an unbiased review of the sound, rather than the electronics, is what is needed...

After I arrived at Marks he was very keen for me to hear what it's all about, so I settled down with a coffee and a ciggy while Mark threw on some tunes. We began the session with the Antimodes switched off, so as such, there was nothing new to hear over what I'd heard before. I'm not sure what Mark had playing, but it was his usual fare of dark synth chillout with seismic bass lines and ambiance aplenty. I thought it was all sounding pretty good until the Antimodes kicked in.

Before I go any further, I must state that Mark and myself employ very different approaches to system building, neither of which is right or wrong, they are just different routes to the same goal. I am an Old Skool audiophile: I try to choose each new piece of equipment for my system very carefully by attempting to match the sonic signatures of each component to achieve a homologous whole. There's a particular sound I like and I have a very awkward listening room which makes it problematic to achieve. It has odd acoustic properties that suck the life out of the bass response from most speakers. I chose the DM2's I have now after much discussion with various people and a couple of listening sessions to determine if they could be part of the solution to my bass problem, and they are. Ergo, one happy camper. Mark, on the other hand, has chosen to tackle his problem from another direction, employing an active rather than a passive solution, using additional electronics to shape the sound.

When the Antimodes were switched on - the effect wasn't subtle. I have to be honest and say that I wasn't totally convinced. Most of the low end information seemed to have got up, looked at us in utmost disgust, then exited stage left in a huge sulk because it couldn't play with the room anymore. I sat there rather embarrassed, nodding in all the right places but thinking, "how can this be?", "where did all the bass go?". Remember, at this point we were still listening to Marks CD's and I have to say I didn't think it worked well with bog-standard two channel playback (sorry Mark :eyebrows:). I was thinking that, with all the expensive equipment gathered in the room, I should be hearing more. I believe it is a setup issue and that with some fine tuning it could be brought back from the brink.

The reason I think it IS a setup issue is because we then sat and watched the Blue Ray, directors cut of Avatar on Marks huge projection screen. Now we're talking!!! Now the Antimodes made sense!!! I could enthuse about the picture quality, natural saturation levels and every other picture based superlative you can think of for ever and a day, but it was the sound that topped it all. As I said to Mark when the film ended, it had been a better all round viewing experience than when I went to see it at my local Odeon, and that's saying something. The whole aural experience was as tight as a Gnats arse. Every little detail, every gut wrenching explosion, the sound of powerful engines ripping through the air, it was all there. When the missile assault was launched on Home Tree, I almost ducked as they tore through the air over my head, and I reeled as the shock wave hit me from multiple explosions as the missiles ripped into the tree and chewed it up. Watching the tree slowly topple I found myself anticipating a huge effect as tree met ground, and I wasn't disappointed. Part of my brain must have been expecting my body to be thrown all over the place because as the thunderous, cataclysmic racket of the collision reverberated through me, I found myself feeling a little disorientated and nauseous. That is not a bad thing btw :D

So, to sum up: I'm not entirely convinced that the Antimodes work so well on stereo playback as they are set up just now. However, they are absolutely the Bees Knees when used in multi-channel movie playback and work exactly as Mark describes. I'm at a loss as to why I don't feel so enthusiastic about their effect in two channel format, but there you go.

I'm sorry if that isn't entirely what you wanted to hear Mark, but even so, Avatar really rocked on your system... ;) :cool:

[electric beach]

:popcorn:

[Reid Malenfant]

Firstly, I need to declare here and now that I don't understand the technical niceties of how all this works, which is probably a good thing if an unbiased review of the sound, rather than the electronics, is what is needed...

After I arrived at Marks he was very keen for me to hear what it's all about, so I settled down with a coffee and a ciggy while Mark threw on some tunes. We began the session with the Antimodes switched off, so as such, there was nothing new to hear over what I'd heard before. I'm not sure what Mark had playing, but it was his usual fare of dark synth chillout with seismic bass lines and ambiance aplenty. I thought it was all sounding pretty good until the Antimodes kicked in.
Noooooo :eyebrows:

You have it arse about face Dave ;) The Antimodes were both on all the time except for the brief times i turned them off. I then proceeded to switch them back in line again after 10 - 20 seconds due to the god awefull sound of the room which i admit i was totally used to until these things were plumbed in :)

In all honesty it may well have been better to have played some music you are more familiar with as then you'd have a much better idea about what was actually happening. All you could compare was a lumpy bass & much slower decay response with the things bypassed than with then in the circuit. In all honesty a few seconds be it 10 or 20 of stuff you just don't really know isn't going to give you much idea about what they can do...

I should have thought about that before you came over & asked you to bring some CDs you knew well & we should have had more time experimenting ;)

All i can add is that to me these things are a true revelation :) Assuming i know what i now know & again assuming that i was starting from scratch building a stereo system one of these or a pair would be included. I'd get a pair of standmount speakers that would be happy to say 100Hz & then one or two good quality subwoofers fed via these devices, i'd be damn happy to :lol:


I did wonder what Steves :popcorn: emote was about :eyebrows:

[synsei]

Ah, light dawns on marbled forehead. Next time I'm over I'll bring some 'choons' with me then :lol:

Ah well, even so Mark, watching Avatar on your setup was an event :cool: ;)

[Reid Malenfant]

Ah well, even so Mark, watching Avatar on your setup was an event :cool: ;)
Yeah, apart from you can pause it to take into account bodily functions, have a ciggy etc i remember you saying the picture was better than at the cinema ;)

No wonder i don't go to the cinema, i just wait for the blu ray release & chill...

Bests to you buddy, hope you & Jo have a good weekend! All stocked up here so no need to go anywhere :)

[electric beach]

I'm very pleased to hear there's an explanation Mark :)

I've been working with sub augmentation for several years, regardless of the bass ability of the main pair. I totally agree with you that reproducing the lowest frequencies does something for the complete spectrum in terms of soundstage, presence, clarity, dynamics - well, just three steps further towards reality as opposed to reproduction and I wouldn't be without a sub now (never had two).

Just realised that BK are in my home town :doh:

[electric beach]

Installed a DSpeaker Antimode 8033s today, in line with a Velodyne CHT12 sub. :)

I can only agree with everything Mark has already said. Met all my expectations, not only in controlling the bass but has an extremely positive effect on the clarity of the complete frequency range. I wasn't prepared for the improvement in soundstage depth and acoustic information. If you think it's just going to get rid of a few room booms then you're in for quite a shock.

I take the feed from the dual output from my active preamp but it's pushing the limit of the input sensitivity, setting off the warning lights. I'm thinking a couple of 14db attenuated Goldenjacks will solve that issue.

DSpeaker have announced the 2012 launch of a new unit for controlling a stereo pair of speakers now, including inbuilt USB/SPDIF Dac, preamp and remote control operation for €850.

http://www.dspeaker.com/

[Reid Malenfant]

Hi Steve, nice to hear you had a sucessful install & you notice the same benefits :) I'm sure that given a few days & lots of different music you'll find yourself stunned at the clarity of each & every bass note. You'll be able to pick each one out & you'll also probably notice that there is far deeper bass there than in your room previously :eyebrows: You just need to play the right material...

The room was simply covering it up with resonances :rolleyes:

I can't remember at what point the two different indicators flash in all honesty as they never have done here. Depending on how often it is 10Db of attenuation should be ok I'd have thought. You'd just turn the sub output up to match things again ;)

Have fun because I know you are going to :eyebrows:

Would be interesting to see someone with an OB subwoofer try out one of these :)

[Ali Tait]

Don't have an OB woofer, but do have OB's with twin 15" Eminence Alphas. Might get a hold of one of these to try, maybe the new one when it comes out.

[Reid Malenfant]

It may well be worth it Ali, while you don't get any enclosure colouration you still get all the room modes etc ;) I think you'd be very surprised indeed :cool:

[Ali Tait]

I'd like to try something like this Mark, I was looking at a bit of Behringer kit on ebay the other week. I didn't press the button though.

[John]

With the open back I find I do not need DSP in my room. My friend discovered the same when he moved away from the Linkwitz approach he found he no longer had the colouration he had to overcome with the DSP
Where it really shines for me is how reasltic drums are and that I still hear the bass notes
It never go as low as a normal sub but for where all that energy is in prog metal and Fusion I am a very happy man
But think for a lot of people using open baffle DSP is essential

[Reid Malenfant]

You having problem waiting for the forum to John :eyebrows:

These bits of kit are only good for below 150Hz, it might be 120Hz in all honesty. No matter what actively driven speaker is used in a room there will still be room modes that this thing can get rid of unless of course it can't go below 120Hz...

[Ali Tait]

Aye, it's a bit slow today isn't it?

[Reid Malenfant]

Aye, it's a bit slow today isn't it?
On & off yes, patience is a virtue :eyebrows:

[Ali Tait]

Aye!

[John]

You having problem waiting for the forum to John :eyebrows:

These bits of kit are only good for below 150Hz, it might be 120Hz in all honesty. No matter what actively driven speaker is used in a room there will still be room modes that this thing can get rid of unless of course it can't go below 120Hz...

Yes I think issues with the server

Yes always room modes but really do not think this is a issue I really have to worry about
I have my bass cut off at 25 its low enough for me:ner:

[Reid Malenfant]

Yes always room modes but really do not think this is a issue I really have to worry about
I have my bass cut off at 25 its low enough for me:ner:
Of course you don't need to worry about it John, until you hear it without them & then you still don't need to worry... But you'd certainly want to be rid of them believe me :eyebrows:

25Hz is lower than most can go admittedly :)

[John]

I guess will just have to wait till I hear one in my system but what you describe in difference seems pretty close to my experience you more than welcome to hear if you ever get down to London

[Reid Malenfant]

It may well be that dipole woofers don't excite the room in the same way that monopoles do, so you could be right ;)

I still reckon it would be educational to find out though...

One day :)

[John]

I hope so be great to have your view

[electric beach]

I guess will just have to wait till I hear one in my system but what you describe in difference seems pretty close to my experience you more than welcome to hear if you ever get down to London

Hi John,

As I'm only 45 minutes away I'd like to pay you a visit sometime if you're up for it. I can bring the Antimode with me (it only takes 5 minutes to set up) and a few other goodies to play with. :eyebrows:

I'd like to discuss balanced power supply with you. It would have to be after xmas, or possibly over the xmas break, as I need every minute of the weekends to finish refurbishing a bathroom before I'll be let out to play.

[electric beach]

I'm finding this little unit to be just what the doctor ordered :)

I love the effect of adding a sub to single driver horns but the deep bass output varies so much with different recordings that it took a bit of faffing about to get the integration right for each. Attempting to find a common setting would leave one album lean and the next booming. With the room modes unexcited the difference is much smaller and a volume adjustment needed only occasionally.

Secondly, the tonal balance is almost even in the room. I used to find that if it was correct in the room generally then it would be too bass heavy sitting back in the chair, reinforced by both the settee and the rear wall only 0.5 - 1metre behind - I had a big difference just leaning forward in the chair. Now they're almost the same.

Thirdly, the soundstage, imaging and presence are excellent now that the speakers can lock into the room and use it to project rather than fighting it. That artist performing in your room feeling puts a big smile on your face. That and Val saying "I just shook hands with Michael Bubble!". :rolleyes: Oh well, she tolerates Sachikos.

Fourth, the sweep test tones used to calibrate are perfect to find all the rattles around the room. I even found that a panel in an internal door was kicking off, two screws in the gas fire and a wall clock in the next room!

Fifth. Before the Anti-mode my REL Strata 3 gave tight bass and integrated well with the main speakers, giving really low bass by using the room modes but resulting in an uneven frequency response. The DSP treatment killed it, taking away the sound projection and leaving me with a thumpy ill-defined soup. My Velodyne CHT12 was a big booming brute that I couldn't reign in. Here the control is a brilliant match; the unit deals with the note decay, not only the frequency peaks and the result is stringed instruments with texture just flowing into the room. Turning the wick up for electric, driven bass gives a driving force to the rhythm now without masking anything above it.

Five Stars! :lol:

[electric beach]

Oh, one issue. I take the feed to the sub from the second of the pair of outputs from an active preamp, intended for bi-amping, which are overdriving the input of the Anti-mode when I get the volume to room filling level. I've contacted Iain at Goldenjacks and I'm going to try a pair of -14db attenuation jacks to limit the signal, although I think it's going to need more than this. Not a major problem but the unit is designed to be fed from an LFE out from an AV amp or a passive preamp.

[Reid Malenfant]

I reckon 14Db will be enough Steve, that's quite a bit of attenuation in reality ;)

Let us know how it turns out with them fitted :)

There is something fundamental that I forgot to mention regarding these things :doh:

Because it's a signal processing device it needs a bit of time to do it's trick, so there is a slight delay (it's tiny) from the input being fed to the unit to the output being fed to the sub. This time delay could be adjusted out of consequence by using a subwoofers phase shift control.

In my case as I'm using digital crossovers I simply put a delay on all outputs to time align everything. I even had to add extra time delay to everything as my Lab Gruppen PLM 14000 has DSP with a delay of about 1.6mS ;)

Funny how there are so many things that need to be taken into consideration to get the optimum performance :) It's a question of understanding it. As long as you can do that then there will be no issues (or is that problems?) :D Just a little reference to another thread doing the rounds on here of late :eyebrows:

[electric beach]

Nice heads up on that one Mark, I'll play around with the phase control. I've no measuring facility so what would I listen for, would it be obvious like snapping into focus, tighter and faster bass or what?

I simulated -10db with the preamp channel controls which have that degree of adjustment and it didn't give much more headroom on the input, so Iain suggested trying the -14db which he does as returnable before making a bespoke value if necessary; he's been most helpful.

[Reid Malenfant]

The DSP controller just covers the bass end.

What I suggest is you listen to a good bit of music that has bass in the vicinity of the crossover point between your main & sub speakers. Then adjust the phase control for maximum integration. IE no peaking & a nice smooth response...

In reality I doubt the time delay will make much difference, it's minimal after all. I'm lucky that I can just cater for it with the Behringer DCX2496 crossovers & eliminate it just by creating a similar delay to all channels.

I actually have to add more to get the time alignment between the drivers as the voicecoils are not in the same plane either :eyebrows: Once that is done & all are aligned to arrive at my ears at the same time it's quite a thing I can tell you :)

[Reid Malenfant]

Just a quick one while I remember :eyebrows: I noticed something last night, after watching some Fringe I was still well awake, so decided to come back to the AV room & stick on something a little up tempo.

So I put on the BD of Tiesto & cranked it a tad, loud enough to just get distortion in the deep bass. At that point I did something I haven't done in ages, I bypassed the DSP :D Loads more bass obviously as the room was now back in the picture, but far less power was being fed to the bass drivers :scratch:

It didn't seem obvious to me until I thought about it, but to get rid of the effects of the room, extra power is going to be needed as the DSP has to add extra waveforms (of some form or other) to the signal fed to the drivers in order to cancel the room effects.

So while it can do the business, with the same amplification it simply can't ever go as loud, probably that'll be the same case with the bass driver to, it can only do so much after all ;)


Off to lay down again :rolleyes: Managed to get to the quacks today, but now I'm hacked off as I appear to be suffering from a trapped sciatic nerve :unfair:

L8rs all :)

[Clive]

All the best with your back Mark.

I too feed some extra power to my bass drivers to try to remove some of the nulls/ cancellations in my room. It's only helps on the edges of the nulls as after all 2 x 0 = 0 so doubling the power at a cancellation freq does little good but it doesn't half increase cone excursion! Moving speakers and items around the room has a greater effect.

[realysm42]

Why do these antimodes cost so much?

Some amps (especially av ones) do this job and cost about the same, is it a question of quality?

[Reid Malenfant]

All the best with your back Mark.
Cheers Clive, something has shifted as no more sciatica today :)

Why do these antimodes cost so much?

Some amps (especially av ones) do this job and cost about the same, is it a question of quality?
I have no idea Martin :eyebrows:

The thing is a lot of AV amps have built in stuff to decode digital audio anyway, & as these are stand alone units & there is no real competition that I know of, I guess they have a captive market :scratch:

They may well cost a bit, but I wouldn't be without them having used a couple for a while. I actually have another new mono & a stereo version that'll be put to use when I get my finger out & build some new speakers ;)



The thing is though, now I have sussed out exactly what's going on, I can make the most of it & work things out to my systems best advantage before cutting wood etc.

If I hadn't realised this before doing so I might well have had a bit of freak out & realise I'd cocked up :doh:


I'm going to get the function generator & oscilloscope onto this as I'm fascinated to see what will happen if I feed 1 Watt of power to one of the bass speakers on bypass mode at various spot frequencies, then switch the DSP in & see what the amp chucks out at the very same frequencies :D

It wouldn't surprise me if the amplifier output power more than doubled :lol:

[realysm42]

Interesting, so as you mentioned a bit further up, the 'work' that these things do equates to more power drain on the sub, makes sense, no such thing as a free meal.

So in theory, if you had the dual core version that does the whole system, that same drain would apply to all of it (or depending on where the antimode needs to deal with frequencies anyway).

So to extrapolate things a bit, wouldn't decent room treatment be the most 'effective' way of dealing with room modes etc? (Albeit more work).

[Reid Malenfant]

Room treatment can only really deal with frequencies that it can absorb. In the case of attempting to get rid of something in the deep bass, you might be looking at over 6ft thick of sound absorbent.

You just need to look at transmission line loudspeakers to realise this, most still output deep bass as the line can't get infinitely long to absorb the rear wave, so they use it as a delay to reinforce the output from the front of the speaker.

I'm coming to my own conclusions on this & you are quite right! The wider the bandwidth that the DSP corrects the more power you'll need to attain the original volume level without it :rolleyes:

So I reckon splitting the bass into a couple of bands will result in less amplifier power being used for the same volume level, even if it means more amplifiers & drivers :doh:


As mentioned earlier, it'll be interesting to actually see how much more power these make your system use, though this will be room dependant. Again though, a small room will win through, as the room modes can only go down to a certain frequency. So bigger room = more correction & power used by the amp :eyebrows:

[realysm42]

Cool, I didn't realise that big rooms could equals big problems.

I'm going to have a go with a dual core version of one of these, I'll let you know how I get on; are you not interested in trying one out?

Btw, I don't know if this is your kinda thing but I'm guessing it might be:

http://www.discogs.com/ASCSam-KDC-Decayed-Society/release/3445545

I heard this in a record store a while ago and thought wtf is this; I wasn't really ready for it then but I was intruiged enough to check it out again and really like it now.

Here's some tracks from it:

http://www.youtube.com/watch?v=KQ2af06quYg&feature=related

http://www.youtube.com/watch?v=hiXat-Ucjoo&feature=related

http://www.youtube.com/watch?v=AL1dbU0D_0E&feature=fvwrel

[Reid Malenfant]

Hi Martin, the music looks like it could be my kind of thing, I'll check it out at some stage soon - cheers :D


Looks like it won't cost me a lot to split the bass frequencies at 40Hz, so I'd have a 10 - 40Hz band & a 40 - 120Hz band. While it means I need more drivers I already have some suitable, I also have amplification as long as I build a few kits I have here :)

Just need a crossover to split the left & right channels & the jobs a good one. Another DCX2496 is going to be less than half the price of two Antimodes, so things haven't worked out too badly at all :eyebrows:

Who says you can't get things done when laying down all day :ner: