High pass filter / Capacitor...help!! [Archive]

Stresss42

08-02-2014, 14:50

walpurgis

08-02-2014, 16:32

Something like this will filter out low frequencies:

http://www.ebay.co.uk/itm/Blue-AC-450V-350uF-5-Nonpolar-Cylindrical-Motor-Start-Run-Capacitor-CD60-/121148589304?pt=UK_BOI_Electrical_Components_Suppl ies_ET&hash=item1c3504c4f8

But a capacitor in series will only give a 6db/oct speaker roll in, maybe a more comprehensive subsonic filter would be better.

Stresss42

08-02-2014, 16:47

Thanks Geoff I'll look at that now.

Reffc

08-02-2014, 20:00

Hi to all...looking for some advice regarding a high pass filter for the Mark Audio Alpair 7.3 ( Pencil design enclosures )- I've been reading that it may be
a good idea to filter out anything below 60 Hz. ?

Does anyone know what capacitor ( i assume electrolytic ) and value to achieve this when wiring on the positive speaker input ?

I don't intend to play loud bassy music but I'm concerned I may damage the drivers when watching films.

I have been searching online but all I'm getting is complicated wiring diagrams, now I have a bad head-ache. :confused:

Very best regards, Steve.

The cap value depends upon the impedance of the speaker in question. If you can supply details of the speaker impedance, I can suggest a cap value for you. For blocking everything below 60Hz using just one cap, as Geoff suggests, you may need a value which starts rolling the tweeter off much higher up, or you can steepen the slope by adding an inductor shunted across to ground 12dB/Octave). If you can supply a few more details such as the frequency range that you'd like the Alpair to cover, then something more sophisticated can be suggested.

Barry

08-02-2014, 20:46

A single capacitor in series with the speaker terminals will effect a simple low pass filter, having a stop-band slope of 6dB/octave. The roll-off frequency is given by 1/(2*pi*C*R), so if R = 8 Ohm and the roll-off frequency is 60Hz , then C = 332uF. So Geoff's suggestion of a series 350uF motor run capacitor (not a motor start capacitor) makes sense.

In practice the impedance of the speaker will not be pure resistance of 8 Ohm, but trying a single series capacitor is a good place to start.

Stresss42

09-02-2014, 15:03

The cap value depends upon the impedance of the speaker in question. If you can supply details of the speaker impedance, I can suggest a cap value for you. For blocking everything below 60Hz using just one cap, as Geoff suggests, you may need a value which starts rolling the tweeter off much higher up, or you can steepen the slope by adding an inductor shunted across to ground 12dB/Octave). If you can supply a few more details such as the frequency range that you'd like the Alpair to cover, then something more sophisticated can be suggested.

Hi Paul, thanks for your reply...The driver in question is a full range metal cone driver - Mark Audio Alpair 7.3 : http://www.markaudio.com/component/k2/itemlist/category/31-Raw-Drivers
( Impenance = 5.4 Ohm - Frequency I hope to achieve = 50/60 Hz to full range )

There's no speaker cross-over at all - cables run directly from the amp to the driver. As I say my only concern is playing Blu ray films with sub bass sound effects etc that may damage
the small 4 " metal cones. Lastly I'm hoping a single capacitor wouldn't effect sound quality at all ??
Thanks again Paul, and thanks also to Barry for your reply. Steve.

Radford Revival

09-02-2014, 15:55

walpurgis

09-02-2014, 16:04

Will is right. The damping (electrical) will be affected. While a biggish capacitor will produce bass roll-off, it's something I'd personally be wary of doing.

Stresss42

09-02-2014, 16:09

Adding a capacitor in series with the speaker could potentially, believe it or not, have the exact opposite consequence of what you're trying to achieve (protected drive units). The impedance peak(s) of the speaker/enclosure are going to be sat right around the sort of frequency you're trying to filter out. These peaks, when driven through a reactive capacitor, lose the damping effect of the amplifier. This could potentially lead to the speakers being damaged when driven at these frequencies due to this lack of damping. The roll-off slope will also look nothing like 6dB/octave due to these peaks. A better way to achieve this would be at the line level with a simple RC filter. You get a predictable LF roll off that doesn't depend on the speakers connected, and you get the full benefit of amplifier damping right down to DC (assuming a conventional solid state power amp).

Thanks very much Will - I was looking at that idea - but wondered if SQ is affected by an RCA plug in type like this :

http://www.ebay.co.uk/itm/1-Harrison-Lab-FMOD-50Hz-Hi-Pass-Subsonic-Filter-Electronic-Crossover-/370989066089?pt=US_Cables_Snakes_Interconnects&hash=item5660abe769#ht_1714wt_1141

[ If these can effect sound quality I may just have to go easy on the volume when watching actions films !! ] All the best, Steve.

Radford Revival

09-02-2014, 16:36

It wont hurt the sound quality, just roll off the bass below 50hz if designed correctly. There's the potential that it could improve things as it alleviates the amp and speakers from the task of trying to reproduce low frequencies outside of the range of the speakers.

Thanks very much Will - I was looking at that idea - but wondered if SQ is affected by an RCA plug in type like this :

http://www.ebay.co.uk/itm/1-Harrison-Lab-FMOD-50Hz-Hi-Pass-Subsonic-Filter-Electronic-Crossover-/370989066089?pt=US_Cables_Snakes_Interconnects&hash=item5660abe769#ht_1714wt_1141

[ If these can effect sound quality I may just have to go easy on the volume when watching actions films !! ] All the best, Steve.

Reffc

09-02-2014, 17:07

It wont hurt the sound quality, just roll off the bass below 50hz if designed correctly. There's the potential that it could improve things as it alleviates the amp and speakers from the task of trying to reproduce low frequencies outside of the range of the speakers.

Good point Will...that would seem to be the more sensible route.

You can make your own Steve by buying a small electronic project box and fitting an RCA socket to inlet and outle and wiring the RC circuit internally but as long as those plugs you linked to are cheap enough, it would be the neater solution.

lurcher

09-02-2014, 19:52

but wondered if SQ is affected by an RCA plug in type like this :

If it did, it will do far less damage to the sound than putting a cap in series with the driver, your will get all sorts of unwanted phase effects up way above the cut off point. The low frequency its self wont hurt the speaker, just check its not loud enough to send the driver to its endstops.

Is it not possible to tell your blue ray player to not send LFE to the outputs? Maybe lie to it and say you have a sub.

Stresss42

02-04-2014, 20:39

If it did, it will do far less damage to the sound than putting a cap in series with the driver, your will get all sorts of unwanted phase effects up way above the cut off point. The low frequency its self wont hurt the speaker, just check its not loud enough to send the driver to its endstops.

Is it not possible to tell your blue ray player to not send LFE to the outputs? Maybe lie to it and say you have a sub.

Sorry about the late reply to all !!! All sorted I'll go for the Harrisson Lab passive in line filters, yet to decide to cut @ 50 or 70 Hz.

Thanks again really appriciate all your advice. Steve. :)

dahdit

04-04-2014, 16:35

I'm glad you got it sorted Steve, it sounds like a neat solution. I have the same issue with the same drivers (Alpair 7.3) but in Frugal Horn enclosures. The difference for me is that I picked up a BK subwoofer recently so I've been looking to high pass the speakers at something like 80Hz and let the sub take care of the bass for reasons that Will mentioned. I've no real complaints with the current sound and the sub just 'murmuring' rather than taking over but I'd like to see what the system sounds like without the drivers doing the hard work at the bass end.

Yours would be a great solution for me if I had a LFE output on my amp or if I had a preamp that I could connect the sub to but my only option at the moment is to connect it to the speaker outputs - I think it's called 'REL-style'. I mostly use a Caiman Dac from a laptop going into either an Amptastic Mini T or a Ming Da 12W SET amp. I started to think that the only option would be to integrate the sub and high pass the main speakers through a Mini DSP unit but any other suggestions would be great. I was thinking of getting a NAD D3020 which apparently high passes the main speakers at either 80Hz or 100Hz when a sub is plugged in but I quite like the amps I've got.

A bit of a thread hi-jack Steve but you're sorted and it's the same issue. Plus I didn't think it worth starting a thread for this.

Stresss42

07-04-2014, 19:22

Hi Steve, I did think twice before posting but after being left with a massive head-ache whilst researching capacitor values I just gave in !! :brickwall:

I've had a second thought about the Harrison labs filters. Similar reason as you - if the signal from my Bushmaster is being filtered @ 80Hz and I want to add a sub later it'll be pointless.
There's no loop output on my Arcam A19 so I'm stuck, just a record out. If the input signal from my Dac is filtered at 80Hz I'm sure the record out will be also.

So I saw this the other night :
http://www.parts-express.com/80-hz-high-pass-8-ohm-crossover--266-458

I think 80Hz is perfect ( correct me if I'm wrong ! ) for the Alpair 7.3. For normal listening I've no worries but would be nervous when watching films. Let me know what you think of the crossover above,
or if you see any better quality ones out there. Nice one Steve, all the best mate.

dahdit

09-04-2014, 10:36

Hi Steve it looks like we're almost looking for the same thing. I’m no expert but I think those crossovers would do what you want in protecting your main speakers and it looks like 80Hz would be a pretty common setting, I’m not so sure that you can just go off the drive unit specs though, the cabinet and how the whole thing behaves in an untreated room (what modes it excites) will have an effect if you ever want to add a sub. More an issue for me with a rear horn mouth opening I think, are the Pencils a closed box design?

I like the Alpairs in the FH3 because they seem more clean and immediate than the box speakers with crossovers that I’ve had so I’m wary of introducing something into the signal path that might affect that but those crossovers look worth a go at that price. I was looking more at this: http://www.minidsp.com/applications/digital-crossovers/subwoofer-integration-with-minidsp

I’m really impressed with the FH3 for music but what this review says about ‘proper’ 2.1 systems got me thinking http://www.avforums.com/review/elipson-music-centre-review.385. I’m guessing that a miniDSP set up would be kinder on the amps as well as the speakers. I’ll keep you posted with any progress but it’s going slow at the mo’ - lots of reading up to do.

Cheers mate

Steve

Stresss42

09-04-2014, 21:05

Hi Steve, no the Pencil design is an open baffle design. If you click on http://theartofsound.net/forum/showthread.php?31503-Speaker-build-Mark-Audio-Alpair-7-Generation3-Pencil
you'll see my complete build from start to nearly finished. ! ( matt black going on this weekend ).

Back to the crossover - I totally agree...I also didn't really want any crossover at all in the signal path, but did consider the ones posted above simply to protect the drivers to
excessive sub bass ( Film/Blu ray ) frequencies. What I might do is finish by build, have a listen and think about some options. May just have to order some Harrison labs / or the ones above, and try them out - think thats the only way I'll find out if they degrade the SQ. Cheers Steve.

Nb..I'll have a proper look at the mini dsp link you posted. Nice one.

dahdit

11-04-2014, 08:08

I missed that! Very nice build Steve, I'm impressed.

In case you're interested, before the Alpairs I had a pair of these in my FH3's http://www.ebay.co.uk/itm/2pcs-HiEND-4inch-full-range-speaker-defy-lowther-fostex-new-NEO-version-/221391579717?pt=UK_Sound_Vision_Speaker_Parts&hash=item338bf76a45 and they sounded very good. So much so that I was a bit disappointed when I put the Alpairs in although it seemed to take a long time to loosen them up for a decent bass sound. I should swap them out now and compare them - cheap enough to be considered a bit like tube rolling but with drive units. I'll keep in touch and let you know what I think. I think the Chinese ones are made by Guide Sound who make a lot of Audio Nirvana stuff - they certainly have that look about them.

I think I'll either try miniDSP out or look at the NAD D3020 which has aptx bluetooth streaming on it as well. Another option would be to have a look at Steve's (electricbeach) Dared DV 6C amp if that has bass management. I was close to getting in touch with him last year after he kindly offered a demo but personal circumstances took me away from hifi for quite a while. You mention Steve in your other thread, I'm guessing that he knows as much about this sort of thing as anyone. Plus we could do with a few more Steves on this thread! :)

Stresss42

11-04-2014, 17:41

Yeah big time, I email'd Steve - Electric beach, but I don't think he's been on here for a while - would be good to see what he thinks of the filter issue.
( You seen his website ? Piano black FH3 with leather front columns ...Wish I could afford them )

On the Dared Amp - did you read the Hifipig review of the Frugel 3 with the Dared Amplifier ? - The reviewer ( Dan -) is on AoS - very nice guy.

I'll have a closer look at those lowther & fostex drive units tonight - might be nice for future projects.

Cheers Steve.

dahdit

16-04-2014, 07:03

Hi Steve, sorry, I've been offline for a while - and still haven't got round to swapping my drive units out, I need a rainy day. Yep, the electricbeach FH3's are lovely looking things. Mine is 'industrial' looking at the moment in bare plywood, the finish could be either tung oil on the wood, veneer, paining or even wallpaper but I keep changing my mind. The Hifipig review is really good, especially as the speakers were 'tuned' to the room during the review and the comments about the addition of a subwoofer are particularly interesting. It makes integration of the sub sound easy though and that's what I'm struggling with a bit.

Let me know of any progress mate and I'll do the same.

Stresss42

16-04-2014, 21:20

Hi Steve, defo interested to see how those other drivers compare to the Alpairs. Close to finishing my pencil build - great to have a long easter weekend to finally lacquer them up.

Now to break in the drivers over 100 or so hours.... Hoping I may not need the high pass filter, will just chuck on a blu ray film soon to find out.

( Prometheus should do the trick ). Cheers Steve.

dahdit

17-04-2014, 13:57

Stresss42

17-04-2014, 18:32

No probs mate - I also started a thread on Piano black finishing : http://theartofsound.net/forum/showthread.php?30476-Piano-Black-finish

Had some brilliant advice from loads of really nice guys on here. Only thing I wasn't prepared for was my misses going mental with the
spray paint smell when the speakers were drying in my study !! ( Plus I think the end result will be Gloss...NOT Piano black..Damn !! ). Cheers Steve.

Stresss42

03-05-2014, 12:02

Hello mate, I wouldn't do the blu ray thing until you're well past the 100 hours 'warm up'! I'm sure I read some posts somewhere of those drivers being wrecked by too much stress too soon - too low too loud I suppose. There are probably ok ways of finding out if the drivers are up to it and less ok ways :) Being long throw units (small area so large cone excursion) it seemed to take a long time for the bass to emerge on mine.

The cabinets are shaping up really well - I might well be onto you for some painting/finishing tips.

Ordered ( with extortionate carriage charge ) ..... http://www.parts-express.com/100-hz-high-pass-8-ohm-crossover--266-462

Hoping the simplicity of the design / high quality components doesn't affect SQ ..at all. Will find out soon enough - will let you know the result. Cheers mate, Steve.

YNWaN

03-05-2014, 13:49

Piano, as opposed to gloss, is extremely difficult to achieve and really needs a two pack resin that is then flatted back and polished back up - a lot of work and prone to cabinet shrinkage causing cracking in the finish (months later).

A while ago, on another forum, a chap built a centre speaker and had it sprayed at a car body shop hoping to achieve a piano finish - the result was nothing like it.

YNWaN

03-05-2014, 13:54

Ordered ( with extortionate carriage charge ) ..... http://www.parts-express.com/100-hz-high-pass-8-ohm-crossover--266-462

Hoping the simplicity of the design / high quality components doesn't affect SQ ..at all. Will find out soon enough - will let you know the result. Cheers mate, Steve.

Did you not fancy building these yourself? They are only one inductor and a capacitor - the carriage could have been spent on an air-cored inductor and a polypropylene capacitor.

Stresss42

03-05-2014, 14:53

Did you not fancy building these yourself? They are only one inductor and a capacitor - the carriage could have been spent on an air-cored inductor and a polypropylene capacitor.

Hi Mark, I did consider it but just ordered those ready made ones instead..as simple as it seems I didn't fancy soldering these few items onto a board - never done it before and would have
messed it up.
Also, agree on the Piano finish. With experience Piano black in a non professional environment is near impossible.
I was quite happy with the lacquered finish untill it blistered in 4 places on 1 speaker only for no apparent reason.
:steam::steam::steam:

YNWaN

03-05-2014, 15:04

I understand.

The blemishes are likely to be down to a humidity problem or the paint rye activating the paint beneath it and drying through the top coat.

You don't actually need a circuit board for any crossover - they just aren't complex enough. You just glue the components to a bit of MDF and solder the components directly together - easier said than done though if you are new to it all.

dahdit

06-05-2014, 13:22

Hi Steve, sorry mate, I'm an infrequent visitor - too much non hifi stuff to do lately, I need to sort my priorities out! That's a bummer re the paint finish. My speakers are still 'industrial' looking (bare plywood) because I can't decide on a finish for them (although I think I've discounted piano black now mate :()

Good advice from Mark - I'm assuming it would be easy enough to work out the inductor value given the capacitor is 140uF? Apart from that it's fair enough that you don't fancy getting a soldering iron out, again well put by Mark. I felt the same but recently went through a pair of crossovers on some old speakers replacing the caps and inductors and quite enjoyed it so I'd recommend having a go if you get the chance again. Make sure you get a half decent soldering iron though. Mine cost about £20 and works great - the £10 one I had before that didn't really work at all.

Looking forward to hearing how the crossovers work. I'm lining myself up for a miniDSP and UMIK microphone from the French or German distributor but I want to mug up a bit on REW first.

...and I will get round to trying those Chinese drivers out!

Stresss42

07-05-2014, 21:28

No probs Steve.

The filters did cost a bit with the silly carriage charge but I'll see how they sound. They'll hopefully just high pass the sound at 100Hz and detract nothing from the sound. Q. ( ??? )
Messing around with the pencil build over the w end - over painting with black gloss. ( Just satin at the moment - don't like it ).. Will avoid the nasty lacquer, really did look nice untill I saw the blister spots. :confused:

Alpair 7.3's are burning in nicely, but as suspected they really do need high passing ( my opinion ) especially for action films / silly sub bass explosions etc.

If you have a nice clean finish for your plywood cabinets why don't you stain them? You could finish them in a nice dark walnut stain, or Oak etc. Honestly wish I did now. Cheers mate, all the best.

dahdit

09-05-2014, 08:45

Hello mate, it's sometimes best (or at least cheaper) to learn from other people's mistakes than your own so thanks for sharing your experiences ;) I'm in two minds about staining and tung oil or yacht/floor varnish or just painting them - looks don't concern me too much. Either way leaves it open for iron on veneer if I fancy a change and have enough sandpaper.

If you're going to high pass the speakers then I think you definitely need a sub, especially for films. Mine is a BK XLS200 FF - I was going to get a Gemini but got mine second hand for less. Even on music it makes a big difference, but there was less difference when I could put the speakers in a corner in a different room. I doubt I've got the integration right yet so I'm ordering the miniDSP today. I'll keep you posted on that but you might want to check out a DSPeaker antimode for integrating a sub for cinema stuff - it looks like it does equalisation/room correction with one button press but I don't know if it will do that by high passing the speakers effectively so as to protect them. I'll let you know how I get on with the miniDSP.

Stresss42

10-05-2014, 17:10

Sub defo on the cards, but to be honest alot needs doing to my Car so I was thinking about something cheaper like the Tannoy SFX. ??
I'm able to use the pre amp output from my Arcam A19 so I'm able to control volume that way.
Wired up the HP filters for the pencils / Alpairs and fixed it to the rear speaker panel last night - haven't heard them high passed yet but hoping for the best.
( Messing about with the internal stuffing at the moment, Black gloss painting - will never end !! ) ...

Defo let me know about the DPS..may look at that in the future. Cheers mate.

Naughty Nigel

11-05-2014, 19:09

dahdit

12-05-2014, 14:37

It'll be interesting to hear how you get on with the crossovers Steve.

Cheers Nigel, that is an issue for me, I have a SET valve amp and a t-amp (both about 12wpc) so my intention with the DSP unit is to do exactly that and actively high pass the main speakers before the amp. Where that crossover point will be I don't know yet, the unit I'll be getting works with a microphone and REW (Room Equalisation Wizard) and I gather it's a tweakers paradise. My thinking re high passing initially came from reading comments in this article http://www.avforums.com/review/elipson-music-centre-review.385 about a 'proper' 2.1 system. The writer says much the same as you.

Stresss42

12-05-2014, 19:10

I haven't read the entire thread so please forgive me if I have missed anything.

However, if you are using valve amplifiers I would recommend that you filter out LF before the amp, rather than in the speaker leads.

There are three reasons for this:

Firstly, some valve amplifiers can be unstable if driving a capacitive load. (Some transistor amplifiers can struggle too.)

Secondly, you will be amplifying LF power unnecessarily. (Again this applies to transistor amplifiers too.)

Thirdly, and most importantly, if the power amps are driven hard with LF sound (i.e. organ music) the amplifier will effectively see the loudspeakers as an open circuit. The high voltage generated under these 'no-load' conditions might just be enough to finish the output transformer.

Nigel.

Hi Nigel,

No worries !... - my Amp is an Arcam A19 and I intend to grab an active sub in a week or 2. I'd love to high pass before the amp but then the only other output I have is record out or ( better ) pre amp
out on my amp...so if I used something like the harrison lab filters I'd be feeding the sub a high passed signal. This is why I had to ( for now ) buy the 100Hz passive filters so I can use the pre amp output and have control
over the sub. I'd be interested though to know the most basic dsp unit that would do this electronically for future upgrade ( no EQ built in just high pass / sub out DSP ?? ) !!!
Forgive my lack of dsp experience, alot of research to do ! Cheers Nigel, all the best. Steve.

Stresss42

12-05-2014, 19:44

Steve...

Really interested about the dsp route for future upgrade mate defo. Do you know of any around the £200 / £250 mark that are simply high pass and sub out ?

All the best, Steve.

dahdit

14-05-2014, 12:08

This is what I'll be using Steve... http://www.minidsp.com/applications/digital-crossovers/subwoofer-integration-with-minidsp

The DSP unit is about 100 euro from the German or French distributors and the calibrated measuring microphone is 75 euro. The total including delivery comes to about £150. The Advanced 2.1 plugin is $10 downloaded from the miniDSP site.

To do what you want then these look like a decent guides http://www.tnt-audio.com/sorgenti/minidsp_e.html and http://www.hifizine.com/2010/09/subwoofer-equalization-and-integration-with-the-minidsp-2x4/

If you follow the first guide and the first half of the second one you won't need the microphone. The second link will give you and idea of what more you can do with it if you have a microphone and use some free software called REW.

Ali Tait

14-05-2014, 13:58

Yep, I'm using one of those as the active crossover on my OB's, good bit of kit.

dahdit

14-05-2014, 18:48

Stresss42

14-05-2014, 19:07

Nice one Steve thank you mate...will have a good read of all of those links, seems perfect. Software doesn't seem at all complicated.

Glad I'm high passing the Alpairs, the passive x-overs will do for now. Defo 100 % upgrade with the dsp no doubt. If only my motor wasn't broke I'd order that now ... :steam::steam:

Ali Tait

14-05-2014, 19:34

Cheers Ali, that's good to know. It seems like a godsend for that type of project. I almost entirely listen to music from the computer so my dilemna will be whether to feed the DSP through the usb or from my modded caiman (Gazjam's old one) through the RCAs. The latter seems a bit odd - digital (computer) to analogue (from the Caiman) back to digital (via the DSP DAC) then processing and back to analogue (DSP DAC).

Be interesting to try the I2s input, I'm just using the analogues at the moment. In any case, the board was obviously better than the Behringer DCX2496 I was using before. Cheaper than the Behringer too.

dahdit

15-05-2014, 16:40

Quite a bit cheaper by the looks of it Ali! I'll certainly be trying the USB input and I'll report back but it occurs to me that I'll need a volume control before the DSP unit so I don't have to change the volume on the sub every time I increase the main speaker volume. I could turn everything up I suppose and rely on the software volume slider on Spotify of whatever I'm playing but I don't trust myself or the computer with that - too easy to slip or scroll the volume up by mistake. I'll probably settle with the variable out from the Caiman but we'll see.

dahdit

23-05-2014, 14:39

I've been playing around with the miniDSP for a couple of evenings and it's dead easy to do what you want to do with it Steve. At the moment it's crossing the sub to the main speakers at 80Hz with a Butterworth 48dB/oct crossover, I'll try some different ones over the weekend (Linkwitz-Riley and Bessel) with different slopes. It looks like a great way of hearing what the differences between these are. I'll try different frequencies as well - the Alpair 7.3 response seems to level out at 100Hz from the specs.

I haven't plugged the mike in to do any proper EQ yet but I've used some of these test tones to compare by ear what I've done so far http://www.audiocheck.net/audiotests_frequencychecklow.php All I can say by ear is that I can hear nothing from the main speakers at the 60Hz tone, about half volume at 70Hz and full volume from 80Hz up. Check out that site, it's a great resource.

At some point I'll need to work out how to up the volume of both sub and mains at the same time like I used to with the high level sub connection - I think running the DSP out of the variable out on the Caiman DAC should do for now. I've asked elsewhere on the site about tuning a t amp into a power amp for that purpose. I'll report back on any progress.

Stresss42

24-05-2014, 21:33

Hi Steve,

Thanks for that audio check link. I downloaded the mp3 file, played it on my " high passed @ 150 Hz " speakers and heard a very predominant peak @ 70 Hz !! ??

Which of course means that the passive in line filters I bought are total S@#T. :steam: I love wasting money mate I tell ya. :mental:

So, the plan is...take the silly passive filters out, burn them, then buy this : http://theartofsound.net/forum/showthread.php?25327-Tisbury-Audio-Mini-Passive-Pre-amp
1 line out will feed my Arcam ( with Harrison labs TRUE 150 Hz high pass !!! ) and the other variable line out from the pre amp to an active sub.

Just don't know if I should order a pre amp with 1 fixed & 1 variable out or 2 variable out ? ( Tisbury will make to order ).
Thanks for the info on the mini dsp by the way, did have a good look at that but just wanted to keep it simple ( because I am !! ). Cheers mate.

Talk about learn from other peoples mistakes. :doh:

Stresss42

24-05-2014, 21:46

By the way, here's a system tester Steve once you get your mini dsp up and running
: http://www.amazon.co.uk/Just-What-Need-Brian-Simpson/dp/B00BKBCL64/ref=sr_1_1?ie=UTF8&qid=1400967859&sr=8-1&keywords=brian+simpson

dunno what type of music you're into but this recording is simply stunning. Never heard anything like it mate. Cheers.

dahdit

27-05-2014, 11:00

Hi Steve. I listen to all sorts really, a lot of acoustic guitar stuff and some jazz. My lad has recently put me on to Koan Sound (you really need a sub for that stuff) and I’ve also been listening to Tomorrow’s Harvest by Boards of Canada. I use Spotify almost entirely so I’ll check that album out.

Sorry to hear that the passive crossovers didn’t work mate but your plan sounds a good one – you’ll have the same issue as me in needing to turn the main speakers and the sub up at the same time. The Tisbury looks good; this company do something similar http://bte-designs.weebly.com/bte-designs-passive-preamplifiers.html and can design to order by the looks of it. I've no experience of either, or of passive pre amplifiers in general though.

I had a bit of a play with the miniDSP over the weekend, just messing about with crossover frequencies and slopes but I haven’t settled on anything yet – I’ll get the microphone set up and do some proper EQ. The good thing about the miniDSP is that you can change the crossover 'on the fly' and hear instant changes.

Ali, it looks like the 2x4 unit can’t accept a USB (music) signal in, the FAQ suggests that I2s signal is there for “control” only so my chain seems to be computer to DAC (Caiman) to ADC (miniDSP) to DAC (miniDSP) and analogue out. Not ideal but it sounds good.

Stresss42

27-05-2014, 20:23

Hi Steve, yes I email'd Anthony from : http://bte-designs.weebly.com/bte-de...mplifiers.html yesterday, so may hopefully get a reply tomorrow. Although I really like the look of the Tisbry.

I was thinking about the issue of turning up the integrated amp / plus the volume for the sub when I wanna watch a film or play music...is it a pain ?
Only other option was possibly an older Beresford TC7510 dac, ( Need 2 optical inputs - ) but the Bushmaster Mk2 with Battery power is just too good to part with.
... so I thought the best option was a passive pre amp.

Cheers mate, Steve.

dahdit

28-05-2014, 09:51

Hi Steve, if you use the passive pre then you'll be using your Arcam in effect as a power amp (albeit a 'variable' one) I'm doing the same at the moment but with a much less capable Cambridge Audio A1 cranked up to full volume but I'm on the lookout for a cheap power amp to have a play with before settling on my setup.

I'm no techie but your source would have to be strong enough to be attenuated before your (soon to be) filtered Arcam (power amp for the main speakers) and your subwoofer amp. The passive would then turn both up or down at the same time rather than messing about with each in turn. Line out levels seem to be fairly standard judging by what I've plugged into my amp in the past. Yes a TC7150 would do the same as the passive. I'm assuming the Bushmaster doesn't have a variable line out?

I'd really recommend miniDSP, I loaded a very rough set of room correction EQ filters into it yesterday and the result was amazing.

dahdit

28-05-2014, 12:23

Oh, and I should point out (maybe it's not obvious from above) that my Caiman acts as a DAC and preamp and it feeds the miniDSP which has a 2 in 4 out configuration - two of these go to the main speaker amp and two to the sub. Your passive would have to be able to control two sets of outputs at the same time.

Stresss42

28-05-2014, 17:44

I'd really recommend miniDSP, I loaded a very rough set of room correction EQ filters into it yesterday and the result was amazing.

Gonna have to look into the dsp...I know I'll have to fine tune the Alpairs to my room. Was thinking this today. If I remove the back panels and add / remove
any more dacron stuffing I'll go insane mate. :mental: ( Upper mid range - bit peeky )...especially to my tinitus - suffering left ear.

I'll contact the people on the link you sent Steve thanks again for that mate. Cheers Steve.

dahdit

28-05-2014, 21:03

Hello mate, I mentioned BTE because on the bottom of that page he describes the red one has being a special design with a sub in and output.

I can't say I noticed the peakiness, maybe because I've mostly used a valve SET amp before the CA one but I had a look at the spl/freq graph for the 7.3 and there's definitely a peak at around <10kHz. That's got me thinking - it's easy enough to put a notch filter on the parametric equaliser of the miniDSP to flatten the peak so I'll have a look when I've had a good play around with it all. It's not a case of re-mastering and music - just tuning up the system/combination a bit. Any combination of crossover points room equalisation filters and other tweaks (phase/delay/shelves/notches etc.) can be stored and loaded onto the DSP unit for any listening position or set up to give the widest listening position. Once loaded up it's a forget about it job and if you find the 'perfect' one you need never touch the unit again.

I think component synergy and room interaction is crucial. Some people spend a fortune and stumble in and out of it by trial and error; that's cool if they enjoy the journey, many do and I can see the box swapping attraction. At the moment I'd like to learn a bit about my fairly basic system and how the bits interact, a bit about theory and then have a nice session hearing the music get better and better. I'll never get too OCD about it.