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I'd like to get some sort of sense for what is currently possible. If those of you who have succeeded in using DSP, room correction, and/or active crossovers might be willing to post specifics, this would help morons like me at least get a sense of what to aim for.

 

So let's say you have a system in which you employ DSP room correction and active bi-amping. It would be great to know (a) what computer/OS you are using, (b) what software you use for the DSP, © what software you use for active crossovers, (d) how you get the information to your DAC, (e) whether the DAC is multi-channel to support using active crossovers, which one it is, etc. (I realize in my ignorance I may not even be asking the right question, but I am just kind of trying to sketch how this thread might evolve.)

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Actually you are asking some of the right questions.

 

(a) DIY computer with Windows 7

 

(b) + © Audiolense XO is used to meassure and to create a FIR filter.

Audiolense does it all: Crossover + frequency, time domain and phase correction.

The FIR filter is 2-in, 6-out for a pair of 3-way speakers.

 

(d) Convolution engine via ASIO: foobar2000 gapless convolver for music playback and ConvolverVST + console.jp for movies/other playback. Jriver is an alternative - has built-in convolution engine.

 

(e) DAC is Echoaudio Layla 3G - a multi channel audio interface with 8 analoge outputs - 6 used for 3-way speakers

 

 

The question you have forgot to ask is:

 

(f) How do you adjust volumen?

 

- For best results, volumen really should be adjusted after the convolution, not before. I am using a Rotel RSP-1068 as a multi channel remote control. It might be possible to adjust using the audio interface itself, but I have never got around to it.

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volumen

 

Maybe Danish for volume.

And always keep in mind: Cognitive biases, like seeing optical illusions are a sign of a normally functioning brain. We all have them, it’s nothing to be ashamed about, but it is something that affects our objective evaluation of reality. 

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I am sorry, it was late at night and I have written something completely gibberish. I cannot edit the post, so here is a modified version:

 

(f) How do you adjust volume?

 

- For best results, volume really should be adjusted after the convolution, not before. I am using a Rotel RSP-1068 as a multi channel volume control. The Rotel unit is a surround pre-amp, but it has an analogue bypass mode that skips the video circuts. It might be possible to adjust the volume using the audio interface itself, but I have never got around to it.

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sshd's avatar is Diana Rigg of The Avengers:

 

The Avengers (TV Series 1961

 

Anyway, back to the topic in hand. My speaker/CD system uses a Behringer DEQ2496 and I only use it as an equaliser - I have passive crossovers. It goes CD Transport-Behringer-DAC-Amp. The DAC has a volume control.

 

If/when I attach my computer to this set up I plan to use a USB/SPDIF converter to connect to the Behringer. I use JRiver so in theory I could use its DSP but at the moment I'm not planning to.

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I'd like to get some sort of sense for what is currently possible. If those of you who have succeeded in using DSP, room correction, and/or active crossovers might be willing to post specifics, this would help morons like me at least get a sense of what to aim for.

 

So let's say you have a system in which you employ DSP room correction and active bi-amping. It would be great to know (a) what computer/OS you are using, (b) what software you use for the DSP, © what software you use for active crossovers, (d) how you get the information to your DAC, (e) whether the DAC is multi-channel to support using active crossovers, which one it is, etc. (I realize in my ignorance I may not even be asking the right question, but I am just kind of trying to sketch how this thread might evolve.)

 

 

Mine is easy. Use a KRK Ergo. It has the crossover, Lyngdorf DRC module, four channel dac, and matching four channel preamp. All in one box. The software and mic for room calibration are all included.

The volume controller is a PGA4311. Four channel digital over analog controller. Many interfaces use the two channel model, the 2311.

The rest of the system is not critical to the crossover and DRC.

 

2012 Mac Mini, i5 - 2.5 GHz, 16 GB RAM. SSD,  PM/PV software, Focusrite Clarett 4Pre 4 channel interface. Daysequerra M4.0X Broadcast monitor., My_Ref Evolution rev a , Klipsch La Scala II, Blue Sky Sub 12

Clarett used as ADC for vinyl rips.

Corning Optical Thunderbolt cable used to connect computer to 4Pre. Dac fed by iFi iPower and Noise Trapper isolation transformer. 

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A) I am using my Macbook pro for my 2 channel music, but am in the process of setting the system up to be used with any source including my PS3, SACD Player and TV. I do not currently have much surround music content on my laptop, but will be exploring surround music besides my SACD's in the near future.

B) For my DSP, I am using REW Software through a miniDSP 10 x 10. I have an extra Behringer DEQ2496 that I am considering adding to my 2 subwoofers (that run as part of the mains and separate from the LFE channel) in conjunction with REW for better/easier control.

C) The miniDSP Software handles the crossovers.

D) I have a few ways of getting the signal to my DAC, which is the miniDSP. I have a separate Benchmark DAC1 that I will use with headphones (to use in 2 channel, of course) and may be used to control a "B Bank", but I haven't decided yet.

1. optical, coaxial & AES/EBU I/O from macbook pro and misc. sources I borrow and add in.

2. what I am adding: I am in the process of buying a surround pre/pro that will run analog outs into the miniDSP that will control active crossovers and possibly room correction (I will need to test if Audyssey does better than my measurements). With this, I will be able to run my PS3 and TV through surround 5.1 using my 2 channel.

 

F) All volume is controlled by the miniDSP- the surround pre would not do any volume control

 

I have no concern over the fact that I will have more than one D/A conversion given the loopback tests and measurements I have read of the miniDSP. The quality of the D/A and A/D in these processors will be more than good enough for anyone's purposes.

 

This is definitely not the most simple setup, it could be done much more easily if I didn't already have this gear and a sorry looking bank account, but for combining your music with home theater, this is not a terrible method.

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My system is homebrew:

 

My own software running on Windows XP acts as a real time convolution engine giving N way crossover with 'live' calculation of the filters, so I can tweak crossover frequency and slope, driver delay etc. and hear the effect. The filters are overlaid with inverse impulse response measured for each driver in the near field (using REW), plus adjustable baffle step compensation (essential I suggest). I'm not trying to to do room correction, merely to make the speakers 'correct' in themselves.

 

A single PCI Creative X-Fi sound card running in an old but silent Dell PC, acts as the destination for any music app, or can take inputs from SPDIF or line in. My software can then access that stream, process it and send out multiple processed channels to the analogue outputs over ASIO. No re-sampling is necessary as the input and output are locked to the same clock. By default the Creative drivers respond to multimedia keyboard volume. My calculations are floating point and the card is 24 bit, so I don't think I'm losing much quality using software volume control. I've tried a few cards, and the Creative is the only one so far that behaves perfectly in terms of what it does when the software isn't running, and total lack of unpleasantness at power up and down. The crossover software uses about 20% of the CPU, but this is a 9 year old PC.

 

Six analogue outputs feed three stereo amplifiers, and then my homebrew speakers: 12" polypropylene woofers in 90l cabinets, 4" polypropylene mid and 1" silk dome tweeter in separate smaller cabinets, all sealed.

 

As far as I can tell, it's a 100% success (I would say that wouldn't I!). In terms of convenience, I press the PC power button and all the apps load at startup (or left running at the last hibernate). I turn on the three amps. Select a track and press play, and that's it. My software is 'transparent' and runs all the time, so any and all multimedia apps will be heard through it. I favour a more complex crossover filter, so latency would be a bit high for video, I fear - I'm happy with just using the system for music. Obviously I could have as snazzy a media player as you can get, but I have a soft spot for Spotify (pay extra and you can have 320 kbps Ogg Vorbis which is pretty acceptable). Spotify responds to standard multimedia Stop, Play, Pause etc. so using a wireless keyboard it's all very convenient. You could probably do it all with your mobile phone if you knew about that sort of thing.

 

I don't know if you're familiar with the sound of active crossovers yet, but it is certainly worth it (an understatement). If I had tried to build my own passive speakers it would have been a disaster, but doing it actively there is little mystery or black arts involved: make a swept sine measurement of each driver to use for inverting the impulse response, select the correct crossover frequencies based on rule of thumb or where the responses aren't yet wobbly, set the delay for each driver based on its distance from the listener and set the amp volume levels by ear by playing a sinusoidal tone at each crossover frequency and alternating between the two relevant drivers in each speaker, listening and bobbing about a bit to get an average level without room effects. Adjust baffle step compensation to taste. No need to touch the settings again - but you will again and again until you think you've got them just right! Forget all the awful so-called 'high end' speakers you've heard: DSP active speakers are phenomenally clean, rich and powerful. Amaze your friends!

 

I would happily give you the software, but there's a lot of hard-coded stuff in there at the moment. I'm gradually working around to a nice GUI and all that. There must be off-the-shelf alternatives out there, but maybe not quite as tweakable at run time. Once you've got your ideal settings, it doesn't matter anyway.

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  • 4 weeks later...

I can be considered to have cheated by buying Genelec's top active studio monitors (8260) with direct digital input and build-in DSP room correction:

 

a) MacBook Pro i7 quad with 16GB ram + 128GB SSD + Promise Pegasus 6 x 1TB RAID 5

b) DSP is build into my speakers

c) Active crossovers are also build into my speakers

d) MBP - Firewire - Weiss AFI-1 DDC - AES/EBU (professional standard of S/PDIF) -> SUB with digital X-over -> DACs build into speakers

e) Volume is controlled directly in the speakers via secondary network card: USB -> network card -> RJ45/CAT 5 network cable (proprietary protocol)

I use the Griffin PowerMate through USB as volume knob.

 

powermate-3.jpg

 

Works like a charm for CA.

 

 

8260 front-back.jpeg

Promise Pegasus2 R6 12TB -> Thunderbolt2 ->
MacBook Pro M1 Pro -> Motu 8D -> AES/EBU ->
Main: Genelec 5 x 8260A + 2 x 8250 + 2 x 8330 + 7271A sub
Boat: Genelec 8010 + 5040 sub

Hifiman Sundara, Sennheiser PXC 550 II
Blog: “Confessions of a DigiPhile”

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Pete... a question for you...

 

Your multi-channel Genelec - do you use it for HT use or purely music?

Eloise

---

...in my opinion / experience...

While I agree "Everything may matter" working out what actually affects the sound is a trickier thing.

And I agree "Trust your ears" but equally don't allow them to fool you - trust them with a bit of skepticism.

keep your mind open... But mind your brain doesn't fall out.

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Pete... a question for you...

 

Your multi-channel Genelec - do you use it for HT use or purely music?

 

My rig is build for music but I also use it for HT.

Out of preference I always use my 15,4" MBP as screen despite a fine projector.

I have an external Bluray player from OWC on firewire for all ripping and some playing.

Promise Pegasus2 R6 12TB -> Thunderbolt2 ->
MacBook Pro M1 Pro -> Motu 8D -> AES/EBU ->
Main: Genelec 5 x 8260A + 2 x 8250 + 2 x 8330 + 7271A sub
Boat: Genelec 8010 + 5040 sub

Hifiman Sundara, Sennheiser PXC 550 II
Blog: “Confessions of a DigiPhile”

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