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What Bass Mgmt. & Room EQ Scheme For Me?

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Thanks guys for your feedback on DEQX, Hapi and other schemes, though which among others won’t seem to offer complete success. Either their DACs have been said not to sound as good as many other standalones or they don’t have the connectivity I may need. 


I have a passively crossed two way speaker system. Knowing the designers as I do, I don't think these speakers suffer much group delay. The sealed midwoofers acoustically roll off soon below 70Hz. I want to build a pair of passive subs for below the midwoofers. Those subs will have paper cones and may be either sealed or dual driver H or W-frame or slot-loaded open baffle subs. Though this system's for music only, if I go with OB subs they may not have quite the desired bass extension, so I would want to blend my pair Rythmik 12" sealed servo subs below them. In any case, I also want to use the Rythmik subs since 3 or 4 subs-particularly in my small 14 ft x 19 room-should yield a flatter low frequency response, as Earl Geddes and JBL have long independently concluded.  


My Rythmik subs have true balanced inputs which is fortunate since for proper placement they will likely require cables of about 30 feet.


My Windows laptop (or desktop) is my music server. While I'm sure there are some decent sounding desktop cards today, standalone DACs world likely offer a much lower noise environment for the DAC’s clock than inside a desktop chassis, along with more room for much better circuitry. And I'd prefer to use my laptop rather than my desktop.


My plan was to purchase a respectable sounding DAC (e.g. Exasound, Bryston, PS Audio), use its balanced outs to feed the Rythmik subs and wye-connect the unbalanced outputs to feed my mains amp and the amp driving the passive subs.


The Rythmik plate amps have LP filters at two slopes, phase, level, along with EQ if needed. But plate amps being what they typically are, I want to use the Rythmiks for below an upgraded Bryston stereo power amp driving the passive subs. That way the plate amps won't color the sound of my 300B SE tube amps driving my mains.


But how then do I get the same control functionality for the passive subs as in the Rythmik sub plate amps-and do so while keeping signal processing and signal path length to a minimum for best sound quality? Page 28 here says that I could feed digital audio from my laptop to this via USB. http://www.dspeaker.com/fileadmin/datasheets/dspeaker/AntiMode20DualCoreEng.pdf And many standalone excellent DACs have USB. Then the Dspeaker Dual Core's RCA outputs connect to the amps driving the passive subs. Plus with this arrangement only one digital conversation needs to occur. And Dspeaker's electronics probably sound good enough to do room eq at least for below my midwoofers, where most room resonances are strongest anyway.


But what kills that plan is that the digital audio received by Dspeaker and the system’s main DAC from my laptop via USB would need to be clocked simultaneously. But Dspeaker has no clock input, nor do any of these boxes with digital inputs. https://www.minidsp.com/products/opendrc-series/summary-table And except for a few (e.g. Antelope) most DACs don't either.  Even if they did have clock inputs, a good clock generator may cost as much or more than a ~ $4K DAC. Or am I wrong and would the Dspeaker Dual Core do exactly what I want without an external clock?


Then I thought of Merging Technologies' Windows compatible Hapi box, as suggested here and elsewhere. Used by the mastering house that digitizes classical analog recordings sold at stores like hdtracks.com, the quality of its optional DAC is probably nearly    as good as its optional A/D converter. And its output connectivity should work for me. https://vintageking.com/merging-technologies-hapi But it’s only available as an 8-channel box and contains no DACs. And ALL 8 DACs are all on one board.       Thus, with the box, the board and breakout cables I'd be paying for twice as many DAC channels as I need. Plus, it has no USB input, and an AES3 desktop (or laptop?) card to output digital audio to it via my pc would cost at least another $400.


ARRRGGGHHHH!!! I can’t believe that after all these years the computer audiophile market still leaves most of us having to dance that accursed A/D, D/A two-step with this http://www.dspeaker.com/en/products/anti-mode-8033.shtml  or one of these analog input boxes. https://www.minidsp.com/products/opendrc-series/summary-table


Be that as it may, with Dspeaker or miniDSP AD/DA almost everything’s in the box and the software might be bundled tightly enough with the hardware making it relatively easy to use. But the only real consolation is that I'd be using either one for bass management and for room eq ONLY below my midwoofers. That way its twice-told digital conversions won't spoil what's feeding and pushing my main speakers. 


However. even consenting to use either of these two clunky A/DD/A boxes, I still can't determine which one has the better converters and which might give me the shorter and cleaner sounding signal path, while meeting at least most of my functionality goals. 


Or which other A/DD/A box might be a better sounding and/or functional choice? https://www.google.com/search?q=a/da+converter&num=100&source=lnms&tbm=shop&sa=X&ved=0ahUKEwiUs9bexP7TAhWBYyYKHXuKBWAQ_AUICigB&biw=939&bih=437


But how compatible would those presumably better sounding AD/DA models be with what kind of bass management software and “user friendly” room eq software for home use discussed here?


Speaking of software, DIRAC subwoofer management apparently is licensed or is otherwise compatible with miniDSP. It seems easy enough to learn. https://www.minidsp.com/applications/home-theater-tuning/multi-sub-optimization-with-the-ddrc-88a . But as most of you probably know, another compatible alternative to use with miniDSP boxes is http://www.audiovero.de/en/acouratedrc.php But I’m doubtful if I could scale Acourate’s learning curve well enough. And REW also looks a little scary https://www.minidsp.com/applications/auto-eq-with-rew without a lot of help from here at this thread and places like here https://www.avnirvana.com/forums/official-rew-room-eq-wizard-support-forum.10/


Unless there's a better sounding hardware solution, besides DEQX?


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Let me see if I have this correctly: 


1. You own a pair of passive 2 way speakers, and wish to leave the standard crossover in place. 

2. You wish to integrate two Rythmik subs into this system, using the standard Rythmik plate amps. 

3. You wish to avoid AD/DA conversion. 

4. You did not mention a file format preference. I assume that 44.1kHz is OK for you.


The SIMPLEST solution for you would be this: 


- PC source* --> (output via USB or CAT5e network)

- four channel DAC --> 

- four power amp channels --> speakers


* The PC source has to run convolution software, e.g. HQPlayer, AcourateConvolver, JRiver, or Roon. You would have to generate filters using one of the methods you listed. 


The problem, as you mention, is the four channel DAC. They either don't exist, or are very rare. You would have to buy either a 6 or 8 channel DAC and live with the fact that you have a few unused DAC channels. Suitable candidates would include anything from the pro audio world.


Alternatively, if you wanted to open the door to high end DAC's, you could do this: 


- PC source --> 

- Pro audio sound card with digital out (e.g. http://www.rme-audio.de/en/products/hdsp_aes32.php --> (output via AES/EBU)

- two 2 channel DAC's --> 

- four power amp channels --> speakers


Theoretically the RME has a clock built in, so it can synchronize the two DAC's. But it may be better to select DAC's which have clock input so that you can externally synchronize them if you wish. The downside of this solution is that the RME can not pass DSD. It may or may not be able to pass DoP. 


If you are after a hardware solution, you could do this: 


- PC source --> 

- digital box of tricks* --> 

- four power amp channels --> speakers


Suitable "digital box of tricks" includes: 


- DEQX - http://www.deqx.com/

- MiniDSP - http://www.minidsp.com/

- Illusonic IAP-8 - http://www.illusonic.com/audio-processors/iap-8/

- Lyngdorf - http://www.lyngdorf.com/

- KRK Ergo - http://www.krksys.com/

- Audyssey - http://www.audyssey.com/


All of these have built-in DAC's, but some may be able to output digital so that you can use an outboard DAC. 


I hope this answers your question. 

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Also, re: the learning curve of DSP software. The steepest part of the curve is understanding the underlying concepts and how to interpret what the software is telling you.


Once you understand this, the difference between software comes down to the interface and how many options they give you. Some software (e.g. Acourate) has a non-intuitive interface full of options and rather obscure sounding options, at that. But it is by far the most versatile and powerful product. Others (e.g. DEQX) gives you fewer options and is easier to get started. 

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The other option is a standard 2 channel dac feeding a preamp with multiple outputs. 1 set to your power amp / passive speakers and the other to your subwoofers. Obviously this will only work if you plan on running your speakers full range and use the subwoofer to fill/augment the deep bass using the plate amp controls. Finally polish it off with some form of software based DSP / room correction applied to all the drivers as a whole.

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Another option is connect the subs speaker-level input, and then do everything in the digital domain with something like Dirac or one of the other room-correction options.  


I think you are right to skip multiple digital/analog/digital/analog conversions.

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