Next level Active DSP Crossover

I'm currently multi-amping my LaScala clones, using a Dayton Audio DSP-408 active crossover. There is a lot to like about it in terms off functionality: 4 channel in, 8 out; 10 bands of parametric eq per out, up to 24db Linkwitz-Riley/Butterworth/Bessel filters and a 20hz-20kHz response. It had a decent UI, with bluetooth/iOS connectivity and a windoze interface, as well. However, I would like to improve the noise floor, is has a slightly perceptible hum that is present when music isn't playing. It's entirely single-ended, but I would prefer balanced, at least as an option. Finally and this is the biggest issue for me: the DAC is limited to 48Hz, 28-/56 Bit processing, which regardless of whether it's audible or not, effectively nullifies my Schiit Audio Bifrost 2's 192Hz, 24 bit capabilities for hi-res audio file playback.

What options are available to maintain the functionality aspects that I like about the Dayton Audio DSP 408 (ins, outs, 10 band PEQ, filters & frequency response, ui and relative affordability) with better processing, at least 96Hz/24 bit, but preferably 192Hz, 24 bit, balanced inputs and outputs? I know there are pro options from companies like Ashly that are more expensive than I'd prefer and more affordable pro options from dBX, Behringer and others skimp on PEQ, or ins/outs and/or have poor UI functionality... I'd prefer to keep in the $500 ballpark (I'm ok with used components) and this is a big ask, have either iOS or Mac OS UI.

can this be done?

IMG_6253.jpeg
 
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I think the closest you’ll get is the MiniDSP Flex Eight, but that is SE output.

Thinking a little outside the box, you could possibly combine MiniDSP Flex balanced 2x4 for DSP EQ, then out to balanced active crossovers like Xkitz… But that may not meet all your needs.
 
I’m not convinced that the mini DSP is significantly better- the lack of analog inputs is a step back

See https://www.diyaudio.com/community/...lee-acoustic-performance.396074/#post-7570882 for more discussion on the now-available miniDSP Flex performance (albeit with balanced connections and Dirac Live installed).

We found out that the one thing about the Flex that you can't really use with extremely high efficiency loudspeakers (i.e., fully horn loaded, like yours shown above) is the analog inputs--they sound horrible on a Heritage Jubilee. But note that the S/PDIF digital inputs (including TOSLINK optical) that also come with this unit haven't been tested yet. The person that I helped recently to replace the fixed Heritage Jubilee crossover (which has its own issues) didn't have a digital out on his preamp/processor, so he had to use balanced analog inputs. I really couldn't listen to the Flex's performance--it was that bad.

I think you're asking for unobtaium with your constraints. The better DSP crossovers define themselves by their low noise and hi-fi outputs, and they simply cost more. Think of this like acquiring tube amplifiers: you might get away with low-cost tube SETs, etc., but their limited output transformer size will come back to bite you.

I'd recommend thinking about this using a different paradigm. If you have extremely high efficiency/high performance horn-loaded loudspeakers, I've found that getting the on-axis SPL response flat to within ±2 dB (using psychoacoustic smoothing) across the board, and also getting the time alignment of the drivers to achieve flat phase to ±90 degrees (again using psychoacoustic smoothing) is a key enabler to a threshold of hi-fi performance that others have only heard using high-dollar electrostatics and certain very high dollar full-range drivers, in addition to all the other positives that fully horn loading brings to the table. Instead of thinking about inexpensive DSP crossovers, think first about getting a DSP crossover that has the required performance, then think about amplifiers and preamps. In other words, stop trying to use cheap DSP crossovers. If you can find one that has hi-fi sound and extremely low noise that also is lower cost, that's great, but I haven't found one yet (and I've tried a few over the years).

In reality, DSP crossover performance for use with fully horn-loaded loudspeakers (including MEHs) is a subject that the low-efficiency direct radiator loudspeaker crowd simply do not understand. The same thing goes for amplifiers having extremely good "first watt" performance--something that I found that many, many amplifiers used by the direct radiator crowd don't have... (Just ask me about my Hypex FusionAmp experience, for example.)

The problem now is the Xilica XP/XD series is apparently no longer being offered from Xilica. You have to increase your spending to Xilica Solaro levels (i.e., around $2K--$2.5K), which is on par with higher quality used amplifiers from Nelson Pass' First Watt, etc. You might get good enough performance using a lesser DSP crossover, but I think you're going to spend a lot of money along the way (money lost even if you resell the equipment) if you keep trying to find that cheap magic bullet of a DSP crossover. They apparently don't really exist yet for fully horn-loaded loudspeaker use. If I find one, I'll let you know, but I haven't found one recently.

Chris
 
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Try to look for Symetrix DSP. Balanced IO, 8x8 and nice specs. The only downside is noisy cooling fan - so it would require a bit of work - to install a larger one. Another slightly annoying thing is that ot uses Phoenix type connectors.

Used can be bought for less than 200 USD. For 500 USD you can find the newer models like Solus 16. I have a Cobra 8x8 that I tested briefly and is currently waiting for new amps to arrive.
 
My experience is that consumer audio DSP's biggest issue is the relatively low voltage I/O that they typically operate at, compared to proaudio.
I've found gain staging to be the culprit behind hiss or hum, far more often than ADC or DAC quality.
Same thing can be said for overall sound quality too.

So my advice is look for whatever used proaudio DSP fits budget and has the I/O counts and functionality you need.

And I know this will get me ignored, but I think high-rez sample rates, rank well below proper gain staging too.
(which makes shopping for a suitable DSP easier).
I'm quite happy using a processor fixed at 48kHz, and don't even bother to integrate my higher rez DACs (up to 384kHz)
 
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I have managed +/- 3dB the the Dayton, from 23Hz to 20kHz
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I've also got my time alignment fairly well sorted
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while $500 is my platonic ideal, I'll accept that I may have to spend more, but my diy Lascala notwithstanding, my most expensive components list between $1100-$1350, so I suppose that's a psychological price barrier for what I'm willing to spend for a crossover.
in a perfect world, I'd love a solution that would allow me to use, say, an 8-channel digital audio interface, such as a Zoom TAC-8 (which I already have in my recording studio) or a Focusrite Scarlet 18i20 which are readily available for around $500 and a Mac-based DSP software solution, since I'm already using the MacBook Pro for a streamer. It should be possible to use the hardware in this manner, provided there is suitable software available.
 
I have managed +/- 3dB the the Dayton, from 23Hz to 20kHz...
Here's what I've learned about displaying plots in REW:

1) show SPL/phase plots with vertical resolution in increments of no greater than 1 dB (minor scale) and 2 dB major scales. Then you can actually see what you've got.

2) The spectrogram view should have no more than 10 ms displayed horizontally when looking for the degree of time alignment of drivers/horns.

3) show an excess group delay plot within the "GD" (group delay) plot, which is available after selecting "generate minimum phase" from the "Controls" menu on the upper right on the plot, then checking the "excess group delay" check mark below the plot. Make sure that the vertical scale on this plot is no larger than 10 ms full scale.

My experience is that consumer audio DSP's biggest issue is the relatively low voltage I/O that they typically operate at, compared to proaudio.
I've found gain staging to be the culprit behind hiss or hum, far more often than ADC or DAC quality.
Same thing can be said for overall sound quality too.

So my advice is look for whatever used proaudio DSP fits budget and has the I/O counts and functionality you need.
Yes, but note that the price pretty much doubles (to about $3.5K-$4K) to own and use what you currently use. That's probably the chief reason why few, if any, are joining in with you (IMO).

But what you say above (in the quote box) is pretty much what I've found, too. The signal voltage levels are usually pretty low, and if you're using a Xilica (a piece of pro gear), you're usually only using the lower range of input signal voltages if driving using a consumer quality preamp. It's better to use a preamp/processor that has a fair amount of gain, and set up your gain structure using that increased dynamic range of gain available.

And I know this will get me ignored, but I think high-rez sample rates, rank well below proper gain staging too.
(which makes shopping for a suitable DSP easier).
I'm quite happy using a processor fixed at 48kHz, and don't even bother to integrate my higher rez DACs (up to 384kHz)
I've tried several DSP crossovers that operate at 48 kHz and those that operate at 96 kHz internal sampling rate (including the Xilica XP/XD series and miniDSP 2x4 HD). In my experience, this is audible (increased snap and clarity) and the reason why I won't choose to go back to using 48 kHz in the future.

This is just like the difference in listening to 44.1 kHz CD files and higher sampling rate/bit depth higher resolution music files. Their sound is especially more "solid" on the decays.

But I'm not listening to these devices or recordings using direct radiating loudspeakers having significantly lower sensitivity/efficiency. The loudspeakers with which I listen to hear these differences are high efficiency full-range horns that have been carefully dialed-in in-room using 1 metre microphone measurements. These setups present a clarity at volume that is unmatched by any other loudspeaker technology that I've heard. I find that these differences become too small to hear using direct radiating loudspeakers (including direct radiating woofers).

YMMV.

Chris
 
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What's your music source? As long as you only use hi-rez streaming and don't need analog inputs (e.g. vinyl) you can use a PC (Apple Mac) HDMI out to a home theater receiver. If you want to use an infrared remote control with your PC to control volume or play/pause etc. you need an IR input such as a FLIRC USB dongle.

PC to Home theater receiver via HDMI is a full digital path all the way to DACs then sent to multiple channels of amplification. No ADC to DAC in the chain. Then you use the home theater amplifiers to individually amp your drivers.

If you must have analog inputs you'll need to add a USB or Firewire (Apple Mac) audio interface to your computer. Something like a $200 Motu M2 or similar/less expensive option. An audio interface also allows you to use your own discrete amps if you don't want the HT receiver amps (like if you need more power than your HTR can supply). Some HT receivers also have pre-outs that will allow you to use discrete amps but the outputs aren't (usually) balanced. On the other hand, USB/Firewire audio interfaces with 8 balanced outputs can be expensive.
 
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The next step from traditional individually amped DSP crossovers is to move toward convolution file crossovers. I've attached instructions on how to do that using VituixCAD and Equalizer APO to give you a general idea of how you'd approach something like that.
 

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I've found gain staging to be the culprit behind hiss or hum, far more often than ADC or DAC quality.
Same thing can be said for overall sound quality too.


And I know this will get me ignored, but I think high-rez sample rates, rank well below proper gain staging too.
You are spot on Mark. The DSP is often blamed when it is actually the gain plan that is at fault.

I built power amplifiers with very low gain to match High Efficiency speakers in my own system so I could set the gains correctly.

The DSP and the power amplifiers should be approaching clipping at a level that is sensible for the target maximum output level of the system.
 
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Yes, but note that the price pretty much doubles (to about $3.5K-$4K) to own and use what you currently use. That's probably the chief reason why few, if any, are joining in with you (IMO).

It's a shame if that's what folks think about price.

The market on ebay for used Q-Sys hardware is pretty active, and with patience and diligent monitoring Cores can had quite reasonably. The Core 510i I'm now using cost me $1300, and came with a 64 ch Dante card, and 16x12 analog I/O.


I've tried several DSP crossovers that operate at 48 kHz and those that operate at 96 kHz internal sampling rate (including the Xilica XP/XD series and miniDSP 2x4 HD). In my experience, this is audible (increased snap and clarity) and the reason why I won't choose to go back to using 48 kHz in the future.

This is just like the difference in listening to 44.1 kHz CD files and higher sampling rate/bit depth higher resolution music files. Their sound is especially more "solid" on the decays.

Yeah, I know I stand fairly alone on the (lack of) importance regarding sampling rates.
I've tried a bunch of comparisons too, both speakers and headphones. Different DACs at different sample rates, different source material rates, same DAC at different sample rates. Yada yada.

I think the basic quality of a recording dominates all that by so much, that samping rate of either the source material or the processing becomes too trivial to care about. But that's just me.....


But I'm not listening to these devices or recordings using direct radiating loudspeakers having significantly lower sensitivity/efficiency. The loudspeakers with which I listen to hear these differences are high efficiency full-range horns that have been carefully dialed-in in-room using 1 metre microphone measurements. These setups present a clarity at volume that is unmatched by any other loudspeaker technology that I've heard. I find that these differences become too small to hear using direct radiating loudspeakers (including direct radiating woofers).
Hmmm.... I'm running very high efficiency speakers too....fully horn loaded, (including horn loaded subs at times with greater efficiency than anything I know of from Klipsch).
I think I hear unmatched clarity too, both indoors and especially outdoors :)

Maybe I'm just a bit deaf re sample rates. (But I'm not about to tell someone else what they can or can't hear.)
 
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built power amplifiers with very low gain to match High Efficiency speakers in my own system so I could set the gains correctly.
Yes, I use Nelson Pass' First Watt F3 for the compression drivers (two-way) on the 1st-gen Jubilees which has very low gain. Pretty much the same thing for the bass bin amplifier: a Crown D-75A. Works great.

Chris
 
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Before you buy something else, have you tried using balanced conductors?

Even though your DSP has single ended outputs, I have had to do this because all my amps require XLR inputs.

I find them quite effective at rejecting noise. I don’t have horns but my midrange is 100+ dB/2.83V.

These easiest way to do this is to buy pre-made long XLR cables, snip then in half, and attach RCA connectors of your choice to each end.

See attached wiring scheme.
IMG_0149.jpeg


Reference:
https://www.diyclassd.com/media/85/b5/1c/1646058855/NC400_04xx.pdf
Page 9
 
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You are spot on Mark. The DSP is often blamed when it is actually the gain plan that is at fault.

I built power amplifiers with very low gain to match High Efficiency speakers in my own system so I could set the gains correctly.

The DSP and the power amplifiers should be approaching clipping at a level that is sensible for the target maximum output level of the system.

Yes sir. I like to keep amp gain as low as possible too, to match up with high-efficiency ....I mean heck, we have to huh?

And I really like how line level pro gear has gain staging adjustments all along the way to help with the matchup, ......analog in, digital in, digital out, analog out....
 
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I think it's wise to limit the drift in the conversation to DSP crossovers driving fully horn-loaded loudspeakers.

I know everyone wants to talk about other subjects than what the OP does, but in this case, I think it's important to stay on topic, because I think many people are lurking, looking for an answer to this question.

Note that the OP actually disallowed PC-based DSP crossover solutions...and coding via PC, etc. in his original question. I think it's courteous to respond with that constraint in mind, since so many others that I've talked to seem to have the same constraint (i.e., they want a dedicated plug-and-play DSP crossover).

Chris
 
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