Quality DSP for 4-way: DEQX, miniDSP, Motu or else?

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#21
DEQX as DSP plus external DAC's

JonBocani said:
( i can also install the dig out optionnal board on my DEQX)
Click to expand...

Hi Jon,

In my experience this would be your best bet.
Use the DEQX DSP and digi out to feed your own your own DAC's.

You can optimise the DAC's to match the DEQX digi out electrical spec. ie higher voltage out on the balanced digi out, or go the whole hog and cut into the traces to access the I2S lines.....This I2S option requires NDA's and OEM MOQ of boards.

I advise battery power for the DEQX DSP and DAC's, the DEQX power supplies are a limiting factor and most DAC's.

A battery powered DEQX with high end DAC's (and an A to D if you have analog source) is a formidable beast!

If you dont fancy all that work and expense, keep your eyes peeled for a used Dolby Lake processor....Its the only unit I have heard that outperforms the standard DEQX by a significant margin.....

However a fully tricked out battery powered DEQX with high end DAC / A to D pack does beat the Lake.
Now a battery powered Lake with high end DAC's....???!!!

Hope that helps and good luck
Derek.
 
#22
Hi Derek,

I think it make sense.

However, i had the unfortunate pleasure, yesterday, to audition few DACs... One of which was a dCS Debussy.

Sounded so good... But how could i buy 4 of them, really ? haha

That is the problem: 4-ways = 4x DACs. And i don't find any good solution that is cheap.
 
#23
One thing to keep in mind is inter channel delay. The FIR brick wall filters used in the DACs of the minidsp and the deqx will all have different latencies and this will mess up driver integration if you're using both platforms at once. You'll need to re time align everything for proper integration if you go this route.

I don't know what DACs and analogue stages the deqx uses but most certainly the minidsp ones are cost effective rather than state of the art.
 
#24
JonBocani said:
Hi Derek,

I think it make sense.

However, i had the unfortunate pleasure, yesterday, to audition few DACs... One of which was a dCS Debussy.

Sounded so good... But how could i buy 4 of them, really ? haha

That is the problem: 4-ways = 4x DACs. And i don't find any good solution that is cheap.
Click to expand...

A good DAC for 8 channels would be a properly configured and implemented ES9018. If you can find some multichannel box that uses one, with discrete digital inputs this would be one way to go.
 
#27
5th element said:
One thing to keep in mind is inter channel delay. The FIR brick wall filters used in the DACs of the minidsp and the deqx will all have different latencies and this will mess up driver integration if you're using both platforms at once. You'll need to re time align everything for proper integration if you go this route.

I don't know what DACs and analogue stages the deqx uses but most certainly the minidsp ones are cost effective rather than state of the art.
Click to expand...
i can manually adjust the delays on the DEQX. But it's one way, of course.
 
#28
as some one said, if you are made of caviar you might wanna consider 4 of these

Mola-Mola DAC

DAC Option
Inputs
" XLR, Optical, USB and Bluetooth (A2DP)
Supported formats
" PCM up to 384 kHz /32 bits (>192 kHz and >24 bits
only via USB)
" DSD up to quad speed (DDSD and up only via USB)
Performance
" Full-Scale Output Level: 20 dBu
" Signal to Noise Ratio: 140 dB
" THD, IMD: not measurable (estimated -150 dB).
" Bandwidth: Up to 80 kHz. Choice of sharp or slow
upsampling filters, minimum or linear phase.
"
Integrated jitter: <1 ps from 10 Hz upwards, <300 fs
from 1 kHz upwards.
" Jitter rejection: >80 dB at 1 Hz after 20 seconds of
lock.
 
#31
5th element said:
One thing to keep in mind is inter channel delay. The FIR brick wall filters used in the DACs of the minidsp and the deqx will all have different latencies and this will mess up driver integration if you're using both platforms at once. You'll need to re time align everything for proper integration if you go this route.

I don't know what DACs and analogue stages the deqx uses but most certainly the minidsp ones are cost effective rather than state of the art.
Click to expand...

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delay difference between linear phase ja 2nd LR xo´s

they sound soo different
 
#32
If the (DEQX/miniDSP) FIR filters are programmed with the same sampling rate, number of taps, etc, etc, they should have the same latency, no??

Dave.

5th element said:
One thing to keep in mind is inter channel delay. The FIR brick wall filters used in the DACs of the minidsp and the deqx will all have different latencies and this will mess up driver integration if you're using both platforms at once. You'll need to re time align everything for proper integration if you go this route.

I don't know what DACs and analogue stages the deqx uses but most certainly the minidsp ones are cost effective rather than state of the art.
Click to expand...
 
#33
as of now, what i'm planning to do is the following:

Source to DEQX dig in (SPDIF)
DEQX dig out (low) to nanoDIGI
nanoDIGI then splitted outs for Midbass and Subs to 2 DACs
DEQX dig out Mid/hi to external DACs
OR i keep one or both Mid/Hi from the DEQX and uses the analog out

Will i have compatibility problems, latency, etc.. I don't know.
 
#34
Davey said:
If the (DEQX/miniDSP) FIR filters are programmed with the same sampling rate, number of taps, etc, etc, they should have the same latency, no??

Dave.
Click to expand...

No I am talking about the inherent delay inside the DAC chips. PCM1792 = 55 sample periods PCM1795 = 38 sample periods. Unless corrected for this difference would totally screw up your phase integration between drivers.
 
#35
Latency & clocking

Hi Jon,

It will be interesting to test different options and with your high resolution speakers and amplifiers you are well placed to hear the differences that more modest systems would mask.

In theory every DSP / DAC / A to D will have different processing times and this will result in distortion ie blurred transients / ghost echoes.

The processing times can vary a lot when you start mixing older budget processors with current high end processors....Also the features and capability of the more advanced units will lead to longer processing times.

So worst case if you had a 10 year old processor designed as a full blown speaker management system running half your system, then a current DSP designed for fast real time crossover and Eq only the processing time difference would be very problematic...

Last potential issue is running an extra layer of processing on one half only ie Digital in to the DEQX and then Analogue in to the mini DSP....This extra A to D stage will add delay on one side only.

Your high res speakers and amps will lift the lid on Pandora's Digital box....!!😉

Cheers
D.
 
#36
The 50 samples latency at 44.1kHz sample frequency is about 0.1 ms or 3 to 4 cm driver distance.

The time delay difference between FIR and IIR filters can be ms to several hundred ms dependin on the FIR length = samples delay.
I agree with: analog low out on DEQX,analog in on minidsp and using minidsp for bass devider filtering (no other EQing).
DEQX mid and high has to be time alligned. (I assumed DEQX took care of this by default)
I have good experience with similar setup with other equipment.
The classical way of testing if a black box has impact on the sound is to make it as linear it can be, 0,0000 dB gain and insert it after the source and before the reference setup.
(Then you can assess the ADC - DSP - DAC audio quality, but not the filter quality)
For the record: I think the miniDSP dacs is as good as they need to be (read transparent) but the on/off pops is annoying on some of their equipment
 
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#37
I agree with: analog low out on DEQX,analog in on minidsp and using minidsp for bass devider filtering (no other EQing).
Click to expand...

I really don't like the double conversion, EVEN for below 800hz...




For the record: I think the miniDSP dacs is as good as they need to be (read transparent)
Click to expand...

I sure beg to differ. In fact i think it's on the same quality level that my Mac Mini 1/8 out... And i'm not kidding at all.
 
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