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Multi-channel preamp/processor for multi-way active system

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#1
First of all, a massive thank you to everyone who contributes to this forum.

You probably saved a lot of $$$ for many users and most important alert many of us before any purchase decisions.

I currently have very simple system but trying to build something more complex and have a play with different combinations, and need some advises.

Currently my system is based around TV.
I am not interested in any modern fancy formats, home theatre and only listen to stereo.

PC / SATBOX / Blu-ray via (HDMI) -> TV (spdif optical)-> NANODIGI (COAX)-> WADIA POWERDAC 151

I use nanodigi to do a simple freq correction, 1st at input level (5PEQs) and then again 5PEGs at output channel.

I have already bought 3 generic Khadas tone boards + 2x 3eaudio TPA3251 3 channel amps that will be powered by 2x HLG-240H-36A Meanwell PS. Plan is to remove passive xover from my current speakers and do it all active.

Before I decided to buy khadas&TPA board I tried active solution with 3 digital amplifiers (wadia 151 ,fx audio d2160 ,sabaj a4) I did set all 3 amplifiers to same output level and then controlled volume with nanodigi master volume.

I couldn’t resist and I as a bargain I bought "faulty" (something wrong with HDMI inputs that im not bothered about) Rotel RSP-1570 that will work only as a multichannel preamp/volume control (will be used only with 6 channel input and preouts)

Can you recommend some multi-channel processors / preamps that would suit best for this task?

I checked some specifications of other similar products from Onkyo, Pioneer, Arcam etc where Signal to Noise Ratio varies from 94 to 100db in analogue bypass.

I would appreciate some suggestions.
Thank you
 

somebodyelse

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#3
It's not clear, to me at least, exactly what it is you're after. Is it just analog volume control between the DACs and the power amps? What's wrong with the nanodigi master volume, or the khadas volume? From what I've seen in other threads the multichannel processors are either monstrously expensive or underperforming.
 
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Thread Starter #4
I used to use nanodigi volume control when 3 digital amps were acting as "power amps" - I did set same output level/volume on those amps to maximum level I would normally listen and then have volume control on nanodigi.

Without having volume control on power amps I think it would be most appropriate to have some kind of multi-channel pre amp between 3 dacs (khadas tones) and TPA3251s (power amps)

I do not want to use nanodigi master volume control as the only volume control as there would be to much attenuation and by the way volume control is not smooth on this device and changes to quick.

It will be 3 way full active system.

the other processors/preamps i looked into are:

Parasound Halo P7
Arcam AV9
Myrand MDP 500

or something simple as below:
PGA4311
https://www.ebay.co.uk/itm/HiFi-PGA4311-Audio-8-Way-Single-ended-4-Channel-Balance-Volume-Control-Board/253270148715?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649

PGA2311 x3
https://www.ebay.co.uk/itm/HIFI-PGA2311-x3-Volume-Control-Preamplifier-6-channle-Input-Preamp-Low-distortio/133206609491?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649
 
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andreasmaaan

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#5
@mixMZ your highest-fidelity option will theoretically be to use the internal volume control in the ESS chip in each Tone Board. This ESS9038Q2M datasheet, which I found on the Khadas website (despite puzzlingly being marked "confidential") suggests that it can be done, although I wouldn't be the person to work out how...

EDIT: in terms of standalone multichannel preamps, the Benchmark LA4 would be hard to outperform, but is ofc very expensive.

Based on Stereophile measurements of the Parasound P5, I suspect the P7 would also perform quite well. The Myryad has also been measured by Stereophile but appears to fall somewhat short of the similarly-priced LA4 on performance.

EDIT2: I'm not sure if you've already found the spec sheets for the PGA4311 and the PGA2311. I guess it's hard to know how close to the spec'd performance those eBay boards you linked would get.
 
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somebodyelse

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#6
The Tone Board volume can be controlled via the XMOS GPIO pins exposed on the 30 pin FPC connector as detailed in the hardware volume thread of their forum. If you're not happy soldering tiny things like that you can get an FPC cable and an adapter board (example only - I've not checked this is the right connector!) If you buffer a single button to all three boards the volume _should_ stay in sync...probably... Or you can control it directly via i2c as in the datasheet above as mentioned earlier in that thread, and be certain what volume each one is set to - see the datasheet @andreasmaaan linked. Or via USB while using the GPIO header to keep using the SPDIF input - perhaps from a Pi? So many options!

You could always DIY a multichannel analog volume control since you seem to be doing a fair bit of that anyway. Bruno's design in The G Word might be a good starting point if you want one that's been measured. Gerbers for it are at linearaudio.net along with a stepped volume control you can use with it instead of a 6-gang pot.
 

Kal Rubinson

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#7
EDIT: in terms of standalone multichannel preamps, the Benchmark LA4 would be hard to outperform, but is ofc very expensive.
This is a 2-channel preamp. You will need 3-4 for multichannel. See: https://www.stereophile.com/content/benchmark-la4-line-preamplifier-multichannel-application
Based on Stereophile measurements of the Parasound P5, I suspect the P7 would also perform quite well. The Myryad has also been measured by Stereophile but appears to fall somewhat short of the similarly-priced LA4 on performance.
The Parasound P7 is excellent as long as you are OK with unbal/RCA inputs but the P5 is 2-channels only.
 

DWPress

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#8
I use a MSB MVC-1 which is an 8 channel volume control device between my MiniDSP 4x10 and the amps for my active XO (W,M,T + 3 subs) the same way Siegfried Linkwitz used it. There are no other analog inputs like a preamp just volume control but it sounds like what you're looking for. Unfortunately, I don't think they're made anymore but I'm considering going in a different direction and might be selling the MVC-1 if you're interested.
 

Kal Rubinson

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#9
I use a MSB MVC-1 which is an 8 channel volume control device between my MiniDSP 4x10 and the amps for my active XO (W,M,T + 3 subs) the same way Siegfried Linkwitz used it. There are no other analog inputs like a preamp just volume control but it sounds like what you're looking for. Unfortunately, I don't think they're made anymore but I'm considering going in a different direction and might be selling the MVC-1 if you're interested.
Is it the basic one or the balanced setup?
 
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#12
@mixMZ how are the 3e audio amps? Given the other eBay cheap class D amp reviews on this forum, I'm a bit sceptical on chifi spec sheets now. Do you have a way to verify performance?
 

somebodyelse

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#13
@mixMZ how are the 3e audio amps? Given the other eBay cheap class D amp reviews on this forum, I'm a bit sceptical on chifi spec sheets now. Do you have a way to verify performance?
Unlike the cheap eBay class D amps, 3e publish AP plots that aren't lifted from the datasheet of the chip. It would be good to see some independent measurements though.
 

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