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Designing a practical ES9038 based eight channel DAC

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This one does 6 x 384K (I assume at 24bits, since 32bits wouldn't "fit") or 8 x 192K : XMOS Multichannel high-quality USB to/from I2S/DSD SPDIF PCB - DIYINHK

AFAIK there exists no DIY-friendly multichannel s/pdif receiver. If I had such a need I'd look into designing one with 4 x s/pdif receiver chips (like the WM8805 or the AK4113/8). I'd have one of the chips run as master and slave the rest of them to it. But that would be very, very off topic to this thread.
 
If so, then this project is not for me (and many with me, I think). It gets to complicated/unsecure to get it to work.
If TP designs this kind of little extra inputchip for PCM, then I am most probably onboard.
But I am maybe not the target group for TP anyways. I can build simple stuff like a Hypex NC400 amp, where just the right connections has to be done between components. I am not in to the more advanced DIY stuff.
 
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Here are my responses, I am interested in pre-ordering when available:

Input:

1 - What actual multi-channel source are you planning to use?
DRC and active xover upsampled to DSD via a multi-channel USB-to-I2S interface
2 - Will PCM/DSD input be sufficient?
Yes

Output:
1 - What are your ideas around the physical layout and casing?
some flexibility is preferred
2 - Do you prefer individual output boards or a monolithic 8 channel board?
no preference
3 - Do you value absolute fidelity(floating - mercury type front end) or lower cost (gnd reffed IVY type front end)?
absolute fidelity
4 - Are you likely to need SE outputs?
no

Control:
1 - How do you anticipate controlling the DAC?
using i2c from an SBC
2 - Is on-board control important to you?
no


Regulators:
1 - do you prefer a tight local PCB layout with on-board regs - or would you rather have the flexibility of Trident/AVCC style regulators?
very well implemented on-board regs

Master Clock:
1 - do you prefer the optimal layout, performance, simplicity and reliability of a local best in class on-board master clock - or the flexibility and added complexity/cost of external clock sources or Rhea modules?
I want to run it in sync mode with external clocks
 
Great input so far folks - I am considering all of the replies I have seen until now.

It is important to note - one design goal here is practicality - I am inclined not to do multiple DAC chips on a single PCB for the reasons of increased cost and complexity.

That said - I may have an idea on how to stack DAC modules... be warned though multiplying current means some heavy overhead in terms of design complexity - and thus price. For that reason I am going to concentrate on the single DAC solution - since the performance of the ES9038 in that regard is already stellar.

Another thing to consider is that the DAC chip only accepts one PCM/DSD time domain... what I mean is there can only be one bit clock (and word clock in the case of PCM). There is no way to input more than one PCM/I2S source at the DAC - such signal integration would have to happen before the DAC. This module will not do any such integration - there are just too many variables and it's not a common enough scenarion to make it worthwhile.

Also note - multichannel SPDIF/AES is definitely not an option for a lot of the same reasons as above. The on chip SPDIF implementation is stereo only - so there is no good reason to level shift on this module - as it is obviously intended for multi-channel use.

Cheers!
Russ
 
Exactly the same situation and requirements
(except the cronus)

Great to hear it's in the works.


Here it is:

Input
1 - What actual multi-channel source are you planning to use?
A modified miniSHARC board >> Cronus (providing clock for the miniSHARC and ASRC (Metronome) before it) >> DAC

2 - Will PCM/DSD input be sufficient?
Yes

Output:
1 - What are your ideas around the physical layout and casing?
Large box (3RU?) hosting everything; the DAC outputs connected to panel-mounted XLR connecters through wires (not board-mounted XLRs). DAC directly connected to Cronus (sitting on/under it). Since Cronus is connected to multiple boards with short wires (above), mounting the DAC on the rear panel would not be practical.

2 - Do you prefer individual output boards or a monolithic 8 channel board?
Individual boards (better placement flexibility, reparability, and upgradeability).

3 - Do you value absolute fidelity(floating - mercury type front end) or lower cost (gnd reffed IVY type front end)?
Mercury-type.

4 - Are you likely to need SE outputs?
No.

Control:

1 - How do you anticipate controlling the DAC?
No DAC controls: all done in miniSHARC and before it.

2 - Is on-board control important to you?
No (above)

Regulators:
1 - do you prefer a tight local PCB layout with on-board regs - or would you rather have the flexibility of Trident/AVCC style regulators?
Trident/AVCC-style regulators (upgradeability and reparability considerations, but no really strong opinion here).

Master Clock:
1 - do you prefer the optimal layout, performance, simplicity and reliability of a local best in class on-board master clock - or the flexibility and added complexity/cost of external clock sources or Rhea modules?

On-board master clock.

Eagerly anticipating this (already have pretty much everything else assembled/tested and collecting dust for a year or so)...

Thanks a lot!
 
Great input so far folks - I am considering all of the replies I have seen until now.

It is important to note - one design goal here is practicality - I am inclined not to do multiple DAC chips on a single PCB for the reasons of increased cost and complexity.

That said - I may have an idea on how to stack DAC modules... be warned though multiplying current means some heavy overhead in terms of design complexity -

Russ, the thing that sets the more recent TPA designs apart from other offerings has been modularity.

What about firstly simply making the Legato more modular - a mono version of the board with separate SE board? Its a low cost solution that still sounds superb. Then do a high current mercury-type version for those who want absolute (theoretical) fidelity or high current handling when connecting multiple DAC channels together.

I agree there is no reason to do a multi-DAC solution. Multiple single DAC boards can still be configured to suit any application.

BTW: It appears many are confused about your onboard/external control question. Perhaps it is better to clarify that this refers to firmware control?
 
Russ, the thing that sets the more recent TPA designs apart from other offerings has been modularity.

What about firstly simply making the Legato more modular - a mono version of the board with separate SE board? Its a low cost solution that still sounds superb. Then do a high current mercury-type version for those who want absolute (theoretical) fidelity or high current handling when connecting multiple DAC channels together.

I agree there is no reason to do a multi-DAC solution. Multiple single DAC boards can still be configured to suit any application.

BTW: It appears many are confused about your onboard/external control question. Perhaps it is better to clarify that this refers to firmware control?

Thx for the feedback. I will attempt to clarify in future posts! I have a few ideas to introduce soon.

Cheers!
Russ
 
Q&A:

1 - What actual multi-channel source are you planning to use?
An HTPC running JRiver with an eight channel Exasound EXAU2I asynchronous, isolated output, usb to I2S converter. This is supposed to be capable of 384kHz / 32bit / 8 channels PCM but never tested this high before.
2 - Will PCM/DSD input be sufficient? Note anything else will likely require some sort of separate input module(s) - so be specific.
All output will be PCM for the foreseeable future.
Output:
1 - What are your ideas around the physical layout and casing?
Only preference would be for DC inputs to be well separated from I2S source, and also from analog outputs. The BII I have with IVY or Legato seems to require me to cross these with my case layout.
2 - Do you prefer individual output boards or a monolithic 8 channel board?
I plan to use the eight channels. My preference is for the cleanest/easiest wiring between DAC and output I/V converter. I like the idea someone proposed of the four channel modules. If space was not a concern, two stacking on the DAC would be great.
3 - Do you value absolute fidelity(floating - mercury type front end) or lower cost (gnd reffed IVY type front end)?
Preference on fidelity, if cost is kept reasonable.
4 - Are you likely to need SE outputs?
Not using them now, but I have used them in the past, so yes.
Control:
1 - How do you anticipate controlling the DAC?
Volume control would be at the source. Not planning to use an Arduino or other external controllers.
2 - Is on-board control important to you?
Yes, it should have an on board microcontroller to configure the dac.
Note: This is a crucial topic.

Regulators:
1 - do you prefer a tight local PCB layout with on-board regs - or would you rather have the flexibility of Trident/AVCC style regulators?
I think my preference is on-board, but the flexibility of the Trident regs (or swapping for others) is probably the way to go.

Master Clock:
1 - do you prefer the optimal layout, performance, simplicity and reliability of a local best in class on-board master clock - or the flexibility and added complexity/cost of external clock sources or Rhea modules?
On board clock​

Note: I am strongly inclined to opt for the local clock unless I see a very compelling reason not to do so.

There are other questions that I am sure will come up in the course of discussion.

My current thinking on output modules is to make them individual channel modules that would be neatly wired using appropriate headers and balanced wiring to the DAC and channels summed there to suite the application. Those modules will be designed such that they will have XLR/RCA connectors on board for direct back panel mounting. I want to hear your thoughts in this regard.

If a modular, single channel output board was designed, it would be fantastic if they were "snap" type boards where you could use all eight together stacked with the dac or snap into individual boards and use separately. That sounds like a complex design and probably needs another board to mate them too however, but it would be nice to have a multichannel output stage.​

Thanks Russ!
 
1 - What actual multi-channel source are you planning to use?
A: SPDIF. Stereo mode. I need separate 4 outputs per channel to be able to connected them to Finemet Teramoto transformer and sum signals there. It give best results.
2 - Will PCM/DSD input be sufficient? Note anything else will likely require some sort of separate input module(s) - so be specific.
A: Yes.

Output:
1 - What are your ideas around the physical layout and casing?
A: Any.
2 - Do you prefer individual output boards or a monolithic 8 channel board?
A: Non relevant in my case.
3 - Do you value absolute fidelity(floating - mercury type front end) or lower cost (gnd reffed IVY type front end)?
A: Not relevant in my case.
4 - Are you likely to need SE outputs?
A: No. I am using balance outputs only.
Control:
1 - How do you anticipate controlling the DAC?
A: I need only to switch between the sources. Analog pot to control digital volume is must for me.
2 - Is on-board control important to you?
A: No so much.
Note: This is a crucial topic.

Regulators:
1 - do you prefer a tight local PCB layout with on-board regs - or would you rather have the flexibility of Trident/AVCC style regulators?
A: Tridents! but also to easily power AVCC separately with supercaps in my case. None of regs beats them!

Master Clock:
1 - do you prefer the optimal layout, performance, simplicity and reliability of a local best in class on-board master clock - or the flexibility and added complexity/cost of external clock sources or Rhea modules?
A: Rhea. I would like to use Pulsar Clock OCXO instead of CCHD.
 
Since practicality is part of this conversation, I want to mention a few thiungs that affect cost.

Whenever we add a separate board, it adds time and therefore cost. For example, making Rheas is actually very time intensive for me, mostly soldering on the tiny pins. I have jigs, but it is still finicky work.

Similarly, making/testing Trident modules takes time. Using onboard regulators reduces build and testing time, because it is all done at once.

These things also require additional packaging and materials.

I am not saying they cannot be done, but the flexibility does incur costs.
 
Since practicality is part of this conversation, I want to mention a few thiungs that affect cost.

Whenever we add a separate board, it adds time and therefore cost. For example, making Rheas is actually very time intensive for me, mostly soldering on the tiny pins. I have jigs, but it is still finicky work.

Similarly, making/testing Trident modules takes time. Using onboard regulators reduces build and testing time, because it is all done at once.

These things also require additional packaging and materials.

I am not saying they cannot be done, but the flexibility does incur costs.
Diyaudio is not cheap hobby :)
If I were to buy all in one, I would probably have bought something like benchmark dac-3. Flexibility is very important here.
 
Not sure what is the point being made TioFrancotirador. There are plenty of stereo DACs on the market, but none are multi channel based on ES9028 or 38. There are also many vendors who will give you bespoke DACs at lofty prices with whatever features one needs. Cost is surely a matter of concern. I look forward to building a high end yet reasonably priced multi channel balanced DAC that I have been looking for, for a long time.
 
Not sure what is the point being made TioFrancotirador. There are plenty of stereo DACs on the market, but none are multi channel based on ES9028 or 38. There are also many vendors who will give you bespoke DACs at lofty prices with whatever features one needs. Cost is surely a matter of concern. I look forward to building a high end yet reasonably priced multi channel balanced DAC that I have been looking for, for a long time.

To be more precise here, what I meant is: I am eager to pay more for flexibility.
 
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