So. What started out as upgrading Tridents to my old dual mono 9018s in the previous thread here spiralled rapidly out of control- thanks Franco Largo for providing the temptations and suggestions for optimisation.
To be honest its been at the back of my mind for 2-3 years but a bit of free time has finally allowed me to get this project off the ground- The best DAC I can conceive of and build.
An added impetus was noticing its a bit of sunset on Twisted Pear Audio, don't know when Brian will finally shut up shop. So I took the plunge a couple of weeks ago and invested in a 9038 and Mercury while they are still available. Delivery due tomorrow or Tuesday I reckon, looks like they arrived in the UK yesterday accordingn to tracking. Nice!
The design plan is:
2 proper Modushop Chassis; 1 for PSUs, 1 for DAC/Music server
DAC:
PSU
8 Transformers
12 seperate supplies
3 umbilical connectors betweeen PSU and DAC:
So thought Id share the design and build journey, a sort of last salutory swan song to the Twisted Pear digital products. Hope you enjoy, (and it all works out as planned!).
To be honest its been at the back of my mind for 2-3 years but a bit of free time has finally allowed me to get this project off the ground- The best DAC I can conceive of and build.
An added impetus was noticing its a bit of sunset on Twisted Pear Audio, don't know when Brian will finally shut up shop. So I took the plunge a couple of weeks ago and invested in a 9038 and Mercury while they are still available. Delivery due tomorrow or Tuesday I reckon, looks like they arrived in the UK yesterday accordingn to tracking. Nice!
The design plan is:
2 proper Modushop Chassis; 1 for PSUs, 1 for DAC/Music server
DAC:
- Music served by my old BeagleBoneBlack,
- Music library stored on onboard SSD
- Source clocking using my old Hermes and Cronus.
- USB hub to allow connecting more storage to the BBB.
- Buffalo 9038
- Mercury IV
- Option on Analaogue output filter, something like 6 pole.
14 x cascoded regulators, 1 for every board in the DAC unit
PSU
8 Transformers
12 seperate supplies
3 umbilical connectors betweeen PSU and DAC:
So thought Id share the design and build journey, a sort of last salutory swan song to the Twisted Pear digital products. Hope you enjoy, (and it all works out as planned!).
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BeagleBone Black- if it aint broke, dont fix it, I say. Nice little unit.
I recently bought a NOS one as a backup so hopefully I've got parts to last another 20 years as long as I can get this up and running with no problems.
I run an old version of Volumio, which while not perfect, works for me. May actually revert back to the original Miero Botic/YMPD distro. Served me well for 10 years, see no reason to change.
I find product development doesn't recognise product maturity; when enough is enough. I guess how are you going to wring new money out of the same old stuff and what do you give your development team to do when its 'done'? Just a PITA for users though, no reason to change the BBB.
I get the impression the same with the TP Products- they are mature products, work perfectly well and not seeing anything materially better out there, they just seem out of fashion. Shame.
I recently bought a NOS one as a backup so hopefully I've got parts to last another 20 years as long as I can get this up and running with no problems.
I run an old version of Volumio, which while not perfect, works for me. May actually revert back to the original Miero Botic/YMPD distro. Served me well for 10 years, see no reason to change.
I find product development doesn't recognise product maturity; when enough is enough. I guess how are you going to wring new money out of the same old stuff and what do you give your development team to do when its 'done'? Just a PITA for users though, no reason to change the BBB.
I get the impression the same with the TP Products- they are mature products, work perfectly well and not seeing anything materially better out there, they just seem out of fashion. Shame.
Concerning power supplies, I’ve had the experience that ‘dirty’ power can be very disruptive. I also use a power conditioner, but it doesn’t seem to catch any of the common mode junk - ground level interference. But without a good explanation, the power supplies seem to become less susceptible with 3-4 months of use.
Meanwhile, even with an RFI filter on the line, I liked what I didn’t hear after snapping a couple of large old Video ferrites over a couple of loops in the power cord to the DAC.
Yep, high quality isolated power is the basis of this project.
Couple of big ferrites is no hardship to try out, thanks for the tip Franco.
Would be interesting to do some careful A-B listening tests on those super capacitors. I saw the IanCanada project, and TBH couldnt see the reasoning behind them apart from "because it could be done". In my experience you have to listen to capacitors to hear what they do. Things like low impedance are guides but I've tried great spec capacitors that sounded dreadful. Too small a sized capacitor has been the source of many a design flaw, but never noticed any difference between way more than necessary and mindbendingly vast amounts of capacitance, he he.
Anyway, I am indeed using isolation transformers exactly to keep as much high frequency gunk off the power lines and away from other components as possible. Very little capacitative coupling. Ditto pre-regulators- very high levels of very high bandwidth filtering, even if not the last word in accuracy. Will need to see if the DC drift is acceptable in this implementation.
Couple of big ferrites is no hardship to try out, thanks for the tip Franco.
Would be interesting to do some careful A-B listening tests on those super capacitors. I saw the IanCanada project, and TBH couldnt see the reasoning behind them apart from "because it could be done". In my experience you have to listen to capacitors to hear what they do. Things like low impedance are guides but I've tried great spec capacitors that sounded dreadful. Too small a sized capacitor has been the source of many a design flaw, but never noticed any difference between way more than necessary and mindbendingly vast amounts of capacitance, he he.
Anyway, I am indeed using isolation transformers exactly to keep as much high frequency gunk off the power lines and away from other components as possible. Very little capacitative coupling. Ditto pre-regulators- very high levels of very high bandwidth filtering, even if not the last word in accuracy. Will need to see if the DC drift is acceptable in this implementation.
What might be of interest is the daughter board Ive designed for the Buffalo. Sent to fab house yesterday so will be a few days before boards arrive.
One issue is, the Buffalo is designed for a single DC supply via Vd. The tridents tap off this via power and ground planes on the buffalo. Now if you're providing isolated supplies to the buffalo, 4 in my case as recommended by Franco, there is a problem in terms of wiring harnesses.
I've designed for independent supplies, all the way back to the transformers, for:
So I've prototyped this daughter board:
One issue is, the Buffalo is designed for a single DC supply via Vd. The tridents tap off this via power and ground planes on the buffalo. Now if you're providing isolated supplies to the buffalo, 4 in my case as recommended by Franco, there is a problem in terms of wiring harnesses.
I've designed for independent supplies, all the way back to the transformers, for:
- AVccR
- AVccL
- Vxo
- The digital rest (Vd, DVcc, Vdd)
So I've prototyped this daughter board: