ProtoDAC TDA1387 X8 project

[hifinet]

Or perhaps do a little surgery on a so-called stacking header (example) for a reversible solution?

Regards,
Kent

Removing or replacing pins 2 and 4 from an adapter header. Excellent idea. Thanks Kent.

[hifinet]

A forum member kindly donated Panasonic NHG-A electrolytic power supply decoupling caps. I think they are the ECA-0JHG102 1000uF 6.3V $0.50 each at Digikey (P5509-ND). Initial sound quality is excellent. Very smooth from the start. Excellent highs. Excellent soundstage and imaging. After 24 hours burn in, they have not changed. The Panasonic FR EEU-FR1A102LB 1000uF 10V have unsurpassed low bass (e.g. 32Hz organ pedal). Much better than any of the other caps I have tried. The FR are much harder edged than the NHG, and the highs are not as good, more recessed. The FR need burn in to mellow out an upper midrange harshness. Planned burn in of the NHG past 60 hours once the sound stabilizes, and then plan to mix FR and NHG. Will the killer bass of the FR continue, while maintaining the excellent SQ of the NHG?

The 6.3V NHG has 3.5mm lead spacing, 8mm diameter and 12.5mm height. The Panasonic FR EEU-FR1A102LB has 5mm lead spacing (taper to 3.5mm), 8mm diameter and 16.5mm height. A 10V NHG ECA-1AHG102 has 5mm lead spacing, 10mm diameter, and 13.5mm height.

[Skip Pack]

Attempting to mimic your build document, I got Panasonic FR-A FROJ102 and Nichicon UFGO102MPM caps, both from Digikey. I do love the dac in spite of 'second-string' output caps (WIMA MKP 6.8uf) and I/V resistor (same as input resistors). Have you tried either of the 1000uf caps I am currently using. Within a week or two I expect to put together a board with the good stuff.

Skip

[hifinet]

Attempting to mimic your build document, I got Panasonic FR-A FROJ102 and Nichicon UFGO102MPM caps, both from Digikey. I do love the dac in spite of 'second-string' output caps (WIMA MKP 6.8uf) and I/V resistor (same as input resistors). Have you tried either of the 1000uf caps I am currently using. Within a week or two I expect to put together a board with the good stuff.

Skip

The Panasonic FR that I have tried are different. I initially used the EEU-FR1A102 with 28mOhms ESR. I thought two of them together was too dry sounding. It worked well in combination with other caps. I would like to try the FROJ102, because it has higher ESR at 56mOhms. Two together would be worth a trial. I have used the Nichicon Fine Gold UFGO102MPM with the EEU-FR1A102, and I thought that they are not revealing enough, i.e. lack detail.

[hifinet]

Capacitor trials are a chore, but PS decoupling caps change the sound significantly. There are many possible combinations. Press fitting them in with masking tape to tilt them can work, rather than soldering and desoldering. I have been soldering them, and use one of those cheap solenoid solder suckers BBT‑580, which actually works pretty well.

[hifinet]

Update on the Panasonic NHG-A. The good aspects are smooth sound, good detail. The main problem with them is weak dynamics. The opposite of the Nichicon UKA (blue), which are hyperdynamic or "punchy" as @fdealexa mentioned. I paired the NHG-A with the FR EEU-FR1A102LB, which helped, but NHG still drags down the dynamics too much. I still think two FR EEU-FR1A102LB sound best. Two Panasonic FR-A FROJ102 will be the next trial.

[michaelagiles]

Good Morning!
I have a kit ordered and have been looking at the build guide etc.
Do you think there is any advantage to a small film bypass on the decoupling caps?
Also - I recall you had used the discrete r2r day from bigbulb. Do you find this Potomac superior? I have one of his AD single chip designs and love it! this set me on the multibit NOS trail and was contemplating the R2R hat before I saw this design.
Thanks!

I have not tried a bypass cap on the power supply decoupling caps. I am still trying various combinations of electrolytics. Based on results with a polymer cap (see below), I am guessing a film bypass cap would not be beneficial. Sound quality changes quite a bit with decoupling caps, and I think the sound of this DAC can be tailored to personal preferences with decoupling caps.

So far, Panasonic FR sound best to me. The most realistic. Silmic II sound very good, big sound, but just not realistic. I know it's personal preference, type of music, system factors (including the DAC power supply), but that's where I am with classical music in my system. 

I have tried a polymer cap 680uF 7 mohms ESR with a 1000uF Nichicon UKA, but that didn't sound good at all. Very grey, sterile, no color.  

Two 1000uF Panasonic FR-A 28 mohm ESR sounds very good, but just slightly lacking color. The same cap combined with a UKA or Audio Note Seiryu was very good.  

Two FR-A 1000uF 41 mohms ESR Panasonic EEU-FR1A102LB (DigiKey) are the ones to get.  Tiny little caps. Cheap. Excellent sound. Big deep bass. Soundstage in a realistic perspective. I recommend starting with these. Be sure to give them a 60+ hour burn in. These are still improving, long after 60 hours.

I have two of Ew's DACs, the AD1865 and the Discrete DAC. Discrete DAC sounds better than AD1865. In my opinion, this DAC sounds much better. I very much like the sound of passive I/V paralleled TDA1387 DACs. I arrived at this DAC after my experience with L1387 and TeraDAK.

I have the blessing/curse of having a system with lots of moving parts.  A bi-amped system with some adjustment in the crossover as well as level adjustment for the individual drivers. So any changes that produce a difference must be investigated to ascertain if it is an improvement that requires a slight adjustment to bring it to light. Or NOT!
Having said all this,  I recently added a small (.01uf vishay pp) bypass to the electrolytics on my dac and found a wonderful improvement to the already spectacular ProtoDAC.  It might be a function of my system but definitely worth a try for those of you so inclined!

[hifinet]

Excellent info. What is the improvement that you notice? For example, lower noise or smoother highs, etc. How are you powering your RPi/DAC, SMPS or linear?

I am certainly going to give it a try. The cap can be added at the 5V and GND pads between the RCA jacks.

[michaelagiles]

Excellent info. What is the improvement that you notice? For example, lower noise or smoother highs, etc. How are you powering your RPi/DAC, SMPS or linear?

I am certainly going to give it a try. The cap can be added at the 5V and GND pads between the RCA jacks.

I added them directly to the electrolytic leads on the under side of the board, they are not large and there is plenty of room.
I use a linear power supply to power a pi4 and then the dac thru the  pi.
I found the added caps smoothed and opened the treble. At first I thought by too much! My xover includes an adjustable shelving filter at 1k for baffle diffraction correction and to tame over rambunctious Full Range drivers as per Nelson Pass SLOB project. The caps allowed me to raise the level above 1k hz a bit which opened the whole upper mid and treble without the hardness I had previously sought to reduce. The ProtoDAC had already helped a lot in this regard but now it is even better. 
I am not sure but I would think the location right on the electrolytics might have an effect, reducing parasitic induction effects.  But perhaps this is getting too fussy.
Have Fun! And enjoy the music!

[Skip Pack]

Excellent info. What is the improvement that you notice? For example, lower noise or smoother highs, etc. How are you powering your RPi/DAC, SMPS or linear?

I am certainly going to give it a try. The cap can be added at the 5V and GND pads between the RCA jacks.

I added them directly to the electrolytic leads on the under side of the board, they are not large and there is plenty of room.
I use a linear power supply to power a pi4 and then the dac thru the  pi.
I found the added caps smoothed and opened the treble. At first I thought by too much! My xover includes an adjustable shelving filter at 1k for baffle diffraction correction and to tame over rambunctious Full Range drivers as per Nelson Pass SLOB project. The caps allowed me to raise the level above 1k hz a bit which opened the whole upper mid and treble without the hardness I had previously sought to reduce. The ProtoDAC had already helped a lot in this regard but now it is even better. 
I am not sure but I would think the location right on the electrolytics might have an effect, reducing parasitic induction effects.  But perhaps this is getting too fussy.
Have Fun! And enjoy the music!