ProtoDAC TDA1387 X8 project

[v12nut]

Well, I do think they are MKP based on this spec sheet for C3D series from Xiamen Faratronic. LS is 27.5mm. Why did you pick these caps? Do you know how they sound?

I have no idea how these sound but for the size and price I thought they would probably be worth a punt,
the audiophiler round 10uF are very big.

I have also found some Yellow Audiophiler 6.8uF which are oval in shape so size wise they will be a reasonable fit.

Cheers

[hifinet]

Well, I do think they are MKP based on this spec sheet for C3D series from Xiamen Faratronic. LS is 27.5mm. Why did you pick these caps? Do you know how they sound?

I have no idea how these sound but for the size and price I thought they would probably be worth a punt,
the audiophiler round 10uF are very big.

I have also found some Yellow Audiophiler 6.8uF which are oval in shape so size wise they will be a reasonable fit.

Cheers

The cap value can be from 4.7-10uF.

From my experience, MKP sound OK in general. They can sound a bit dull, but never nasty or harsh in my experience. They tend to have upper midrange losses. MKS can sound harsh. MKC have lower losses in the upper midrange. The NOS Soviet K77-1 MKC are said to be very good. Built like a Soviet tank. The seller ELECMENTS 13 has a special requests email: elecments13@gmail.com

[hifinet]

The cap value can be 4.7 to 10uF for 10kOhm impedence, typical for solid state line stage. Tube stages can have impedence of 50k-100k. This affects the calculation.

High pass filter calculator

10K impedence and 10uF gives a corner frequency of 1.5915Hz. You want any phase shifts from the filter to be far away from the audio band. With 20Hz, that is usually 10Hz as a rule of thumb with audiophile designs. 6.8uF is 2.3405 Hz. 4.7uF is 3.386Hz. Well within that limit.

For 50K impendence for a tube preamp, 1uF gives a corner frequency of 3.183Hz. 100k is 1.5915Hz with 1uF.

[v12nut]

The cap value can be 4.7 to 10uF for 10kOhm impedence, typical for solid state line stage. Tube stages can have impedence of 50k-100k. This affects the calculation.

High pass filter calculator

10K impedence and 10uF gives a corner frequency of 1.5915Hz. You want any phase shifts from the filter to be far away from the audio band. With 20Hz, that is usually 10Hz as a rule of thumb with audiophile designs. 6.8uF is 2.3405 Hz. 4.7uF is 3.386Hz. Well within that limit.

For 50K impendence for a tube preamp, 1uF gives a corner frequency of 3.183Hz. 100k is 1.5915Hz with 1uF.

Thank you, useful info.

[hifinet]

Hey gang,

Got my ProtoDac built.  I have sound, but full of distortion. Where do I start?

Thanks!

If distortion is in both channels, the problem is with the I2S lines. The I2S signal is garbled. Reflow the solder to resistors R1-R3. Check the resistance of each of the three paths from module pins 1, 2, 3 to GPIO 35, 12 and 40, respectively. Each should measure about 430R.

[eDad2003]

Hey gang,

Got my ProtoDac built.  I have sound, but full of distortion. Where do I start?

Thanks!

If distortion is in both channels, the problem is with the I2S lines. The I2S signal is garbled. Reflow the solder to resistors R1-R3. Check the resistance of each of the three paths from module pins 1, 2, 3 to GPIO 35, 12 and 40, respectively. Each should measure about 430R.

This is also what happened to me. In my case, I failed to recognize that the module diagram was top view, so when I flipped the board over to solder I ended up inverting the pins soldered. Rookie mistake. Doh!

[Ludomaniac]

I swapped from Wima MKP to Jantzen Superior Z-cap today, and the soundstage opens up even more, clarity and definition in the whole area. They are not that expensive either, £45,- for a pair at Hificollective. I also use the AudioNote Kaisei 2200uF on the powerside which also is a cheap upgrade. I'm really amazed by what this design can do - thank you so much!!

[hifinet]

@Ludomaniac Thank you for the feedback.

[hifinet]

A more detailed RC high pass filter calculator. This is the filter on the output of ProtoDAC.

The Bode plot of amplitude and phase response. In audiophile equipment, you want phase shifts outside the audio band as much as possible.

Why you shouldn't use a 1uF cap at 10kOhm impedence. Corner frequency is 15.915Hz, but phase shift at 20Hz is 38.51 degrees.

[hlucas]

Hi all,

After a long search, I acquired an Allo Kali and am really happy with the result.
My next project is integrating ProtoDAC with a USB to I2S board so that I can use it at my workplace. Please let me know if anyone has tried that.

Also, I upgraded Moode to the latest version and went through the settings. However, I couldn't find V2-ProtoDAC setting under CamillaDSP Signal processing menu. The CamillaDSP version is 2.0.1. But I am not sure about sample configs version. How can I check it?

Thanks