[fmzip]

This happens on old caps where the rubber seal may have shrunk as it aged, you will be ok with a cap made in the last 3-4 years, check the datecodes on the caps you intend to use.

ESD bag will not help much if the electrolyte touches the board, will eat the copper clean off the board, does to same to skin.

@b0bb

I have these in new date codes, can I use any/all/none of these choices:

109D107X0025F2 100uF 25V 20% (7.92 X 20.22mm) Axial 4 Ohm​

109D157X0030F2 150uF 30V 20% (7.92 X 20.22mm) Axial 2.5 Ohm​

109D277X0050T2 270uF 50V 20% (10.31 X 23.4mm) Axial 1.8 Ohm​

109D567X9025T2 560uF 25V 10% (10.31 X 23.4mm) Axial 1.8 Ohm​

109D337X0030T2 330uF 30V 20% (10.31 X 23.4mm) Axial 1.8 Ohm​

109D107X0060F0 100uF 60V 20% (7.14 X 16.28mm) Axial 2.5 Ohm​

109D477X9030T2 470uF 30V 10% (10.31 X 23.4mm) Axial 1.8 Ohm​

 

[b0bb]

@b0bb

I have these in new date codes, can I use any/all/none of these choices:

109D107X0025F2 100uF 25V 20% (7.92 X 20.22mm) Axial 4 Ohm​

109D157X0030F2 150uF 30V 20% (7.92 X 20.22mm) Axial 2.5 Ohm​

109D277X0050T2 270uF 50V 20% (10.31 X 23.4mm) Axial 1.8 Ohm​

109D567X9025T2 560uF 25V 10% (10.31 X 23.4mm) Axial 1.8 Ohm​

109D337X0030T2 330uF 30V 20% (10.31 X 23.4mm) Axial 1.8 Ohm​

109D107X0060F0 100uF 60V 20% (7.14 X 16.28mm) Axial 2.5 Ohm​

109D477X9030T2 470uF 30V 10% (10.31 X 23.4mm) Axial 1.8 Ohm​

109D157X0030F2 150uF 30V 20% (7.92 X 20.22mm) Axial 2.5 Ohm​

 

[oldearwax]

I have been thinking after getting to solve some problems, to make a mod (super-mod anti-digital hardness), that I like and that tube lovers may like, an i / v stage based on vacuum tubes, maybe the variety of brands can better adjust the sound to the tastes of each user more easily, would be a very versatile mod, also there is space within our 004 to put an additional circuit, it would be necessary to design a specific pcb and add a small transformer.
Maybe some starting points:
https://hq-audio.net/products/pcb-pure-tube-i-v/
https://www.tubecad.com/2011/03/blog0203.htm

Once the design is optimized it should not be too expensive an investment I think

Both tube-i-v have 1uF coupling cap in the cathode follower stage.
I would avoid HV coupling cap in tube audio, unless you want to spend $$ on V-cap (1uF US$ 459 each).
Cathode follower has output impedance = 1/gm. For 6DJ8, it is about 80 Ohm.

 

[b0bb]

Cathode follower has output impedance = 1/gm. For 6DJ8, it is about 80 Ohm.

6DJ8 cathode follower has 80 ohm output impedance, about 8x too high.

Below is the calculation of the output impedance of the 004 emitter follower stage on the DAC
Emitter follower is formally as a common collector amplifier

Values for the 004
RE = 15 ohms
R1 = 4.7k (lower bias chain resistor)
R2 = 2.55k (upper bias chain resistor)
β = 50 From MJE171 datasheet
Ie = 29mA (output stage bias current)
r'e = 25mV/Ie = 25mV/29mA = 0.86ohm (small signal AC resistance)

Zout = 15// (0.86 + (4.7k//2.55k)/(50 + 1)) = 10.3 ohms

6DJ8 cathode follower has 80 ohm output impedance, this is 7.77x too high. (80 ohm vs 10.3 ohms)

Additional info here
https://www.electronics-tutorials.ws/amplifier/common-collector-amplifier.html


Note this is simplified analysis, LKS used a complementary PNP/NPN output, the above are the numbers for a Class-B biased output stage.
In the case of Class-A both halves are running in parallel, reducing Zout to very much below 10ohms

 

[b0bb]

On a side note, the I/V output stage is set for Pure Class A operation.

29mA is almost exactly half of the full scale output current of the mono mode 9038Pro of 60mA

The output stage transistors (almost) never turn off.

 

[b0bb]

For example:
"Amber Rubarth - Sessions from the 17th Ward, DSD128", this is one I use to see if I can improve noise or interference. Other DSD albums are less delicate and have no noise.

I just picked up the DSD128 version, did not notice any burst of noise or any unusual noise issues in any of the tracks.
I used the HD800 headphones for this.
Overall a very well done recording, very quiet background.

Can you elaborate on which track and time index where you had the problem ?

 

[ESL57]

I just picked up the DSD128 version, did not notice any burst of noise or any unusual noise issues in any of the tracks.
I used the HD800 headphones for this.
Overall a very well done recording, very quiet background.

Can you elaborate on which track and time index where you had the problem ?

Thanks for trying it. It was logical that in your dac you would not notice it, these random noises from that album only come out of my 3 dacs in this LKS, they are noises that if you lower the volume of the LKS they are very present, I made a recording of them and Xoverman listened to it, something similar to the noise of leaks from a dry decoupling capacitor in a tube amplifier, random noises and crackles, and it does not matter to set DPLL15 to maximum and this works, because if you lower the DPLL too much, a loud blowing noise enters when the signal is unblocked, asking to raise the DPLL level higher. Is it possible to send an attached audio file? I think these files are not accepted directly.

 

[b0bb]

Is it possible to send an attached audio file? I think these files are not accepted directly.

Compress the file using pkzip or equivalent utility and upload it as an attachment.

 

[ESL57]

6DJ cathode follower has 80 ohm output impedance, about 8x too high.

Below is the calculation of the output impedance of the 004 emitter follower stage on the DAC
Emitter follower is formally as a common collector amplifier


Values for the 004
RE = 15 ohms
R1 = 4.7k (lower bias chain resistor)
R2 = 2.55k (upper bias chain resistor)
β = 50 From MJE171 datasheet
Ie = 29mA (output stage bias current)
r'e = 25mV/Ie = 25mV/29mA = 0.86ohm (small signal AC resistance)

Zout = 15// (0.86 + (4.7k//2.55k)/(50 + 1)) = 10.3 ohms

6DJ cathode follower has 80 ohm output impedance, this is 7.77x too high. (80 ohm vs 10.3 ohms)

Additional info here
https://www.electronics-tutorials.ws/amplifier/common-collector-amplifier.html

If I think that an impedance adapter transformer would be necessary, not even using tubes with low impedance like 6as7 or 6080 can handle those 10ohm.
Here they tested results with this:
https://www.diyaudio.com/forums/group-buys/306118-dac-es9038-pro-gr-2-a-11.html

 

[ESL57]

Compress the file using pkzip or equivalent utility and upload it as an attachment.

 

[b0bb]

If I think that an impedance adapter transformer would be necessary, not even using tubes with low impedance like 6as7 or 6080 can handle those 10ohm.
Here they tested results with this:
https://www.diyaudio.com/forums/group-buys/306118-dac-es9038-pro-gr-2-a-11.html

Correct.

Adding an interstage coupling transformer adds cost and complicates an already complex situation.

If you want to experiment with tubes/valves pick up the diy 9038 DAC boards like the one above
Twistedpear Audio also makes the Buffalo which is a standalone DAC minus I/V

 

[b0bb]

@ESL57 I listened to the problem audiofile you attached.

There was a burst of noise followed by a click, this pattern repeats.
It might be the DPLL not being able to maintain a stable lock.

Check your I2S cables and connector on the 004 to see if anything got broken.

Also check the I2S receiver chip and the 74xxx244 line drivers

The chip handling I2S and USB data is the left one in the picture.
(I am in the process of swapping these out for the 74ALVC244)

 

[ESL57]

[USER = 535147] @ ESL57 [/ USER] Escuché el archivo de audio del problema que adjuntaste.

Hubo un estallido de ruido seguido de un clic, este patrón se repite.
Puede ser que el DPLL no pueda mantener un bloqueo estable.

Verifique sus cables I2S y el conector del 004 para ver si algo se rompió.

También verifique el chip receptor I2S y los controladores de línea 74xxx244

El chip que maneja datos I2S y USB es el de la izquierda en la imagen.
(Estoy en el proceso de cambiarlos por el 74ALVC244)

Bobb all digital inputs go through those 2 non-inverting buffers chip? I ask this because I sent through all the inputs that supported native DSD, and through coax inpunt the same files but packed DoP and the noises were exactly the same, there was no success.

 

[b0bb]

Bobb all digital inputs go through those 2 non-inverting buffers chip? I

Yes, SPDIF goes thru the chip on the right

 

[b0bb]

3 minor mods to SU-6.

Made SU-6 much smoother and organic, an unexpected surprise.
https://www.head-fi.org/threads/singxer-su-6.902272/page-30#post-16233262