[fmzip]

@b0bb when you swapped out the SMT pots for the 1240W's, did you epoxy them to the board or is it solid enough with the three solder joints?

 

[b0bb]

@b0bb when you swapped out the SMT pots for the 1240W's, did you epoxy them to the board or is it solid enough with the three solder joints?

No epoxy, just soldered it on.

 

[b0bb]

hello bob
Can these resistors be fitted for 9028pro.(5ohm)VSMP Z-Foil

Check your board, not sure what LKS used on the 9028, if it is close enough like within 10-15 ohms you could try it.

 

[fmzip]

The other way around, the designs mentioned not good enough for use with the 004, output impedance of the tube is way too high to drive the passive LPF.

If you are looking for additional smoothness replace the Accusilicon AS-318B with the Crystek CCHD-950X

Check with @fmzip who has made the switch, I think @fmzip gave away the AS318B after trying the CCHD-950X
Also try replacing the noise caps for the TPS7A47 and LT1763 regulators with film caps, this reduces harshness due to the fridge magnets* LKS used

*the horrid ceramic caps LKS installed on the board, make good fridge magnets if you grind them up, add it to a latex base and magnetize it.

@ESL57, I had the Accusilicon for awhile, the Crystek that B0bb suggested is much smoother. I will not go back to the Accusilicon.

 

[fmzip]

@b0bb, I have some 150uf 30v 109D's in my stockroom but they are +/-20%. Would this be an acceptable upgrade to the tantalum yellow bead caps?

 

[b0bb]

@b0bb, I have some 150uf 30v 109D's in my stockroom but they are +/-20%. Would this be an acceptable upgrade to the tantalum yellow bead caps?

Yes provided it was made recently

 

[Xoverman]

This thread is getting more and more interesting, this dac gives a lot of play for the enjoyment of the changes. Just remember that my tests were always aimed at solving the problem of random noise in DSD files recorded with low level, my 004 is not GEN1, better call it GEN0 (my pcb is different). Swap Vcom's Epcos capacitor for polymer-aluminum to hear it, definitely not the way to go, sure to have more current leakage than other types like wet tantalum, silicon or Teflon capacitors (these last 2 only manufactured at low capacitances). My goals are the same as most of you, low frequencies are not all the best (improve the analog power supply and it was not night and day either) and highs still a bit of digital harshness. I will follow your recommendations ... B0bb, I will remove that yellow 100nf and try the things suggested in the i / v stage.
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
A lot of work ¿? Does this dac really deserve it?
Once the design is optimized it should not be too expensive an investment I think

Hi ESL57,
Please try a isolation transformer with screening for the power supply of the DAC.
Disconnect the PS PE ( earth) from the DAC ( ONLY IF YOU USE A ISOLATION TRANSFORMER!!!!!!!! )
Connect the DAC housing ( case) the Amplifier case.
Try a USB reclocker / isolator.

 

[ESL57]

The other way around, the designs mentioned not good enough for use with the 004, output impedance of the tube is way too high to drive the passive LPF.
LPF on 004 expects to be driven from a very low impedance source.

If you are looking for additional smoothness replace the Accusilicon AS-318B with the Crystek CCHD-950X

Check with @fmzip who has made the switch, I think @fmzip gave away the AS-318B after trying the CCHD-950X
Also try replacing the noise filter caps used by the TPS7A47 and LT1763 regulators with film caps, this reduces harshness due to the fridge magnets* LKS used

*the horrid ceramic caps LKS installed on the board, make good fridge magnets if you grind them up, add it to a latex base and magnetize it.

Yes, I really would like to try the Crystek 950x, I did not find what I was looking for with this Accusilicon even after 200 hours of burning. But I see that the 950x version that you all installed is the 25ppm version, if so, it is out of stock in the main providers, waiting for availability or this is similar.¿?.
CCHD-950X-25-100 , 25ppm 15ma
CVHD-950X-100 , 20ppm 25ma
https://www.digikey.es/products/es?keywords=CCHD-950X-25-100 (out of stock)
https://www.digikey.es/products/es?keywords=CVHD-950X-100 (in stock)

 

[fmzip]

Yes provided it was made recently

You mention this because of the soldering concerns/part exploding mentioned previously, correct? I wouldn't be soldering it in, I'd leave it to a skilled technician this go around.

Maybe as a failsafe, I can cover the entire board with an ESD bag and pop a hole out to solder this location...

 

[fmzip]

Yes, I really would like to try the Crystek 950x, I did not find what I was looking for with this Accusilicon even after 200 hours of burning. But I see that the 950x version that you all installed is the 25ppm version, if so, it is out of stock in the main providers, waiting for availability or this is similar.¿?.
CCHD-950X-25-100 , 25ppm 15ma
CVHD-950X-100 , 20ppm 25ma
https://www.digikey.es/products/es?keywords=CCHD-950X-25-100 (out of stock)
https://www.digikey.es/products/es?keywords=CVHD-950X-100 (in stock)

crystek.com/crystal/spec-sheets/vcxo/CVHD-950.pdf
https://www.crystek.com/crystal/spec-sheets/clock/CCHD-950.pdf

Here's the pdf's @b0bb

 

[ESL57]

crystek.com/crystal/spec-sheets/vcxo/CVHD-950.pdf
https://www.crystek.com/crystal/spec-sheets/clock/CCHD-950.pdf

Aquí está el pdf [USER = 408594] @ b0bb [/ USER]

CVHD-950x is identical in electrical characteristics and precision to the CCHD-950x only that one says "CMOS" and the other "HCMOS", even crystek put the same graphics in one and the other datasheet, I don't know if there will be sonic differences.
https://www.mouser.com/datasheet/2/94/CVHD-950-182272.pdf
The difference: it seems that the CVHD has voltage control on pin 1 and the CCHD on pin 1 is not connected .... compatible?
I think so, because Accusilicon AS-318B also pin 1 is on-off, any suggestions?

 

[fmzip]

CVHD-950x is identical in electrical characteristics and precision to the CCHD-950x only that one says "CMOS" and the other "HCMOS", even crystek put the same graphics in one and the other datasheet, I don't know if there will be sonic differences.
https://www.mouser.com/datasheet/2/94/CVHD-950-182272.pdf
The difference: it seems that the CVHD has voltage control on pin 1 and the CCHD on pin 1 is not connected .... compatible?
I think not

I don't think it's compatible either but I am not an engineer either

 

[ESL57]

Hi ESL57,
Please try a isolation transformer with screening for the power supply of the DAC.
Disconnect the PS PE ( earth) from the DAC ( ONLY IF YOU USE A ISOLATION TRANSFORMER!!!!!!!! )
Connect the DAC housing ( case) the Amplifier case.
Try a USB reclocker / isolator.

Thanks for your suggestions, after many months of tests and countless changes and improvements of electronic components, my conclusion is that the problem is still inside the LKS, eliminate Amanero and use Gustard U16 without success, Ifi I-usb power, Ifi i-purifier, external grounded, ungrounded, direct ground to the chassis and not to the chassis, transformers outside the chassis, tested in other friends' houses the same (different electrical installation), different PCs and software, some DSD albums are noisy and in other of my dacs they are not. 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.

 

[b0bb]

CVHD-950x is identical in electrical characteristics and precision to the CCHD-950x only that one says "CMOS" and the other "HCMOS", even crystek put the same graphics in one and the other datasheet, I don't know if there will be sonic differences.
https://www.mouser.com/datasheet/2/94/CVHD-950-182272.pdf
The difference: it seems that the CVHD has voltage control on pin 1 and the CCHD on pin 1 is not connected .... compatible?
I think so, because Accusilicon AS-318B also pin 1 is on-off, any suggestions?

CVHD-950 is a Voltage Controlled XO, any noise pickup on that pin strong enough to raise the voltage causes a shift in the output frequency.

Should not be used for the 004.

CCHD-950X is out of stock at the major suppliers.
You could try the SIT-5357 but it is 2-2.5x the cost and much more difficult to solder onto the board.

 

[b0bb]

You mention this because of the soldering concerns/part exploding mentioned previously, correct? I wouldn't be soldering it in, I'd leave it to a skilled technician this go around.

Maybe as a failsafe, I can cover the entire board with an ESD bag and pop a hole out to solder this location...

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.