[Monolithic]

@b0bb - A few questions regarding upgrading to 1.3v on the Gen2 board:

1) Any reason to leave the C1/R1, C2/R2 pairs on the board after removing the regulators? I'm assuming C1/C2 are charge pump caps and R1/R2 are feedback/set resistors

2) For the input wire, did you run a flexible wire from the C3/C4 smd caps (yellow dots) to the Belleson regulators? I didn't know if two points of through hole support were enough to handle the heatsinks. Was thinking of possibly using a third stiff wire to the input cap through hole as well, but it appears to be a fair distance away (red dots indicate through hole mounting points). (C5/C6 along with output E-caps are moved onboard with respective Belleson regulators)

Thanks.

 

[b0bb]

@b0bb - A few questions regarding upgrading to 1.3v on the Gen2 board:

1) Any reason to leave the C1/R1, C2/R2 pairs on the board after removing the regulators? I'm assuming C1/C2 are charge pump caps and R1/R2 are feedback/set resistors

2) For the input wire, did you run a flexible wire from the C3/C4 smd caps (yellow dots) to the Belleson regulators? I didn't know if two points of through hole support were enough to handle the heatsinks. Was thinking of possibly using a third stiff wire to the input cap through hole as well, but it appears to be a fair distance away (red dots indicate through hole mounting points). (C5/C6 along with output E-caps are moved onboard with respective Belleson regulators)

Thanks.

1) Is a matter of preference, if it does get in the way you could remove it.

2) The distance between the regulator chip is much wider on the Gen2 board, extra stiffening support makes sense.

 

[Monolithic]

1) Is a matter of preference, if it does get in the way you could remove it.

2) The distance between the regulator chip is much wider on the Gen2 board, extra stiffening support makes sense.

@b0bb - Would you recommend moving the C3/C4 input bypass smd caps onto the Belleson board at the input or would it just be of marginal benefit?

Thanks again.

 

[b0bb]

@b0bb - Would you recommend moving the C3/C4 input bypass smd caps onto the Belleson board at the input or would it just be of marginal benefit?

Thanks again.

Keep the ceramic caps as close to the polymer cap as possible.
I soldered the original bypass parts across the output terminals.

 

[Monolithic]

@b0bb - How did you connect the input on the Gen1 board?

 

[b0bb]

@b0bb - How did you connect the input on the Gen1 board?

Solder a stiff wire to the +ve terminal on the input ceramic bypass cap

 

[b0bb]

Minor mod for the RCA output.
33nF 160V 1% Vishay MKP1837 Extended foil polypropylene.

PP caps improve the imaging and detail of the 004 but makes the sound somewhat cold, extended foil caps help address this shortcoming.
Alternative is polystyrene but it can be hard to handle, low melting point makes it difficult to solder.

Grey square caps in the picture

The MKP1837 is much larger than the PHE426s I was using earlier.
Bigger cap required wire bending to get it onto the board.

MKP1837 is still available but is being phased out, it replacement is the MKP385, Vishay's version of the PHE426.

 

[piaseczek]

Minor mod for the RCA output.
33nF 160V 1% Vishay MKP1837 Extended foil polypropylene.

Thanks b0bb, I'd like to confirm that these 4 x 33nF are not to be replaced for XLR users?

 

[piaseczek]

For those still using the LM317s in the digital PSU possible mods are described below.

Calculation of the minimal ESR for the given value of the output capacitor:
http://www.acoustica.org.uk/t/3pin_reg_notes3.html
2200uF 16V Panasonic FRs in my 004 have to small ESR (18mOhm) than the recommended (~50mOhm).

The zener diode trick to lower the noise of the LM317:
http://www.acoustica.org.uk/t/3pin_reg_notes1.html

"Knowing this we can obtain even better performance out of the humble LM317 and the like, and here's where we go off the beaten track: The trick is to retain C2 but replace R2 with something like a zener diode. This brings lower noise all the way down to DC - because the dynamic impedance of the zener will much lower than the required value of R2 to achieve an equivalent output voltage. Effectively this stops the pairs of curves on the ripple rejection and output impedance graphs above converging again at low frequencies; you can picture this as mimicking the action of a truly enormous 'perfect' cap at C4 without the cost. Using a zener diode of voltage Vz then the final output voltage will of course be (Vz+1.25)volts."

 

[piaseczek]

Guys, my biggest fear becomes a reality. I have a problem with desoldering the components from the PCB.
To desolder I'm using the soldering station with a regulated temperature, high quality flux and copper wick.

The method - I apply flux, then through the copper wick I hot the solder with the tip.
Unfortunately hole is not clear and I can't remove the component.
Maybe the temperature is too low, what temperature should I set?

Thanks.

 

[piaseczek]

Ps. I have desoldered the amanero PSU board without any problems.

 

[fmzip]

Guys, my biggest fear becomes a reality. I have a problem with desoldering the components from the PCB.
To desolder I'm using the soldering station with a regulated temperature, high quality flux and copper wick.

The method - I apply flux, then through the copper wick I hot the solder with the tip.
Unfortunately hole is not clear and I can't remove the component.
Maybe the temperature is too low, what temperature should I set?

Thanks.

I can tell you that depending on what area of the board you are working on, desoldering will be very challenging. I work at at a company that assembles PCB's and we have the very best reworking equipment and trained staff. You really need a solder station with vacuum, even saw the operator use a heat gun to heat the PCB up a bit as the internal ground plane makes things very challenging to work with.

 

[fmzip]

Hey all, haven't been around in awhile, been LOVING the DAC with all the mods! Really do not want to tinker anymore, it sounds that good. Unfortunately, my aging Anthem D2V preamp might be on the way out. My preamp has a balanced input which I am using with the LKS DAC. I am running fully balanced, amp, preamp and DAC.

Should I be overly concerned in purchasing a preamp that doesn't have a balanced input? Or am I getting a bit nuts over nothing?

 

[b0bb]

Should I be overly concerned in purchasing a preamp that doesn't have a balanced input? Or am I getting a bit nuts over nothing?

Run it balanced, RCA out on the 004 uses an active filter, balanced is passive.

There is about 20% amplitude overshoot on the RCA outs on the step response tests, this makes for the trashy high frequency glare some people complain about.

PS finally got around to modifying the SU2 to use 768kHz sampling, added a supercap controller to it. SU6 is now on the shelf.

 

[b0bb]

You really need a solder station with vacuum, even saw the operator use a heat gun to heat the PCB up a bit as the internal ground plane makes things very challenging to work with.

Yup exactly.
This has been mentioned more than a few times now.