[b0bb]

Did you replace all the caps with the parts of the same capacitance that were already there? I can see from my photo that the FP caps that are already there are 470uf which is why I am asking

No, caps values have been changed to the values mentioned earlier.

Stock 470uF is underrated for input filtering, could do with more ripple current handling and better surge voltage handling, 6.3V is a little too close to the 5V operating voltage.
Overrated for output side, affects regulator transient response to sudden voltage changes which are quite common in digital loads

 

[MartinWT]

Both, trimmer is in the audio path, cermet performs worse than metal film for audio.

Thank you. Please may I check this is the model? They are pricy and I don't want to get it wrong.
https://www.mouser.co.uk/ProductDet.../Y405310K0000J0L/?qs=OeYRSXBqOJtCaiZcGrHwDA==

I assume that, as I don't use the single-ended outputs, I only need 4 rather than 6.

 

[b0bb]

Thank you. Please may I check this is the model? They are pricy and I don't want to get it wrong.
https://www.mouser.co.uk/ProductDetail/Vishay-Precision-Group-Foil-Resistors/Y405310K0000J0L/?qs=OeYRSXBqOJtCaiZcGrHwDA==

I assume that, as I don't use the single-ended outputs, I only need 4 rather than 6.

Yes, use 4 if you do not care for the unbalanced RCA outs.

 

[MartinWT]

Yes, use 4 if you do not care for the unbalanced RCA outs.

I've ordered them from Mouser.

 

[fmzip]

Bought myself a vacuum solder pump thinking it would make my life easy replacing a bunch of capacitors! NOPE!!!

Should have bit the bullet and bought a Hako for $100 more. This one has zilch for suction. Even with a part removed, it can't clear a hole.

https://www.amazon.com/gp/product/B08S7D7XGN/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

Bringing the board to the shop tomorrow to use the right tools, or to let someone with better skills tackle the job

 

[fmzip]

My guess:
the earlier boards only have one set of holes for both the resistor and capacitor, so the assembly instruction is to place the resistor on the bottom.
The newer boards have the extra holes but the assembly instruction stays.

There are also CPF2 61.9 Ohm 2 Watt resistors, which are smaller.
I use CPF2 and CPF3 in my tube amps, they are better than garden variety carbon films.

Just measured my resistors, they are 68.1 ohm like @b0bb

The CPF2's are the only one's that come in this value but 1% tolerance, instead of .1%. Is this still beneficial to use CPF2 1% versus the 1% resistor 1/4w resistor that's already on the board? b0bb, what are your thoughts? Trying not to spend 250 bucks on the custom ones you went with....

https://www.mouser.com/ProductDetail/Vishay-Dale/CPF268R100FKE14/?qs=/ha2pyFaduiwd9HVfcMNdLHRnbxGqUVMVykT7B8MhvE=

If anyone needs 61.9 ohm CF3's, I have 4 I can mail to you.....

 

[b0bb]

board? b0bb, what are your thoughts? Trying not to spend 250 bucks on the custom ones you went with....

https://www.mouser.com/ProductDetail/Vishay-Dale/CPF268R100FKE14/?qs=/ha2pyFaduiwd9HVfcMNdLHRnbxGqUVMVykT7B8MhvE=

Not sure why you want to spend money replacing the stock resistor with something that has 2x worse tolerance and 2x worse temp drift (TCR).
You are not going to see/hear much improvement unless you are willing to improve things by an order of magnitude aka 10fold or more.

 

[fmzip]

Not sure why you want to spend money replacing the stock resistor with something that has 2x worse tolerance and 2x worse temp drift (TCR).
You are not going to see/hear much improvement unless you are willing to improve things by an order of magnitude aka 10fold or more.

I appreciate your patience with my questions, I am sure it can be frustrating to some degree. I'm totally inept at the technical explanation for the most part which is why I post what are likely to be foolish questions to the talented experts posting in this thread. I used to purchase electronic components but I am not an engineer. I can use a soldering iron on thru-hole components, that's it. My 30 year career has been in printed circuit board assembly, how all this stuff functions is still beyond me.

The directions you have posted for modifications have been stellar, just trying to see if there is was a viable option other than the $58 per part Texas Components on this particular resistor. From the sounds of it, there aren't. After today's parts are in, I've completed all steps provided except #6. I'll get the Texas Components resistors on order today.

b0bb's Modification Guide: Steps 1-7

b0bb's Anamero USB Modification Guide

If you have some time at some point, would it be possible to continue to add to the guide with further steps? I found it extremely helpful following a simple step by step guide in order of importance. Thank you again for the time you put into this, very much appreciated!

 

[MartinWT]

The CPF361R900BEE14 that I used are 0.1% tolerance, 25ppm/C drift and sound fantastic compared with the stock ones. Only £2.48 each from Mouser.

 

[fmzip]

The CPF361R900BEE14 that I used are 0.1% tolerance, 25ppm/C drift and sound fantastic compared with the stock ones. Only £2.48 each from Mouser.

Unfortunately, I need a 68.1 Ohm......not available in that series

 

[MartinWT]

I think b0bb said that the exact value is unimportant as the ES9038 sets the I/V current on startup. Substitute the nearest value.

 

[b0bb]

I think b0bb said that the exact value is unimportant as the ES9038 sets the I/V current on startup. Substitute the nearest value

Substitution is not recommended.
Additional work will have to be carried out to re-adjust the frequency compensation for the opamp.

I said 2 things.
If you change the the i/v transfer ratio
1) Gain changes, drops in this case, it will worsen the output issues you were already seeing
2) The bandwidth of the feedback loop for the I/V converter changes, the transient and step response to quick input changes is impacted, this makes the top end handling much worse, commonly referred to as the "Sabre32 sound"


This was in response to a very specific question from @ESL57 about the operating current

The operating current is programmed into the ES9038 at startup by its support microcontroller.

Changing the resistor value will not change the operating current, only the i/v transfer ratio.

@Xoverman asked about a week later about substituting the I/V resistor

Please keep the replacement resistor as close to the stock I/V resistor as possible.
The SMD trimmer on the board has a very limited number of adjustment cycles, avoid readjustment as much as possible.

The I/V resistor in parallel with the I/V cap is responsible for the frequency compensation due to the input capacitance seen at the I/V input.

Not sure if the Gen2.x have different input capacitance, @AuxInput mentioned 220pf

Gen1 100pF//68.1ohm fc = 23.4MHz
Gen2 100pF/61.5ohm fc = 25.9MHz
Gen2.x 220pf//61.5 ohm fc = 11.8Mhz

 

[MartinWT]

I meant a very close substitute value, of course, but there don't seem to be any on Mouser.

 

[ESL57]

Hello, I haven't been here for a long time, I'm glad to see that this is very active and there is a lot of new about mods, which I like. For my part, I made some changes to increase the output gain in the I / V stage, this masked much more the noises in some DSD files, but I don't quite like the sound achieved, I think I will return to the 68.1ohm resistors and I will remove the TO220- 75ohm ones that I use for tests, I made more changes between other capacitor tests and I changed the trimmers for precision multiturn. I'll test B0bb's anti-noise capacitor mods. Now 2 questions, my voltage rails from the analog source were at 16.5v and -16.5v, do you have B0bb and the rest of GEN1 ?, What do you think about using "styroflex" capacitors in parallel with the I / V resistors instead made of polypropylene?

 

[fmzip]

Got my board back today after my soldering guru at the shop cleaned up my poor attempt at rework

I don't know about the rest of you but post mod power-up excitement is always filled with mixed emotion. Fear first sets in.....did I botch this up permanently??!!

Then, the sensational relief as soon as music begins to play, instead of white noise or static!


Fortunately, I was blessed by the music & mod gods with musical BLISS after completing steps 1-7, with the exception on the IV resistors as mentioned previously. I listened to a variety of tracks for several hours and was simply blown away with the transformation of sound. Example, my B&W 803's and the combo of the ESS Sabre DAC forced me to dial my preamp's treble back to -3db and boost the bass to +6db. Even with Anthem's Room correction dialed in, my ears would bleed from the highs. Things have steadily improved with the prior mods of steps 1-3 along with the addition of my Kitsune SU2. Steps 4, 5 &7 completed, my system is totally different. Mid range and bass is so much more accurate and powerful. Bass can now be dialed back to +3db, treble to -1db. Really quite remarkable! I thought to myself why mess around any further??

As we know with the disease we all have, curiosity is hard to contain. Can there possibly be another level of audio nirvana??? Should I order the custom resistors from Texas Components for $258?? What's another $258 in the grand scheme of things?? Thanks @b0bb , I haven't had this much pleasure spending money on audio in a very long time. All your suggestions thus far have been spot on! Resistors should arrive in about three weeks.

I'm going to try to do my level best and just listen to music for the time being, listen to things settle in and avoid checking this thread several times a day! Let's see how THAT goes....