@Tommar
Yes, those are 10uf and 1uf. I would increase to 22uf (c26) 2.2uf (c25) (or 47uf and 4.7uf). Use tantalums, better in that position than elco (i use film, rubycon mu 22uf and 2.2uf, best but also most expensive). And make sure cap is as close to the board as possible, the shorter leads the better. Job of that part of the circuit, in short, is to reduce noise.
Yes, it is usually better to have chips from the same batch unless you trim, but not always the case. Yes, replace riv resistors with metal film ones. Since you have oscilloscope, check if it is oscillating just in case.
Trimming would require you to have low level sine undithered input, and measure output on spectrum analyser. You basically adjust to bring down harmonic peaks. I wouldn't bother honestly if you don't have the required gear.
@MrHifiTunes those resistors should be metal film, and quality matters. Their purpose is to prevent parasitic oscillations. 22R is enough for most cases.
As for trimming, read up above. Mainly due to gear required to do the adjustment.
Yes, those are 10uf and 1uf. I would increase to 22uf (c26) 2.2uf (c25) (or 47uf and 4.7uf). Use tantalums, better in that position than elco (i use film, rubycon mu 22uf and 2.2uf, best but also most expensive). And make sure cap is as close to the board as possible, the shorter leads the better. Job of that part of the circuit, in short, is to reduce noise.
Yes, it is usually better to have chips from the same batch unless you trim, but not always the case. Yes, replace riv resistors with metal film ones. Since you have oscilloscope, check if it is oscillating just in case.
Trimming would require you to have low level sine undithered input, and measure output on spectrum analyser. You basically adjust to bring down harmonic peaks. I wouldn't bother honestly if you don't have the required gear.
@MrHifiTunes those resistors should be metal film, and quality matters. Their purpose is to prevent parasitic oscillations. 22R is enough for most cases.
As for trimming, read up above. Mainly due to gear required to do the adjustment.
You don't want absolute low ESR for decoupling the op amps, you have to try, it is often worse.
UKZ are goods but sometimes too much (and indeed low ESR). Anyway you need more caps to experiment, this is the fun of diy and they are not expensive. You can try w/o soldering first. Always switch off the device when you swap caps or op amps.
Definitly buy the UKZ, some FC, UKG before they are gone, some basic Elna. 47 uF is more than okay and 25V perfectly fine.
I will not dismiss the carbon resistor in the I/V, that is true it is more noisy and not wanted theorically in a feedback loop, but you will not really ear it and the tonal can be interresting according on how is sounding the rest. As usual, proof is in the pudding.
👍 Thanks, very helpful.
Is there a description on how and where to measure the parasitic oscillation?
Is there a disadvantage increasing the value?
Same for measuring the trimming.
I have an oscilloscope
Yes, for ease of use, use online tone generator, this one works fine.
https://www.szynalski.com/tone-generator/
With 22R on output, cable influence wouldn't make a difference, but you can check by connecting cable to dac output, on the end of the cable use connector which is loaded by for example 10k resistor (or whatever your input impedance on the following device is, also if you have info of the capacitance you can load it with that value as well). Hook up osciloscope, and play 1k 10k tune, sine and square. I'm going with that you know how to use osciloscope, so no need to detail that step?
22R fits most cases, i went with 47R in one occasion, simply because it was susumu rs, as a much higher quality resistor. No difference soundwise that i noticed.
You need spectrum analyzer. You can't do it on osciloscope.