V-dac modifications

[FalseMetal666]

I corrected my explanation above.

Fantastic, thanks again. I'll be tinkering with this stuff over the weekend.

 

[carlmart]

Reading the opamps thread, I think there might be a good quad to try, which is also DIP.

https://www.mouser.com/Semiconducto...s/_/N-4h00g?P=1z0y3wa&Keyword=opa4227&FS=True

 

[FalseMetal666]

I corrected my explanation above.

Is there any reason to measure offset for the Quad amp, or is the dual the only one that matters in this instance?

 

[carlmart]

No, only the dual matters.

 

[FalseMetal666]

Reading the opamps thread, I think there might be a good quad to try, which is also DIP.

https://www.mouser.com/Semiconducto...s/_/N-4h00g?P=1z0y3wa&Keyword=opa4227&FS=True

Yep, that's the one I bought already and will be installing this weekend in a socket for easy swapping. The Cimarron part with OPA1612s will be arriving Monday, so I'll have a chance to compare.

 

[carlmart]

There should be differences in quality. Usually I avoid calling them better or worst, as that is something the user should decide. Differences is a better word.

Picking changes on such cases as yours, which would demand coming and going between difficult to install parts, is difficult. Except if you are using a socket, which I do like.

A good compromise for sockets is the soldering type, where you can solder the IC to the socket. But that is very difficult with 14-pin ICs.

 

[FalseMetal666]

I installed the OPA4227 and also changed C10 to 100uf, and upgraded C22 to a Silmic (same value as stock, 100uf). Hard to say if there's any change at this point, but I feel like bass response is better and background is quieter. Who knows.

I measured DC offset on the dual opamp and was getting varying measurements from 0.5mv to 1.0mv for both pins 4 and 8. However, I don't really trust my multimeter (or my ability to read it). So, the output caps remain the same for now and will be swapped over to Vishay MKT1813s, 2.2uf, soon.

 

[carlmart]

First of all, I think you shouldn't "try" to listen to the differences that may happen (or not) when you change something. Particularly when you can't swap parts quickly to check on that..

Try not to "imagine" or "think" on what has changed. Dramatic changes may happen, but they are rare. Sometimes it means distortion increase, which is the opposite of what you should look for.

Just plain listening, and see if you enjoy it and can listen for a long time, without irritations.

My advice is to pay attention to the separation of the instruments, the wideness and deepness of the stage, the small harmonics that come or go with the change. Stage deepness is difficult or impossible to evaluate with headphones though.

This I call training you ear. Many people tell me that I can listen to things because my ear is trained (I worked as sound recordist for films and TV), but training you ear is something anyone can do.

Just pay attention and try to separate the different sounds you hear. Anyone with healthy ears can listen to anything, that is not a "golden" thing, as many call it. If I can listen to something, you also can. You just need to focus.

About the meter points, of course you should be careful, particularly when you can short the output to a power pin, or short circuit a power pin to ground. Meter probes should be kept clean, as they do tend to oxidize.

Digital meters, good ones, are now very good, quite cheap and a good investment. Mine is a Mastech, which was cheap and is very precise.

Get yourself some good meter probes with small tweezers. Now you can find some designed for SMD components, which I haven't got yet. But separate cables with points that can grab the pin or wire, particularly the ground, are important.

https://www.sparkfun.com/products/11060

https://www.ebay.com/itm/Universal-...t-Lead-Probe-Wire-Pen-Cable-Hot-/361019706380

https://www.ebay.com/itm/1-Pair-Ban...m=132474589056&_trksid=p2047675.c100008.m2219

Your metering may be right, and the offset be very low, just a few mV. Check any power pin at the same time to see if the probe is fine, and trust what it shows you after several tries.

If the offset is that low, you can safely bypass the output caps. Remember there are caps ahead in the Schiit, which BTW you can bypass too.

But on the Schiit you have to check if there's no input offset, as it's tubes voltage we are talking about. So maybe you should let them be.

 

[FalseMetal666]

What's the worst that can happen if I remove the output caps in the DAC? Mostly just curious.

 

[carlmart]

As you already have a blocking capacitor on the next stage, nothing bad will happen, only clicking noise if you were using a cd player and load the disc.

 

[FalseMetal666]

As you already have a blocking capacitor on the next stage, nothing bad will happen, only clicking noise if you were using a cd player and load the disc.

Nice! SO LONG, OUTPUT CAPACITORS!

 

[carlmart]

The ideal thing is to have just one capacitor at the last reproducing stage input, headphone or speaker amplifier. Film type, if possible.

In any case do check the V-DAC DC offset output.

Schiit, which is a serious company, certainly picked the input capacitors carefully. So I wouldn't touch those. What value are they?

 

[FalseMetal666]

Assuming I'm looking at the electrolytics near the input jacks, I'll have to crack the unit open later to check.

 

[carlmart]

No, don't do that. I think it may void your Schitt warranty.

 

[FalseMetal666]

No, don't do that. I think it may void your Schitt warranty.

Ok, I'll skip that then haha

I plan on placing an order for a few of these to replace all the ceramic caps: https://www.mouser.com/ProductDetail/Vishay-BC-Components/BFC241641004?qs=sGAEpiMZZMv1cc3ydrPrF6b39BhxIu4v74fT2oEOK4Y=

On the expensive side but my curiosity is piqued since the DAC sounds significantly better than when I started. I've probably spent enough money to just buy a decent new DAC but this is more fun.