Preamp Output Capacitor: Mundorf Supreme vs. Supreme Silver Oil

@grannyring Finally sprung for the duelund cast tinned copper. These capacitors are absolutely amazing. Now I have them in my dac (audio mirror tubadour III se), pre, and speaker crossover. They just sound so natural. 

@imhififan Yeah, no idea at all. I didn't really believe it until I experienced it. Loved the caps for the first few days and then the bass just receded. I switched over to the normal Supremes and it was back.

If you read a lot of capacitor discussions, you can see some other people finding that the bass response of the s/g/o decreases over the first 300 hours (e.g. https://forum.audiogon.com/discussions/mundorf-silver-gold-in-oil-supreme-caps-any-good).

@cal3713 ,Thanks for the link, I just wondering what cause the bass response decreased.

@ricgoretti. If you look at my system pictures, you can see the Mundorfs in there, they're not large. I think they're 2uf, plenty of room. And despite some of the criticisms, I really do enjoy them. Especially if you've got a system that images nicely. If I had too much bass instead of too little, I'd be gushing about the supreme silver/gold/oils. Really beautiful tone and imaging. And not nearly as expensive as the Duelund and v-cap options. 

@grannyring and yes, definitely putting some Duelund's in. Unfortunately I didn't know my amp's input impedance was modifiable... I actually have to re-buy the exact same caps I sold you. It's been fun learning about building/modifying equipment. Still mostly playing Legos, but learning is fun.

@atmasphere Thanks Ralph, I've just been cheating by using the calculator at vh audio (https://www.v-cap.com/coupling-capacitor-calculator.php). Fortunately because the pre is basically an advanced kit, I do have some ideas of what range is normal for use. 

I also just leaned that I can change the resistor on my amplifier (diy first watt f4s and sit3s) to a any value within a decent range. Moved both up to a 200k input impedance to allow for the use of smaller caps.

I'm in the same boat with Don Sachs II and 2 outputs. One for 100 kOhms (tube amplifier) and one for 20 Kohms (Accuphase). In the first one is a Miflex 0.47 uF and in the second one AudioCap Theta 3 uF bypassed by russian teflon 0.02 uF. Studying an upgrade for the second out but capacitors of 3 uF are very large. Maybe a Mundorf will fit. Interested in your topic. From Brazil.

Yes, actually the original reason I started modifying the capacitors was because the miflexs were right on the edge of being too small for my amplifier's input impedance.

Be careful- just increasing capacitor values can get you into trouble. The output section probably the least, but in many cases, the designer is juggling the inductance that a larger capacitor has against the capacitance- and has arrived at a value that has the best compromise between bass bandwidth and coloration. Bass bandwidth good, coloration bad :)

(This is why we have direct coupled outputs on our preamps- this problem is avoided.)
There is a timing constant involved (which sounds like you might already know) the formula is F = 1/R x C x 2Pi
Its a bit inconvenient as stated, but if you replace 1,000,000 for the 1, then R will be in ohms, C will be in microfarads and F will be in Hz. Ideally you want the -3dB point (which is what this formula gives you) to be no more than 2Hz- allowing the preamp to then have no phase shift at 20Hz which will give you neutral bass. R in this case is the input impedance of the amplifier.

Those Duelund tinned copper caps are so special. If you can afford those, they will easily surpass the Mundorf caps in every sonic area. I think you suspect that is true.  They are pricy! 

Also, I just discovered the thread I cited above did have some s/g/o to silver in oil comparisons. It was hard to explicitly search for differences because the only difference in terms is gold (and people write out the cap names variably).

Looks like maybe supreme silver oils do have better bass.

@alexberger and I'll probably also try some Duelund tinned copper. Thinking about putting those on one output and one of the Mundorfs on the other.

@imhififan If you read a lot of capacitor discussions, you can see some other people finding that the bass response of the s/g/o decreases over the first 300 hours (e.g. https://forum.audiogon.com/discussions/mundorf-silver-gold-in-oil-supreme-caps-any-good).

@noromance Yes, actually the original reason I started modifying the capacitors was because the miflexs were right on the edge of being too small for my amplifier's input impedance.

@alexberger Although the miflexs' had nice tonality, they presented a very flat image in my system. Adding in the Mundorfs put a lot more layering into the soundstage. It very much went from 2d to 3d.

You sure they're the correct values?

Why do you need all these Mundorfs after using Miflex KPCU?
What was wrong with  Miflex KPCU?
Did you try Jupiter Copper?

they had no bass (actually, they lost bass as they broke in).

The capacitor lost it capacitance after broke in ?