Tube Amp, Preamp upgrades -- what did you do that improved your units?

@hilde45 you may have to go underground over to DIYAudio on this one to find the builders and mod-ers.:)  Not all, yet most here buy and try and rotate new $ amps to find the sound they are searching for instead.  I did high-end Mundorf caps only on my 120 monos. Super duper pleased with the results and would never swap back to the low grade stock caps. Voids warranty and not recommended per Mike at QS of course. Find a competent tech nearby who does this in their sleep if you proceed.

@grannyring Yes on the .27uf combo from Audience or Sonicap. Both should be a step up. I am basing this on the parts quality used throughout the amp which are modest. Someone is making the QS caps, but I am fairly certain they are not quite up to the Audience XO level of quality. 
Yes on the 47uf preamp caps. I added the bypass idea which is a no brainer and will yield sonic improvement. Look up the dimensions of this Mundorf cap and be sure they will fit. Just make sure. I bet they do, but……

Yes, agree. Modest at best on the stock caps in the amps and preamp. Studying a bit inside, maybe Solen or Sonicap ? is OEM with the odd .27uf on the amp IT side and 2.0uf in the preamp. The mfg owner-designer shared he likes aluminum foil caps. There are four $4 715P Orange Drops in these amps on the OT side. Replaced those on mine after year one, along with a five+ others who followed here on A'gon. Yep, a no-brainer.  I was astonished at the results, making the simple cap upgrades for these very solid amps which already have good bones. 

"@grannyring ...You can use the Odam 2.2 uf there. In this output position 2.2uf is perfectly fine. This position is not the same as the stage coupling caps we discussed not changing the value of."

grannyring, interesting, I wanted to ask you about this for hilde45 if you felt jumping from 2.0 to 2.2uf was okay or not for the QS LS. Not seeing a lot of 2.0uFs out there any more like the old vintage stuff.  Good to know. 2.2 it is!   

Re: Mundorf EVO Silver-Gold (non-oil) version sku #80510 is smoother, .22uF 1000vdc, and is not "tipped up". Actually,  the non-oiler version caps are better sounding than the Silver Gold Oil (SGO) version with oil in amps.  Yes, the opposite of what most might think about adding "oil". I learned this from an amp designer colleague when using them in my larger Cary amps, Cary preamps, and now using them again in my Quicksilver Mono 120s with KT150 tubes. 

>>They DO sound more pronounced until fully settled in. Easy to get impatient<<

Kinda discovered this by accident after not wanting "oil" caps that dry out in my prior big amps that get hot. 200hr burn-in required on the non-oiler version cap too, and it is an aggravating roller coaster ride before the EVO silver-gold non oil caps truly form and stabilize to their final set point. Sounds nice when they do.  

@grannyring Yes Solen Fast caps are made in France. They could very well be used by QS. They are the very definition of modest quality…at best. Dull and flat sounding compared to the better ones mentioned here. Used by many builders because they are very low cost. Some builders do have real cost constraints to contend with.

Yes, "modest quality" at best. A little "dull and flat" is a good way of describing it. The bottom line is the stock caps in the amps are built to a low price point. Well built amps and super affordable, yes. 95% of the regular customers are okay with the good sound and reliability in stock form. Makes good business sense for QS. The retail price is far below many others, and this is partly why.

The other 5% of us over the past two decades+ who’ve upgraded caps want to get even more out of the venerable QS monos. Upgrading with high-end well made caps (many mentioned on this thread) and better input/driver tubes allowed me to keep the amps, liking them now much more than originally anticipated. Amazing what these small and affordable changes did for the sound and added musical enjoyment. For added confidence, read through old and recent threads on AudioAsylum, DIYAudio, and other forums and you’ll find members who’ve completed these exact same upgrades on their QS amps with success. If you are going to do it, buy the best caps you can, it will likely pay off for you. Best of Luck.

Can be lower risk and higher reward when high quality-upgrade replacement parts of exact same specs are used and installed by a competent tech.  

Watch a Paul M video from PSAudio where they fully acknowledge even their higher end gear is all designed and built to a price point to control costs, keep pricing down, increase profitabilty, not using overly exotic parts.  And, then sharing in their other design lab they build and upgrade experimental prototypes built with the best parts available to help determine what is truly possible to achieve the best sound. "What is now proved was once only imagined" ― William Blake

 

 

@ihcho How about upgrading transformers?

Do Quicksilver amps have high enough quality transformers and they don’t need to be replaced?

No on upgrading transformers. They are good, high in quality and function.  

The bones of the amp, circuit, transformers, sockets, point to point wiring, is solid. Not naming the transformer manufacturer, they are quite good in stock form.  More spec info available in reviews. One of the reasons I bought the amps, powering my larger custom 4-ohm 92.5 db speakers. The amps don’t even break a sweat. Nor do they run hot like many of my former tube and SS class-A amps did.