Upgrading Quicksilver preamp or amp caps -- warranty impact?

Considering upgrading caps in my Quicksilver line stage and 60wpc monoblocks.

Looking for experiences from people who have done this.

Did it make a difference?
Did you do it while under warranty?
Did you try seeking Mike’s permission to do that so warranty could remain intact?
Any negatives in your experience?

P.S. If you did this with OTHER gear, your experiences are welcome. 
Yes, checking with Mike is a good idea. Thanks for the suggestion.

@noromance did you do this? Do you have anything to share related to my OP? Thanks.
Big Quicksilver fan here (although more the amps than the original Full Function Preamp I had)--I don't mess with Mike's work.
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@tvad I have a thick skin, plus, I know you're a nice guy.
@hedwig I got this suggestion from another QS owner who got some more expert opinions about the level of caps in the units and he and 5 other QS folks upgraded and had great results. YMMV, but it's not as if these amps are 15k amps with premium caps in them, right?
Mike sells upgrade caps right on his website. Check with Mike, he has a good ear.
@russ69 I missed that. They seem to all be fairly low price. I'm thinking of better caps, such as Mundorf.
@hilde45, only Mike @ QS could confirm warranty info for you for yours.

re: caps
I’ve come across 50+ Quicksilver amps and QS owners with upgraded tubes and upgraded coupling caps in them. The bones of the amps are great! The design, transformers, chassis, layout is an amazing value. Pop over to AudioAsylum, AudioCircle, DIYAudio sites to learn more. Some builder/members mod them over there.

Keep in mind these QS monos are built at a price point, and yet the foundation is there. However, if QS offered high end tubes and top-shelf coupling caps in them, the amps would list for 2x the price new or more. The stock caps are pretty good, a bit veiled over to me, yet do have a nice midrange tone in stock form. I wanted more.

When you install really good input/driver tubes, followed by top-shelf coupling caps, they can compete with amps at 2-3x the price new. Following a hunch, wanted to prove they could be taken to a new level to compete with my other amps. Sure enough.

My QS monos sounded good in stock form and yet could not compete with any of my former upgraded Cary amps. After a year of listening to my QS Mono 120s, and after lots of tube rolling first six months, I finally went to top-shelf coupling caps. Wow, now they sound fan-friggin-tastic, more transparent, layered, added harmonics and three dimensional. The added reality of the change in tone and musicality alone was worth it. As soon as I did it, it was "there", and jumped again after full cap burn-in and settling occurred. Very pleased now.  YMMV, Good Luck.
@decooney Thanks for relaying that. While I'm not a DIY person, this is not major surgery and if it brings the amp up to 2x or 3x the level, well, wow! I’ll go check out those other forums. The caps listed on Mike’s website clearly are not the kinds of upgrades you’re talking about.
@hilde45, if you are going to go to the trouble of replacing caps, go at least to the copper foil caps from Jensen or Jupiter. Other than the Duelands, they are the most organic sounding caps I have tried. Will make a big difference on your quicksilvers.
@johnss  Thanks -- that's very helpful. I may wait until warranty period is over to do this (another couple years) but if Mike gives the all clear, sooner. (I don't know why he would unless he has some reason to trust the person doing the work.)
+1 what @johnss said. If you are going to do it, don’t skimp, buy very high quality caps. Leave the work to a competent professional, and don’t forget to discharge the caps if you do it yourself, proceed with caution.

While people do it hoping to make improvements, as I recall the man himself founder/owner/designer prefers people not mess with his amps (at all), and to keep it under warranty. Makes sense, I’d say the same if I had to warranty my products and did not want people screwing around with my designs. Definitely the safe way to go. Or, buy his caps and what he likes. And, then you have the DIYers who want something more and different.

In my case, wanted to test the exact same caps I used in my prior Cary amps, to see how much of the sound was attributed to the circuit designs and tubes, and how much would actually carry over with cap change alone. After using them in a few other amps, Installed the exact same SilverGold caps used in TOTL Cary FE211 Founders Edition Mono amps, now installed in my Quicksilver Mono 120s. A lot carried over, surprisingly. Would not have believed it myself unless I had tried it first hand.

Removed the factory installed affordable and reliable $5.95 Orange Drop caps (used a lot in guitars) originally insatalled in my Mono 120 amps and replaced them with $50ea (2 per amp) Mundorf Capacitor 0.22uF 1000Vdc MCap® Supreme EVO SilverGold Black SESG (non-oil) version. Same microfarad, and higher voltage capacity.

Piano keys now sounds like piano. Guitars sound like guitars. Tone, texture, delicacy, transparency, depth in my former amps is back again. Warning: the super long burn-in roller coaster ride can be very frustrating with some of these high end silver-gold caps for first 0-200hrs. Worth every penny and the wait in my particular situation, never looked back, YMMV.


Removed the factory installed affordable and reliable $5.95 Orange Drop caps (used a lot in guitars) originally insatalled in my Mono 120 amps and replaced them with $50ea (2 per amp) Mundorf Capacitor 0.22uF 1000Vdc MCap® Supreme EVO SilverGold Black SESG (non-oil) version. Same microfarad, and higher voltage capacity.

This makes a lot of sense. Is it possible that QS uses a $5.95 cap because it's the best one for the design? It's possible but not probable. He's making an amp to a price point. The tubes in my QS preamp were $12 each. Replacing them made a big difference.

Paul McGowan discusses this issue in (at least) two videos.


If I were a mainstream mfg, I too would likely focus on Reliability, Availability, and Cost to stay in business. All key factors. As long as the "standard" version lasts and sounds "good enough" for 95% of the mainstream consumers, it keeps variation away, keeps costs down, and makes the product more affordable for consumers. Makes good business sense. Let the other 5% of DIY’ers do what they want to do and take on the risk themselves, etc etc. Less headaches for the manufacturer. It also comes down to those who want upgraded vs. standard. Standard works fine. And, sometimes changes or upgrades don’t always work better, fwiw.

as mentioned, the manufacturers can not afford to install high end copper foil caps, they retail price increase would just be too much. Also if you want to go further, replace the bias and plate load resistors with wire wound. will make the amp much quieter, and let more micro detail come through. But again, not cheap.
@hilde45 I have reached out to Mike recently about using lower gain tubes and have not as yet heard back. 
Let us know if you do. 
P.S. I may be putting my current version of his Line Stage Preamp up for sale soon as it’s not a good fit for my system.
@johnss My system is very, very quiet. I guess units can differ.
@gochurchgo If you put your line stage up for sale, I bet it goes quickly!
If you work on the amp changing caps, if its not done at the factory you void the warranty plain and simple. To get around this problem we offer coupling cap options. We use the copper foil V-Caps as they are some of the most neutral made, and have the further advantage of reliability.

That latter aspect is important. We've auditioned a lot of parts and one thing I've noticed is that while nearly all of the paper and oil capacitors sound excellent, over time they can develop a slight amount of electrical leakage. In an amplifier circuit this can throw off the operating point or bias of the circuit! That in turn can fry power tubes and output transformers- definitely not for the faint of heart to put it lightly.

So you might want to consider that when looking into boutique capacitors.
@hilde45, regardless of how quiet the system sounds, it can be quieter. If you look at the specs for self noise, metal film are good, but are far from the best. The lower you can bring down the noise floor, the more micro info will be uncovered. I can't post an attachment here, but if you google vishay metal film self noise, you should be able to find the PDF vishay published a few years ago.
@johnss I hear you -- and you make a good point about the effects which will become evident once the noise floor is lowered. I remember the early flat screen TV's. How great they looked. And then came the true black OLED technology -- and boy, did we realize now what we didn't realize then. I trust this is the kind of truth you're referring to, and I'm game to experience it.
Sitting here listening with my MD FM tuner, and its hard to believe I’m listening to radio - upgraded caps in the tuner, DAC, preamp, mono amps. Depth, transparency, micro detail, decay. Piano and guitars just sound amazingly good even with FM, and better with streaming too.

One of the most affordable and effective upgrades with my past three systems. In every case it brought my integrated, preamps, amps to a truly enjoyable level of listening. If you do it, don’t skimp, buy really good caps. +1 what @johnss said too. Will never forget my first modded CD player.  Extra high quality parts make a real difference.