Quicksilver Mid Mono Tube Rolling

All, Just acquired Quicksilver Mid Mono Amps. They came with Tesla EL34 and EH 6922 Tubes (Dont know the make for 12AX7s). 

For folks who have experience with Quicksilver Mid Mono's, would appreciate thoughts on these Amps and your experiences tube rolling on these amps. 

Thanks in advance for the suggestions. 
Great amps you have acquired!!!     I have had great luck with both Gold Lion KT 88 and KT 66 but am currently running JJ EL34 which I like a lot.   I re tuned about six months ago with all JJ and the amp sounded fantastic but the input tubes got noisy so I put the EH I had been using and it still sounds pretty damn good.   When funds allow and when those tubes get tired I am going to do Gold Lions for the input and driver tubes.  I use them in other equipment and they seem to last forever and in my experience sound better than any other new production tube for their type.  Do that and you will save yourself so e headaches.  I like to try different tubes but the problem with constant tube rolling is that it loosens the spring tension inside the tube socket.  So I try to avoid that by using the best current tubes that I know sound good.   

I have had a Gold Lion in my conrad Johnson pre for about 4 years... it ate lesser 6922 in about 6 months because it runs them hard...  Gold Lion 6922 is the only tube that has lasted and has also been dead quiet .
Make sure you turn the bias fully counter clockwise before turning the amps back on if you change the output tubes.    Then after it warms up a minute or two slowly adj bias and check 15 minutes after that and then a few times during the first hour or so to make sure bias is stable....   

I can't say enough good things about Quicksilver.   I bout my amps used about six years ago, they were about a year old and have been rock solid.    Had a few bad tubes, blew a fuse a few times but never a hard failure.

I just bought the Quicksilver Headphone amp and it is built exactly like the Mids....   like a tank.      

The Mid Monos are worth every bit new and are a steal used.... enjoy
I've had V4's on two different occasions, the last time were the balanced version. I had the GED KT 88's. Don't believe I ever changed input tubes. Always enjoyed those amps. I plan to return to one of Mike's amps at one point soon. It could be mid-mono, Sixty watt mono, or mono 120. If I can afford it and they will drive my Harbeth C7's, I'm hoping the Sixty Watt mono may be the answer. I also like the tube choices of the mid-mono and Sixty watt mono better. I'd like to have the EL 34, KT 77, KT 88 options. The mono 120's are more of a KT 150 amp by design, although I believe 88's are ok. 
Also , there are several build revisions of the amp..... the older ones without dual bias pots for each tube can not use KT90 or KT120  like the later ones can.  So be aware of that....   aside from that any EL34 or 6L6 will work for the outputs, but these amps were voiced for the EL34 tube.  
I used to have these amp some time go.  Excellent amps! I had great results with these tubes as well NOS 6P3S "Russian 6L6" 
@fjn04 1,385 posts03-20-2020 9:35pm... The mono 120’s are more of a KT 150 amp by design, although I believe 88’s are ok.
Yes, the QS Mono 120 amplifiers really are designed for KT150s with the larger transformers and higher plate voltages. In my Mono 120s I started wth KT120s, was going to try KT88s next, but Mike @Quicksilver discouraged me from doing so. Popped in a matched quad of KT150s and wallah, never looked back. I’m a diehard EL34 convert now. Like the KT150s more than I thought I would (especially when paired with really good input tubes to sweeten them up). There is a tad more air on top, more weight on bottom, added dynamics - nice linear midrange from KT150s. The real music comes in with good input tubes and 100-200hrs on caps and KT150s. Amazing with electrostatic speakers too. A few other tips to share privately offline.

My Mono 120s were stocked with decent EI 12AU7 inputs and basic JJ 12AT7 driver tubes which sounded decent. Tried a few others. Finally, had to..., 1960s Mullard Blackburns and wow, really nice.

Mid Monos, Mono 60s, Mono 120s. Can’t lose. Point to point, quality build, great value, all very nice. Put a really nice preamp in front of them and they really do compete with amps at 2-3x the price.


Oh, and, a buddy just bought the Mid Monos. Dropped in some vintage input tubes. The Mid Monos just displaced his higher $ rig now up for sale.  

Johnny R, @audioconnection
Cool - Bet that combo sounds really nice! A buddy had the larger 2905s and prematurely re-sold them because (I would suggest) he did not have amps like the Quicksilver Mono 120s to drive them properly. Only had lower power SETs driving them. As you well know, electrostatics can sound amazing with the right amp matching.

If you like the Quads (i do too) you gotta hear was this combo sounds like too, my local dealer had these and the larger ones playing for weeks - quite a amazing with 120 monos. Large speakers though, very tall.

>> Have you ever heard these 845PX before behind some nice tube amps? <<<

Quicksilver Mono 120s + SoundLab Majestic 845PX speakers.

I’ve spent a bit of time rolling tubes into my mid monos and I recommend that you purchase the best NOS 12ax7 and 6dj8’s you can afford.  I wouldn’t waste any more money on new production tubes.  Even the Psvane 12az7’s don’t sound as good as a pair of quality NOS tubes.  I’ve had good luck with Brett Jesse, but there are plenty of reliable tube vendors.  
For output tubes I like in this order

Mullard xf2 double getters - I came across a quad for cheap, but they aren’t worth the money.
Old production Tesla’s
Winged C’s - these are the tubes I use everyday.
Gold Lion KT77’s. Decent current production tubes. 

My other suggestion is to upgrade the output caps.  I have Mundorf Supremes, but I’d also recommend Audio Notes.  
I know this all sounds extreme, but the amps are relatively affordable and they Respond well to better tubes - a testament to the design and construction of the amps. 
Thanks for the suggestions. i do have the Tesla EL34's and GL KT88's .. 

Any suggestions on whats the best 6DJ8's that I should be looking to try ?

I have found that the driver tubes make little difference.    Mike of QS said the input tube makes the bigger difference of the two.  I have a pair of 6n23p Reflector in there and they seem to last forever in that position.  

I am going to sound like a hippocrate about tube rolling, but I put a JJ Ecc88 in my pre and JJ  ECC803s in each Mid mono and the combination sounds phenomenal with the JJ EL 34.  I must have had a dirty socket or pins, I had noise last time I tried the 803s
@abhi123 OP4 posts04-22-2020 7:31amThanks for the suggestions. i do have the Tesla EL34's and GL KT88's .. Any suggestions on whats the best 6DJ8's that I should be looking to try ? Regards
 - What preamp are you using with your Mid-Monos?
 - What speakers are you running? 

Helped a buddy with his new QS Mid-Monos past few months, and the Input tubes DO make a difference. Stock coupling caps are decent copper/alu but I changed them in my other QS.  Mike was selling them with JJ / EI tubes and lately some generic Chinese  x7s in another amp another friend got last week. Both complained about brightness at first, partly due to break-in needed.  Tried  vintage 6DJ8, JAN military, Valvo, Tungsram, and a few other vintage 12AX7s.  Sounded okay.  Some vintage tubes in the QS preamp helped a lot, but ODDLY enough new non-vintage PSVANE 12Ax7-T MKII actually worked well for HIM in the Mid-Monos.  The first time I tried PSVANE in my Mono 120s, did not work well - had to run mid 60s Blackburn Mullards in mine. However, he's happy as a clam with PSVANE in the mid-monos, fwiw, but his speakers are 97db sensitivity. Was not expecting them to work well for his amp, but they did. It really does matter what else is running in your system. starting at the source and preamp, interconnects too.