Quicksilver audio silver 88 mono amps

The electrolytics that are problematic are not the coupling caps. They are both 600v 50 uf rated. I would speak first with Mike Sanders if or when there is an issue. The + leads on both fried manifesting in a howling sound from the amp. I performed the replacement of these caps until my friend who has regular contact with Mike Sanders performed the final fix which involved some minor mods to acommodate a beefier power supply and better caps. 

I went through 5 different pre-amps before settling on a Bill Thalmann upgraded CJ PV9a which complements the QS amps in my set-up very nicely. I am using the Tung Sol KT 150 tubes which I prefer over the KT 88s, ymmv. A matter of trying both. I am unfamiliar with the KT 90 and KT 120 tubes in these amps.

Fsonicsmith you are spot on in recognizing the importance of the power and output transformer in tube amp designs. I am  certain this is the primary reason why all QS amps are all so consistently excellent across the board. The mid monos are a great value at the price as is the 20 watt integrated. I have had zero problems other than the cap issue noted over the past 5 years. Yeah, Mike doesn't seem too keen or that it is necessary to "upgrade" but it must be noted, these products are still built to a price point and better performance can be gotten using better components. I'm with you on that deconney.

Enjoy your Zardozmike, you made a great choice!   

 

@zardomike
IMO, good KT88s paired with nice small signal/driver tubes for those amps. Not a big fan of the KT90s or KT120 tubes in a few different QS amps, could just be me. Others may hear differently.

I'm going to experiment with the kt88's also, they've been my go to power tubes forever.  A really solid performer. 

@zardozmike
Recently helped a friend with an older Jolida integrated who was enamored with the sound of the upgraded QS monos. After some pushing and prodding by a few us and a local dealer buddy -  removed his over-provisioned KT150 tubes (he mistakenly tried in that amp) to go back to different KT88s in his Jolida that was originally designed to run KT88s at lower plate voltage, bias, etc. KT150s were a waste and not running in their optimized state in THAT older Jolida. And of course, newer Jolida avail for KT150s though, different topic of course. Back to KT88s....  

Popped in New Plate Current Matched Quad of Psvane KT88-T Classic MKII Series tubes. Viva sells them too.. Wallah, kinda got lucky, and his older Jolida sounded like a completely different amplifier, was a nice surprise. Not sure if your QS would respond the same but it was worth trying different KT88s in this other amp, fwiw. He loves the amp now...

I just bought a used pair of 88 monos and am blown away by the way they've transformed my system. Mike Sanders knows exactly what he's doing and offered up some great advice...just email him if needed. He'll respond quickly. They've added a whole new level of transparency and sophistication to the sound which I considered to already be good. Granted, I'm coming from a McCormick DNA 2.0 rev B, stepping down in juice from 600 to 80 watts and moving to tubes nonetheless, these babies are flat out fantastic! I replaced the JJ KT88s with Tung Sol KT120s and the difference was remarkable. The music became more life-like, with improved dynamics and bass by adding authority. I also replaced Electro Harmonix 12AX7 with Tung Sol and finally the GE 12BH7A with Sylvania (which had an unexpected massive impact). Now some or all of these tube replacements could have been because of age and since I bought the units used, I won't truly know. I give these monos extremely high marks for transparency, width of sound-stage, organic sound, imaging, precision of instrument placement, transient speed, mid-range lushness, harmonic depth and bass extension and control. If there is an average quality to these amps, I would rate depth of sound-stage to be just "adequate". It gets the job done here, but I think I expected a little more from tube monos...still not a complaint in any regard. The bass is what struck me most since I didn't expect this level of performance with reference to my previous "goliath" SS amp. In fact, the 88's outperform the McCormack even in this area and not just by a little, by far! Don't let anyone tell you that you need the watts to make deep, full bass sound extended and beautifully timed with bloom. The depth and control these mono's offer is the best I've heard and again... solid state over 30 years of audiophile listening. For the record, I'm running these with the Musical Fidelity NU Vista 3D CD, Audio Research LS25 MKII, Running Springs Duke and Haley, Auralic Vega, Wired for Sound modified Sonos Connect, Audio Physic Virgo 5s, DH Labs Red Wave Rhodium power cables, and all Audience AU24 SE and SX interconnect and speaker cables.