Quicksilver Silver Mono Mods

[typereg6]

I recently purchased a pair of completely stock QS Silver 90 Mono amps based on QS reputation for simple KISS designs and robust buld quality. After living with these for a while I am looking to improve things like "inner detail" and the sense of "spaciousness" in the sound. I haven't had a much luck from the manufacterer and saw several posts helping mod other QS designs but I'm not sure which of those mods would be applicable to this circuit design? I can't seem to find a schematic for the amp anywhere. Any help would be appreciated.

Pics of internals:

An externally hosted image should be here but it was not working when we last tested it.

- Can I use KT120 or KT150 tubes in this amp without circuit changes? Should they be biased the same (90ish mA) and would they have significantly extended life over the KT88. Will they produce more power or sound better? (I am sonsidering the Tung-Sol KT120 heavily)

- What would be the best "bang for the buck" approach to improving this amp or let me ask it...where do I start first

 

[JonSnell Electronic]

The limiting factor is the mains transformer. Heater current is more on KT150 than KT88 and the transformer will only deliver so much power.

 

[typereg6]

Is that an issue with the KT120's?

 

[Alastair E]

Hmm--Thats odd, I'm not seeing the O-P, only Jon's reply....

 

[fdegrove]

Hi,

Hope this helps:

http://www.quicksilveraudio.com/history/Mono100Manual.pdf

http://www.gizmoblog.eu/upgrade-quicksilver-audio-mono-100/

From reading the above link there were problems with this particular model. Not sure if QS corrected this at some point or not.

Cheers,

 

[typereg6]

These are actually the original Silvef Mono 90's not the 100's

 

[jazbo8]

-Why would a manufacturer ask for the power tubes to be bias so high... significantly shortening their usable life

The 90mA~110mA bias is for two tubes. Can you see if the screen grids are cross-connected like the Mono 100?

 

[typereg6]

Yes it is for the pair? Are the coupling caps the ones that connect to the smaller input and driver tubes only?

 

[jazbo8]

Yes for one pair. I do not understand your second question on the coupling capacitors... Could you post a picture of the output tubes below the chassis so we can see how they are wired?

 

[Badge]

I own a pair that I have had for many years. They are highly modified. I suggest you send Mike a e-mail at Quicksilver about tube compatibility. I have stuck with KT88's. I have gone though a number of them in search for better sound. The current favorite is the Gold Lion remakes.

 

[jazbo8]

I own a pair that I have had for many years.

Does your unit have the screen grids cross-connected to the other tube's plates?