2. amps-preamps
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Tubes to replace stock in Quad II Forty's amps?

Have a pair of Quad II Forty amps and have decided to retube them in an effort to get rid of some intermittent hums and pops. Great sounding , want to them to sound even better.
I have ruled out GEC 's and such , as money is sort of an issue. Svet's, SED, EH, KT88's , KT90's? Etc.. Ideas. Also, will the brand of rectifier tube(5U4G) make difference in overall sonics?
Lastly, will the input tubes 6SH7 matter in the picture.I been told to suspect these as a source of pops and spitting noises on rare occasion.
Thanks, again. I am new to the world of tubes.
montyoldboy
montyoldboy's avatar
montyoldboy OP
14 posts
 
Will an input tube 6SH7 in this case, take out anything if it goes bad or is bad in an amp? I am worried and hope to get some NOS ones off ebay.One seller has untested NOS military 6SH7GT. If these are bad will they destroy some other component down line in my already troubled amps? Thanks
dewald_visser
176 posts
 
Avoid untested tube unless you can test them before you put it in your amps! A faulty input-tube can destroy a power-tube... Be very careful!

Regards,
Dewald Visser
dogberry
814 posts
 

Waking up an ancient thread here! I've owned Quad II/Forty amps for nearly 18 years, and have experimented with various tubes. I haven't found a better rectifier than the Svetlana (St Petersberg) 5Ц3C black plate. I have been using Sophia Electric blue glass coke bottle KT-88s, and have been happy with them. In the interest of widening my options though, I was reading great things about Svetlana Winged C 6550C. Am I correct in understanding that these are a drop-in replacement for KT-88 tubes?

newbee
4,817 posts
 

Those St Petersburg Svetlana/SED 6550's haven't been available for some time. I replaced mine with Tung Sol 6550's. Gold Lion KT88's get the job done as well and seem to be well received by most folks. However I haven't heard these tubes with your amps. 

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