2. amps-preamps
  3. 1270085894

Noise at start-up of one mono-block

I have a pair of Quick-Silver mid-mono monoblocks. Over the past couple of days, each time I switch the left one on and after the tubes heat up, (about 5 to 10 minutes) the amp makes a loud buzzing sound.

If I switch the amp off and on again then the buzz stops and does not come back until the amps has been shut-off over night.

Any ideas on what the problem could?

The amps are less than a year old.
The tubes are biased and the bias holds.
The noise occurs even if the pre-amp is off.

Is this the result of a faulty input or driver tube?
nick_sr
nick_sr OP
263 posts
 
Swapped the output tubes (not the driver tubes) and the buzzing moved from the left to right side.

Conclusion, faulty or worn output tubes (EL34s).

Now, I have to replace the pair for a new matched pair. Should I replace the output tubes on both amps?
rrog
1,958 posts
 
I would replace the output tubes in both amps. With fresh output tubes in both amplifiers you should get a powerful balanced sound.

Also,I recommend ordering the tubes from Quicksilver. They know best when it comes to sorting and matching tubes for their products.
nick_sr OP
263 posts
 
Thanks Rrog for the advice.

If I am going to change all the tubes I was considering changing from EL34 to KT88.

Do you, or any one else have any experience with running the Mid-monos with KT88s.
rrog
1,958 posts
 
I was going to recommend trying KT88s in your amp. I don't have experience with your amplifiers, but I have owned other Quicksilver amplifiers with KT88 tubes and the sound was very good.
nick_sr OP
263 posts
 
I picked up a matched quad of electro-harmonix KT88's from my dealer who sold me the amps. There not from Quicksilver but I had to make a choice, no music for the long Easter week-end or wait for Quicksilver tubes. The choice was clear.

I haven't had a chance to have proper listen and the tubes probably need to burn in a bit before I come to any conclusions. Based on my first impression, the sound is much different, drums and bass are more pronounced but with less warmth.

Thanks for the input.
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