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Question About Capacitor Upgrade in Tube Amp

Hi,

I am preparing to do a coupling capacitor upgrade on a recently purchased tube integrated amp. The two 0.22uF on the preamp tubes are fairly straight forward. But I noticed another similar model 0.33uF cap on the large filter capacitor for the B+ supply that is installed across the hot lead to ground.

Does this cap on the B+ just block high frequency noise from the power supply or does it have any effect on the amp tone? Is there any reason to "upgrade" this cap?

I know it may be hard to tell exactly what is going on without a schematic.

Also any recommendations on a good cap to use in the upgrade of the coupling caps? I was looking at Mundorf SilverGoldOil for the quality at not too crazy a price. The amp already sounds good but lacks a little clarity that I think a coupling cap swap will help with. It is SET 300B amp.

Thank you!

 

calieng
calieng OP
144 posts
 

I received the Mundorf Supremes last night and got them installed this morning.

Initial impression: Upper frequencies which were rolled off are now fully there. Cymbal crashes and other higher frequency elements that were in the background or missing are now fully there.

Bass that was previously full is now taught, well defined with some punch. Best bass in a 300B SET I have heard so far.

For a little over $100 and a few minutes of time the coupling cap upgrade in this Willsenton R300 is an absolute no brainer. It is a must do upgrade. The amp is sonically deficient otherwise. So for under $1400 for amp, shipping, and upgrade I have an amp that sounds amazingly rich, holographic, and musical.

Thanks again for all the advice. 

tomic601's avatar
tomic601
13,065 posts
 

sounds like much more than an “ initial impression “…. 

charles1dad's avatar
charles1dad
10,250 posts
 

@calieng 

Congratulations with your positive outcome. It seems that the stock coupling capacitors were a sonic bottleneck. I’d say that was 100 USD well spent.

Charles

alexberger
935 posts
 

Vcap CuTf are great for 300B SET - clean, clear, transparent, fast, soundstage not harsh at all.

Duelund Custom are excellent too - great tone harmonics, soundstage, a little bit slow and full bass.

Bu I think these two options are too expansive for such not expansive amplifier.

Does anyone compared directly:

1. Vcap CuTf vs Mundorf Supreme Silver Gold Oil?

2. Duelund Custom Cu vs Cu-Sn versions?

 

calieng OP
144 posts
 

Yes given the cost of the map I did not want to spend too much on the upgrade but honestly I do not think it could sound any better. Bass, middle, and treble are all clear and in balance with each other. 

I am sure all the other caps recommended would have made a significant improvement as well. Maybe with just slight variations in bass or treble response. But the difference from the original cheap factory caps was much more than I had expected.

 

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