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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
jaytor's avatar
jaytor
747 posts
 

The Vishay Z-foils are very transparent and low-noise. These resistors can be ordered in arbitrary custom values from Texas Components. The latest version is the TX2575. These are only available in sizes from 10 ohm to 100Kohm. The older TX2352 is available from  1 ohm to 250K ohms. 

For higher power requirements or resistors outside these ranges, I like the Audio Note non-magnetic tantalums and silver-tantalums, but these can get pretty pricey.

calieng OP
144 posts
 

Interesting.

NOS Allen Bradley Carbon comp resistors are all the rage for tube guitar amps. For their warmth and organic tone. I wonder how they fair in hifi? They do tend to drift in value a fair bit. So maybe not so good in hifi setting.

sns
3,005 posts
 

The nude Vishays are nice, use them in my 300B amps.

terry9
2,259 posts
 

And for really low values, less than a couple of ohms, nichrome wire just can't be beat.

jaytor's avatar
jaytor
747 posts
 

NOS Allen Bradley Carbon comp resistors are all the rage for tube guitar amps. For their warmth and organic tone. I wonder how they fair in hifi? They do tend to drift in value a fair bit. So maybe not so good in hifi setting.

Carbon comp resistors are very noisy and add distortion. This may be (is likely) desirable in a guitar amp, but not what I want in my hifi amp. 

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