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

Showing 3 responses by perkri

The small film caps that are put across the electrolytics, are bypass capacitors.

A small high quality bypass cap can greatly improve the SQ from the bigger electrolytic.

I recently recapped a tube amp and I put Myflex capacitors with great success.

Also recapped a Marantz 7T and because of space restrictions, used Audionote electrolytics with Myflex bypass capacitors on each one. Also sounds fantastic.

Deoending on how long you plan on keeping the amp, buy the best capacitors you can justify putting into it. They will make a difference. Humblehifi’s capacitor list has served me well in the past when deciding on what caps to use.

 

And ignore the comments about your amp not being worth the effort. It’ll be worth the effort. Anyone who has done a recap, either themselves or by a tech will tell you it’s worth it. 

Another quick thought, from personal experience. 
 

If you are doing the work yourself, one part out, one part in. Take pictures of every section you are working on before you start and after you finish. Speaking from experience here. Didn’t do that on my first recap project.  Nothing worse than being called away from the work, coming back and having a “oh crap, where does that go again…”

 

Please forgive the note if it’s already common practice, or if you are already comfortable with pulling every and then replacing everything.