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Upgrade capacitors in tube amplifier?

I have upgraded crossovers with very good results.  I now have a "very good" IMO chinese tube amplifier that can probably be improved with a couple of capacitor upgrades.  

I don't have a schematic, but I have a picture and I expect some of you knowledgeable folks can point me to/confirm the ones to change.  My thought is to change the two large silver ones first and then maybe the four smaller silver ones (on the circuit boards). 

Would probably replace with something like Jantzen Superior Z-Cap or comparable and go with a higher voltage if space permits.  

https://imgbox.com/rtBfoyg0

Thoughts?


chinook9
puffball08's avatar
puffball08
311 posts
 
For your coupling capacitors (particularly the 0.33mfd), and importantly, if you physically have the room, consider either Jupiter Copper Foil Paper & Wax or Miflex KPCU-01. The Jupiters are a bit more expensive but you won’t go wrong with either.

I’ll second (or third) the suggestion for Takman REX Carbon Film resistors. Very musical.

While you’re at it, consider the output transformers. Look into Lundahl.

And look at the power supply rectifiers. I don’t see a tube, so it must be silicon. If it has Schottky rectifiers, you could consider replacing with (third generation) silicon carbide (SiC) rectifiers.

And has been pointed out above, once you start down this road, you’ll probably end up spending as much on component upgrades as the initial cost of the amplifier. Be sure your comfortable with that.
tomic601's avatar
tomic601
12,911 posts
 
RAM tubes, best computer matching on planet

thanks to the genius of Roger Modjeski ( RIP )
noromance's avatar
noromance
9,764 posts
 
Tung Sol EL34B.
calieng
144 posts
 
I agree - don't mess with the circuit if it sounds good.  Their branded tubes are decent and I did not hear any significant difference with other tubes but the tube construction is a little better with Tung Sol or some others. 

The biggest upgrade you can do is buy the R-300B model. It is amazing! I also have the R8 with KT88 tubes and the R-300B is significantly more organic sounding. I have not owned the model you have but likely is similar in tone to the R8. I am running the R-300B thru Klipsch Forte III....simply amazing match.
chinook9 OP
68 posts
 
The biggest upgrade you can do is buy the R-300B model. It is amazing! I also have the R8 with KT88 tubes and the R-300B is significantly more organic sounding.

calieng3, thank you for this information. Yong Lee recommended the R300B as an upgrade and I have been looking for anything on the comparison of the other Willsenton amplifiers and the R-300B.

I am playing with the R-35i now, but I know, with Covid19 limiting my other hobbies, I will be trying to improve upon it before too long.

My hobby, at this time, is to work at getting the best possible sound (IMO) for the least possible cost. 
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