Tube Amp, Preamp upgrades -- what did you do that improved your units?

Your amplifier has 4 coupling caps that can be improved on.  The two orange ones are .22uf and are Orange Drop brand. Replace with Vcap Odams if you can afford them. Audience Auricap XO if you need to spend less.  Both will fit.  
It also has 2 white QS branded caps that are an odd value .27 uf.  Most all caps come in .22uf. Don’t just replace with .22uf.  You want to match the .27uf value. Both Audience XO and Sonicap Gen 1 from Sonic Craft have .22uf and .047uf value caps that can be combined in parallel for the .27uf value. They are both not expensive. 
The bridge rectifier is soldered directly to that large blue electrolytic filtering cap mounted on top of the chassis. It can be upgraded to fast recovery type (Fred) if not already. Not sure what is in there now. 
Other stuff, but not sure you want or need to go that far. 

I would replace with the Mundorf caps. They will improve sonics a little. Better bass and a touch more clarity. Not expensive and easy to do since the preamp is already disassembled. I would add one bypass film cap to each Mundorf electrolytic. A bypass cap is simply one cap soldered in parallel. Use a .22 uf to .47uf Audience XO or Sonicap Gen 1.

The Orange Drop caps are nowhere near the Vcap Odams in performance. The Odams are far more nuanced, resolving, dynamic and real sounding. Not close. However, neither is the price ☹️
Both the Audience XOs and Sonicaps are also a nice step up.


If you are close to Nashville, I could do the work for you. Important the work be done cleanly and right. My guess is you are out in the Northwest by looking at your username pic.  

One last thing.  You could also upgrade the wires going from under the preamp mounting board to the RCAs. VH Audio Airlok silver 18 gauge is great.  The Airlok copper is much less and also good.  You only need a foot or two. 

@grannyring rannyring Thanks for all the thought you’re putting into this question. I’m in Denver, so I’ll go with a good local tech on this.

A couple follow ups if you don’t mind:

First, about the amp: you wrote,

It also has 2 white QS branded caps that are an odd value .27 uf.  Most all caps come in .22uf. Don’t just replace with .22uf.  You want to match the .27uf value. Both Audience XO and Sonicap Gen 1 from Sonic Craft have .22uf and .047uf value caps that can be combined in parallel for the .27uf value. They are both not expensive.

You mention the odd value .27 uF. That struck me, too. 

QUESTION: But if  the combination you mention (Audience XO and Sonicap Gen 1) to equal that value is as you put it, “not expensive,” would the upgrade be worth the surgery?  You did say that “Both the Audience XOs and Sonicaps are also a nice step up” — so perhaps you’ve addressed this concern in your later post?

Second, when you say,

I would replace with the Mundorf caps. They will improve sonics a little. Better bass and a touch more clarity. Not expensive and easy to do since the preamp is already disassembled. I would add one bypass film cap to each Mundorf electrolytic. A bypass cap is simply one cap soldered in parallel. Use a .22 uf to .47uf Audience XO or Sonicap Gen 1.

QUESTION: …are you talking about the black caps in the preamp, again? You had suggested that I “replace the [black] 4 - 47uf 500v filter caps with Mundorf M-Lytic HV 500V 2-Lead Single Section Axial cap from Parts Connextion.” So,  are you now amending this to reaffirm that suggestion but adding another cap along with it?

I’m sorry to not be following easily. We're got two different units here (preamp and amp) and various caps and parts. I'm compiling a table to order correctly. I need to instruct the tech who will be doing the work and so if I’m not clear on it, he won’t know what I need.