Re: [Harp-L] Amp Mods

[MARK BURNESS <markwjburness@xxxxxxxxxxxxxx>]

Hi Robert,
 
Can you scan the schematic and post a link to a hosting site?
 
If it's anything like the G40V it would probably do with a few internal component changes. The G40V aimed to keep the preamp signal a little cleaner than a lot of other amps because of the additional gain stage.
 
In the short term, I'd try a 12AU7 in V1 maybe an 12AY7/12AT7 in V2? 
 
 
 
I wouldn't worry too much about avoiding the Chinese tubes, getting the right balance in tone & response with the preamp valves will depend more on the gain structure, rather than where those tubes were made. Buy whatever you can afford/gives you best peace of mind, but no 12AX7 from anywhere will have the same gain as a 12AU7 from China. I wouldn't worry too much about changing the power tubes unles you can rebias the amp/get it rebiased easily locally...bias will be more relevant than tube brand.


________________________________
From: Robert <harmonicaman1968@xxxxxxxxxxx>
To: harp-l@xxxxxxxxxx 
Sent: Friday, 21 June 2013, 22:51
Subject: [Harp-L] Amp Mods


I'm wondering if anyone here has ever done any mods on a Pignose G60VR. It's a 60W tube amp using 2 - 6L6's in the final amp stage and 4 12AX7's before that. One of the 12AX7's is for the spring reverb. I'm not sure what each of the other 3 do, besides pre-amp stuff, but I do have a schematic, and can understand it to some extent.

Eventually, I want to swap out some of the original Chinese parts, like the tubes and the speaker. 

It's got a high-low switch that cuts out half of the first pre-amp tube on low, and jacks for an effects loop. 4 and 8 ohm outputs for different speaker combos. One twelve inch speaker in the box.

I'm not up on which tubes would be most advisable, or which speaker. It's a very clean amp, not much breakup as designed from the factory. For guitar, it's great. For harp, not as much, yet.