Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: dwp on August 06, 2010, 09:07:26 pm

Title: Master Volume on Barry's HPR princeton reverb build layout.
Post by: dwp on August 06, 2010, 09:07:26 pm

guys, forgive me if this is in the archive post, but I didn't get to it there.
What about the Master Volume wiring shown on the chassis layout, but not on the schematic.
Is this like cut control on AC30 or true Master Volume? muting?
Do you you need the switch on the 1MA pot to bypass/remain transparent, or will 1MA suffice?
Would like to add MV, wanna hear more about the one shown.
Thanks in advance, dwp

Title: Re: Master Volume on Barry's HPR princeton reverb build layout.
Post by: Fresh_Start on August 07, 2010, 10:53:24 am

It's a "crossline PPIMV".  I put one in my first Princeton Reverb build but didn't really like it much.  That preamp's pretty clean unless you mod it some.  Also, I prefer a good attenuator to a MV down to a point.  Didn't seem to need a switch.  It's just like the "cut" control except it affects all frequencies.

HTH

Chip

Title: Re: Master Volume on Barry's HPR princeton reverb build layout.
Post by: bnwitt on August 07, 2010, 02:53:45 pm

I didn't care for that master volume either. I much prefer the Bruce Collins altered Trainwreck one that I later put on a silverface Twin Reverb conversion.

Title: Re: Master Volume on Barry's HPR princeton reverb build layout.
Post by: dwp on August 07, 2010, 09:00:27 pm

thanks for the replies, Fresh and BNW. Will not go there. So what about a raw knob on this build, will it still work on a build with no mid pot? last DR I rigged the Allen style raw knob on, I also added the mid pot. And it was pretty dark, would want to figure out how to get alittle more high end through it if I did it on this build.

I have til Tuesday to commit, that's when the chassis arrives. I would like to give him some form of grind/meat/or MV control, one pot mod only.
Thanks again, dwp.

Title: Re: Master Volume on Barry's HPR princeton reverb build layout.
Post by: mresistor on August 08, 2010, 07:38:41 am

I've been giving some thought to installing a Hall VVR3 in my HPR. Any thoughts?

Title: Re: Master Volume on Barry's HPR princeton reverb build layout.
Post by: dwp on August 08, 2010, 04:26:56 pm

pretty secretive mod, power brake sorta?  my search yielded pic of heat sinks and mini PC board, my constitution won't allow that at this time.....

Title: Re: Master Volume on Barry's HPR princeton reverb build layout.
Post by: mresistor on August 09, 2010, 11:06:47 am

dwp - it's a power scaling kit - reduces the power output while still letting one obtain cranked amp tone - some amp makers are starting to utilize this circuit. London Power makes one as well.

http://www.londonpower.com/london_power_technologies.htm (http://www.londonpower.com/london_power_technologies.htm)

http://www.londonpower.com/powerscaling_vs_vp.htm (http://www.londonpower.com/powerscaling_vs_vp.htm)

Halls is a simpler design, but achieves a similar result

http://www.hallamplification.com/main.html?src=/#2,2 (http://www.hallamplification.com/main.html?src=/#2,2)