Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: j_bruce on August 02, 2020, 08:07:30 am

Title: VOX Berkeley w/one tube reverb layout/project
Post by: j_bruce on August 02, 2020, 08:07:30 am

So having finished the Gretsch 6159 and the Airline 9028  for my friend's daughter (she vastly prefers the Airline which sound great with her vintage Epiphone) he generously dropped mo off a VOX VT-40 in a basket as a gift. The box and speaker are good, might be some usable parts to scrounge at some point on the board. But I am going to build something VOXy to put in there.

I decided on the Berkeley but want a reverb so am going with the one tube reverb from Tubenit's schematic.

I used the Vox schematics found here on the forum:
https://el34world.com/charts/Schematics/files/Vox/Vox_berkley_preamp.pdf (https://el34world.com/charts/Schematics/files/Vox/Vox_berkley_preamp.pdf)
https://el34world.com/charts/Schematics/files/Vox/Vox_berkley_poweramp.pdf (https://el34world.com/charts/Schematics/files/Vox/Vox_berkley_poweramp.pdf)

I took a shot at the layout. I need to take a careful second look for errors but would be happy to hear any suggestions.

The horizontal lines indicate bends in the chassis. this will have top controls with bottom tubes.
(https://voxamps.com/product/vt40/ (https://voxamps.com/product/vt40/) has details of the original)

Cheers!
Jerry

Title: Re: VOX Berkeley w/one tube reverb layout/project
Post by: tubenit on August 02, 2020, 09:39:53 am

Just tossing out another idea to consider and NOT saying you "should" do this.  In fact, it's a draft and I haven't built one yet.

The mosfet cathode followers work great, IMO.  And there is some info on them here:
https://el34world.com/Forum/index.php?topic=21873.0

2 things that I think you might have to experiment with (if you tried this) are:

1) dropping resistor on the B+ rail to node E     Might want it higher?
2) .01 cap going into the LTPI      Might want it as high as .0047 or .01


With respect, Tubenit

Title: Re: VOX Berkeley w/one tube reverb layout/project
Post by: j_bruce on August 04, 2020, 07:23:40 am

Tubenit, that is a nice idea. I originally though AC15 for that box but the two channel with tremolo I thought would take up too much space. Your Idea would likely fit at least as well as mine.

I had an AC10SRT way back when and will probably build one at some point.

Cheers!
Jerry

Here's a layout file you can view more easily