Hall Amplification VVR3 in Selmer Treble & Bass 50 Mk3

[Willholmania]

I managed to get hold of a Hall VVR3 for fixed bias amps but not from Hall, who don't seem to answer emails these days (I've tried four times). I found some instructions online for the VVR2 version (http://soundgaragetales.com/tempo/VVR2.pdf) but can't find anything for the VVR3. The difference appears to be the addition of a place for an extra component above the large 5w 10Ω resistor at the top of the board in pic on the link above. I left it empty and now have no output from the amp, having double checked everything else.

Does anyone have instructions for this version of the board or any idea whether I should add a wire link in this vacant position?

I'll try to upload some pics in a minute.

Thanks.

Will.

[Willholmania]

[Chuck H]

Schematic?

I could search for one myself, but honestly I'm tired of doing that on behalf of every poster that doesn't provide one. It's time I'll never get back after all. No offence.

So, can YOU locate and link a schematic for your amp? Please.

[Jazz P Bass]

Here is the Selmer schematic: Selmer Tn'B 50 MkIII Schematic

So the Selmer is a fixed bias output section.

Is that the VVR version that you have?

How are you hooking it up?
Full voltage cut or Cut B+ & Bias voltage?

How about a pic of the VVR board that you have?

Factory pics.

VVR3 & VVR2

[Willholmania]

Hi Jazz

Yes - they're the only factory pics I can find. However, my board is different. Whether it's an earlier or later incarnation I don't know, but hopefully you can see the extra slot for R6 next to the large white power resistor. Sorry about the iffy pics but the board's a very tight fit in the Selmer chassis (hence the remotely mounted mosfet and pot) and it's very hard to photograph.

[Chuck H]

Jazz asked how much of the amp you are scaling. Please report on that. Also, follow the voltage and take readings along it's path. Is there adjustable voltage coming out of the VVR unit? Do you have plate voltage?

[Willholmania]

I'm a bit confused - I'm scaling the whole amp, which I understood to be the same as scaling the B+ voltage. The bias is also scaled and tracks the scaling of the B+ via the dual-ganged pot and a second, much smaller mosfet.

I'll measure some voltages. I just wondered whether anyone had any experience of the VVR3 version of the Hall board. Thinking about it, it's pretty likely that the VVR3 superseded the VVR2!

[Jazz P Bass]

The VVR3 is the same as the VVR2 with the exception of " It also has a new feature that will allow you to set the upper limit on your voltages. "
That may be what R6 is for.

[Willholmania]

Thanks. Any idea where that info came from? I'm assuming the higher the value of the (so far) mythical R6, the lower the maximum voltage and the quieter the amp at full tilt. In which case it's reasonable to guess that a wire link in its place will simply allow the amp to go as loud as it did before the addition of the VVR3 circuit.

[Jazz P Bass]

The info was 'gotten' from Hall's VVR3 web page.
http://www.hallamplification.com/main.html?src=%2F#2,2

I would not assume anything about R6.

At least trace it out to see what it is connected to.

A few voltage measurements would certainly help.
B+ In & B+ Out would help.
You may have a problem that has nothing to do with R6.

As to the wiring, on Page 11 is the 'B+ Only' & Bias setup. (Bias is not shown, as it is the same on either configuration)
Take note of the external (builder installed) diodes that separate the power amp/ screen B+ from the preamp voltages.

Page 12 shows the 'Whole Amp' setup.

[Willholmania]

Thanks again, Jazz. But page 11 ands 12 of what? I can't see a build manual for the VVR3 on the link you included in your last post.

[Willholmania]

By shear chance Dana Hall just replied to an email I sent a while back, inkling instructions for VVR3. A wire link is what I need.

I'll let you know how it works out.

[Jazz P Bass]

VVR Instructions

Now that is great to know!
The page #'s were to the setup pdf link that you supplied.

[Willholmania]

Just to let you know; I fitted the wire link in the space labeled R6 and it now works as it should.