Diy stripped down ac30

Do you mean Top Boost only? Doug Hoffman has a somewhat minimal AC30 layout (no tremolo) with a BOM. The Trainwreck Rocket is basically a Top Boost only AC30 with some power rail tweaks.

 

To clear things up... you want a *Normal Channel* only, one *Volume Control*, one *Top Cut*, and 4 x EL84 AC30. You do not want reverb. You do not want Vibrato/Tremolo. You do not want tone controls other than the *Top Cut*, Correct?

 

If you run the Top Boost at '10' and the Top Cut at '10' do you get "Normal"?

Asking for a friend....

 

No, there's still difference.

So what you're going to end up with is a low gain 30w Bassman with four EL84s.

It won't sound particularly Voxy. It will still chew expensive tubes at a great rate, but that's as far as it's Voxiness will extend.

You've plugged into and prefer the Normal channel of an AC30?

 

The normal channel is great with a “cough” Les Paul and fat sounding humbuckers, played into a well damped sealed cabinet with something like the G12H55 or 2 in it. All the windows shake! And hurrah for very old, very nice and quit deaf neighbours! Unfortunately it’s emigrated with the wife and daughter and it’s a month or so before I follow them. Travel restrictions are not just breaking up the family, they’re preventing noise too!

There’s a non top boost circuit diagram here:
https://www.korguk.com/voxcircuits/

However, on models with top boost (at least the C2 I have) the first gain stage for the normal and top boost channels share a cathode resistor/cap. In essence, this allows a little control of the lows when playing the normal channel. So to get the True Tone, the whole circuit is required. However it’s probably simple enough to dump all the top boost bits and simply fatten up an early coupling cap to taste.

If basing the amp on a modded top boost version, there’s a good chance half the first tube will become redundant. Suggest wiring as per the parallel Chanel of the marshal 18w. It’ll probably fatten up the sound and should lower the noise floor a bit too. Circuits here:
https://mhuss.com/18watt/schematics/

Are you going for tube rectifier with choke or solid state?

 

Brian May does well with this setup. Normal channel only, no reverb/vibrato, and bypassed tone stack for maximum gain. He runs through a treble booster however...

 

Might be cool to build this with a germanium rangemaster on a tagboard in the chassis- there should definitely be room in there with no trem or reverb. You could even bypass it with a footswitch. I’m a vox guy and I can dig that.

of course, this is almost exactly the original vox top boost mod but with a transistor instead of a tube, so it might run counter to what the OP is after.

 

But how will you channel jump?

 

If your favorite show is on do you look for the remote?

 

Now I want to try an AC30 because I have always wondered how a tube based range master type setup would affect the gain characteristics.

I run a home brew silicon into my boogie mark 1 clone and it really tightens things up. It’s kind of a POS build quality wise so at some point I’ll be building a lower watt version, and I’ve thought about the concept of wiring the treble booster directly to the board like you said.

 

Nice! I run a naga viper into the normal channel on my ac15hw and it’s a monster. The original vox top boost was actually a bolt-on upgrade to the 60s vox amps- the normal channel is actually pretty dark, and the addition of an extra gain stage and Eq brightened it up a lot. http://www.voxshowroom.com/uk/amp/ac30_tb_hood.html

I actually like the normal + naga sound better than just the top boost channel, but it also sounds amazing to me with both channels jumpered and no boost.

 

That's not the same as a Bryan May AC30.- which Vox used to sell.

His amps are like a power slave unit. They have no topboost or normal channel. Only a volume control.

Bryan uses a whole rack of effects including a comprehensive preamp array that shapes tone. Basically it plugs into the amp where the effects loop 'in' would be, right in front of the phase inverter tube. There's no preamp at all in his amp.

 

To be fair, none of this is applicable to the mid 70’s when he developed his “tone”.

 

It's not the same as his current setup, but Rangemaster into AC30 Normal channel is the main sound on the early Queen records.

@Newbcaster if you find a schematic, please share. I liked the normal channel on my AC15 far better than the top boost, and don't think that it is any less Voxy.