Anyone tried mixing Normal and TB channel on an AC30 like in a JTM45 style amp?

[VintageCharlie]

Hi folks,

as i am getting more into experiments with an amp based around elements of an AC30/JTM45, i was wondering about the approach to channel mixing. In the Marshall they are mixed before the tone stack with 270k or 470k mixer resistors, in an AC30 they are mixed right before the PI with 220k.
Has anyone tried to mix the channels in an AC30 Marshall style, so that the EQ works on both, they are in phase and can be easily blended together? Will try this soon myself, but am waiting for some parts and wanted to hear if there already are some experiences with this.

[sluckey]

Is this what you have in mind? Should work fine. I haven't done this. I'm using Hoffman's AC-30 schematic for the example...

[Alnico]

Yes, the first amp I built was exactly that. This was nearly 30 years ago, so I only have a photo of a photo...

[VintageCharlie]

Is this what you have in mind? Should work fine. I haven't done this. I'm using Hoffman's AC-30 schematic for the example...

Yes, exactly that. If you make this change, then the AC30 TB/normal channel becomes identical to the JTM45 in regard to the preamp topology. I am wondering how much of a tonal difference (apart from the differences in function) comes from mixing them there as opposed to the stock position before the PI.
Will certainly try that out.

[VintageCharlie]

Yes, the first amp I built was exactly that. This was nearly 30 years ago, so I only have a photo of a photo...

Haha that is truly historic - a photo of a photo

So how do you like this arrangement and have you had a chance to compare it to the stock arrangement in the same or similar amp?

I like how this works on a JTM45, but i am a bit worried it might take away some things I like about the AC30 tone.

Cool build with a mixture of VOX/Marshall alements and Hiwatt-style layout.

[sluckey]

Yes, exactly that. If you make this change, then the AC30 TB/normal channel becomes identical to the JTM45 in regard to the preamp topology. I am wondering how much of a tonal difference (apart from the differences in function) comes from mixing them there as opposed to the stock position before the PI.
Will certainly try that out.

Easy to try the mod (or undo). I would expect the TB channel to sound about the same as it always has sounded. Of course the normal channel will change considerably. And if you jump the two channels together you will have a whole new set of tones to blend together. I bet you will end up with a much more versatile amp and will probably favor the tones of the jumped channels. I have all my Plexi style amps hard wired in the jumped mode and only have a single input jack.

[VintageCharlie]

Yes, exactly that. If you make this change, then the AC30 TB/normal channel becomes identical to the JTM45 in regard to the preamp topology. I am wondering how much of a tonal difference (apart from the differences in function) comes from mixing them there as opposed to the stock position before the PI.
Will certainly try that out.

Easy to try the mod (or undo). I would expect the TB channel to sound about the same as it always has sounded. Of course the normal channel will change considerably. And if you jump the two channels together you will have a whole new set of tones to blend together. I bet you will end up with a much more versatile amp and will probably favor the tones of the jumped channels. I have all my Plexi style amps hard wired in the jumped mode and only have a single input jack.

That really does sound like the way to go fir this style of 2-channel amp. I am wondering why the plethora of VOX-inspired builders like Matchless, TopHat, Dr Z, Morgan, etc. have not gone this route, even in the models that have some Marshall elements. Will try this out and report back. I have another AC30 to compare it after i mod the clone, so i should be able to notice if and what changes on the Top Boost channel. Here i hope that nothing changes, as it is perfect as is (mine has an added mids control a la Marshall in there already).