dual gain and MVs

cbass · Post by **cbass** » Sat Jul 12, 2014 1:30 pm

So I was thinking my 100 watt super drive gets a very good clean sound when the gain is backed down and the MV is up.
Would there be any problems with switching gains and mv's for a psudeo channel switching deal.
Basically you could dial in your gain sound then adjust the other master to ma ch volume on your clean sound.or make a solo boost.
I am going to try this on a new build I already have a head schem just wondering if there would be any problems in r reasons why it wouldn't work
I think I could use a 4pdt relay . I thought about just switching the pot grounds but then I guess the controls would be interactive.

Smokebreak · Post by **Smokebreak** » Sat Jul 12, 2014 1:57 pm

That's exactly how I've done it in the past, for a pseudo channel switcher like you said.
It was Marshall topology, so I used 2 Normal MVs, in parallel, and switched the wipers out to the PI . Then those were linked via relay to trigger with the channel switch. My channel switch was like 800 and plexi, so my plexi was "clean", 800 was "OD". Lots of range there.
In addition to the clean/OD thing, you could also match the gain levels, up to a point, and use the switching as a lead boost.

cbass · Post by **cbass** » Sat Jul 12, 2014 2:03 pm

Cool I'm not talking about switching the hi lo inputs but the gain pot so you could have one pot set for dirty and the other for clean then each would have its own MV to match the sound level.
Or you could set it for rhythm crunch and solo boost. I just use the single gain control with my SD it gets a much better clean sound that way. And sounds the same to me when cranked

Smokebreak · Post by **Smokebreak** » Sat Jul 12, 2014 2:19 pm

Yea I think we're sayin the same thing, design wise. My gain pots/channel switch were at different stages but they don't have to be. The way I had it, it was capable of more extreme dirt level differences, but you could just parallel up the gains too, and switch them with the MVs

Smokebreak · Post by **Smokebreak** » Sat Jul 12, 2014 2:48 pm

Here's one way to do it
I drew it as 2 DPDTs, as if you are concerned with the loading of the paralleled pots, you can put the grounds on the other pole of each switch, to lift the ground of the pot not in use, to keep 1M loading.
Or you could just use 1 DPDT, and not worry with relays to link them.

cbass · Post by **cbass** » Sat Jul 12, 2014 3:21 pm

Yes that would work I was thinking switching just the wiper would leave the controls interactive with each other but it wouldn't just make it like having 500k pots which would be fine that's much simpler than what I was thinking thanks a lot Jeremy

eddie25 · Post by **eddie25** » Sat Jul 12, 2014 5:17 pm

I'm really curious how this turns out, looks nice and simple. You gonna use a relay?

cbass wrote:I just use the single gain control with my SD it gets a much better clean sound that way. And sounds the same to me when cranked

The one after the first or second triode? I guess if you have the other stage set as a 1M to ground it would sound the same cranked, but a little different at lower settings. That would be an interesting comparison... Did I read before that you did one with the dual gain split into two pots? Is that how you came to this conclusion? Just curious cause I've been checking out that SD schem a lot.

cbass · Post by **cbass** » Sat Jul 12, 2014 5:31 pm

eddie25 wrote:I'm really curious how this turns out, looks nice and simple. You gonna use a relay?

cbass wrote:I just use the single gain control with my SD it gets a much better clean sound that way. And sounds the same to me when cranked
The one after the first or second triode? I guess if you have the other stage set as a 1M to ground it would sound the same cranked, but a little different at lower settings. That would be an interesting comparison... Did I read before that you did one with the dual gain split into two pots? Is that how you came to this conclusion? Just curious cause I've been checking out that SD schem a lot.

I'll put it on a switch first then if I like it I'll fix it up on a relay
Yes after the second stage first stage on the low input.

Yes I tried two different gain pots and found that it sounded very good with the first stage cranked and the second stage down around 2 or so I get huge clean sound being a 100 water may have contributed to that.. This one will be a 50 watter.So ended up with just the single control. I got a dual pot but never did try it.[/quote]

JazzGuitarGimp · Post by **JazzGuitarGimp** » Sat Jul 12, 2014 5:55 pm

To keep the the same frequency response, you may need to increase the value (maybe as much as 2x) of the coupling cal coming off the previous stage. Akso, if there is a divider resistor sitting between the coupling cap and the top of the pots, it may need to be adjusted to taste.

Are you going to be using the lar-mar MV? If so, the grids of the output tubes may be allowed to float (red plate) during the time the relay takes to switch between contacts. This will likely cause a huge POP in the speakers.

cbass · Post by **cbass** » Sat Jul 12, 2014 6:07 pm

JazzGuitarGimp wrote:To keep the the same frequency response, you may need to increase the value (maybe as much as 2x) of the coupling cal coming off the previous stage. Akso, if there is a divider resistor sitting between the coupling cap and the top of the pots, it may need to be adjusted to taste.

Are you going to be using the lar-mar MV? If so, the grids of the output tubes may be allowed to float (red plate) during the time the relay takes to switch between contacts. This will likely cause a huge POP in the speakers.

Lou the MV is after the fx loop recovery stage and before the pi
I guess I should put up a scheme [img

727]http://i176.photobucket.com/albums/w197 ... ive601.jpg[/img]
[img

685]http://i176.photobucket.com/albums/w197 ... rive60.jpg[/img]

Smokebreak · Post by **Smokebreak** » Sat Jul 12, 2014 11:40 pm

Ah the earlier SD with the first gain pot already cranked! Are you gonna build a 50w? You should go with 2 dual gangs on a switch(and give that presence a shot)!

granted, you won't be able to get such a clean clean, but it's real smooth for OD.
The Oranges of late dual the same. Check out the Rocker30 for kicks. Same darkness but no ultra tight chugchug. Thick rockin. Not a far cry from Merlin's medium gain, topology wise, both excellent sounding amps. You could always put that on a switch.

Bruce Egnator has modded some of the Naylors, I've read. I'm curious to hear about that too.

cbass · Post by **cbass** » Sun Jul 13, 2014 2:23 pm

Smokebreak wrote:
Bruce Egnator has modded some of the Naylors, I've read. I'm curious to hear about that too.

I'd be real curious to hear about that as well.

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