modified tube reverb unit idea. doable?

[mort]

Ok so the idea is to use the basic layout of the Fender tube reverb but instead of a mix control, have a wet level and a dry level with an extra gain stage or two for the dry signal, so the unit can also be used as a sort of variable boost on the dry side, while controlling the wet signal individually.

Here's what I'm starting with: http://www.thevintagesound.com/ffg/s...6g15_schem.gif

I'm just throwing this thread out in case anyone else has tried something like this and has any helpful thoughts, and I'll return later with a preliminary drawing of what I think might work.

Question: as for the added gain stages for the dry channel, would adding a whole 12ax7 be way too much? I was also considering adding a 7 pin single triode... any thoughts on how much gain to add would be appreciated.

[mort]

Ok here's the general idea. This may not work as drawn but gotta start somewhere...

For the dry side boosting I'm thinking maybe a pot before the tube might be a good idea.

And as for splitting the wet and dry signals into two different pots, if there's a dry signal pot between the input and first stage, do I even need one on the output of the dry side?

Thoughts?

[mort]

Here's a 2nd drawing with the dry volume before any gain stages and the final pot to be used as a wet control, allowing all of the dry signal at the end of the path into the output. I wasn't quite sure if I needed another filter cap on the junction of the dual triod plates and 22k resistor, or if that B+ should be taken off of the other side of the 10k resistor( does that make sense?)

[mozz]

I have to add this, these units are know to be tone suckers, that is when you use a long cord on the output, it knocks the highs down. My suggestion is to change the output impedance to something more cable friendly. Maybe what you are doing will cure this problem.

[Chuck H]

What you need to keep in mind is that you probably don't want a clean wet and a dirty dry. So, what you pretty much need to do is reverberate the already processed signal and not have them in parallel. Further... If you're using extra dry stages as a "boost" it implies that you wish to overdrive the amp to follow. That would distort the wet signal, clean or otherwise, and that means it will sound like a distorted reverb and not reverberated distortion. Ok, so lets boost the signal before the wet dry mixing. But wait! We need to pad the boosted signal to feed the reverb and the final mix must be padded to NOT overdrive the amp to follow or, again, we get a distorted reverb and NOT reverberated distortion.

What you are proposing is best done as a preamp with reverb. Where ALL the signal distortion processing is done and then reverberated and then sent as a clean signal to an amp that basically acts as a slave or power amp.

You can buy a preamp with reverb too. Though maybe not as good as you would do it.?.

JM2C

[mort]

Ok, had a conversation with the potential owner and it seems I misunderstood about boosting the dry signal. The goal is just to have a dry signal control seperate from the wet control, instead of just having a mix control. Does it really matter whether the dry signal pot goes right at the output or right after the input?

[Chuck H]

Ok, had a conversation with the potential owner and it seems I misunderstood about boosting the dry signal. The goal is just to have a dry signal control seperate from the wet control, instead of just having a mix control.

I still see some potential confusion in the expected results, but for the purposes of just answering the question I digress...

Does it really matter whether the dry signal pot goes right at the output or right after the input?

Yes. If the unit is used into the input of the amp, having the volume control at the input will affect the signal similar to a guitar volume pot with the same affect of HF roll off due to altering the resonant peak and interaction with cable capacitance.

[mort]

The idea for the dry control came from a different reverb unit that uses one. With the dry control at 12 o'clock it's supposed to be at "unity gain" which I suppose means the same gain level as the wet side? Turning up the control gives a slight boost to the dry gain going into the amp without necessarily increasing the wet effect. That's basically what I'm trying to pull off but using the old Fender circuit as the base design.

[Enzo]

Unity gain means the output is at the same level as the input.

[mort]

ok, so if all I wanted to do is split the mix control into two pots, would it be drawn like this?