D-763 RV schematic help please

[tubenit]

I have a tweed style chassis that is packed out with very little room.  I've been pondering IF it's possible to add Sluckey's vactrol tremolo to it (space wise).  It would be a massive amount of work to convert it.

Even IF I don't convert this amp to have the tremolo,  I'd like to have a reasonable starting place schematic to perhaps build this in the future.   

I'd truly appreciate another set of eyes on this.  Currently this is a working amp without tremolo and I've got a paralleled 12AT7 for the reverb driver.

My questions:

1)  I've had success using triodes from two different 12A_7 tubes in the past for a "one tube reverb".  Any reason you
     know of that it would not work on this?

2)  The insertion point in the signal chain for the tremolo:  would you use V-yellow or V-green for the insertion point?

3)  Anything you'd change on the tremolo?  Particularly, the tremolo pot & the values around that.

I realize this might need numerous tweaks after being built.  My main goal is to have a starting place schematic.  (I do have a layout to go with this but may need to edit it after getting feedback here).

With respect, Tubenit

[shooter]

fwiw I believe Sluckeys version used the LED in place of the cathode R.  Couldn't find the thread but Trox did some pretty extensive evaluation on "where" best to insert trem into a ??Vibroverb/Vibrochamp   Might help.

I believe Steve's version had the insertion point at PA tubes grid R's, so inserting into the preamp "might" need tweaks

[sluckey]

I would insert the trem at point "RV" initially. Just be aware that the 50K pot and your 150K resistor will form a voltage divider that will reduce the signal level to about 25% of what you would have without the 50K pot. This may or may not be acceptable. Be prepared to experiment a bit. Your yellow "V" may be a better insertion point. Changing the insertion point will not affect your layout.

I have no experience with 1 tube reverb so I trust your knowledge in that area. However, to me, it just seems more logical from a layout standpoint to use the 12DW7 for the reverb driver and recovery and use a 12AX7 for the trem and third gain stage.

Shooter, the 10K cathode resistor is just to keep the oscillator alive so there will be no delay in startup when you stomp the footswitch. The LED in the optocoupler is parallel to the 10K. And my insertion point is the input to the PI.

[shooter]

just to keep the oscillator alive

ah, thanks, I trust you on all things oscillator 

my insertion point is the input to the PI.

that, I have to go back n learn    since I'm stealing n for some reason I've inserted (on schematic) at the PA tubes grid R's
thanks

[tubenit]

However, to me, it just seems more logical from a layout standpoint to use the 12DW7 for the reverb driver and recovery and use a 12AX7 for the trem and third gain stage. 

You know I think you're right about this!  I was approaching it to see what are the minimal changes to the layout board  that are needed to add tremolo?  But, I think it's wiser to go with the best layout and not "possibly" the most convenient. And your suggestion makes more sense for how the pots are oriented to the layout board.
 
I've made note to try both insertions points that you've suggested.  I'm also guessing the pot value for the tremolo may need to be changed?  I don't mind experimenting and certainly will assume responsibility to ultimately figure this out.

I'd like to make this work in this chassis IF possible? Not much room to work with. I've got to take the back panel off the amp and really study this.

I appreciate all the responses!  THANK you both!   With respect, Tubenit

[sluckey]

I would be prepared to change the trem pot. I used 50K-RA because that's what is found in the Fender AB763s and that's the amp I put this circuit in. The more I look at your schematic, the more I want to insert at your yellow V point. In fact I would start with a 250K pot and just remove that 220K grid leak resistor. I don't envy you working in a tweed style chassis.

Shooter, look at this...

     http://sluckeyamps.com/misc/bandmaster.pdf

[tubenit]

Unfortunately, this idea will have to wait til another build.  I took the back panel off and realistically unless I remove the entire board and reposition some other things ………. it's not going to fit to where I'd have reasonable confidence that it wouldn't have significant floor noise. 

Right now I've got a beautiful sounding amp with quiet floor nosie, but it just doesn't have tremolo with it.

IF I ever get around to building this idea, I promise that I'll post a final schematic, layout, photos and a sound clip.

THANKS for the help!  With respect, Tubenit

**   I've attached a revised schematic and a layout IF anyone wants to pick this project/idea up.  CHECK for ERRORS & if
       there is a discrepancy, go with the schematic.