Requesed to install an active effects loop in super reverb RI

[67polara]

Well Sunday I went to a local bar that has a blues band and lets people sit in with the band.  Anyways I took my D clone with me to let Teddy Lee Hooker play it, well he loved it and then asked if I could put an effects loop in his Super Reverb.  I get it home and pull the chassis and what do you know there is no room for another tube to be installed.  The closest location would put the tube directly under the power switch.

My question is what mods to an effects loop circuit need to take place to replace the tube with two JFET's?

I want to do as little surgery to the amp as possible and I am sure I can find a good location for 2 JFET's.

I think the JFET's will do an excellent job of reproducing exactly the sound that went in and out.

Just pick any loop circuit and tell me what I need to change please. 

Thank you

[TIMBO]

Hi 67, Does it have to be an ACTIVE loop. In all my builds i have used the passive loop ( two jacks and a bit of wire ) and found it works well. But i can't be sure that it will suit all builds. Are you able to try it before you drill any holes??

[tubenit]

Have you seen the IronSounds  solid state effects loop?   Looks to be compact and relatively inexpensive.

http://www.ironsounds.com/index.html

With respect, Tubenit

[kagliostro]

Here one other option

http://metroamp.com/store/index.php?main_page=product_info&products_id=499
http://home.comcast.net/~jbjdav26/Zero%20Loss%20FX%20loop%20instructions%20Rev%203A.pdf



or external options like this (that you can build by yourself)

http://www.ceriatone.com/images/layoutPic/OvertoneLayout/C-Lator.jpg



or this

http://www.ceriatone.com/images/layoutPic/OvertoneLayout/KleinLayout.jpg


Kagliostro

[Boots Deville]

Yeah, if it's acceptable to the amp's owner, I'd install a passive loop and use it to connect an external active Dumbleator style loop like kagliostro has shown.   They can be made pretty small with the PT and 12AT7 inside the box.  Check out Allen Amp's small power transformer for this.   If you look at his power transformers, it should be the first one listed.

[jjasilli]

Another option: maybe mini tubes or nuvistors inside the amp's chassis.  Otherwise a passive loop > an external active box, mounted on the inside wall or floor of the cab, will still keep the whole works in one combo cab.

[phsyconoodler]

A Super Reverb already has an effects loop.Simply separate the shared cathode resistor/cap that V1 and V2 share and give them their own cap/resistor and then take a patch cord from the low input on the reverb channel into your delay or slapback echo unit and plug the out into the high input on channel one.There.You have an adjustable,active effects loop.

[67polara]

Thank you all for your input.  I believe the external mounted d-lator is the ticket for me.  I only need drill one hole in the chassis to make it all happen.  Thanks all for your help.  Sometimes you need to step back close one eye and look at it again to see the forest through the trees.

Tony

[phsyconoodler]

Gee,nobody seems to want to use what's there already.Wonder why?A friend of mine,Johnny V,a Juno award winning bluesman here is Canada has used the super reverb normal channel as an effects loop for the last 35 years.He plops his Roland delay unit on top with a rubber mat,plugs in and gets killer good delay and all adjustable too.
  To make it work properly all he did was separate the shared cathode R/C on V1 & V2.
No one seems to use the normal channel much anyway,why not take advantage of it?

[Gareth81]

This sounds very interesting, phsyconoodler. Looking at the schematic, the cathode on pin 3 is already has seperate r/c pairs,but the cathode on pin 8 doesn't. Is this the position your referring to?
Why does this make a difference?