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View Full Version : reverb mod on fender hrd



vroomery
October 7th, 2007, 01:42 AM
I've seen some mods for the hrd but nothing that does what I really want though. See I really like the spring reverb on my amp, but I have no means of controlling it (on/off) from a foot switch. Is there any mod out there that would serve this purpose. I am planning on getting a fulltune full drive in the next few weeks so I wouldn't need the foot switch for the amp's drive channel. So basically I want reverb to sub for one of the switches on my foot switch.

Any advice or tips would be greatly appreciated.

-Vroom

chordshredder
October 7th, 2007, 06:35 AM
Take a wire to a new footswitch plug from the junction of R38 and C52/R39, And the shield to ground. This would short out the reverb signal when the switch is closed. You will still be able to adjust the reverb depth using R39.

chordshredder
October 7th, 2007, 02:01 PM
An even less obtrusive way would be to use a mono Y splitter and add the foot switch to the reverb pan out line to short that signal.

I would not entertain modding the gain switch, One reason is it uses 39 VAC and diode steering to select the gain functions the other its printed circuit board, once you cobble it up its not going to be worth much to anyone.

vroomery
October 7th, 2007, 09:18 PM
An even less obtrusive way would be to use a mono Y splitter and add the foot switch to the reverb pan out line to short that signal.

I would not entertain modding the gain switch, One reason is it uses 39 VAC and diode steering to select the gain functions the other its printed circuit board, once you cobble it up its not going to be worth much to anyone.

can you possibly explain that a little more specifically? Sounds like a pretty easy way to do it, but I've never done anything like this before and I really don't want to mess something up haha.

chordshredder
October 7th, 2007, 10:16 PM
The cable from the reverb pan output is shielded and uses an RCA jack, you want to connect this to the cable going back to the amp but you also want to tie in a shielded cable to a new switch that shorts down that signal so you need a y-adapter with 3 female RCA connections, a short 1 foot or so patch cord- shielded with male rca plugs on each end, from the reverb out to the y- adapter and a shielded cord how-ever long you want to the new box with a footswitch plugged into the other jack.

chordshredder
October 7th, 2007, 10:27 PM
There is a schematic for your amp at:

http://www.blueguitar.org/new/schem/fender/hotrod_deluxe.pdf

If you understand any of it you should see why you dont want to get involved modding in the gain switching footswitch.

Since the reverb output transformer in the reverb tank is just like a guitar pickup you can kill that signal by shorting that line. That being said the cable and box need to be shielded or they will introduce hum. If you look at schematics of Fender Blackface reverb and tremelo circuitry very similar foot control of shorting out the signal.

vroomery
October 7th, 2007, 11:32 PM
yeah that makes sense kinda...i feel retarted for saying this haha, but my main hang up is understanding the function of the y-adapter and physically where cables would go. I know you explained it, but I just got really confused (again mostly because i've never seen a y-adapter used for anything other than a signal splitter). If you maybe explained the elementary function of the y-adapter that might help me understand. I'm sorry for being stupid haha but i can't get this through my head as to how it would physically work.

vroomery
October 7th, 2007, 11:51 PM
is this basically the idea?

http://img2.putfile.com/thumb/10/28001480842.jpg (http://www.putfile.com/pic.php?img=6817955)

chordshredder
October 8th, 2007, 07:15 AM
Eureaka! You Got It Toyota;

So glad you know how to draw on a PC. Yeah it is odd as it is adding a kill switch instead of teeing in a signal input or takeoff. Looks like the easiest way to try it what you want. Should work unless switching action is annoying - popping. But you haven't harmed the amp to try it out.

vroomery
October 8th, 2007, 07:43 AM
Eureaka! You Got It Toyota;

So glad you know how to draw on a PC. Yeah it is odd as it is adding a kill switch instead of teeing in a signal input or takeoff. Looks like the easiest way to try it what you want. Should work unless switching action is annoying - popping. But you haven't harmed the amp to try it out.

Awesome...I personally haven't done stuff like this before so the fact that its all external really is a plus. Thanks for the idea and I'll let you know how it goes.

chordshredder
October 8th, 2007, 06:46 PM
Please let me know how it goes.
I took a footswitch and modded it to work with a Crate G60 so it channel switches and turns on of the tremelo. I have a weber kit to build this winter that is a clone of a fender deluxe. The reverb kill in the all tube fenders is to short down the grid of the reverb recovery tube.

Good luck and nice talking with you for now.