Some help please, idiot trying to build a box...

[MDUK]

Hi i'm trying to build myself a very simple on / off switch for the reverb module on my hughes & kettner triamp. The reverb module is attached to the amp via a phono loop that goes amp out -> reverb module -> amp in. Unfortunately this is not footswitchable.
My idea was to buy some phono extension leads and build a box with phono in -> on / off switch -> phono out so i can just cut the signal when i want. I am relatively new to home made boxes and have very limited electronics knowledge and so wouldn't really know how to go about it. I have built a BYOC phaser (which works!) but i don't think this really qualifies as its as easy a building a lego house. I know this is very simple and all i need really is a footswitch and input and output phono jacks, but i could use some help on how to wire these. Also an LED would be very useful.

So my question is:
1) What parts would i need? Ie DPDT or 3PDT? Anything else?
2) How would i wire this together?

Thank you in advance for your help.

[petemoore]

Hi i'm trying to build myself a very simple on / off switch for the reverb module on my hughes & kettner triamp. The reverb module is attached to the amp via a phono loop that goes amp out -> reverb module -> amp in. Unfortunately this is not footswitchable.
  >>I still gues it is, there is no 1/4'' phono jack on the back of the amp chassis labeled 'Footswitch'?...if not that's 'odd'...
My idea was to buy some phono extension leads and build a box with phono in -> on / off switch -> phono out so i can just cut the signal when i want.
  >>>This is more likely to introduce noise/signal loss, running long [even shielded] signal wires.
   I am relatively new to home made boxes and have very limited electronics knowledge and so wouldn't really know how to go about it. I have built a BYOC phaser (which works!) but i don't think this really qualifies as its as easy a building a lego house. I know this is very simple and all i need really is a footswitch and input and output phono jacks, but i could use some help on how to wire these. Also an LED would be very useful.

So my question is:
1) What parts would i need? Ie DPDT or 3PDT? Anything else?
2) How would i wire this together?
  You'  "Could' try grounding the reverb signal along the chain somewhere...I still guess there's a way to switch that reverb on your amp..guess only..I don't really know H&K stuff.
Thank you in advance for your help.

[MDUK]

No there is no footswitch for the reverb, only channel switching and fx loop. The reverb is a seperate module, 'strapped' onto the back of the amp, and connected to the amp by a phono loop, there is a dial on the amp itself which control's the reverb level. So you have to either have it always on, or not at all.

[MDUK]

Bump

Anyone got any further comments? Going by this am i correct in assuming that its a bad idea?

[jrem]

Find the schematic for the amp.  Get the voltages off of the reverb sending unit.  Look to ground the signal on the way back from the unit.

Or figure out what the voltage is on the reverb mix pot, and switch the wiper to the "off" end, probably ground.

But my guess is just building an a/b box for the two phono plugs will result in hum when it's "off", and you'll potentially have some voltages going through that switch, which is why ground is your friend  . . .

[jxoco]

I guess that I would try to find a schematic of a similar unit.
Is it a tube or solid state, then try to find matching sorts of amps in the fender or ? line.

You would be best served by a SPDT switch, that would give you the option of normally open or normally closed.
And I would think that a circuit on the delayed side of the reverb tank, the output side, that would bring the signal down would be what you want.

[MDUK]

Its a tube amp, I have found a schematic at:

http://www.freeinfosociety.com/electronics/schematics/audio/hughesandkettnertriamp.pdf

The reverb send and return is on page 5, in the bottom right hand corner. I'm not sure if it says the voltage or not, could you please help me out there? I can't see it.
So this isn't as simple as an on / off switch with phono sockets either side then...?

[jxoco]

I'm looking at some schematics here;
http://www.schematicheaven.com/fender.htm

fender princeton reverbs, etc...

And it looks like the footswitch is simply grounding the signal from the output of the reverb tank back to the amp.

Have a look..

[MDUK]

I'm sorry i had a look at the schematics, but i don't really know what i'm looking for. Perhaps i'm in over my head and should just go buy an RV-5 I suppose more electronics experience is needed for building boxes.

[jrem]

A quick look on page 13 indicates there is an OEM pedal switch for this amp.  My suggestion is go buy that.  Else figure out a way to cycle relay #7.  Or build the switch on page 13.

[petemoore]

  Here's a guess, that it's liek other amps.
  At least it's possible that the Channel switching jack is stereo and that one of the two 'hots' is assigned to Channel switch
..we'll say tip to ground switches channels ...and ring to ground  switches reverb.
  If you can see the switching jack is stereo...or
  Amp manuals usually tell this, even online brochures?

[MDUK]

The OEM pedal switch is for the floorboard, which i have. It has 7 buttons: Amp 1 A & B, Amp 2 A & B, Amp 3 A & B, and FX loop. I think the other two are used for grounding and live, something like that. So 6 channel switches and an fx loop switch. Not reverb. Seriously guys, thanks for the help but it would probably be easier to go and buy a reverb pedal.

[jrem]

okay, my bad, I inadvertently assumed the FX send was the reverb.  Looks like the reverb send/rec is futher right on that page.  Funny, they have a relay for everything else, can't imagine why they would assume you wouldn't want to turn the reverb off.

Look at page 11, that's the relay board.  Term 1 on the plug must be from the 'send', term 2 must be to the 'receive' on page 5.  Trace them back with an ohm meter to verify. 

Now back to page 11 . . .    try pulling pin 6 of the input buffer opamp low with a resistor, that should shut up the reverb.  You can't just ground the signal from page 5 or you'll lose all of the signal, do it after the opamp buffer. Or lift the 15v+ supply to that opamp, that will probably shut up the reverb, also.   Or clamp pin 6 of IC2 low with a pull down, that might be better cause it would keep all the noise off of the return signal.

hmm, wait, see the pot at the bottom right of page 11?  pull the wiper to ground, done, no more reverb in the mix.  No voltage to speak of, also.

Regards, John.