Hoffman ab763 trem question

[87MJ]

Hey there,

First off, hats off to you guys on this site - I can't tell you how much I've learned reading thru the posts and Hoffman's info pages.  The wealth of information, and willingness to share this info, is awesome...

Anyway, I just finished up my first build, an AB763 Hoffman style Deluxe Reverb, but with a tweed normal channel along with the normal reverb channel.  So far it seems to work fine, but I'm troubleshooting a couple minor things (I hope) with the trem and reverb.   Before I get too far into troubleshooting - 2 quick questions:

1. When switching the trem off using a footswitch, is it normal for it to pop?  No popping when turning it on.  Seems like this shouldn't be popping like this.

2. When the trem intensity is at 100%, I get that famous clicking.  If I back it off to 99% or less, the clicking goes away.  Only get it when its fully pegged.  Any thoughts?

The other wierd thing is that reverb works fine by itself, trem works fine by itself (aside from the above), but when both are on, I get the clicking (less pronounced than in 2 above though).  I figure if I get 1 and 2 taken care of, that might solve this issue.

I'm starting to trace everything, check grounds, etc. now;  I just thought maybe I could isolate the problem with some input from you guys before tearing into it too much.

Thanks.

[Fresh_Start]

The other wierd thing is that reverb works fine by itself, trem works fine by itself (aside from the above), but when both are on, I get the clicking (less pronounced than in 2 above though).  I figure if I get 1 and 2 taken care of, that might solve this issue.

The "return" from the reverb circuit is a low voltage, super sensitive lead.  I've had good success eliminating tremolo bleed into the reverb circuit by shielding the leads to and from the Reverb control in several Blackface builds.  Physically isolating the leads to and from the Intensity pot helps.  Go straight up from the board with those leads and route them over to the Intensity pot in the air.  I often have to remind myself that we have 3 dimensions to work in when routing wires.

Hope that helps,

Chip

[87MJ]

Chip,

Thanks for the tip - I stupidly had the vibrato and reverb signal wires bundled together coming off the pots.  Separating them got rid of the all the ticking issues - now it sounds great.

Now for the popping - seems to be the footswitch I was using - I had a two switch from a Peavey Bandit 112 (SS) that I was trying to use for this.  When I disconnect the FS and manually ground out the trem with a jumper at the jack, no popping.  So guess I'll have to get my hands on a Fender style footswitch and try it out.

Hopefully that's it for gremlins...

Thanks again.

[Fresh_Start]

Glad my advice worked for once!

For the footswitch, just make sure that the cable is shielded.  The grid for the reverb recovery stage is in that cable and it makes a darned good antenna.  Hoffman's Fender pedal works fine (relatively speaking), but his 2-button Marshall style pedal does not have shielded cable.

Chip