| Author |
Topic: Copper foil sheet to reduce reverb hum |
Tom Campbell
From:
Houston, Texas, USA
|
Posted 1 Feb 2021 4:45 pm |
|
Anyone use "copper foil sheeting: to wrap around their reverb unit to reduce hum?
I've used it to insulate the control cavity in regular "under-arm" guitars to prevent various audio interference.
I have a reverb unit in my Evans amp that needs some attitude adjustment!
Last edited by Tom Campbell on 4 Feb 2021 6:46 am; edited 1 time in total |
|
|
 |
Stephen Cowell
From:
Round Rock, Texas, USA
|
Posted 1 Feb 2021 7:48 pm
|
|
Reverb pans are themselves shielded... except for the bottom.
One problem with reverb pans is that the cables can create a ground loop... this can cause hum. Most reverb pans have the ground on one jack lifted, so that the pan is only grounded through one of the cables. I believe this is best done with the output, since the input to the reverb pan is lower impedance and is often transformer-isolated, at least in Fender tube amps.
You can test this by unplugging one of the connections to the reverb pan part-way... breaking the ground but connecting the tip. You may find that one of the grounds is broken... amps normally come from the factory without hum in the reverb. Good luck.
_________________
Too much junk to list... always getting more. |
|
|
|
Tim Marcus
From:
San Francisco, CA
|
Posted 1 Feb 2021 8:11 pm
|
|
wrapping it in copper won't work. Sorry 
_________________
Milkmansound.com |
|
|
|
J Fletcher
From:
London,Ont,Canada
|
Posted 2 Feb 2021 7:21 am
|
|
| I wonder if the pans are prone to the hum you get from a single coil pickup , as the coils in the reverb pans are single coil . Noticed this problem myself , usually when I turn the reverb control past 4 or so on a Fender style amp . |
|
|
|
Steven Paris
From:
Los Angeles
|
Posted 2 Feb 2021 7:26 am
|
|
| Tim Marcus wrote: |
| wrapping it in copper won't work. Sorry |
How about mu metal?
_________________
Emmons & Peavey |
|
|
|
Pete Burak
From:
Portland, OR USA
|
Posted 2 Feb 2021 10:12 am
|
|
| Moving the Reverb Tank farther away from the amp and speaker usually eliminates hum. |
|
|
|
Tom Campbell
From:
Houston, Texas, USA
|
Posted 2 Feb 2021 11:03 am
|
|
Yes J. Fletcher...anything past 4 is unusable.
My reverb unit is currently positioned vertically against the the left wall of the amp... looking at it from the back of the amp.
Pete, Think I will try to reposition it on the floor of the amp...that is as far away from the preamp and power amp as I can get. |
|
|
|
Tom Campbell
From:
Houston, Texas, USA
|
Posted 2 Feb 2021 3:21 pm
|
|
Thinking of changing out the cables from the reverb unit to the power supply.
Will 18 gauge shielded audio cable work? |
|
|
|
Godfrey Arthur
From:
3rd Rock
|
Posted 3 Feb 2021 8:29 pm
|
|
An easier solution is to move the tank if possible to somewhere where it has less hum as mentioned.
_________________
ShoBud The Pro 1
YES it's my REAL NAME!
Ezekiel 33:7
Last edited by Godfrey Arthur on 3 Feb 2021 9:07 pm; edited 1 time in total |
|
|
|
Bill L. Wilson
From:
Oklahoma, USA
|
Posted 3 Feb 2021 9:03 pm Reverb Wires.
|
|
| I made new reverb wires for my Peavey LTD out of George L’s guitar cable and RCA plugs. Works great and quiet as a mouse. |
|
|
|
ajm
From:
Los Angeles
|
Posted 5 Feb 2021 7:53 am
|
|
Time out for some questions.
We need to make sure that you are actually fixing THE problem that just happened, and NOT a problem that someone created.
Otherwise, you are just masking the real problem.
We also need to try to determine if this is a design problem that is inherent to all amps of this model, and is not unique to your specific amp.
It would surprise me if a manufacturer shipped an amp with a known problem like this. (Not that it hasn't ever happened, of course.)
What model of amp is it?
Does anyone else have this amp?
If so, do you also have a problem like this?
How long have you owned this amp?
Has it always done this?
Has anything ever been altered/changed with the amp?
Specifically, has the reverb pan been moved?
If so, did it work before the move?
Also, as noted by another poster, reverb pans are meant to be oriented a specific way. If you change this, you may be creating another problem.
"My reverb unit is currently positioned vertically against the the left wall of the amp... looking at it from the back of the amp."
Does anyone else have this amp?
If so, is yours like this?
Are the cables connected to their correct jacks on the tank? (In to In, Out to Out.)
"...anything past 4 is unusable."
A setting of "4" doesn't seem like it would be that high.
Does this happen at all volumes, or only when it gets loud?
"Pete, Think I will try to reposition it on the floor of the amp...that is as far away from the preamp and power amp as I can get."
This may be fine, but where is the tank supposed to be mounted?
"Thinking of changing out the cables from the reverb unit to the power supply."
Just a minor correction, but I suspect that you meant "amp chassis" or something similar, and not "power supply".
"Will 18 gauge shielded audio cable work?"
The reverb send/return should be low level audio signals.
They are not power amp level signals.
Yes, 18 gauge will work, but it is WAY overkill.
18 gauge is on the order of lamp electrical power cord.
The important thing is that the cables are shielded. |
|
|
|
Tom Campbell
From:
Houston, Texas, USA
|
Posted 5 Feb 2021 2:24 pm
|
|
Problem solved.
Installed new shielded audio cables..18 gauge, 2 ft.
The old ones were 3 ft.
Attached a (steel) sheet metal cover over the open back of the reverb pan.
Hand held the reverb pan and moved it around the inside of the cabinet...turning it end for end, front to back in order to find the quietest location. This end up being on the wall furthermost from the transformer.
Put the pan back in it's vinyl bag.
The amp is now as quiet as my Quilter combo amp.
Thanks for all who made suggestions! |
|
|
|
