Fender Hot Rod Deluxe Reverb Noise

CarpeDiem

I've got a Fender Hot Rod Deluxe mk3 which has started to sound increasingly noisy when the Reverb is turned up, but isn't there when the reverb is off or below 2. There is no unusual noise when the amp is on standby. I tend to use the amp clean, using pedals for dirt, which is why I'm keen to find the cause of the noise. Does anyone know what could be causing the noise? Thanks in advance!

ICBM

Sounds like noise being picked up by the reverb tank. It could be caused by a bad ground connection in the tank - although less so if the reverb still works - but more likely just some electrical noise in the room. Try moving the amp somewhere else or just turning it round and see if the noise level varies.

CarpeDiem

ICBM said:

Sounds like noise being picked up by the reverb tank. It could be caused by a bad ground connection in the tank - although less so if the reverb still works - but more likely just some electrical noise in the room. Try moving the amp somewhere else or just turning it round and see if the noise level varies.

Many thanks @ICBM - I'll try moving the amp somewhere else as you've suggested. Interestingly, I didn't notice the noise when I had a band rehearsal.

CarpeDiem

I moved the amp to a different position in the room, as @icbm suggested, and plugged in to a different power point and the noise has gone. I'm now curious as to why moving the amp would have made such a difference? The original power socket is good condition, and all connections to it are tight.

ICBM

It’s unlikely to be anything to do with the mains socket. The reverb unit return transducer is effectively a single-coil pickup, so is prone to picking up electrical noise.

jpfamps

I've found a few Fender amps where the reverb tank is the wrong way around and thus prone to picking up noise.

The reverb out from the tank should be on the right hand side looking into the back of the amp, ie away from the mains transformer.

The mains transformer sprays out electromagnetic interference which can be picked up by the tank.

Wiring the amp to 240 VAC rather than 230 VAC will also reduce noise emitted from the PT.

CarpeDiem

Many thanks for your comments @ICBM and @jpfamps I've checked that the reverb tank wires come out on the right hand side. I suspect it's 230v as the amp hasn't been modified since new.

jpfamps

CarpeDiem said:

Many thanks for your comments @ICBM and @jpfamps I've checked that the reverb tank wires come out on the right hand side. I suspect it's 230v as the amp hasn't been modified since new.

The wires have to come out the right-hand side!

There are two connections at either end of the tank: input and output.

The output is quite high impedance and is connected to a relatively high gain input, and so is prone to picking up noise.

The tank should be installed so the output is on the right; this means the connectors will be facing away from the back of the tank, ie the tank is orientated so the output is at the opposite end to the mains transformer.

CarpeDiem

Thanks for your more detailed explanation @jpfamps As a result, I removed the reverb tank. It is wired with the output at the opposite end to the mains transformer. However, when checking all the connections, I noticed that the the phono input and output connectors didn't seem as tight as I would expect. I compressed them slightly and the noise has now gone. The reverb is also working better, so I'm guessing it had deteriorated gradually over time and I hadn't noticed. Thanks again for your and @ICBM help.

jpfamps

CarpeDiem said:

Thanks for your more detailed explanation @jpfamps As a result, I removed the reverb tank. It is wired with the output at the opposite end to the mains transformer. However, when checking all the connections, I noticed that the the phono input and output connectors didn't seem as tight as I would expect. I compressed them slightly and the noise has now gone. The reverb is also working better, so I'm guessing it had deteriorated gradually over time and I hadn't noticed. Thanks again for your and @ICBM help.

That's a common problem too, as is corrosion on the sockets on older amps.

Glad it is sorted.