Swwweeet Sweet 5e3 music.... But there is some hum?

[BluesDude]

Wow that amp is fantastic with a strat!


I can crank the amp without a guitar plugged in and crank everything up or down... hardly any noise except a slight white noise.

Plug in the strat set the guitar vol at 10 and Dime the amp vol ... I get some hum no matter where I position the guitar relative to the amp. The hum is fairly noticeable (but it is not a roar). Role the guitar vol down to 7 and the hum quiets down a fair amount.

At lower amp vols the hum is less noticeable also.

Is this normal? Is there any form of reference that I can use to know if I have the amp is relatively quiet for this type of amp?

Perhaps it is not the amp...

Is there anything I can do to quiet the hum in terms of the Guitar or cable plugged into the amp?

Thanks.

[BluesDude]

I did some additional troubleshooting to try to isolate the cause. The hum sounds like a 60hz hum (maybe 120 hz).

Here is what I tried and the results (just listening).

1) Rechecked the amp with nothing plugged in to get a frame of reference. Maxed controls (tone and vols) in several settings. The more they were turned up the bigger the white noise (different that the hum I want to minimize).

2) Plugged in only the cable (no instrument). Got the hum... it of course increased as vol was increased.

3) Plugged in the strat (not playing it). Got more hum. Same results... hum vol increased as the amp vol increased. The hum was there but changed pitch slightly when I switched between neck, middle, and bridge pups. When I switch to the Neck/Middle pup position, the hum reduced quite a bit. I am assuming this is because the bridge/neck pups are wound in in opposite direction of the middle pup to reduce hum.


I am beginning to believe the source is the guitar and cable picking up some sort of emf or other signal.

Am I wasting time on this issue? I have read other posts that are leading me to conclude that it is a common problem related to environmental interference, cables and single coil pups.

Can anyone provide some insight or opinion?

How have you dealt with this issue?

[Tom Phillips]

Everything you describe sounds normal to me.
You will probably also discover that the hum pickup with the guitar plugged in varries as you physically change the position of the guitar in the room. You also need to make sure you aren't sitting too close to the amp. The hum goes away when you turn the Guitar volume control all the way down. Right? That shows that the hum is picked up by the guitar wiring and pickups. Again this is all normal and everyone is in the same boat especially with single coil pickups.There is much lively discussion out their about shielding the guitar cavity and about making noiseless pickups without affecting the tone.

[tubeswell]

Yeah What Tom said.

I shielded my strat according to this:

GuitarNuts.com - Shielding a Strat(tm)

and it cut down the hum you are talking about BluesDude

[BluesDude]

... The hum goes away when you turn the Guitar volume control all the way down. Right?

Yes. Thanks for the confirmation.

[black_labb]

there is a bit more to it than just the guitar. i am guessing you have a switching input jack. when nothing is plugged in the input is grounded. when the cable only is plugged in then the switch is open allowing the input to get some hum. this hum could be from the wires/68k resistors going to the grid on the input. try to keep these wires as short as you can or shield them as they are the most sensitive in the amp.
the reason the hum reduces with the volume control is partially because you are reducing the amplitude of the hum from before the volume control (pup and wiring before the vol). you are also reducing the impedance (resistance to ground) as the wiper of the vol pot is connected to the output. when you dial it all the way down it shorts the hot to ground, which gives you the same result as the switching jack being closed.

if you are able to try to minimise the length of the input wire, and keep it away from other wires and components. also there may be a bit of a ground loop causing the hum. have a read of this and it will help you understand Star Grounding

[passfan]

You can also youtube some demos of that amp and hear how much "hiss and hum" a normal one has.

[BluesDude]

Thanks BlackLabb and Passfan.

[passfan]

Yeah What Tom said.

I shielded my strat according to this:

GuitarNuts.com - Shielding a Strat(tm)

and it cut down the hum you are talking about BluesDude

Many thanks to tubeswell for that link. I just finished shielding my custom built flying v and it doesn't make ANY!!!! noise at all now. I can even take my hands off the strings and you'd swear the volume had been rolled down. People freak when it finally starts feeding back. Best link I ever followed, thanks.