Noise

[Koop]

I built an 18 watt TMB type amp and I'm getting a bit of noise - a 60 cycle hum that that's noticeable unless I touch the chassis of the amp or my guitar strings with my fingers.

I notice a similar sound with my Egnater, but not as loud. My 18 watt is not in a cabinet at this time - would that have any bearing on the noise level?

[Lynxtrap]

Does it hum when you have no guitar plugged in or the guitar turned down?

[Koop]

Not so much.

Please let me add, when I turn up the gain the noise goes up with it.

[Koop]

Jeeze, 86 looks and only one response. I could've done better by posting x...xyz.

Is there a bias against 18 watters or newbies or is it just me setting my expectation too high?

[selloutrr]

start from the top..

do you know the guitar is good, the cable, does the amp's power share with florencent lights, other appliances.

now on to the amp.

how is is grounded inside? where?
did you test the filter caps for leaks? yes even new caps can be bad.
ground loop

is everything secure? all screws nuts bolts are tight. firm contact to chassis. did you solder your ground bus to the chasis or bolt it? did you clean and buff or scar the surface first?

[selloutrr]

pics would help

[M Fowler]

Having had a lot of AC line noise in my home I can tell you it will make an amp sound terrible besides the hum and grounding problems.

You pretty much answered your own question I think!

I notice a similar sound with my Egnater, but not as loud. My 18 watt is not in a cabinet at this time

The amp should be in a cabinet to shield it. Also, play it in another location just to test the dirty AC line theory.

[Reeltarded]

I agree with Mark on the electric service. I'd bet you have a very unbalanced load at the breakers. That sounds familiar, the background noise coming up when you become some .00X% of the ground potential.

Shouldn't take a licensed/experienced electrician more than 10 minutes to tell you, and maybe about the same time to fix it. I am lucky to have favor with a really good one.

Even on a good line, I prefer conditioning, and a variac with a meter to control the feed.

[selloutrr]

if your AC line voltage dips and peaks a constant voltage transformer will smooth it out.
If you run a variac it's advised to run an isolation transformer to protect yourself from shock.

[Reeltarded]

Yes, and to keep 9 spare variacs if you are using recent ones.. for some confounded reason.

These Tenma look-a-likes really suck.

[Koop]

Thanks for the information. The service is obviously noisy - I have the same noise at different volumes through three different amps when I plug them into the same outlet. I'll look into a conditioner. Thanks again.

[selloutrr]

not sure a conditioner will do the trick I'd contact an electrician.

[Jana]

"Jeeze, 86 looks and only one response. I could've done better by posting x...xyz.

Is there a bias against 18 watters or newbies or is it just me setting my expectation too high?"



Alrighty, I will add to your post--Maybe the world doesn't revolve around your noisy guitar. Maybe you already answered your own question. Maybe a little patience is in order and you allow those that might have some insight some time to respond. We don't sit here holding our collective breath waiting to jump when you post a question.

[martin manning]

We don't sit here holding our collective breath...

Well, not on Friday afternoons around the holidays, anyway ;^)

[Lynxtrap]

Just to make sure, you do have safety ground in your amp and wall outlet don't you..?