hissing sounds & AC30 and AC15...

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no it's not a snake! I have been using an AC30 and an AC15 in the past couple months and recently i've been hearing this hissing sound coming form the amps. Not a buzz, but a hissing sound. I used to hear it on my Mark IV before and couldn't figure out what it was? I've checked my cables, tried an external cabinet, etc...
The hissing is more apparent when the topboost it being driven as well, but not when the master is cranked and not the topboost.

any ideas, any help?

thanks fellas

[lex666]

Re: hissing sounds & AC30 and AC15...

Assuming your cable is of good quality and proper working condition, is the noise still present with no pedals, effects, etc? It the noise still there with different guitars plugged in?

Try a noise suppressor/tone squisher.

[glassman]

Re: hissing sounds & AC30 and AC15...

The proper term for this hiss is flicker noise. It's caused by variation in the current across the tube; with the effect becoming more prominent as the frequency increases. It is totally normal for a tube to hiss )to some degree). If it has gotten worse lately, that is a different story. Do you turn the power and standby on at the same time?

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Re: hissing sounds & AC30 and AC15...

i already use a noise suppressor in my board, and i always wait to turn the standby on.

[guitarded]

Re: hissing sounds & AC30 and AC15...

My Mark IV will do this if I am boosting the signal in the loop too much. I deal with this by adjusting the input and output volume of my multi-fx until the the perceivable volume is approximate the same with the loop engaged or disengaged.

If uyou are not using the loop putting an ISP Noise Decimator in front of the amp may help. Also the order you place your pedals in front of the amp will make a significant difference as well.

no it's not a snake! I have been using an AC30 and an AC15 in the past couple months and recently i've been hearing this hissing sound coming form the amps. Not a buzz, but a hissing sound. I used to hear it on my Mark IV before and couldn't figure out what it was? I've checked my cables, tried an external cabinet, etc...
The hissing is more apparent when the topboost it being driven as well, but not when the master is cranked and not the topboost.

any ideas, any help?

thanks fellas

[guitarded]

Re: hissing sounds & AC30 and AC15...

Also check the grounding on your guitar or have someone do it for you.

i already use a noise suppressor in my board, and i always wait to turn the standby on.

[\m/(00)\m/]

Re: hissing sounds & AC30 and AC15...

I guess I can try things out, it's a high pitched hissing, or whistling type sound. It doesn't sound like it'd be a ground issue on the guitar as well...
time will tell

[trevorus]

Re: hissing sounds & AC30 and AC15...

My AC30 has a bit of a hiss on the top boost channel. I changed the preamp tubes, and it helped a bit.