#9

Power tube bias issue? Long shot and not an area of my expertise, but with my Ampeg B-15 I always had a tech “adjust the bias” when changing tubes, not that I completely understood what that meant, which the tech very politely understood.

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#10

I believe the AC30 does not need to be biased http://carlscustomamps.com/cathode-vs-fixed-bias

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#11

Ahh, long shot indeed! I learned much from that link though, thanks!

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#12

Stupid questions but are you plugging directly from guitar to amp? Also does it make the sound with nothing plugged in?

#13

If it has a reverb tank try moving it around, rotating it etc. I have a custom AB763 DR clone, and moving the spring tank and using shielded Mogami cables to and from the amp made a HUGE positive difference in noise levels. I also notice way more noise when I put my Eventide H9 on top of it, (the closer to the power tranny, the worse it gets), so now I keep it on the floor below.

#14

I have tried going straight into the amp (removing pedals). Noise level is about the same.

This bad metallic kind of noise only occurs when something is plugged in. There’s some low white noise if you turn the amp completely up without anything plugged in but that seems normal levels

I can try removing the spring reverb tank. I dont know if I have any fancy shielded cables but I’ll have a look.

#15

Single coil pickups? Tried a different guitar or amp? Has this combination of amp/guitar ever run noise-free at your current house?

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#16

If you have the reverb turned down it shouldn’t make any sound? Also you’re saying it only happens with an instrument plugged in? I would consider RF (I think that’s it) interference in the room or area maybe?

#17

This sounds like a guitar issue or something funky at the input jack. If the amp is reasonably quiet with nothing plugged in, then the problem is happening before the gain stages otherwise you would hear it being amplified in the preamp or power amp.

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#18

Yeah, does the noise level go up and down when you move guitar around and change pickup settings?

If you move around parallel to mains power etc sound like this can change if from pickups.

Also light dimmer switches can cause noise like this, even if “off”.

Honestly shit like this drives me crazy. If in house I’d go to breaker and shut off everything but room you’re using just to see what happens.

I’d borrow a radial JDI and xlr to ts just to see what happens too.

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#19

It was …a cable. I swore I tried a different cable maybe I somehow just swapped them around (with the effects loop there’s 4 cables).

My main guitar is an hss strat. I had it recently set up and they did away with a lot of excess wiring inside which helped improve its noise performance significantly. They said it is still somewhat susceptible to noise and I could follow up with getting the inside covered in shielded tape to make it perfect. Knowing this I did try my other guitars (a strat retrofitted with p-90s and a short scale sg bass which I believe is single coils. I don’t have anything super low noise like a les Paul humbucker

It seems like the amp is working at normal levels (out in the garage, just the guitar plugged straight in) with the other cables besides this one.

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#20

With my hss strat i can move around or pivot to find better noise spots, but I think that’s the guitar not the amp.

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#21

This would be ultimate solution

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#22

I did try running guitar into the 3.5mm of rip and then out the 1/4” to the amp a second ago. It sounded so muddy that way and when I turned the ground lift on it was such a loud buzz

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#23

Also do wanna say that I really appreciate all of yalls suggestions which pushed me to keep trying stuff to figure out what it was. I was about ready to take a sledgehammer to the amp (not really, but it has given me a headache today)

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#24

Noise problems are infuriating. Totally understand. Glad you got it sorted. FWIW, these little rascals are pretty handy to keep around.
image

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#25

I’m imagining your anguish when you bring home that new hand wired goodness only to plug it in and hear the same amp demon again.

Glad you got it sorted!

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#26

got everything hooked back up in my studio room and I think this is even more silent than a couple days ago (maybe that one cable was on the verge of giving out and it finally gave out today). there is a sort of white noise you can hear from the amp but no awful metallic demon noise (I’m guessing that’s normal…telling myself it is atleast so I can stop worrying about it hah)

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#27

Just wanted to update on my noise extermination journey.

Made some of these using Mogami 2524 and Neutrik NP2X-B ends (including one of the silent ends for the guitar input) from redco. I’m not sure I can tell a huge difference, but they feel very nice and they were fun to make!

After a lot of trial and error, I have found a method that allows me to get to unnaturally low levels of noise with, in my opinion, no difference in feel.

  • guitar ->
  • front of amp pedals (tuner and EQD plumes) -> front of amp
  • amp fx send ->
  • intellijel pedal i/o (this is similar to an active DI, it has a very high input impedance, also has a triode emulation apparently) to get to modular levels ->
  • er-301 (which exhibits the hf digital noise issues when I try to put it in the guitar chain as mentioned here) ->
  • RIP (this part probably isn’t super important, I could go out of the 301 directly with some attenuation) ->
  • Interface ->
  • Ableton (so ableton is basically getting a 301’d DI guitar signal. Within ableton, I’m using the ACON digitial denoise plugin, which is basically an FFT EQ based on a noise profile that you can set the reduction curve with an FFT) ->
  • Interface out to DIYRE L2A reamp box (ground lift here is important) ->
  • Reverb/Delay pedals.

This is obviously a very complicated and specific setup, but I’ve learned some lessons that I think that could be more generically applied:

  • Don’t muck with a bunch of weird stuff in front of the amp. The front of the amp and preamp tubes are where a lot of the real feel of the amp comes from. Even in terms of pedals, keep that part of the chain as light as possible.
  • Using FFT-based noise reduction works best on DI’d guitar signals. If you try to do it after reverb you get artifacts and you definitely can’t get as aggressive with it. You still need to be careful not to lose hf pick attack, but you can sweep around with the emphasis curve and figure out what needs to be present to give you that. A cool thing about having it in the effects loop of the amp is that you can get rid of the natural hf “white noise” that’s just generally present with tubes that would be amplified by the power amp section (so thus my mention of this method being “unnaturally quiet”…but IMO not in a bad way).
  • If you’re interface has a “zero”-latency mode (like monitoring through UAD console, or RMEs totalmix, or whatever) you can switch between monitoring out of that (so bypassing the noise reduction) so that there’s no awkward latency when recording, while being able to do a second pass of the DI’d signal you recorded in ableton through the noise reduction.
  • Impedance matching is important. Trying to use a passive DI (i.e. RIP) going into the synth from the guitar signal was getting me this real dull sound I couldn’t fix with any sort of eq. You could probably figure out some sort of active front end in pedal format (maybe some sort of preamp pedal) in lieu of the intellijel pedal i/o.

I hope these ideas are helpful for anyone who tries to go on this journey.

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#28

the noise within one’s sound environment is a peculiar set of sounds known only to the owner of the environment. it’s funny how personal these things are. thanks for sharing ur experience this was helpful

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