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MonstaTone
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xx My Lucky 13 is NOISY!!!
« Thread started on: Sep 4th, 2012, 12:46am »

I love the tones of my Lucky 13! Especially with the gain mods.
It is super noisy though. My amp is a very early one, serial number 30.

The clean channel hisses with the volume all the way down.
The reverb has a horrible hum that goes away when the knob is turned all the way down.

I have tried new tubes, but the noises are still there.
I have placed the chassis in a combo cab, so the reverb tank is very far away from the power transformer.

Anybody else have an early L-13 with these problems?
Any help would be greatly appreciated. I am an amp tech, and nothing seems out of order with the amp, it is just noisy.
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ryanmichael95
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xx Re: My Lucky 13 is NOISY!!!
« Reply #1 on: Sep 4th, 2012, 03:09am »

Which tubes did you replace? The preamp tubes? That's where I would think the problem lies. Either that or a grounding issue.
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JRW
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xx Re: My Lucky 13 is NOISY!!!
« Reply #2 on: Sep 4th, 2012, 2:24pm »

(Note: Edited to correct my opening statement below once I got home and took a listen to mine.)

I have some low type of background noise with the volume down that is not bad and is definitely not a white noise type of hiss. For the reverb I have a slight hum but not all that noticeable unless the reverb is set past half way and the volume is at 4 or above (I actually rarely use the reverb) So from your description, it sounds like your noise and hum level is much worse. For the reverb, have you measured the resistance between the center and outside conductors for the RCA jacks on the tank itself to see if the tank is in spec, along with checking the ground shield connections and also the ground in the tank?

If you started replacing preamp tubes at the PI and worked backwards to V1 along with the output tubes with no results it might be noise in the resistors or something else - probably not very helpful advice at this point  if you have already done all this.
« Last Edit: Sep 4th, 2012, 11:34pm by JRW » User IP Logged

MonstaTone
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xx Re: My Lucky 13 is NOISY!!!
« Reply #3 on: Sep 4th, 2012, 11:42pm »

It's definitely not the tubes.
I'll have to pull it apart this weekend and see what is up. I was just wondering if anyone else thought the L-13 was noisy?

There is way too much hiss on the clean channel, even with the volume turned down.

The reverb works and sounds phenomenal, but the hum is unbearable above 3 on the knob.
I'll check all of the grounds. It's a bummer that the transformer is board mounted. Makes it really hard to get to the connections......
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xx Re: My Lucky 13 is NOISY!!!
« Reply #4 on: Sep 12th, 2012, 1:42pm »

AC Heaters ? Try a 6V DC battery or rectify the current heater circuit and see if that helps.
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MonstaTone
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xx Re: My Lucky 13 is NOISY!!!
« Reply #5 on: Sep 13th, 2012, 01:00am »

I didn't mess with the heaters, but I finally found a little time to look into my amp some more.

Here is what is happening:
Clean channel - volume knob turned down - tons of white noise
-None of the knobs affect the noise, with the exception of the Reverb and Presence knobs

Reverb - very noticeably adds noise and hum when turned above 2

I pulled V1 - no affect on the noise
I pulled V2 - the amp went to standard noise levels, but the majority of the white noise is gone.

So.....I re-tensioned all tube sockets and cleaned them - no help
I, once again, replaced V2 - no help
I checked all solder connections in the amp - no help
I checked all capacitors for leakage - none

Not sure what else to do.
The lead channel is fairly noisy, but I usually have the gain turned up to about 8 or 9.
The clean channel on almost every other amp I have built, owned, or worked on has been much more silent than this amp.
The amount of noise I have on the clean channel is equal to the amount of noise on most amp's gain channels!
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Giga
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xx Re: My Lucky 13 is NOISY!!!
« Reply #6 on: Sep 13th, 2012, 03:54am »

Could it be bleedthrough from the clean channel into the lead channel ? (I don't have a L13 schematic so I don't know if that's even possible...)

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xx Re: My Lucky 13 is NOISY!!!
« Reply #7 on: Sep 13th, 2012, 10:16am »

That's what I thought. I grounded every signal connection in the lead channel, one at a time and there was no difference. I was hoping it would be as simple as adding an LDR to ground the lead channel out when not in use. It has one LDR already after the 2nd (pretty sure it's the 2nd) gain stage of the lead channel.

I'll check plate resistors later on this week.
I'm going to try to call Soldano this morning. Problem is, they are 3 hours ahead of me, so I have to call at 5AM before I go to work.
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luckythirteen
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xx Re: My Lucky 13 is NOISY!!!
« Reply #8 on: Dec 15th, 2014, 7:36pm »

I had the same problem, Mine ended up being a bad pcb! It was drawing current to v1. my tech was able to isolate v1 and the problem went away.
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xx Re: My Lucky 13 is NOISY!!!
« Reply #9 on: Feb 24th, 2015, 01:13am »

Hi All, reviving this post - I've delivered my L13 with hum issues to a local tech, will report back. I've told him about the potential current leakage to V1 so will see what he finds.
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