Marshall 2203 REEEEEEEEEEE-work

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Re: Marshall 2203 REEEEEEEEEEE-work

Post by PLX »

lll wrote: Mon Jul 25, 2022 9:18 pm Again (and most of this will be) general rule of thumb:

For guitars

-hi pass 100Hz @ 12dB per octave
-lo pass 8KHz @ 12dB per octave

Other freqs of note:

-500 Hz drop dBs to taste if too honky
-250 Hz drop dBs to taste if too woofy
-3,4,5,6KHz add dBs if you need more bite
-8KHz add to add "air"

There are lots of other frequencies that have effect of course, but you gotta train your ears by testing and fiddling to see what they do.

Be aware that getting all "surgical" with EQ, you're gonna want to give your ears a break after awhile, then come back to it. Ear fatique is a real thing; even when listening at reasonable levels.

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Re: Marshall 2203 REEEEEEEEEEE-work

Post by lll »

Standard tuned 6 string guitar:

Guitar string frequencies are 82 Hz, 110 Hz, 147 Hz, 196 Hz, 247 Hz, and 330 Hz.

EADGBE
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Re: Marshall 2203 REEEEEEEEEEE-work

Post by PLX »

lll wrote: Sat Jul 30, 2022 5:01 pm Standard tuned 6 string guitar:

Guitar string frequencies are 82 Hz, 110 Hz, 147 Hz, 196 Hz, 247 Hz, and 330 Hz.

EADGBE
Yeah, But I calibrate my tuner concert pitch down from 440Hz to 413Hz
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Re: Marshall 2203 REEEEEEEEEEE-work

Post by lll »

PLX wrote: Sat Jul 30, 2022 5:05 pm
lll wrote: Sat Jul 30, 2022 5:01 pm Standard tuned 6 string guitar:

Guitar string frequencies are 82 Hz, 110 Hz, 147 Hz, 196 Hz, 247 Hz, and 330 Hz.

EADGBE
Yeah, But I calibrate my tuner concert pitch down from 440Hz to 413Hz
Compare those freqs to the handy dandy chart I posted.

But mainly, remember the general rule of hi-pass at 100Hz in relation to said freqs... the low 'E' does 82Hz.

Anything below 82Hz isn't technically there (at least from the guitar)... so it's cut out to give room for the bass guitar and other lo-freq instruments.

That doesn't mean, of course, you can't add stuff (super raging chug metal, etc).
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Re: Marshall 2203 REEEEEEEEEEE-work

Post by PLX »

lll wrote: Sat Jul 30, 2022 5:09 pm Compare those freqs to the handy dandy chart I posted.

But mainly, remember the general rule of hi-pass at 100Hz in relation to said freqs... the low 'E' does 82Hz.

Anything below 82Hz isn't technically there (at least from the guitar)... so it's cut out to give room for the bass guitar and other lo-freq instruments.

That doesn't mean, of course, you can't add stuff (super raging chug metal, etc).
Oh hey, I tried dialing up the variac.. that didn't kill the weird noise.

Gotta keep looking.

:|
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Re: Marshall 2203 REEEEEEEEEEE-work

Post by harddriver »

PLX wrote: Sat Jul 30, 2022 6:47 pm
lll wrote: Sat Jul 30, 2022 5:09 pm Compare those freqs to the handy dandy chart I posted.

But mainly, remember the general rule of hi-pass at 100Hz in relation to said freqs... the low 'E' does 82Hz.

Anything below 82Hz isn't technically there (at least from the guitar)... so it's cut out to give room for the bass guitar and other lo-freq instruments.

That doesn't mean, of course, you can't add stuff (super raging chug metal, etc).
Oh hey, I tried dialing up the variac.. that didn't kill the weird noise.

Gotta keep looking.

:|
You said you live near a transmitting tower, so the variac could be inducting the RF and or your V1 preamp tubes can also do the same thing if it not a mechanical plate issue with the preamp tubes. If it is a indeed electrical/static or RF look for inductance sources.

Maybe try the amp again without the variac first see if the noise leaves or lessens. Then you have to try preamp tubes one at a time.

Alot of people can get transient Radio waves inducted through the guitar pickup while connected to the amp because it become like a big antenna.

Is the noise bad I didn't her anything on you recordings? Has it always been there since you fired the amp up or did it just start?

I had a power supply for rack effects unit that my brother laid right next to the channel footswitch and he kep bitching that my amp I built him had gotten noisey. So I dropped by and asked why he has this power supply next to the footswitch that switch the input of the amp from 4th extra gain stage to 3 gain stages. That power supply was inducing the noise.... I about threw it into the next room and walla the amp was quiet as a mouse again.
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Re: Marshall 2203 REEEEEEEEEEE-work

Post by PLX »

harddriver wrote: Sat Jul 30, 2022 8:28 pm You said you live near a transmitting tower, so the variac could be inducting the RF and or your V1 preamp tubes can also do the same thing if it not a mechanical plate issue with the preamp tubes. If it is a indeed electrical/static or RF look for inductance sources.

Maybe try the amp again without the variac first see if the noise leaves or lessens. Then you have to try preamp tubes one at a time.

Alot of people can get transient Radio waves inducted through the guitar pickup while connected to the amp because it become like a big antenna.

Is the noise bad I didn't her anything on you recordings? Has it always been there since you fired the amp up or did it just start?

I had a power supply for rack effects unit that my brother laid right next to the channel footswitch and he kep bitching that my amp I built him had gotten noisey. So I dropped by and asked why he has this power supply next to the footswitch that switch the input of the amp from 4th extra gain stage to 3 gain stages. That power supply was inducing the noise.... I about threw it into the next room and walla the amp was quiet as a mouse again.
The RF noise I've had here is constant though. This noise is directly tied to what notes you play, so that leads me to think it's just an issue in the amp.. but I'm open to consider anything to try to get rid of it.

Here's the list of things I tried and the noise remained:

:idea: Rolled all pre-amp tubes out one at a time.
:idea: Swapped out both power tubes.
:idea: Dialed the variac back up from 70VAC to 100VAC (noise got louder directly proportional to the amp getting louder)
:idea: Switch off effects pedals one at a time.
:idea: Remove all pedals from signal chain and plug guitar straight into amp.
:idea: Tried a different guitar.

The noise is in the recordings posted in this thread - I was working very diligently with post EQ to dial it out. That's when I realized I had an amp issue, not an EQ issue.

It's really deceiving because you don't hear it when 1) playing chords 2) playing notes below middle C 3) playing notes in the upper register.

You only hear it when playing single note passages in the middle register. That's when it really comes out.


Your comments made me think of a couple things I have yet to try, but probably should have thought of:

:idea: Remove the variac and plug the amp directly into my filtered power supply.
:idea: Secure the two unused power tube hold-down springs to stop vibration.
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Re: Marshall 2203 REEEEEEEEEEE-work

Post by harddriver »

What you describe does kinda sound like ghosting, it sounds like a swelling harmonic overtone that rides at the tale end of the fretted notes at the higher registers of the neck.

I don't think your filtering is low enough to cause this and I have never really heard of a JCM800 circuit doing this, only mostly cranked Plexi with like 16/16uf on the preamp and really low filtering on the screens but it seems the low filtering on the preamp seems to be mostly causal.

Are you sure that you are not fretting out on the higher registers of your neck? I'm just throwing things out there... I know you said you changed guitars and all.

This is the best I could do concerning ghost notes...
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Re: Marshall 2203 REEEEEEEEEEE-work

Post by harddriver »

Are you grounds good on all three filter caps?
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Re: Marshall 2203 REEEEEEEEEEE-work

Post by PLX »

It's almost exactly what that video demonstrates at 3:30.

He describes it as "intermodulation".. It's not as prominent as in that video, but that is the damned noise I'm getting !

:x
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