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Post subject: EVH5150III red channel noise problem
Posted: Mon Jun 17, 2019 8:47 am
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https://www.youtube.com/watch?v=9jX0Lr2wEHU

Can anyone help?
I've already tried changing the tubes
I've had this amp for three years, the noise didn't use to be there
The noise is persistent even when I set the gain on zero.


Last edited by antonis91 on Thu Jun 27, 2019 1:42 am, edited 1 time in total.

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Post subject: Re: EVH5150III red channel noise problem
Posted: Sun Jun 23, 2019 6:51 am
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First is to check all 12AX7 tubes and replace the noisy one.
Start by V1

http://support.evhgear.com/schematics/E ... ctions.pdf


V1 ½ CH1/CH2 Preamp and ½ CH3 Preamp
V2,V3,V4 – CH3 Preamp
V5,V6– CH1/CH2 Preamp
V7,V8– Power Amp Output
V9– Power Amp Phase Splitter


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Post subject: Re: EVH5150III red channel noise problem
Posted: Thu Jun 27, 2019 1:39 am
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stratele52 wrote:
First is to check all 12AX7 tubes and replace the noisy one.
Start by V1

http://support.evhgear.com/schematics/E ... ctions.pdf


V1 ½ CH1/CH2 Preamp and ½ CH3 Preamp
V2,V3,V4 – CH3 Preamp
V5,V6– CH1/CH2 Preamp
V7,V8– Power Amp Output
V9– Power Amp Phase Splitter


Thanks for the reply. I 've tried changing all of them with no result! What else might be the problem?


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Post subject: Re: EVH5150III red channel noise problem
Posted: Thu Jun 27, 2019 1:57 am
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Your Y-T link show the amp with something ( guitar , pedals ? ) plug in the amp.

You must try the amp with nothing plug.

Noise may come from you gear not from the amp.

You replace all tubes by know good ones, not only one by one ?

To me it look a tube or the gear you plug :(


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Post subject: Re: EVH5150III red channel noise problem
Posted: Thu Jun 27, 2019 3:13 pm
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stratele52 wrote:
Your Y-T link show the amp with something ( guitar , pedals ? ) plug in the amp.

You must try the amp with nothing plug.

Noise may come from you gear not from the amp.

You replace all tubes by know good ones, not only one by one ?



To me it look a tube or the gear you plug :(


It does the same noise with nothing plugged in!
I replaced all the tubes that affect channel 3 at the same time


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Post subject: Re: EVH5150III red channel noise problem
Posted: Thu Jun 27, 2019 4:08 pm
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The amp must see a tech. :(


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Post subject: Re: EVH5150III red channel noise problem
Posted: Thu Jun 27, 2019 4:24 pm
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antonis91 wrote:
I've had this amp for three years......

Time to put it out to pasture and buy a really durable and dependable rig.

Like a Mustang GT40.

:lol:
Arjay

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"Here's why reliability is job one: A great sounding amp that breaks down goes from being a favorite piece of gear to a useless piece of crap in less time than it takes to read this sentence." -- BRUCE ZINKY


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Post subject: Re: EVH5150III red channel noise problem
Posted: Fri Jun 28, 2019 9:04 am
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That sounds like a bad Q1 JFET. It is used for muting the red channel. If it goes leaky, which is common, it will make that kind of sound. It cost less than a buck for a J113.
Other possibilities are a bad plate resistor, although they get more of a sizzle and crackle. Pull one tube at a time and listen. Or replace them all with low noise metal film.
Its unlikely to be a capacitor. Their signature is noise, then a pop and it gets quiet for a while.


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Post subject: Re: EVH5150III red channel noise problem
Posted: Fri Jun 28, 2019 9:38 am
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TimsAudio wrote:
That sounds like a bad Q1 JFET. It is used for muting the red channel. If it goes leaky, which is common, it will make that kind of sound. It cost less than a buck for a J113.
Other possibilities are a bad plate resistor, although they get more of a sizzle and crackle. Pull one tube at a time and listen. Or replace them all with low noise metal film.
Its unlikely to be a capacitor. Their signature is noise, then a pop and it gets quiet for a while.


I have a feeling you are right. The capacitors are fine, I checked them today. I 'll check it on Monday and I 'll let you know. If you are right I love you


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