EVH III Ch 3 NOISY!! I wonder why........

[nevetslab]

I've now got two EVH III Amp heads in the shop, first one hasn't been serviced since Sept 2015. None-the-less, Ch 3 is, of course an ocean of noise. I wonder why? There are five....count 'em.....FIVE cascaded stages of gain, each with a different bit of voicing...all between the input gain stage that has the Gain control, and the final stage that's a cathode follower. Two of the gain stages (on V5) are using 220k plate resistors...only ones of the 3 channels in the amp.

Now, besides sitting with a box of new ECC83 tubes, probably from different mfgrs to select from in hopes to find some combination to minimize all this wide-band noise....is there any other trick (besides slipping in some 12AY7's when nobody's looking) to lower this ocean of noise? That's what both of these amps are in here for.

Fender EVH 5150-III head.pdf

[The Dude]

IMO, those things are just inherently noisy, as you said, because of the insane amount of gain. I don't think any amount of tube swapping will make you happy- at least it didn't me. A noise gate in the loop is the best solution. I played through one for a while. My solution was to not use channel 3, but that hardly helps you.

[moshpit903]

I am no amp tech but I have had 2 of these amps,both 50 watt heads,and still own my second one and its as quiet as can be on channel 3,thats what I use with gain at 2-3..I have changed preamp tubes to suit my sound needs but it rocks on every day.

[nevetslab]

I am no amp tech but I have had 2 of these amps,both 50 watt heads,and still own my second one and its as quiet as can be on channel 3,thats what I use with gain at 2-3..I have changed preamp tubes to suit my sound needs but it rocks on every day.

Well, I wouldn't sell that one then! I've gotten these EVH III amps in our rental inventory tolerable, but noisy none the less. 5 cascaded stages of 12AX7's between volume pots is rarely going to be quiet.

[drewl]

That and certain Mesa's.

It's a crap shoot trying to find the right combination of tubes and placing which can take a while to get it to be slightly less white noise hell.

[moshpit903]

Well, I wouldn't sell that one then! I've gotten these EVH III amps in our rental inventory tolerable, but noisy none the less. 5 cascaded stages of 12AX7's between volume pots is rarely going to be quiet.

I didn't know it has 5 stages,but know its got plenty of gain on tap..I have the schematics and will look and see the gain stages.

The EVH line came out with their LBX 15 EL-84 tube head 2 years ago with 2 EL-84's and 5 or 6 preamp tubes,and I bought one brand new 2 weeks after becoming available and that amp had a lot of hiss,like a caged animal..I did like it but sold it to get my 50 watt head(s).

When I got my latest one new in November of last year I put in some new Eurotubes matched pair of JJ's 6l6-Gc's and have installed a Tungsol 12ax7 in V1 and some of the 9th gen chinese 12ax7b's in there and it sounds awesome,even when I turn it up there is no extra noise,well except for my playing ! I guess I am lucky and keeping this one,its had zero issues and has plenty of power to get the job done.my best tube amp to date.

[moshpit903]

That and certain Mesa's.

It's a crap shoot trying to find the right combination of tubes and placing which can take a while to get it to be slightly less white noise hell.

I did trade for a Mesa single rectifier for a backup,and once its up and running I am hoping to be set for a while,but from some reading here and elsewhere finding out that they can be a pain in the a** to work on..

[nevetslab]

I did trade for a Mesa single rectifier for a backup,and once its up and running I am hoping to be set for a while,but from some reading here and elsewhere finding out that they can be a pain in the a** to work on..

I do admire how well the Mesa amps are built....I own one of their Stereo Simuclass 2-90 Power amps and like it, but, they ARE tedious to work on. If you love taking car engines apart, these are the amps to have, as it will satisfy the tear-down / disembowlment effort delight quite well.

[moshpit903]

I do admire how well the Mesa amps are built....I own one of their Stereo Simuclass 2-90 Power amps and like it, but, they ARE tedious to work on. If you love taking car engines apart, these are the amps to have, as it will satisfy the tear-down / disembowlment effort delight quite well.

Yep I do like doing car engines,transmissions etc apart,and I just completely rebuilt a Coleman generators engine and got it working mostly,but man I am really hoping I do my repair right,and I am actually trying to fix it right but I still worry thinking I should take it to a tech..I just found one 50 miles from me instead of 200+ miles,and he is well liked so somethings going to happen soon..his bench rate is $45 and up and thats good for me.

[J M Fahey]

I do admire how well the Mesa amps are built....I own one of their Stereo Simuclass 2-90 Power amps and like it, but, they ARE tedious to work on. If you love taking car engines apart, these are the amps to have, as it will satisfy the tear-down / disembowlment effort delight quite well.

Well, *Mesa Engineering* was originally applied to Randall Smith´s engine rebuilding shop.
I guess the DNA shows.

[drewl]

Don't be intimidated.
Most problems can be resolved without having to remove the main PC board.

Work the problem, don't complicate things.