anybody reduce the gain on ch3 on evh 5153 100 watt head?

[Speeddemon]

I have 50w...

...I slapped a 12au7 in the red channel & it brought the gain down to a perfect spot.

That's what I tested in my 50W as well.
Way opener mids, greatly reduced compression. More of a Gary Moore tone in the red channel, with the gain around 1 o' clock.
It may have helped I was using a 60's NOS RCA 12AU7...

In the end I did end up with 2 (!) 5751's in the red channel. This hardly changed the character, but made the gain range from 7 'o clock to 9 'o clock way more useable for Thin Lizzy, old Priest (Stained Class-era) levels of gain.

 

[fusedbrain]

Yeah, when I've tried this, I've always found that the 5751's retain the core tone of the amp better than other lower gain tubes. You can also get nice nos 5751's for reasonable prices. And the nos one sound way more like 12ax7's than the cp ones I've tried.

 

[JakeAC5253]

Put a small value resistor from the wiper on the 3rd channel gain pot to the grounded lug.

 

[fusedbrain]

Put a small value resistor from the wiper on the 3rd channel gain pot to the grounded lug.

Yes, that's definitely an option as well. R29 is a 1 meg to ground off the wiper of the gain pot. Another 1 meg // over R29 would drop this to 500k and dump some more signal to ground instead of sending the signal to the next gain stage. You could mess with the values of the // resistor a bit, but I probably wouldn't go lower than 560k, which would give you approx 350k to ground at that point in the circuit. It's easy to test different values here with a couple alligator clips before you bust out the soldering iron.

 

[donho]

would reducing r29 and r63 be the same as using a 5751 in v5 and a 5751 in v6?
thanks

 

[JakeAC5253]

Put a small value resistor from the wiper on the 3rd channel gain pot to the grounded lug.

Yes, that's definitely an option as well. R29 is a 1 meg to ground off the wiper of the gain pot. Another 1 meg // over R29 would drop this to 500k and dump some more signal to ground instead of sending the signal to the next gain stage. You could mess with the values of the // resistor a bit, but I probably wouldn't go lower than 560k, which would give you approx 350k to ground at that point in the circuit. It's easy to test different values here with a couple alligator clips before you bust out the soldering iron.

Good point. I hadn't checked the schematic, but the resistor I am talking about is already there as R29. 1M isn't doing much to lower gain though. If you are going to go with a full replacement, start with 220k and see if you like the effect, then adjust from there. If you are going to piggyback, then try 330k or so. Any higher value in either instance won't provide enough of a difference to warrant a mod IMO. You could also make this switchable so you could have a low mode and a full mode.

 

[sixstringking713]

you guys are making this more complicated than it has to be..

there's 2 bypass caps in ch3 gain stage that will reduce the gain if you just clip em..

I cant look at the schematic right now but I kno thats an easy mod. Search for it online.

(I'm an EE by day)

I modded my evh50w few years ago

EDIT:
guy online said C16 and C30.. Try at your own risk
http://www.guitarampboard.com/forum/vie ... =5&t=16570

 

[donho]

you guys are making this more complicated than it has to be..

there's 2 bypass caps in ch3 gain stage that will reduce the gain if you just clip em..

I cant look at the schematic right now but I kno thats an easy mod. Search for it online.

(I'm an EE by day)

I modded my evh50w few years ago

EDIT:
guy online said C16 and C30.. Try at your own risk
http://www.guitarampboard.com/forum/vie ... =5&t=16570

we are talking the 100 watt head. this guy at guitarampboard is talking 50 watter. dont know if the cap numbers are the same.

 

[sixstringking713]

you guys are making this more complicated than it has to be..

there's 2 bypass caps in ch3 gain stage that will reduce the gain if you just clip em..

I cant look at the schematic right now but I kno thats an easy mod. Search for it online.

(I'm an EE by day)

I modded my evh50w few years ago

EDIT:
guy online said C16 and C30.. Try at your own risk
http://www.guitarampboard.com/forum/vie ... =5&t=16570

we are talking the 100 watt head. this guy at guitarampboard is talking 50 watter. dont know if the cap numbers are the same.

oh my bad..

for the 100W head it looks like C19 and C20

Do it at your own risk!! lol

 

[fusedbrain]

Well there's 2 issues with clipping cathode bypass caps, and they both "make it more complicated".

First, removing cathode caps is going to change the tone of the amp. Yes it will reduce gain, but it will screw with the tone. It may be better (doubtful) it may be worse (likely) but the tone WILL change.

After you clip the caps and realize you screwed up, now you have to pull the board to fix it. THAT'S complicated.

YMMV

 

[sixstringking713]

Well there's 2 issues with clipping cathode bypass caps, and they both "make it more complicated".

First, removing cathode caps is going to change the tone of the amp. Yes it will reduce gain, but it will screw with the tone. It may be better (doubtful) it may be worse (likely) but the tone WILL change.

After you clip the caps and realize you screwed up, now you have to pull the board to fix it. THAT'S complicated.

YMMV

you could just clip one lead and bend it slightly away from the board... and if you dont like the tone, push it back down to the board and put a drop of solder..

can you go into detail what those "2 issues" are specifically?

 

[bmf5150]

Is there anyway to make the original evh 5153 100
Watt head a little less mid forward and tad bit clearer and brighter like the 100 stealth is but keep the lower gain of the original head?

 

[TotallyRadGuitars]

Is there anyway to make the original evh 5153 100
Watt head a little less mid forward and tad bit clearer and brighter like the 100 stealth is but keep the lower gain of the original head?

Which channel? On the Red channel, the original and stealth have basically the same amount of gain - the difference is the stealth has a 5.1k cathode resistor on the 3rd gain stage while the original has 18k - so arguably, if by "gain" you mean "distortion," the original has more than the stealth does. The other difference is that the stealth has a .047 cap on the low pot of the EQ (original is .022) and a jumper across the mids pot. If you want the Stealth's red channel sound, it's those 3 changes and they are otherwise identical.

The blue channel changes were documented earlier in this thread - more changes there between the amps. If you just want clearer/brighter, you could add that bright cap to the blue channel gain pot + leave the other values original, and have an immediately noticeable change unless you use the gain very high on that channel.

 

[mrmega]

love this beast, but would like to lower the gain on ch 3.

Hey, I own this amp (EL35 100Ws) and along with the Marshall Vintage Modern it's my favorite. I never run the pre gain very high even for metal. I'm honestly curoius, why reduce the gainin the amp? Does keeping the pregain knob lower not achieve what you want?