Fell in love with my EVH 5150 III all over again!

[ledvedder]

This amp has been sitting to the side for quite a few months. The other week I decided to fire it up and it crapped out on me. I ended up replacing the fuse and power tubes, when I noticed one of the tubes had white on the top. After replacing them, I set the bias to 55mv. I believe these came from the factory biased cold (50mv), and many recommendations on the net say 60mv. I figured I'd find a happy medium.

Then, I decided to try some preamp tube swapping. I ended up with a Tungsol in v1 and a JJ 5751 in v2. Since it always seemed just a bit to gainy for me, I tried channel 3 with the gain set around 2. Holy crap! I absolutely loved it!

So, with channel 2's gain around 4 and channel 3 around 2, this thing is sounding so sweet! With the lower output pickups in my LP Classic, the punch and clarity have made me fall in love with this thing all over again!

 

[Speeddemon]

I don't know if you happen to have access to a vintage RFT 12AX7 by any chance, but that's what I put in mine in V1. Less aggressive, bigger and bolder.
And I wanted to drop the Gain in the red channel some more, so I have 5751's in V2 and V3. If you REALLY want to change the character and gain level of the red channel, try a 12AU7 in V3. My experience (with a NOS RCA from the 60's) was instant Gary Moore tone there. Really organic mids, a lot less gain though. Chugging is almost impossible at that point. But it was a cool experiment nonetheless.

 

[napalmdeath]

Don't know where you got your info. They should be biased around 34-36mA. That's where I baised mine. They usually come around 30-32 from the factory.

Is this the 50 watt? If so, 55 is WAY hot!

 

[LP Freak]

Don't know where you got your info. They should be biased around 34-36mA. That's where I baised mine. They usually come around 30-32 from the factory.

Is this the 50 watt? If so, 55 is WAY hot!

Maybe he means per tube

 

[ledvedder]

Maybe he means per tube

Yeah, the bias point reads both tubes, so 55 is essentially 27 or so per tube.

 

[ledvedder]

Don't know where you got your info. They should be biased around 34-36mA. That's where I baised mine. They usually come around 30-32 from the factory.

Is this the 50 watt? If so, 55 is WAY hot!

Where did you get this info?

 

[LP Freak]

Maybe he means per tube

Sorry, I meant per pair not per tube so 55mA per pair would be fine

 

[ledvedder]

I don't know if you happen to have access to a vintage RFT 12AX7 by any chance, but that's what I put in mine in V1. Less aggressive, bigger and bolder.
And I wanted to drop the Gain in the red channel some more, so I have 5751's in V2 and V3. If you REALLY want to change the character and gain level of the red channel, try a 12AU7 in V3. My experience (with a NOS RCA from the 60's) was instant Gary Moore tone there. Really organic mids, a lot less gain though. Chugging is almost impossible at that point. But it was a cool experiment nonetheless.

I have an RFT on the way, since I read that a lot of folks loved it in v1 of their 5153. I do also have a few JJ ecc82 tubes (12au7 equivalent). Maybe I'll give those a try in v2/v3.

 

[fusedbrain]

Yeah, 34 - 38mA per tube is around 60% dissipation for a 6L6 with +/- 470V - 480V on the plates, which is fine.
However, with amps with a crap ton of pre amp gain, you don't want the bias to be too warm because you already have all the harmonics you need, and too hot makes the amp mush out.
Ya just want a nice clean, tight power section.
Probably best to start low around high 20's mA and do it by ear, raising the bias until the fizz falls away.
As long as you don't go over about 42-ish, you're good, but you'll probably end up around mid 30's like Napalm said.
And he's also bang on about the factory bias for the EVH amps: 30 - 32mA for the 6L6 amps is how they leave Fender. That's also what Howard Kaplan was posting all over the place when these amps first came out.
It's kinda on the cold side, but good for tube life and warranty claims.
Still not as ridiculously cold as Peavey used to ship the old 5150's.
And that bias wasn't adjustable without a mod.

 

[napalmdeath]

Where did you get this info?

I've owned a 50 watt 6L6 3 times, and biased them, plus a couple others. Factory was always 28-30 for the pair, (there's only one adjustment, not one for each tube).

Yeah, 34 - 38mA per tube is around 60% dissipation for a 6L6 with +/- 470V - 480V on the plates, which is fine.
However, with amps with a crap ton of pre amp gain, you don't want the bias to be too warm because you already have all the harmonics you need, and too hot makes the amp mush out.
Ya just want a nice clean, tight power section.
Probably best to start low around high 20's mA and do it by ear, raising the bias until the fizz falls away.
As long as you don't go over about 42-ish, you're good, but you'll probably end up around mid 30's like Napalm said.
And he's also bang on about the factory bias for the EVH amps: 30 - 32mA for the 6L6 amps is how they leave Fender. That's also what Howard Kaplan was posting all over the place when these amps first came out.
It's kinda on the cold side, but good for tube life and warranty claims.
Still not as ridiculously cold as Peavey used to ship the old 5150's.
And that bias wasn't adjustable without a mod.

I'm just clarifying, if you only have one adjustment/reading, you should be in that 34-36 range, and not 55-60, no? That 55-60 is per tube, with a single adjustment. Thats too hot! I'm just clarifying if he biased it at 27.5, or 55. Big difference!

I always used a Pro One, and plugged into one socket, biased around 34-36mA, and called it a day.

 

[napalmdeath]

Yeah, the bias point reads both tubes, so 55 is essentially 27 or so per tube.

What method did you use? Single probe? I'm just making sure you didn't bias 55 per tube. That would be 110 combined.

 

[ledvedder]

What method did you use? Single probe? I'm just making sure you didn't bias 55 per tube. That would be 110 combined.

I measured across the 1 watt resistor (R157). I believe this measures total MV across both power tubes.

 

[napalmdeath]

I measured across the 1 watt resistor (R157). I believe this measures total MV across both power tubes.

10-4. If it's combined, you're still on the cold side. Colder than factory. I never biased mine hot, but certainly warmer than factory. I tend to prefer around 60% with shitloads of preamp gain. More like 68-72mA, which is still closer to 60%, which is technically cooler, yet warmer than factory. IMO, it does make a difference, as does better preamp tubes. I usually ran with a Tungsol in V1, and USA GE/Jan 5751's in V2 & V3. I sold one to "The Hoff" on here that was the best sounding of the bunch. I had a British Mullard in V1, Sylvania USA in V2, and black plate RCA in V3, and it was sick. Most expressive, most musical of the 3 I owned. They LOVE NOS glass, and respond very well to them.

 

[ledvedder]

10-4. If it's combined, you're still on the cold side. Colder than factory. I never biased mine hot, but certainly warmer than factory. I tend to prefer around 60% with shitloads of preamp gain. More like 68-72mA, which is still closer to 60%, which is technically cooler, yet warmer than factory. IMO, it does make a difference, as does better preamp tubes. I usually ran with a Tungsol in V1, and USA GE/Jan 5751's in V2 & V3. I sold one to "The Hoff" on here that was the best sounding of the bunch. I had a British Mullard in V1, Sylvania USA in V2, and black plate RCA in V3, and it was sick. Most expressive, most musical of the 3 I owned. They LOVE NOS glass, and respond very well to them.

I ordered an RFT to try in v1. Wish I had more cash to spend on more NOS tubes, but that will have to do for now. The JJ 5751 in v2 seems perfect to my ears.

 

[ledvedder]

I don't know if you happen to have access to a vintage RFT 12AX7 by any chance, but that's what I put in mine in V1. Less aggressive, bigger and bolder.
And I wanted to drop the Gain in the red channel some more, so I have 5751's in V2 and V3. If you REALLY want to change the character and gain level of the red channel, try a 12AU7 in V3. My experience (with a NOS RCA from the 60's) was instant Gary Moore tone there. Really organic mids, a lot less gain though. Chugging is almost impossible at that point. But it was a cool experiment nonetheless.

Wow, I just tried a JJ ecc82 in v3. Along with the 5751 in v2, it completely changes channel 3. The gain seems much more usable now. But, I'm not sure how it would sit in a band mix. I'll have to give it a try this week.

 

[napalmdeath]

Wow, I just tried a JJ ecc82 in v3. Along with the 5751 in v2, it completely changes channel 3. The gain seems much more usable now. But, I'm not sure how it would sit in a band mix. I'll have to give it a try this week.

Red channel is insane with the gain. The reason I personally don't own one. Even all the tube swapping, Red was always out of control for me. I lived on the blue channel, and Green and Red were just a waste. I'd be down for a single channel EVH with just a blue channel. I used it as my lead channel too. But, in the end, I just found them uninspiring, after the honeymoon with better tubes.

 

[Speeddemon]

Wow, I just tried a JJ ecc82 in v3. Along with the 5751 in v2, it completely changes channel 3. The gain seems much more usable now.

Yep, my experience as well. Suddenly from 0 to 6 is a useable and continuously changing range on the gain knob, instead of 0 to 1.5.

But, I'm not sure how it would sit in a band mix. I'll have to give it a try this week.

The thing that in my experience can make the band-mix sound perhaps lacklustre, would be that sort of plasticy ring/nasalness in the red channel's mids. I've actually done more leads on Blue, because it's so much more open, raw and dynamic.

 

[ledvedder]

Yep, my experience as well. Suddenly from 0 to 6 is a useable and continuously changing range on the gain knob, instead of 0 to 1.5.



The thing that in my experience can make the band-mix sound perhaps lacklustre, would be that sort of plasticy ring/nasalness in the red channel's mids. I've actually done more leads on Blue, because it's so much more open, raw and dynamic.

Yeah, that's what I was hearing on the red channel. The gain structure was much more usable for me, but there was something odd in the mids. I'm thinking 2 5751's might be a better fit.