EVH 5150 III EL34 50w C137 Mod - Blue Channel Demo

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SpiderWars":pugfq3on said:
What is the C137 mod?
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You clip one leg of the resistor and it basically returns the blue channel to the 6L6 blue channel specs. Opens the blue channel up a good bit.
 
Yup...heard of this mod. I haven't played the EL34 version so don't know the blue normally. I like what I'm hearing.
 
I love the Blue channel on my EL34 EVH but I'm not playing the stuff as heavy as what you are playing there.

I will say, that sounds amazing and nice textured crunch!! Also, you did great with the talking on the camera btw. :)
 
I'm on the fence with this ... on one hand I sort of dig that the stock blue channel on the EL34 amp is very different than the red channel, and I like it when I put a drive pedal in front. Without the drive, sure its flubby for certain types of music, but is fine for others ... so more versatile I guess. One the other hand, I really liked the blue channel on the 6L6 50 watt amp I had, but sold to get this one. It would be cool to make it switchable, which I'm sure is possible for someone who is NOT me to do, lol. I think I can handle the c137 mod, but its seems pretty permanent for someone with very limited skills in this area.

The tone from the video sounds good, a pretty drastic change to the stock tones of that channel.
 
Rayneman said:
I'm on the fence with this ... on one hand I sort of dig that the stock blue channel on the EL34 amp is very different than the red channel, and I like it when I put a drive pedal in front. Without the drive, sure its flubby for certain types of music, but is fine for others ... so more versatile I guess. One the other hand, I really liked the blue channel on the 6L6 50 watt amp I had, but sold to get this one. It would be cool to make it switchable, which I'm sure is possible for someone who is NOT me to do, lol. I think I can handle the c137 mod, but its seems pretty permanent for someone with very limited skills in this area.

The tone from the video sounds good, a pretty drastic change to the stock tones of that channel.
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It would be very easy to add this mod to a switch. You could drill and put a small switch somewhere to switch the cap in and out.
 
I did a little reading on the mod and read that C137 is a 1000pF cap. Since snipping it opens up the amp, I'm guessing it is some sort of snubber. That's not unusual in a case like this, Mesa does similar with the Simul-class vs non-Simul amps to account for difference in tones from the power amp.

IME, over-snubbing almost always sounds bad.

FWIW, if you are going to the trouble of putting it on a switch you could just as easily put it on a pot. BUT...I don't know the location in circuit and thus the voltage on the two points used so...be careful.
 
SpiderWars said:
I did a little reading on the mod and read that C137 is a 1000pF cap. Since snipping it opens up the amp, I'm guessing it is some sort of snubber. That's not unusual in a case like this, Mesa does similar with the Simul-class vs non-Simul amps to account for difference in tones from the power amp.

IME, over-snubbing almost always sounds bad.

FWIW, if you are going to the trouble of putting it on a switch you could just as easily put it on a pot. BUT...I don't know the location in circuit and thus the voltage on the two points used so...be careful.
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I saw a picture of the mod schematic once, and I want to say it was an extra cap in the tone stack. Maybe paralleled in front of the tone stack? Something weird like that.
 
Sounds great man.

So I was thinking based on the convo so far that this was similar to my Recto switch for 6L6 vs EL34s - where it adjusts the bias? I know nothing about the layout of this amp nor am I an EE but C137 doesn't look like it would be in a conducive spot for a switch let alone a pot.

Go to the :55 ish mark here. Not sure what this guy did exactly - it looks like he removed C137 altogether. Kinda hard to tell.



curious none the less...
 
He just snipped one leg, connected wires to the 2 new points (where he snipped), twisted them and ran them to a switch.

You could use a pot instead of switch OR you could install another cap in series with the existing one and that would reduce the capacitance (and lessen the effect).
 
Could you detail the recording gear and method used. I'm inspired to record if I could make clips this good. Man it sounds so sick.
 
^ If I to guess he is using his iRig Pre straight into his Samsung S10
 
Hmm, I just got one and yeah the blue channel is pretty dark. I think I'll try this mod and see what happens. I want to use the blue for more like classic rock. The clean is actually pretty clean and the red is almost too heavy, but it's good for solos and stuff. :checkthisout:
 
Dr. Tweedbucket said:
Hmm, I just got one and yeah the blue channel is pretty dark. I think I'll try this mod and see what happens. I want to use the blue for more like classic rock. The clean is actually pretty clean and the red is almost too heavy, but it's good for solos and stuff. :checkthisout:
Click to expand...

Something to consider, you can put the mod on a toggle switch, since all it's doing is disconnecting one connection of one component.
 
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