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Super Moderator
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Discussion Starter · #1 ·
So I did a couple of mods to the 5150 III recently that really make the amp quite a bit better. First off, I have yet to hear anyone that likes the stock blue channel on this amp, which is an absolute shame because all the other 5150 III heads have an amazing blue channel. It's come to light more and more over the past year or so that simply snipping out a small capacitor fixes this.

This is the easiest mod you can make to this amp and it totally kills. Just snip out capacitor 137 and the blue channel comes to life, making it just as great as the blue channel on the other 5150 III amps.



Now for the second level of experimentation. Now that the blue channel rocks, let's make some changes to the red channel. This will be easier, as it's just tube preference.


I went into this morning wanting to mess with preamp tubes to make two changes to the red channel of the 50w EL34 amp:

1) make the gain knob more of a usable sweep, and
2) get rid of the squeaky midrange the red channel can have.

I wound up with this configuration that accomplished both:

V1: Mesa SPAX7-A (a decently high-end 12AX7)

Red channel specific tubes:
V2: JJ12AU7 (much lower gain)
V3: Sovtek 12AX7LPS
V4: Mesa 12AX7

This worked! I highly suggest replacing V1 and V4 with higher-quality tubes than the amp ships with. The 12AU7 reduces the gain of the red channel, making the gain knob useable throughout instead of topping off at 10 o'clock. The Sovtek LPS gets rid of the mid honk, making the amp sound much more balanced. If I had any spare Tung Sols lying around they would've gone in V1, V4, and V5, but the Mesa tubes will do just fine for now. All-in-all I recommend experimenting with the tubes in this amp and had success with this today, for sure.
 

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Sir Groove-A-Lot
Charvel So Cal & San Dimas
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Nice. I see that capacitor-snip done all the time on these amps, but I've never got the bottom of what the actual complaint is about the blue channel?

The JVMs suffer the same issue as the EVH red channels - Way too much fucking gain, making the gain dial redundant by the time you're around noon. There are mods to compensate for this (changing the value of some of the grid resistors), but I feel they neuter the amp in a way that's unpleasant to my ears (takes away quite a bit of low end) so I just leave it as it is. Preamp valves will be my next experimentation point.
 

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Nice! Guess I'll be tearing into mine tonight and try the blue channel mod.

Also, if you get a chance, try the EL34 to E34L swap I think I mentioned in one of our conversations. Supposed to give a bit more headroom but the main thing I noticed is this thing growls so good now. And the low end tightened up quite a bit.
 

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Discussion Starter · #4 ·
Nice. I see that capacitor-snip done all the time on these amps, but I've never got the bottom of what the actual complaint is about the blue channel?
It just isn't good. They tried to make a vintage sound, but it just sounds like mud IMO and never has enough gain even boosted. The EVH blue channel is iconic and many bands use it as their main heavy tone. Snipping out this capacitor fixes it in the 50w EL34 amp, which is the only amp they tried this.

Nice! Guess I'll be tearing into mine tonight and try the blue channel mod.

Also, if you get a chance, try the EL34 to E34L swap I think I mentioned in one of our conversations. Supposed to give a bit more headroom but the main thing I noticed is this thing growls so good now. And the low end tightened up quite a bit.
I need to do this! I've just never biased an amp before and need to learn how to use my multimeter before I try this! Soon!
 

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I am Groot
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32,450 Posts
Also, if you get a chance, try the EL34 to E34L swap I think I mentioned in one of our conversations. Supposed to give a bit more headroom but the main thing I noticed is this thing growls so good now. And the low end tightened up quite a bit.
+1 since I did this to my Stiletto Deuce. Tighter bottom end and a fierce lower midrange.
 

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OldSchool Blacksmith
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Makes me want to buy one now... just like everything else on these boards... no wonder I have too many guitars and 3 amps now. :lol:
 

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I did the C137 capacitor mod about a year ago. The 50watt should have never shipped that way(the 100watt head does not sound like this). I also experimented with preamp tube configurations as this amp is VERY sensitive to what preamp tubes you put in there (more than any other amp ive played with). I used a sovtek in v1 but i forgot what i used in the others. I know in the last tube position, I was constantly going back and forth and couldn't decide to the point where I wish I could have somehow put BOTH in and used a switch to switch between the 2. It was so obvious and lately, Glen Fricker said alluded to his opinion that tube changes don't make a difference and its all placebo. To his credit, he is doing a test/shootout video on this very subject.

I might try these EL34L. Can you guys post a link to which ones you bought?
 

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Nice! Guess I'll be tearing into mine tonight and try the blue channel mod.

Also, if you get a chance, try the EL34 to E34L swap I think I mentioned in one of our conversations. Supposed to give a bit more headroom but the main thing I noticed is this thing growls so good now. And the low end tightened up quite a bit.
+1 since I did this to my Stiletto Deuce. Tighter bottom end and a fierce lower midrange.
I actually didn't like E34L's in my Stiletto. I thought it neutered some of the midrange sweetness, but then, I've never had to compete sonically with a Triple :lol:
 

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I was shocked with the obvious difference in tone.
You also got me in for a set of 2. Do you have sock in JJ or something? :p

Also,

I didnt know there were 2 other people here that had these amps. Hell, I thought I was the only one.
 

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I am Groot
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32,450 Posts
I actually didn't like E34L's in my Stiletto. I thought it neutered some of the midrange sweetness, but then, I've never had to compete sonically with a Triple :lol:
Which mode do you most often use? I lived in Fluid Drive, which is more Recto-like, and therefore benefited from the lower mids. If you prefer Tite Gain with a boost, then I'd stick with EL-34s.

FYI: I'm talking about the Deuce II, since the original blows.
 

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Which mode do you most often use? I lived in Fluid Drive, which is more Recto-like, and therefore benefited from the lower mids. If you prefer Tite Gain with a boost, then I'd stick with EL-34s.

FYI: I'm talking about the Deuce II, since the original blows.
Yeah... almost always a boosted Tite Gain :yesway:

Of course... I wonder if I can mix a set of EL34's and E34L's... like, set the EL34's in the '50w' slots, as I almost always run in 50w, but then the E34L's in the extra '100w' slots, so I can flip to Fluid Drive and into 100w mode? Could be fun? I'd think the mixing would be OK since they're virtually the same tube, just a different frequency response.
 

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:lol: :ugh:

It's been a couple years since I did mine and I can't remember what brand I got. I can't even remember how I came about finding out to use the E34Ls.
after looking at tube depot and the tube store, the only brand im seeing in the EL34L is JJ. There is also a "EL34II". I wonder what those are all about *shrugs*.
 

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I am Groot
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I use the Tung Sols, which they market as EL-34B.
 

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after looking at tube depot and the tube store, the only brand im seeing in the EL34L is JJ. There is also a "EL34II". I wonder what those are all about *shrugs*.
I use the Tung Sols, which they market as EL-34B.
JJ EL34II = TungSol EL34B :yesway:

I've run both in my Stiletto, and they are virtually identical, IME.

I know a lot of folks dig on the E34L, but I haven't had a good experience with it yet. Maybe I should get a set and load it into my RT2/50...
 
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