taming the EVH 5150iii 50 watt combo via preamp tube selection..

spookyelectric

Silver Supporting Member
Messages
2,143
So I picked up a 50 watt EVH 5150iii combo a couple weeks ago and I’m really digging it so far. Still need to break the speaker in more, but that’ll come with time.

I’ve been looking at trying to tame the red channel a little bit, at least so I can have the gain set higher than 9:00 on the dial, and I’ve seen a few different ways that folks have tamed theirs. I’ve been looking at the preamp tube gain factor chart on thetubestore.com which has the following:

12AX7 – 100%

5751 – 70%

12AT7 – 60%

12AY7 – 45%

12AU7 – 19%


Here are the different preamp tube combinations I’ve seen so far for taming the 5150iii:

  1. 12AY7 in V1 – this is supposed to clean up the green channel to make it more of a clean channel, and since V1 also feeds the blue and 1/3 of the red channel, it’s supposed to give the blue channel more of a plexi level of gain, and the red channel more of a JCM800 level of gain. Overall, seems like this would be a decent choice for those looking to dial all channels back a bit and give them the freedom to gain them up more via boosts/overdrive pedals.

  2. 12AT7 in V1 and 12AU7 in V4 – supposed to warm up the green and blue channels and drop the gain a bit, but not as much as the 12AY7 does. The 12AU7 in V4 is supposed to help give a more useable range of the gain knob on the red channel, since positions V2, V3 and V4 are the tube slots specifically for the red channel.

  3. 12AU7 in V2 – supposed to drop the gain level to “vintage metal’ levels of gain (old Judas Priest, Scorpions, etc.) since V2 is the first gain stage solely for the red channel, so positions V3 and V4 have less to work with.
I’ve been using option #3 above and it seems to be working pretty well, but it gives the red channel a little sag/squish at higher gains, almost like having a tube rectifier does on older tweed amps, especially when I dig in. I wonder if moving the 12AU7 to V4 would help tighten it up, since it will allow for more gain at the initial gain stage, it just won’t amplify it as much at the end.

I’m thinking of just ordering a 12AY7, 12AT7 and possibly a new production 5751 and playing around with the above combinations until I find what works best for me. I have some older 5751’s (50’s & 60’s RCA stuff) but the new production shorter plate stuff tends to hold up better in a combo amp since they get really jostled around with the vibrations from the speaker.

Anyone else have any good preamp tube combinations to tame the 5150iii?
 

Guinness Lad

Member
Messages
15,861
My Mesa Mini Rectifier is also pretty hot, and the Soldano SLO100 I had as well. One thing you can do it keep the guitar off 10. In many ways you get more range because you can now turn up if needed. I think your better off dealing with the guitar settings then messing up the amp function.
 

spookyelectric

Silver Supporting Member
Messages
2,143
It's not really messing up the amp function though-- just dialing in the gain levels to have their range be more useful (and not as hissy on higher settings).
 

spookyelectric

Silver Supporting Member
Messages
2,143
it's a little bright, but I think more speaker break-in time will allow the bass to catch up to the highs and mids.

The lower gain preamp tubes in V1 are supposed to also warm the sound up a bit from what I've read.
 

HoustonJr

Member
Messages
215
Lower the gain knob. Really. I was looking into this too. I love the voicing of the amp, but wish both the blue and red channels could have the gain tamed.

Here's the response I got from a local Amp technician when looking into this:

"I have done some experimenting with trying to reduce the gain in high gain amps with very mixed results. A lot of theory suggests that lowing voltages will lower gain, but it also changes the frequency response and tone along with it. What was bite & clarity can turn to mush & mud. The overdrive characteristics change somewhat because you may have more headroom. (harder to get the tube to saturate). Same with tube changes. The only setup I've seen really work effectively is the use of a reactive loadbox. (lookup Palmer, Koch, Weber etc) The Weber mass is decent and one of the less expensive. So for the price of retubing or modding you get a device that you can use on any amps you may acquire AND your 5150 can be used full out anytime it's needed. Great solution for recording too! I have a Peavey 6505 plus & a Marshall JCM800 half stack, both loud amps, using a reactive load box is the only thing that has worked for me as far as retaining any where near the original tone of the amp."

Hope this helps. I've learned to live with the gain on both channels hovering between 8:00-11:00.
 

eigentone

Gold Supporting Member
Messages
7,562
Gain factor's not all that changes among those tubes. If you just want less gain from some functions in a 12AX7 slot, the 5751 is the best tube to substitute. It is the only tube designed to be a substitute for a 12AX7. Subbing other tubes can mess with the power and resistance in your amp.

Grab a few 5751s - old ones are not expensive - and just try swapping them one at a time and listening for the changes.
 

Axe-Man

Member
Messages
6,385
This is really just the wrong amp.

The red ch is the amp. It's a wonderful, aggressive, brutal, articulate but also sterile high gain metal machine and nothing else stock.

It would need some serious mods on the blue ch to become a better amp and the clean is avg.

Best affordable small metal amp ever IMO but it's no blues or rock amp.

Don't muck up what the amp does so well looking for something it's not. Buy a mini Recto if you want more of a hard rock chameleon.
 

agbiggs

Member
Messages
184
I've tried using Jet City's Blue Retrovalves, which are designed to be lower gain, to reduce the gain in my 5150 LBX. Still, tons of gain.
 

mixn4him

Silver Supporting Member
Messages
1,700
There are 2 bypass caps for ch2 and 3 that can be removed and will bring the gain levels down. For tubes I found that changing the output tubes and biasing the amp made the best change in tone and feel of the amp. Sovtek 5881/6L6 waffle bases are the ticket.
 

bettset

Member
Messages
4,184
i found that putting a delay in the loop smooths the tone. ch 3 is plenty hot. the volume/tone control on the guitar helps as suggested. i turn the amp up, i'm not trying to use alotta gain. i do use evh's settings. but this thing is made to rip on :munch
 

deathrider817

Member
Messages
728
I've tried using Jet City's Blue Retrovalves, which are designed to be lower gain, to reduce the gain in my 5150 LBX. Still, tons of gain.
Same with my LBX with several tube changes..usually only have gain at 2-3 tops on red channel,blue channel dimed! As Axe-man said above,use it for what it is!
 

agbiggs

Member
Messages
184
Off-topic, but I'd much rather the LBX have a clean channel and a dirt channel (preferably the blue crunch channel) than two massive gain channels. I can get a decent EVH tone out of the blue channel if I keep the gain low, but otherwise it's a metal amp.
Same with my LBX with several tube changes..usually only have gain at 2-3 tops on red channel,blue channel dimed! As Axe-man said above,use it for what it is!
 




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