EyesOfTheSouth
New member
I do like the amp "as is" but a few things were bothering me. First off, all the channels seemed a bit bright. I could remedy this by running both the treble/presence knobs around 9:00. However, it seemed odd having to run them that low. And second, CH3 has entirely too much gain and is voiced quite different from CH2. Even with the gain at 9:00, it is too much and has a ton of "ratty" sounding artifacts associated with running too much gain. Because of that, I never use CH3. I just boost CH2 with a TC Electronics Spark Booster if I need more push..........essentially using it as a 2 channel amp + boost pedal.
I tracked down the tube layout online and sat down with a big box of tubes to experiment. Here is the layout:
V1 – ½ CH1/CH2 Preamp and ½ CH3 Preamp
V2,V3,V4 -CH3 Preamp
V5,V6 – CH1/CH2 Preamp
V7,V8 – Power Amp Output
V9 – Power Amp Phase Splitter
I will definately say that this amp responds pretty dramatically to preamp tube types. The differences were actually night and day in some cases. Typically, an extremely high gain amp will only yield subtle if any difference IMO. I was really surprised.
I started by simply putting an RFT 12ax7 in V1 (which affects all channels acccording to layout). I always have great luck with this tube for fattening/darkening gain channels. It is my favorite for Marshalls and it appears to do the same for the EVH. Although there was a noticeable change, it wasn't one of those "night and day" differences I mentioned earlier. But it did seem to darken the amp on the extreme presence end of things..........so I left it in place and moved to other positions.
Next, I decided to try a JAN GE 5751 (70% gain of a 12ax7) in V2. According to the layout, this should only affect CH3. And yes it worked........it reduced the gain and made CH3 less noisy. However, I didn't like what it did to the EQ and feel of CH3. There seemed to be a reduction in low end and a looser/more vintage vibe going on......so I removed it.
Next, I stuck a 9th generation Chinese 12AX7 in V2. It made CH3 so ridiculously thin, ratty and cheap sounding that I removed it as fast as possible. What is strange is that I love these tubes in Marshalls
Next, I tried a Sovtek LPS in V2.......and this was the jackpot ! It did not reduce the gain but it added much more focus and just about completely eliminated the "ratty" artifacts from the gain. I was quite amazed that a single tube could make so much difference. I could now run the gain up close to high noon whereas before I had to keep it around 9:00 to keep the fizz/artifacts to a minimum. Another effect is that it changed the EQ by beefing up and solidifying the low end. It almost reminds me of the differences you would expect when moving from a 50 watt to 100 watt version of the same amp. It really brings CH2 and CH3 much closer together EQ-wise.......as in stock form, CH2 is the beefier channel. Now CH3 sounds like CH2 with more saturation/gain.
Before I stopped, I decided to try a Tung Sol Reissue in V2 as well. I do think it sounded better than the stock tube as far as eliminating high gain artifacts, but it had nowhere near the "stoutness" of the Sovtek LPS. It was also much brighter.
Since the Sovtek LPS worked so well in V2, I decided to throw one in V5 as well (affecting both CH1 and CH2). There was a slight EQ change.......darker. But the difference was really subtle as compared to the effect it had on CH3 in V2. But I'm leaving it there anyway, because I do think it is slightly better.
I did not try the stock tube back in V1 with the Sovtek LPS in positions V2 and V5. So I can't really say how much of this effect is coming from The RFT 12ax7 I put in V1. I'm guessing its a combination of both.
Bottom line is that if you are having issues with CH3, I HIGHLY recommend trying the Sovtek LPS in V2. In my opinion, it has changed that channel from an essentially unusable one to a really good one.
I tracked down the tube layout online and sat down with a big box of tubes to experiment. Here is the layout:
V1 – ½ CH1/CH2 Preamp and ½ CH3 Preamp
V2,V3,V4 -CH3 Preamp
V5,V6 – CH1/CH2 Preamp
V7,V8 – Power Amp Output
V9 – Power Amp Phase Splitter
I will definately say that this amp responds pretty dramatically to preamp tube types. The differences were actually night and day in some cases. Typically, an extremely high gain amp will only yield subtle if any difference IMO. I was really surprised.
I started by simply putting an RFT 12ax7 in V1 (which affects all channels acccording to layout). I always have great luck with this tube for fattening/darkening gain channels. It is my favorite for Marshalls and it appears to do the same for the EVH. Although there was a noticeable change, it wasn't one of those "night and day" differences I mentioned earlier. But it did seem to darken the amp on the extreme presence end of things..........so I left it in place and moved to other positions.
Next, I decided to try a JAN GE 5751 (70% gain of a 12ax7) in V2. According to the layout, this should only affect CH3. And yes it worked........it reduced the gain and made CH3 less noisy. However, I didn't like what it did to the EQ and feel of CH3. There seemed to be a reduction in low end and a looser/more vintage vibe going on......so I removed it.
Next, I stuck a 9th generation Chinese 12AX7 in V2. It made CH3 so ridiculously thin, ratty and cheap sounding that I removed it as fast as possible. What is strange is that I love these tubes in Marshalls
Next, I tried a Sovtek LPS in V2.......and this was the jackpot ! It did not reduce the gain but it added much more focus and just about completely eliminated the "ratty" artifacts from the gain. I was quite amazed that a single tube could make so much difference. I could now run the gain up close to high noon whereas before I had to keep it around 9:00 to keep the fizz/artifacts to a minimum. Another effect is that it changed the EQ by beefing up and solidifying the low end. It almost reminds me of the differences you would expect when moving from a 50 watt to 100 watt version of the same amp. It really brings CH2 and CH3 much closer together EQ-wise.......as in stock form, CH2 is the beefier channel. Now CH3 sounds like CH2 with more saturation/gain.
Before I stopped, I decided to try a Tung Sol Reissue in V2 as well. I do think it sounded better than the stock tube as far as eliminating high gain artifacts, but it had nowhere near the "stoutness" of the Sovtek LPS. It was also much brighter.
Since the Sovtek LPS worked so well in V2, I decided to throw one in V5 as well (affecting both CH1 and CH2). There was a slight EQ change.......darker. But the difference was really subtle as compared to the effect it had on CH3 in V2. But I'm leaving it there anyway, because I do think it is slightly better.
I did not try the stock tube back in V1 with the Sovtek LPS in positions V2 and V5. So I can't really say how much of this effect is coming from The RFT 12ax7 I put in V1. I'm guessing its a combination of both.
Bottom line is that if you are having issues with CH3, I HIGHLY recommend trying the Sovtek LPS in V2. In my opinion, it has changed that channel from an essentially unusable one to a really good one.
This will move up and down a little bit as line voltage varies but it was still wayy cold. There was a definite improvement in the way it sounds and responds when I set it at 60Mv. Interestingly when I checked the numbers with a bias probe it was still at only about 56 to 57% tube dissipation when set to 60 Mv. Still rather cold but that's where I'm going to leave it. I did try it at the more normal 70-75% dissipation but I can't say it really sounded any better so I will be leaving it at the EVH recommended 60Mv. As always YMMV.
