Santiago Alvarez (electronics engineer, JVM, YJM, AFD...)

santiall said:
is the tube heating, the filament inside glowing orange after a minute or so?, I've just had a quick look in google and that amp seems to have individual fuses for the output tubes. It can be just that...
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It is yes, last week when I first noticed it the tube was not glowing or heating up.....but currently it is.

Really weird tbh
 
Hi Santiago,

I just purchased a JVM 205H and absolutely love it. Still learning the ins and outs of such a versatile amp. Just curious...how hard for a similar sound to Van Halen's 1984 album (e.g. 'Drop Dead Legs', 'Girl Gone Bad', 'House of Pain', etc.) with the JVM 205? EVH was obviously still using his famous Plexi at that time. Not a ton of gain but an awesome and monstrous guitar tone, in my opinion.

Thank you
 
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deckard1070 said:
Hi Santiago,

I just purchased a JVM 205H and absolutely love it. Still learning the ins and outs of such a versatile amp. Just curious...how hard for a similar sound to Van Halen's 1984 album (e.g. 'Drop Dead Legs', 'Girl Gone Bad', 'House of Pain', etc.) with the JVM 205? EVH was obviously still using his famous Plexi at that time. Not a ton of gain but an awesome and monstrous guitar tone, in my opinion.

Thank you
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HI, I guess the obvious answer will be OD orange but you may try OD green with a bit of boost or even OD ornage boosted.
The speakers are very important for his tone as a lot of distortion came from the power amp
 
santiall said:
...The speakers are very important for his tone as a lot of distortion came from the power amp
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Thanks so much. Can you please briefly explain the relation between the type of speaker and the power amp distortion? Not sure I quite understand. Would any JVM mods get one closer possibly? C83?

Thanks!!!
 
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deckard1070 said:
Thanks so much. Can you please briefly explain the relation between the type of speaker and the power amp distortion? Not sure I quite understand. Would any JVM mods get one closer possibly? C83?

Thanks!!!
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Hi, hmmm, ok let me try... when you distort a signal you are basically crating harmonics that didn't exist in the original signal. The different harmonics and amplitudes created is what defines the distortion.
Amplifiers like a JVM, 5150, Rectifier, etc etc... pretty much every high gain amp, create the harmonics in the preamp, shape them within the preamp and with the tone control, and send them to the power amp. The speaker does the final shaping.

In an amp like a plexi, without master volume and without much preamp distortion, the harmonics are created in the power amp and shaped pretty much by the speaker only. You may have some control on how those harmonics are created but not much, that's why the tone control in amps like those isn't that effective in many situations and your 'equalizer' ends being the speaker. Then of course you need to add the room, the microphone and the recording itself to define what you hear in the record.

C83 reduces gain and increases bass, makes the amp feel loser and not as responsive to me but you may try if you want. I'd experiment with out modifications first though
 
Thank you, Santiago!

What’s the reason for the switch in your opinion? The switch from having the gain from the amp mainly come from the preamp section as opposed to the customary power section? Is it just to give the player more control over the gain settings and overall gain structure since preamp distortion is more controllable than power amp distortion?

Also, how much of EVH’s tone do you think comes from his hands in your opinion? There are lots of stories of other guitar players playing through Ed’s exact rig and they still sound like themselves.

Thanks so much.
 
deckard1070 said:
Thank you, Santiago!

What’s the reason for the switch in your opinion? The switch from having the gain from the amp mainly come from the preamp section as opposed to the customary power section? Is it just to give the player more control over the gain settings and overall gain structure since preamp distortion is more controllable than power amp distortion?

Also, how much of EVH’s tone do you think comes from his hands in your opinion? There are lots of stories of other guitar players playing through Ed’s exact rig and they still sound like themselves.

Thanks so much.
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it is just how the amplifiers naturally evolved. Amps 80 years ago didn't have master volume as we know it, just a simple volume like a plexi, a Fender,etc. People then starting demanding more distortion and lower output levels and the only way is to add distortion in the preamp (what we call gain) and some means to control the listening level (master volume).

VH sounds like him because it's him, same as I sound like myself (usally bad) and you sound like you. Even if you try VH's gear you won't be like him, it'll be you playing his amp. Nothing to do with VH, that's the nature of playing guitar. You can get a Les Paul, a Jubilee, play it and you won't sound like Slash either.

If you think about it, it'd be very boring if we all sound like someone else just because we playu the same amp... also I don't think it is a good thinkgapart from the inital 'wow' factor, hey: he sounds exactly like you-name-it... and there he stays, as someone who sounds-like, no personality, and probaly never playing in any band with aspirations.
 
Thanks, Santiago!

Agree with everything you said. With regard to playing like EVH, I actually play nothing like him. But, I love his guitar tone!

I just picked up the following book with the hope of learning more about the inner workings of guitar amps...

Screenshot 2026-04-25 at 3.29.37 AM.png
 
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