Turn your 100watt head into a "Stealth"

[JimiJames]

Passing this along.
This is for the 100watt head, to make it like the "Stealth".

[MrBeasty]

Is that the only difference? I thought there was a revoicing too?

[projectx102]

Theres more to it than that. http://www.thegearpage.net/board/showth ... ?t=1542953

[donnyboiler]

The guy there EVHindenberg who said this "Yes that's correct. I modded my 100w channel 2 by removing R26 and bringing R25 to 100k." is bang on the money. I modded my old 100w head the exact same way, that's how to get the 50w blue channel. There are NO other differences between the blue channels in those two amps. The only other thing that looks different is the voltage divider but in actual fact the blue values are the same here between the two heads.

Another thing worth mentioning is C23. The older 100w heads and the early Vietnam 50w heads have it (It's called C8 in the 50 watters but it's the same cap). I've had a few of each and in my opinion the newer spec without the cap is more touch sensitive and sounds more open. The cap in question is in-line right before the second gain stage. When they removed it they also combined the two resistors either side of it into one value (on the 50w preamp only), but if course that makes no difference. If you have the cap, just jumper it and try your amp without. The difference is subtle but worth mentioning.

https://soundcloud.com/donnyboiler/evh- ... ithout-c23

Just thought that was worth mentioning - as good as the instructions on the above link are, you'll never get the exact Stealth tone on the earlier heads without jumpering C23 as it's downstream of all the Stealth jumpering business and won't be in the Stealth heads. They're based on the newer 100w circuit which can be found here http://support.evhgear.com/schematics/E ... mbined.pdf.

So it's remove R26, mod R25, jumper C23 if you have it, add the cap over R37 as described in the above link and do the jumpering business, in a nutshell. The main jumpering bit looks incredibly straightforward, just tapping off the signal right after V1A (red channel's first stage) and dropping it back in after V1B (blue and green channel's old first stage) - from the back end of C13 to the front end of R25. So V1B is now defunct and there's no switching before the location of the jumper so signal will just follow the new path. Bam. Add the resonance knobs and you have a Stealth. Great link.

[projectx102]

Yes my head was an older one and I did remove that cap and jumper it.

[rgorke]

Are you all drilling and adding the resonance pots on the back panel?

[projectx102]

I did on mine

[rgorke]

Do you have a picture? Just curious on how it looks and how difficult it might be. Seems like the original 5150 -3 head prices are pretty low and modding might be better than getting the stealth.

[projectx102]

These are all I have as I had to close it up and rush out to rehearsal.What I can tell you is it sounds killer.

[echoplexi1974]

So weird to see ribbon cable and ICs in a tube amp. I'm sure it's nothing new but just weird after working on plexi circuits for so long....