Tube Amps / Music Electronics
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|2/27/2000 6:00 PM|
||marshall 2203 brown sound|
I've got a marshall 2203 master volume
amp and i want it to have a litlle more
EVH brown sound!
I changed the 2th gain stage cathode
resistor from 10k to 2.7k and bypassed
it with a 0.68mf cap! (gives a bit more
I also added a 0.68mf cap on the 4th
stage cathode resistor
Does anyone have a suggestion wat
type of coupling caps sound the best
in such a circuit?
Some of the original caps got broke
so i'm going to replace them and also
the tone stack caps!
I also want to replace all the small pf-
caps,with silver mica or ceramic!
I don't know what sounds better in
this amp, silver mica or ceramic pf-
caps, so if anyone knows please respond
( coupling caps i have in mind are;
orange drops 418p or 715p, or wima-
mks4 caps, maybe someone has a
Anyway i hope someone can help me
Best regards,! Frank.
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|2/28/2000 5:36 AM|
my suggestion would be to a) copy a stock plexi circuit really close, and maybe even try some of the tricks her, such as the zener trick to lower the B+ voltage, yet retaining the filament voltage, that way you'll get the variac effects of lowering the input to 90v, W/O risking cathode stripping....
|2/28/2000 7:34 AM|
I posted some info similar to this yesterday so i'll rehash it again with a lot more detail.
The brown sound is actually not a mid scooped tone but actually a low mid boost. His tone is also not really distorted all that much. He's got to cover the lead and rhythm parts! Also he's pushing his rig pretty hard so you're going to hear a LOT of preamp distortion along with the power amp distortion. There's a lot of urban myth and downright B.S. associated with Eddie's setup some of which was started by the man himself. Take everything you read with a grain of salt!
On a side note regarding rail voltages what I've found is that higher voltages on the power tubes give you a tighter more aggressive quality with distortion that is very controllable. Using low voltages on the preamp will obviously reduce your headroom but it will clean up with pick attack. If you drop your B+ with a zener for this situation you'll wind up with an amp that's a one trick pony.
All that being said, here's one rather versatile way to get close to the earlier EVH tone. What you basically need to do is to turn your Marshall into a High Octane tweed Fender!
First, replace the EL34' with 6L6's. That's going to make a big difference right there all by itself.
Basically you want your rail voltages in the preamp similar to that found in a 5F6A bassman. Leave the power amp running at around 470v. That'll keep the amp tight and give it a more aggressive quality. It'll give you a similar effect as using a variac without the associated risks.
The next thing to do is to change the caps in the tone stack. Swap out the 0.022 mid cap and give a 0.01uF a try and change the slope resistor to a 47K or a 56K. This will goose up the low end response without giving you a fuzzy sounding distortion because it's being implemented at the end of the preamp.
Also I wouldn't really recomend bypassing the second cathode resistor. If you do that the amp will have a much looser feel which is NOT what you want. You could consider lowering the cathode resistor to around 2.7k, but you really don't need to go much smaller than that.
Depending on what type of guitar, pick-ups, speakers and such, you'll probably want to noodle with the cap values somewhat to stroke it into where you want it. There's a LOT of variables but the stuff above should get you pretty close as a starting point.
|3/1/2000 3:26 PM|
Years ago GuitarPlayer mag ran an interview with EVH. There was a picture of the back of EVH's Marshall. In it were 6L6s or 5881 tubes. So your recomendations are right on the money. Also in the picture was a Soldano SLO-100 amp. FWIW.
|3/1/2000 3:30 PM|
Sylvania 6ca7's 6ca7's and el34's are supposed to be the same, BUT the Sylvania 6ca7's were actually 6550
s that dond quite meet spec in some cases, and in others, simply just relabelled 6550's Either way, they DO sound more like 6l6's than EL34's in my opinion... even more like 6550's, however
|2/28/2000 6:57 AM|
I first say that you may have selected the wrong beast for the job. (maybe) EVH's amp was a JCM800. There's a bunch of things you could do to your amp but it all depends on what you want to acheive. There's a mess of opinions about how to obtain his "brown sound."
He used power tube distortion to help him get that tone as well as the sound of the phase inverter breaking up. I say this only to point out that the JCM800's master is designed to get gain at lower volumes and the master is connected off from the treble pot (pre-PI) so the phase inverter's tone doesn't really come into play with the JCM800's.
For what ever it's worth I like to change the 10K cathode resistor to 4.7K and leave it unbypassed. The 820ohm cathode resistor (V2A) is a good spot to parallel a .68uF for more gain.
Personally speaking I like the ceramics in Marshalls. Silver Mica is a bit to "crass" sounding to my ears when they are in a gain-amp. I like them in a clean amp, like Fender Twin for example.
These are all fine caps. I would also make sure that the caps will fit onto the board. The components are sort of close together on the PCB and the larger coupling caps might be a little tricky but use your discretion.
I hope it helps
|2/28/2000 7:38 AM|
||Re: marshall 2203 brown sound..opsss|
Sounds like we've got several similar ideas but come at it from different directions. Should be interesting how this thread develops on different peoples ideas of how to get the EVH tone
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