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Agree! The EVH greenbacks are fantastic. I have 12 of them lol! Used is an even better deal if yer just after the speakers...... I bought 3 used 4x12s out of the local big box rental stock for $400 each, took out the speakers and flipped the empty cabs for $150 a piece. I have a bunch of great...

Yeah, sure... but you would have to pull the board, as the pots are pcb mounted. The taper on the stock pots is more of an inconvenience than a deal breaker. You just need to be aware of whats going on.

Yeah, I think I put a 100k pot in series with the existing 39k nfb resistor. 39k off the 8ohm tap seemed a bit much. It opens the amp up a bit so it doesn't feel so compressed and dark. The presence pots are audio taper, so that doesn't help either. All the good stuff is bunched up between 1...

Just a heads up: NEVER put El34's or 6CA7's in a 6L6 5153 100watt. The PT was not designed to put out the heater current required by those tubes, and worse, you will likely melt the heater traces on the power supply pcb @ the fuse holders. I've seen this on a couple of occasions, and manged to...

You might have the polarity of the output section reversed, and you are getting positive feedback instead of negative feedback. Looking at the pic, the easiest way to check this would be to reverse the 2 wires between the master vol and the power tube grids. If you ever remove the master and...

Yes sir! Ladies and gentlemen, that right there is one fine sounding musical instrument amplifier. Seriously dude, that amp sounds f'n great! :rawk:

Found these pics on another site. Supposedly the Master vol on a Suhr SL68 MkII. Looks like the pot is shorting the bias splitters. This would increase the negative bias voltage to the power tubes as you turn it down, gradually cold biasing the tubes and slowly turning them pretty much off. It...

My BE100 is from 2015. It has a fat switch to parallel a .022uf cap over the .0022uf coupler, and C45 switch. The C45 switches the voltage dividers, as you said. Position 1 is 68k/68k, and pos 2 is 560k/220k, with 680pf over the 560k. Edit: I typed 280k, it should be 220k.

I was wondering if he has the PI coupling caps connected to the wipers of the dual gang pot. That would keep the effective bias splitter value constant at 117k and the bias stable. Dave has mentioned that when you turn the master down, it loads down the PI.

Should also mention that the max grid resistance for a JJ el84 is 300k in fixed bias, and 1meg in cathode bias, in case you were wondering.....

I thought this was interesting: https://www.aikenamps.com/index.php/what-is-blocking-distortion I think all the likely solutions have been covered. You will have to experiment and see if the issue is in the preamp, power amp, ot both areas. Let us know how it goes!

Just saw the other post. Yeah, blocking distortion for sure, but I think its more likely at the el84. The tone stack is lossy, so there likely is not enough level at the second triode to cause it. You could add a 33k grid stopper between the volume pot and the second triode if you want, but I'd...

I took a look at the schematic. The issue is likely the signal level into the el84. El84's are very easy to drive, and you are hitting the wall on input level. Try a 47k grid stopper in place of the 5.6k and see what happens. If it helps the farting, but changes the tone too much, lower the...

There's a picture in this thread of the output transformer and speaker jacks inside my amp. All you are doing us moving a wire from one jack to another. I don't have any other pictures of the inside of my vh4, and I moved recently and all my gear is still packed up. I won't be taking the amp...

Yes I do! A lot of stuff has come and gone, but I don't expect to ever sell the vh4. Great amp, and yes, it still has the nfb mod : )

I have no knowledge of this guy or his $9k builds with the "musical caps"....but...... In reference to the screenshot you posted, there actually is some merit to what he is saying.... Steel and aluminum have vastly different electrical properties, and most steel chassis have a zinc plating on...

The main issue with the PT supporting an output tube change is the heater current draw of the new tube type. EL34's draw 1.5amps per tube. KT88 / 6550 draw 1.6amps per tube. So an increase of 400ma across a quad. About the same as adding another 12ax7 preamp tube to the amp, which guys have...

Well...if you have the 1987x reissue, its actually pretty simple, given that the circuit in the reissue is a bit of a mash up of lead spec values. Both V1 coupling caps in the reissue are .022uf, and both V1 cathode resistors are 820ohm, so all you would need to do is replace the large...

Stock screen grid resistors are 100 ohms. When replacing large screen drop resistor with choke, change screen grids to 470 ohms, as choke will drop way less voltage than stock 400 ohm dropping resistor. You will have to pull the tube board to swap screen grid resistors. Older amps have tube...

I'm thinking it could be a triode stage configured as a cathode follower inserted between the tone stack and p.i. input, to drive the p.i. with a low impedance signal.....or maybe not.....:scared: Also, I believe the EVH Iconic has a solid state phase inverter.