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Zaphod told me that when using an SS rectifier, my preamp and PI voltages would be raised, leading to a somewhat colder sound.

Please excuse my ignorance, but which resistors should be changed/added to bring the preamp/pi voltages back to original spec? Or at least closer.......

Raising R22 will lower the voltage to the preamp and PI. Raising R21 will lower the preamp voltage.
Stew

So, why do you want to do this?? The EZ81 is a very good tube rectifier.

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

You know. I have both EZ81 and SS rectifier on a switch and I really can not tell the difference in sound. Other mods I can hear a difference but not the SS rectifier. And, with less gain like you like I would think that it would be absolutely undetectable. I just leave my amp on the EZ81 and the sound is very tight. The EZ81 does not seem to sag as much as I thought it would. Just my $.02.

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Les

http://www.soundclick.com/unimind

I went back and read what you posted on my other thread... I think that the fixed bias and especially adding the negative feedback (with or without a presence control) made a bigger difference than the SS recto.

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Les

http://www.soundclick.com/unimind

You're not the first person to say that either. EZ81s don't sag that much. 5Y3s sag a lot more (with the exception of the Sovtek kind).

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Great tones come in small glass jars!

The main reason I did the SS rectifier is because I know Im gonna have to switch rectifiers anyhow when I get the new iron from you. The EZ81 isn't gonna work with the 36 watt setup correct? So I have just been messing around with different approaches. I can hear a pretty substantial difference with the SS, maybe because I havent adjusted the voltages yet. I absolutely prefer the amp with the EZ 81, except for the slight bit of tightness the SS has. I now know how to install a SS rectifier too, and how it sounds in this circuit, which is partially why I'm doing this, to learn.



I agree with that. What I said is the two things combined made for a pretty large difference. Especially the way I have it set up. I think If I had more gain/distortion going on, it would be less noticeable. As it is now, the boosted voltages(or something) in my preamp have done away with almost all my overdrive. Dont get me wrong, I already have ten Fender amps, I bought this amp for the overdrive sounds, I DO want it to distort. I'm just very picky about my lead tone, I want the exact amount of overdrive I want, know what I mean? When my new iron gets here( perhaps today!!) I will take everyones suggestions into account, get my voltages correct, make my mods switchable, try to get the amp the way it sounded at day one, but louder, and maybe a hair tighter on the bottom. Thats my goal at least. The original plexi circuit, the way it was right off the Trinity schematic, was perfect for me gainwise. Just needs to be a bit louder.

You can use a 5AR4 in there as a tube rectifier but you'll need to open the hole to fit an octal socket. Never tried the EZ81 with the extra tube load.
you can put a sag ressitor in there to simulate the rectifier somewhat. I think zaphod mentioned this in another post.

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

I would love to try both, and see which I like better. Perhaps one would be better in a certain situation, and the other in another situation. Hence the switching option. I guess the problem with that is the preamp voltages will be off at least somewhat when you're switching from one to the other correct? Can't have it spot on for both. Maybe I could find a decent compromise though.

The easy solution is to have a switch which either selects a sag resistor or zener(s) in the B+ line. Both switch positions will get you around the same voltage out. But in one position you get EZ81-like sag, and the other position no sag. For a 36W amp the sag resistor would be a pair of 220 ohm 10W resistors in parallel.

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Great tones come in small glass jars!

What do you guys think about this 6v6/EL84.... or both at the same time..... Seems do-able with the 36 watt iron correct? Otherwise, theres gonna be some tube socket hole issues to take care of.

Its very doable and will sound fantastic. One 6V6 push-pull pair and one EL84 push-pull pair, so that there's one EL84 and one 6V6 on each side of the OT primary. That keeps the DC currents in the OT fairly balanced. The 6V6 pair has a separate cathode resistor from the EL84 pair, so they can biased correctly. Use 820R/22k resistor in the PI tail like you would for a 6V6 amp. You have to have the grid reference (aka "grid leak") resistors in a kind of ladder arrangement for the tubes, so that the 6V6s get more drive than the EL84s, to compensate for their difference in gain. In the diagram below the signal from the PI is applied at the 6V6 grid ends of the 250k resistors.

_____8.2k __6V6
|
250k
|____8.2k__EL84
|
220k
|_______ Gnd
|
220k
|____8.2k__EL84
|
250k
|____8.2k__6V6

Alternatively, you can run a single pair of EL34s with a 36W transformer set. Trinity has neat blanking plugs for empty socket holes.

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Great tones come in small glass jars!

I have an Egnater Rebel 30 212 that has both 6V6 and EL34 tubes in it. It has a blend pot so you can go from full 6v6 to full EL34 or anywhere in the middle. So that might be something you could try to incorporate.
Middle on the blend gives 30w output and 20w on either end on the Rebel 30.
Not quite sure how to do it yet, but I am looking to try it on a SE (tr)amp.

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Tele's make the best noise

Ok, so in Wesmont terms that would be run the brown ot wire to pin 3 of a 6v6, jumper it from there to pin 7 of an EL84. Then take the blue ot wire and do the same thing to the remaining 2 tubes?? Or is it the same color wires on the same tube type??

Yes, that.


I thought those amps ran EL84s with 6V6s. EL34s have different load impedance requirements from 6V6s, whereas EL84s and 6V6s are around the same. EL34s work better beside 6L6s.


I once did figure it out. I forget the details now but IIRC it involved a custom dual-gang pot. A simpler way would be to use one 500k dual gang pot as a post-PI MV for the 6V6s, and another one for the EL84s. Both airs of MV pots in parallel with each other.

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Great tones come in small glass jars!

I didnt fully understand what you meant with all the grid reference values at first. I did however find another thread where you spoke of this same thing. I think I undertstand now. Just stack two resistors, a 250k and a 220k in series where each of the 470k used to be, connect the El84s to the junction of each said pair. Connect the 6v6s to the top, same as normal, correct?

Thanks a whole lot for all the help Zaphod, you have practically built this amp from afar through this forum, I do appreciate it.

That is correct, typed the wrong number. El84 and 6v6 is what the rebel has.

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Fantasy Noise is what my shop of dreams is called and was the only way to beat my addiction, like many here I suffer from G.A.S.


Tele's make the best noise

The Rebel uses a custom 4 gang pot. Not easy to DIY really.
Easier to have a switch to select one or the other or both.

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http://pdfelectronics.com

Yes, that's correct. And don't forget the 8.2k grid stoppers in series with all four grids.


Now it all comes back to me....!


Or a more legeant solution might be to have a pair of dual-ganged MV pots (say 1M) in parallel with each other at the PI output. The wipers of one MV would go to the EL84s' grids, and the wipers of the other pair would go to the 6V6s' grids. Then blend tones to your heart's content.

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Great tones come in small glass jars!

That's what the rebel does with the 4 gang pot!

Iirc the pot is obviously right after the PI. And you have 2 outputs, each is split by two again. So 4 output signals each for one tube. And with the four gang pot each output tube has it's own volume control essentially. As you turn up the EL84 volumes the 6V6 volumes go down. So probably 4 gang pot with two audio tapers and two reverse-audio tapers.

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