My 'Jose' mod Plexi attempt diary

Thanks guys! I am really happy, cause it has very different character than my xtc copy - more open, aggresive, riffs are super tight! XTC is more melodic, compressed, bit muddier (but in the way that i absolutely love).

The only problem is this transformer, or maybe i am overreacting a bit. It is definately getting hot after ~1h of playing. I can grab it and hold even for >10sec, of course it is not pleasant but it definately cannot burn my skin. I also noticed that it does not depend on load - with all preamp tubes pulled off it is still getting hot.
 
Recon":7sed9fmh said:
Thanks guys! I am really happy, cause it has very different character than my xtc copy - more open, aggresive, riffs are super tight! XTC is more melodic, compressed, bit muddier (but in the way that i absolutely love).

The only problem is this transformer, or maybe i am overreacting a bit. It is definately getting hot after ~1h of playing. I can grab it and hold even for >10sec, of course it is not pleasant but it definately cannot burn my skin. I also noticed that it does not depend on load - with all preamp tubes pulled off it is still getting hot.

What brand teansformer did you use?
 
It is just a 5yo transformer ordered according to my specifications in small local manufacturer. I already ordered another, much better one in much better firm ;)

Recently, I also tweaked a bit preamp section and tested some other clipping options:

- MPSA06 with additional 2.2k resistor in series to ground - for me too aggresive, but i guess for metal its totally awesome :)
- 14V zener - too aggresive - a lot of large grain which i hate (like with 10V zeners)
- 27V ! - love it, classic hot rodded rock tone with a bit of saturation, easy to boost for more liquid lead sound, definately will keep it as one of 3 options.

Maybe i will try also something like 30-33V zeners, cause direction is obviously right!

Current clipping setup: None/27V/20V
 
Recon":usy8rt1u said:
It is just a 5yo transformer ordered according to my specifications in small local manufacturer. I already ordered another, much better one in much better firm ;)

Recently, I also tweaked a bit preamp section and tested some other clipping options:

- MPSA06 with additional 2.2k resistor in series to ground - for me too aggresive, but i guess for metal its totally awesome :)
- 14V zener - too aggresive - a lot of large grain which i hate (like with 10V zeners)
- 27V ! - love it, classic hot rodded rock tone with a bit of saturation, easy to boost for more liquid lead sound, definately will keep it as one of 3 options.

Maybe i will try also something like 30-33V zeners, cause direction is obviously right!

Current clipping setup: None/27V/20V

Anything higher than that and you might as well not bother. In my builds 24v is too high. You can get to the same place just by turning up the gain. I think 18v is the sweet spot for all-around clipping. And then MPSA06 for modern sounds.
 
Thanks for precious advices!

I agree with MPSA06 for modern sounds - i have very similar feeling.

When it comes to my 27V - volume sag is definitely noticeable, also character of distortion is different (than without clipping). Maybe it depends on preamp and MV configuration more than i was suspecting. Untill now, I really like 27V diode, but 20V is very interesting too.

I will write here schema, but i must find some spare time ;) I am also planning to record some more samples, maybe louder, with better quality.
 
Okay, i've finally decided about clipping style: none/15V zener/MPSA06

Why? I was aware that changing temporary 6l6gs's into el34 JJ (cause i'am using 100% typical plexi inverter power amp style) will cause some noticeable changes mainly in presence/depth circuit, due to much bigger amount of negative feedback with el34, but in this case changes were even more perceptible. Now amp is less aggresive, definately less gainy, but still very open sounding. And that is why now i see why everything above 20-22V zener is basically pointless. I found that now 15-18V zener gives me desirable amount of distortion, and to obtain more modern 90's sounds MPSA06 is the best.

Finally after implementing el34's and adjusting clipping circuits amp is still open sounding, less fizzy and compressed just enough for my taste, and quite as hell (in terms of noices) :rock: i am really happy, and starting to like it even a bit more than my xtc copy :yes:
 
Okay, another post of my monologue ;)

I am attaching final result of my build, after some tweaks and with el34 JJ power tubes. Boosted by 12db clean boost to make it more liquid :rock:

Enjoy and share your impressions!

 
Yep, there is one: 2n2, but most of the time it is 'turned off' cause i am cranking gain pretty hard.
 
One more question. What snubbers are you using? 500pf? I like to use real small ones... for example my JCA has 47pf. I find using something too big like 500pf makes the high end roll off too much.
 
Hi!

I am using 220-500p snubbers cause i like rather dark and fat sounding amps (but bright enough to cut through mix ;)), and 100p in phase inverter.
 
Okay one last update - i've changed power transformer, and now everything is okay, and even more clean inside:

file.php


One last sample from my sound eden :yes: definately it will be my main gigging amp !

 
swamptrashstompboxes":1y806u3r said:
Sounds great. I love those EBMM Luke tremolos.

Yeah, that is right, i've had few other tremolos including floyd rose, and here it is a whole different story, different feel, more user friendly, and let's say melodic - in terms of 'pitch changing liquidity', dont know how to call it :confused:
 
Recon":3krjzfwx said:
swamptrashstompboxes":3krjzfwx said:
Sounds great. I love those EBMM Luke tremolos.

Yeah, that is right, i've had few other tremolos including floyd rose, and here it is a whole different story, different feel, more user friendly, and let's say melodic - in terms of 'pitch changing liquidity', dont know how to call it :confused:

That is a good term actually.

It's it's own beast really. I need a real floyd or edge most of the time tbh, but it's better than any non-locker I have ever played. But yeah they are cool AF. I wish you could get just the bridge for a build.
 
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