My 'Jose' mod Plexi attempt diary

  • Thread starter Thread starter Recon
  • Start date Start date
Recon

Recon

Member
I dont wanted to litter FourT6and2 topic further, so i am creating new one, dedicated strictly to my build. After succesful run and some tweaks i will upload schema of this project and some video samples.

Okay so main arrangements:
- 50W
- tube fx loop
- 1 gain knob
- clipping style selector
- master volume after tone stack and fx loop
- rather brown voltages
- AC heated tubes + maybe elevation to DC
- one channel
- mustards

Current progress:

XB8pfke.jpg


zDDJJLn.jpg
 
Nice.

What's up with the 4th tube socket? You doing an extra gain stage? Ideally you want V1 to be the very last in line for the heater string. Right now you've got that tube piggybacking off V1.
 
Thanks!

Fourth tube is for buffering and recovery stage of fx loop. About heating chain - good point, im a bit aware of it too. If it will cause some problems with hum i will rearrange it, and maybe elevate to DC.

Cheers!
 
Okay, your suggestion forced me to rethink this arrangement, and I decided to fix it right now - cause later it will be extermely hard to modify in the jungle of other wires.

Meanwhile i progressed a bit too.

Wp45LOJ.jpg
 
Thanks!

New progress: clipping selector, bright cap wiring, main ground rail, started filling board.

doadQMq.jpg
 
Hmmm... if it were me, I'd probably go from the PI to that other socket and then from the PI to the CF instead of running two heater chains under the preamp board. But it might work out ok the way you have it. Fingers crossed :)
 
But this is actually just as you said:) There is one heating chain from power tubes to PI and then to this extra socket, and from extra socket to the rest of preamp. Second line is wired only for indicator. Cheers!
 
Hah, now i see you meant different arrangement, hope this will work just fine! Preamp board is pretty high, and heating wires are passing just under preamp filtering section (100uF) of board :thumbsup:
 
FourT6and2":2m6mexjw said:
Hmmm... if it were me, I'd probably go from the PI to that other socket and then from the PI to the CF instead of running two heater chains under the preamp board. But it might work out ok the way you have it. Fingers crossed :)
Click to expand...

Agreed. No need to run a set of wires back, just go from the PI tube to the loop and V2.
 
Yestarday was an amp day, so there is a progress: Main F&T filter caps, further board filling, some minor updates etc. It is finally starting to look like an amp :rock:

5jmNnRg.jpg
 
Hi, thanks!

I used just a classic bolts with ~4mm pads (two stacked nuts actually, but im planning to change by real pad) , to raise them a bit :)

Cheers!
 
V2a - i wanted to sav some space inside chassis, what's more - holes were to small.

Okay next episode - i had some troblems with Power Transformer - manufacturer swapped accidentally 0V and 60V taps, and i was grounding 60V. Voltage on main filter was 515V on standby, so I decided to decrease it by 51V by simple MOSFET/zener circuit called 'B+ reducer'. Now i have about 465V on standby, which is nice!

So, to sum it up - Power supply is almost finished, main filter is working good, bias supply too (-35V to -65V). I've also moved a bit heating line so now it is passing just under 80uF preamp cap.

Fknb08C.jpg
 
Thanks, me too! Althrough i didn't thought that this chassis will be so small - it is so hard to organize it! Ceriatone ones are bigger and better.
 
Okay guys i did it, sounds huge, bit more aggresive and open than my XTC clone. I didnt have el34 tubes, so i ran it exceptionally on 6l6GC Mesa tubes. I was bit afraid about noise due to the unusual heaters wiring pattern but it is super quiet.

Unfortunately it also turned out that my PT is too weak for this configutarion, and after ~1h of playing it is getting hot, I didnt measured temperature, but i can hold my finger (even making some pressure) on it for 10 or more seconds. I am afraid that in el34 situation it will be even worse. Maybe i will buy InMadOut Plexi 50W replacement trannie.

PSU voltages:
6l6GC Plates: 440V
6l6GC grids: 439V
PI: 320V
Fx loop: 305V
Preamp 1: 282V
Preamp 2: 270V
Bias: 40mA

Guts and samples:

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