CJ-11 layout help

[ncusack]

Hello,

I have a hammond 270EX and 1750E I plan to use in a CJ-11 build. I drew up a board layout using the schematic found here.

http://revolutiondeux.blogspot.ca/2012/06/divided-by-thirteen-cj-11-amplifier.html

The few differences in my design are a dedicated boost switch since I dont have a pot with the switch and SS rectification because I'm using whats on hand and the voltages should be similar to the GZ34.

I plan to split the ground running a preamp ground to a lug close to the inputs and a power ground run to a lug closer to the earth ground lug.

I'm just wondering if I should move anything around for best results.

Please let me know if I'm way off the mark

[topbrent]

looks like a fun project! 

[Willabe]

Is the gut shot picture in the link you posted a Divided by 13 amp or just someone's clone?

The layout in that amp makes little sense to me the way the tubes are laid out in the chassis.

The 2 preamp tubes look like their so close together that they can barely get the tube shields on. The 2 6V6 power tubes are split around the speaker jacks and way far apart sending plate, screen, cathode and grid wires back and forth and tangled up with the OT secondary speaker wires.


          Brad          

[Willabe]

I'm looking at you eyelet/turret board and I think it looks good but I can't really tell in some spots because you don't have parts with their lead wires going to their eyelets/turrets.    

I haven't built many amps from scratch but the 3 I did I took into consideration where the tubes, transformers, pots, jacks, etc, everything was going in/on the chassis.


           Brad          

[topbrent]

Basically, all /13 amps have "strange looking" layouts.  They do have some clever packaging of fairly traditional circuits.  
...Old tech in fancy new pants...

If I was setting out to build this amp, I would keep life simple and do as ncusack has done and just follow traditional layout arrangements for the pairing of these two extremely common circuits (AB763 front-end on a 5E3 PI/PA)
 

Note, that CJ-11 chassis picture in the revolutiondeux link is the real deal, not a clone.  It is one of a set of gutshot pics originally taken by a fellow EL34world member J.H.    These pics were then used to dissect and document the circuit over at http://freestompboxes.org/viewtopic.php?f=2&t=8769.  

It's nice when there are several sets of eyes looking at stuff, as I was I was initially incorrect in a few key areas of this amps circuit.  (Thankfully,) those errors were corrected and voila, we now have a good schematic of the CJ-11.  
(You need to be a freestompboxes.org member to view all the attached pictures. ) 

[sluckey]

Standby switch.  (SB)
Are there other amps out there that put the standby switch on CT of the 5V windings?

I have seen several schematics where the SB cuts the CT on the HT windings. 

Os density in play here.   

A long time ago it was common to take the B+ from a center tap of the 5V rectifier winding.

[MikeDL]

Hope nobody minds me resurrecting this thread.  I want to use a different power supply design and was hoping someone could tell me the voltages for A, B, C, and D.


Thanks!

[PRR]

> voltages for A, B, C, and D.

A is around 360V. If that is right, B C D will be right if you keep those resistors the same.

[MikeDL]

Thank you -- close to what I guessed.  Not too confident I fully understood what was going on with the 5v windings.

[PRR]

> what was going on with the 5v windings.

"Nothing".

The way in that plan is "correct" for directly-heated rectifiers. It minimizes a 60Hz ripple due to 5V being added/subtracted to/from the 290V AC.

Someone here didn't see that and (with goading) set it up to try. Turns out the effect is nearly invisible.

But GZ34 is (I think?) a cathode type. This connection is then "wrong" for best result. Again I think the effect is nearly invisible on oscilloscope and utterly insignificant to the amplifier.

Heat your rectifier however you usually do. 2.5V one way or the other is "nothing".

[frankk]

Rather than start a new topic I thought I'd resurrect this old one in the hope that the original contributors are still around.

Did anyone build it?  Where you happy with the result?  Anything you did, or would change?

I am just starting sourcing parts to build this too, although I am considering adding reverb borrowing from the Princeton Reverb schematic (unless someone convinces me otherwise).  I plan to use a Princeton Reverb style chassis, Mercury Magnetics tweed deluxe 290V (FTDP-ME) PT and the Mercury Magnetics tweed deluxe OT (FTDO-59).  I also thought about replacing the gain switch with a 100k pot so gain would be variable, mainly because I have space to use in the front panel - that would work right? 

Unless of course someone convinces me otherwise on any of that :)

[Alistar]

+1 Frankk
Ive got the perfect starter for this...

[darkbluemurder]

I started building this amp earlier this year but have not got around to finishing it. I guess it will take me a while before I complete it but the project is still on.


Cheers Stephan

[frankk]

I've finally got round to starting a build of this (with reverb) and have a turret board layout here:
https://www.thegearpage.net/board/index.php?threads/build-thread-ab763-preamp-with-reverb-5e3-power-stage.1785490/