I presume the voltages on the modified Kelly schematic are measurements from Francesca.
So, who makes the appropriate power transformer and is there a favored OT for this project? It would be nice if they were Pacifics, like Ken apparently used.
Thanks for the help, I'm starting to have fun with this.
Express Build Started
Moderators: pompeiisneaks, Colossal
Re: Express Build Started
For Express trannies, Moose (here on the forum) is the man. We pretty much all use his iron.
Re: Express Build Started
anyone have the exact measurement of the main board and powerboards?
i found one pic here but it says it measures 2 1/4 X 9 1/2 inches but it has 8 turets across they all wouldnt fit in 2 1/4 - maybe if the board was 3 inches wide but not 2 1/4.
i found one pic here but it says it measures 2 1/4 X 9 1/2 inches but it has 8 turets across they all wouldnt fit in 2 1/4 - maybe if the board was 3 inches wide but not 2 1/4.
Rockstah Amps: http://www.rockstahamps.com
Rockstah Amps Youtube: http://www.youtube.com/user/RockstahAmps
Builds and modification sound files: http://www.soundclick.com/rockstahplexitweaksandmods
Rockstah Amps Youtube: http://www.youtube.com/user/RockstahAmps
Builds and modification sound files: http://www.soundclick.com/rockstahplexitweaksandmods
Re: Express Build Started
I recall a thread that said the perf board holes use 0.265" spacing so 2 1/4" x 9 1/2" actually sounds about right. I didn't know the correct spacing when I built my Express so I used 0.250" spacing and my board came out slightly smaller than that.rockstah wrote:anyone have the exact measurement of the main board and powerboards?
i found one pic here but it says it measures 2 1/4 X 9 1/2 inches but it has 8 turets across they all wouldnt fit in 2 1/4 - maybe if the board was 3 inches wide but not 2 1/4.
Re: Express Build Started
anyone know where to get board material with correct turret holes for a francesca?
Rockstah Amps: http://www.rockstahamps.com
Rockstah Amps Youtube: http://www.youtube.com/user/RockstahAmps
Builds and modification sound files: http://www.soundclick.com/rockstahplexitweaksandmods
Rockstah Amps Youtube: http://www.youtube.com/user/RockstahAmps
Builds and modification sound files: http://www.soundclick.com/rockstahplexitweaksandmods
Re: Express Build Started
You might try PM'ing Allynmey on this board. I don't know if he has any left or not, but he did have some a little while back. This stuff is extinct and hard to find.rockstah wrote:anyone know where to get board material with correct turret holes for a francesca?
Climax mods in the direction of Francesca
Just for fun, I modified my Climax this morning to reflect the Francesca circuit. I made just two changes in the lead channel:
* In the 1st triode of the lead channel, I removed the 0.68uf/2.7k-ohm pair and substituted a 22uf/1.5k-ohm pair in the cathode circuit.
* Between the 2nd and 3rd triodes, I removed the two 330k resistors and rewired the 0.002uf cap to the grid, adding a 165k-ohm resistor (the two 330k resistors in parallel) from grid to ground (Francesca has a 150k there).
I've always disliked the bright nature of the Climax's lead channel and used tube selection to tame it somewhat. These two parts of the circuit contributed to the brightness, so they were the first to go. Previously, I reduced the volume control bright cap to 50pf from 500pf.
I measured the B+ at the plates of the EL34s with no signal input: 430 VDC, about 10% more than the Kelly schematic shows for Francesca. I know that Ken Fischer wanted even higher plate voltage in the Climax, but Gerald Weber wanted to be able to use 6V6 tubes and he prevailed.
Now, the Climax has less brightness, but is still extremely loud when overdriven, and it's just "too clean". Still, it's an improvement to my ears. I think I have to play with tubes again or bring out the VariAC to get it going in a browner direction. While working on the mods, I was reminded how well it's made - not HiWatt-right-angle-wiring beauty, but solid construction.
PS: I ordered a set of Hayboer transformers for an Express project.
* In the 1st triode of the lead channel, I removed the 0.68uf/2.7k-ohm pair and substituted a 22uf/1.5k-ohm pair in the cathode circuit.
* Between the 2nd and 3rd triodes, I removed the two 330k resistors and rewired the 0.002uf cap to the grid, adding a 165k-ohm resistor (the two 330k resistors in parallel) from grid to ground (Francesca has a 150k there).
I've always disliked the bright nature of the Climax's lead channel and used tube selection to tame it somewhat. These two parts of the circuit contributed to the brightness, so they were the first to go. Previously, I reduced the volume control bright cap to 50pf from 500pf.
I measured the B+ at the plates of the EL34s with no signal input: 430 VDC, about 10% more than the Kelly schematic shows for Francesca. I know that Ken Fischer wanted even higher plate voltage in the Climax, but Gerald Weber wanted to be able to use 6V6 tubes and he prevailed.
Now, the Climax has less brightness, but is still extremely loud when overdriven, and it's just "too clean". Still, it's an improvement to my ears. I think I have to play with tubes again or bring out the VariAC to get it going in a browner direction. While working on the mods, I was reminded how well it's made - not HiWatt-right-angle-wiring beauty, but solid construction.
PS: I ordered a set of Hayboer transformers for an Express project.