Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Willabe on March 26, 2011, 08:28:37 pm

Title: Please check my layout for 5G9 Tremolux New Scratch Build
Post by: Willabe on March 26, 2011, 08:28:37 pm

Hi All,

This is my first total scratch build and I'm looking forward to this.        

I wanted to run this by you guys to see if you think this layout will work. It's just the pre and LTPI. I'll post the rest when I finish it up.

Since I'm punching out my own chassis and it's not a high gain amp, I wanted to move the pre-amp tube sockets to the front/face of the chassis and mount some of the R's/C's to the input jack and vol./tone pots. Chassis is 17"x 6 1/2"x 2 1/2" al.
  
I thought I'd go with a single input jack and use an A/B relay for flip/floping between the 2 channels to make use of the interactive volume controls. This way I don't need an A/B box and 2 extra patch cords, between the guitar and amp input.

5G9 has the same pre as 5E3, but LTPI, fixed bias PP 6V6's and OP tube trem. I have already built a 5E3 and wanted to try this.

Here's the schemo,        http://www.el34world.com/charts/Schematics/files/fender/tremolux_5g9_schem.pdf

If you see any problems with the layout please let me know so I can fix/adjust them before I start on the eyelet board.


           Thanks,       Brad        :icon_biggrin:

Title: Re: Please check my layout for 5G9 Tremolux New Scratch Build
Post by: sluckey on March 27, 2011, 08:00:17 am

That looks workable to me. Why did you split the cathodes on the preamp? And why the separate B+ nodes for the preamp? Your relay works fine for one or the other preamps, but I thought part of the mojo of that circuit came when you had both channels 'jumpered' together?

Title: Re: Please check my layout for 5G9 Tremolux New Scratch Build
Post by: Willabe on March 27, 2011, 11:23:52 am

Thanks sluckey, for your input.

Quote from: sluckey on March 27, 2011, 08:00:17 am

Why did you split the cathodes on the preamp? And why the separate B+ nodes for the preamp?

Just to give each triode it's own little star ground point, then to the buss to the next little star ground. Might be over kill but I have the room and the Nichicon radial caps are low priced.

Quote from: sluckey on March 27, 2011, 08:00:17 am

Your relay works fine for one or the other preamps, but I thought part of the mojo of that circuit came when you had both channels 'jumpered' together?

They don't have to be jumpered. When you plug in to one channel as you turn the volume up on the other unused channel it lets the signal bleed off more and more through the unused channels plate coupling cap, then the 100K plate resistor, to the PS filter cap to ground. It scoops out the mids and gives a cleaner sound, less gain. It works pretty good.

Set chn. 1 to full, set chn. 2 to 1/2 vol. and you can flip flop between a nice mid scooped clean and full over drive.

I posted my schemo for the FWB PS for the relay with some questions, in the 5G9 A/B switching thread I started. I could use input on that too.
Here's the link.....       http://www.el34world.com/Forum/index.php?topic=11312.0:icon_biggrin:    It's the last/most recent post.


                 Thanks again,       Brad         :icon_biggrin:
 

Title: Re: Please check my layout for 5G9 Tremolux New Scratch Build
Post by: topbrent on March 27, 2011, 07:47:09 pm

Nice implementation.  I have played a few original 5G9 amps and they are really a wonderful amp.