5e9 Layout with 12DW7 Reverb

[J3ona1]

Hi Folks,

I wanted to design a board for a 5e9 (https://el34world.com/charts/Schematics/Files/Fender/Fender_tremolux_5e9a.pdf) with one tube reverb (from https://guitar.com/guides/diy-workshop/build-tube-spring-reverb-unit-amplifier/) and have done this as my first pass. I made space by using diodes for rectification, and will use the weber 5e9 chassis. I'm open to any feedback and potential issues you spot with the layout. I just stuck the Reverb circuit on the board in between the bright channel volume and the tone control.

[J3ona1]

I updated the layout here because I forgot to open up the project workspace to show the whole layout (doh!!). I also added the ot wiring and labeled the chassis holes/grommets that tranny wires are coming out of. Thanks in advance for your help. I really appreciate yall.

[tubenit]

Thanks for sharing this!  Watching your project with interest. 


Many yrs ago I did a Carolina Blues Special and used before & after the volume pot as the insertion points for the reverb.  It worked fine. 


However, I found I did sometimes have to adjust the reverb when I adjusted the volume as they were interactive. That was never an issue for me as I tend to take a set and forget approach to amp settings.


With respect, Tubenit.

[J3ona1]

Thanks tubenit. I owe you and the other good people in this forum a beer! Anytime you're near Atlanta first round is on me.

[tubenit]

When you get her all done ........... I hope you'll make a few sound clips. I bet this amp will have a really nice reverb with it. 


With respect, Tubenit

[J3ona1]

Thanks tubenit! I definitely will make some clips! I've corrected some errors with the underboard wiring and added a missing coupling cap. Newest version of the layout is attached.

[pdf64]

There seems some stuff that might be problematic, but I need a schematic to properly analyse it.

[Lectroid]

I'd like to see the whole schematic too.  I never saw a Tremolux in the wild.  But the dwell control looks odd to me, I'd like to see it in the whole circuit.

[J3ona1]

PDF, Lectroid and Tubenit. Happy Holidays to yall! Here's a first draft of the 5e9a Tremolux with reverb. Thank yall so much for taking a look at the layout, and thanks in advance if you can take a look at the schematic.

[SEL49]

The signal coming out of the reverb tank is the weakest signal in the entire amp. The 10K and 22K on the output of the reverb tank creates a voltage divider that will lose 1/3 of that weak signal. I would change that.

[acheld]

I see that you're elevating your heaters via the power tube cathode voltage.  I've never seen that -- won't that inject hum into the output?   

[pdf64]

I see that you're elevating your heaters via the power tube cathode voltage.  I've never seen that -- won't that inject hum into the output?   

No, the balancing point should be decoupled to AC 0V, by the cathode bypass cap.

[J3ona1]

...The 10K and 22K on the output of the reverb tank creates a voltage divider that will lose 1/3 of that weak signal. I would change that.

Thank you for the catch SEL49, and thank you so much for all the help you've given me over the years. That red LED on the trem oscillator trick makes the trem on my Princeton Reverb build sound amazing! Updated schematic for the current build attached.

[pdf64]

The dwell control looks strange, I don't think rotating it over its range will make much difference.
From an EE perspective, with some controls turned up full, there will be a lot of signal interaction with other control settings, possibly some unexpected / undesirable behaviour.

But from a user's perspective, just don't turn things up so high.

[J3ona1]

I'd rather nix the dwell and use the switch space for a switchable cathode cap. Im thankful that I have a reverb unit so I don't have to force a dwell control into this build. Thank you PDF!!

[tubeswell]

On the dry (non/ reverb) channel, if you want to preserve the mojo of the original amp, I would move the volume pot wiper connector straight to a mixing resistor at the grid of the 1st PI stage (and not have it going through the reverb channel dry signal voltage divider). YMMV

[SEL49]

If you decide to keep the dwell here's a better circuit.

[J3ona1]

....I would move the volume pot wiper connector straight to a mixing resistor at the grid of the 1st PI stage (and not have it going through the reverb channel dry signal voltage divider). YMMV

I attached a modified schematic tubeswell. Did I catch your drift? Thank you for your help!

[tubeswell]

Yes, that’s what I meant. Will it work better? Maybe. It’s all about options. The reverb channel may still get somewhat overwhelmed by the other channel. Difficult to work in reverb on older circuits.