Prince Tremolo Reverb the 2nd

Bitsleftover

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No NFB with a cathode bypass cap would be an interesting option to have, since it’s the configuration that would give the most gain.

NFB vs no NFB makes a difference but I’m not sure the two options for the NFB location would be very audible.

I would go with a simple switch that disconnects the NFB.

That’s actually how I had it set up before the PT failed. It would certainly be easier to wire that way.
Fortunately these components can all be mounted to the switch so I’ll have an experiment around when its together and see what works best. Doing it this way has the added advantage of being able to totally forget about the NFB loop until the rest of the amp is working correctly without worrying if the -ve feedback is actually +ve.
The parts were dispatched from Tube-Town today so I should be able to make a start soon.
I’ll be folding the chassis in work tomorrow when no one is looking!
Ive found/rescued a nice sized piece of ally that should be just the job!
 

Lowerleftcoast

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That is how I would wire the ground bus.
It looks like the trem is hooked to the B power node, but there is a node that isn't being used unless my eyes are off. I would be inclined to move the trem down to the unused portion (still has decent voltage in that node!)
The Princeton Reverb has a node that is not used. There is a mod that connects the PI to that node (Stokes Mod).
I am with echuta13, IDK if providing a different node for the trem would make much of a difference. The two nodes, without a load in between, form a *second order RC filter*. It has a slope of 12dB per octave. A *first order RC filter has a slope of 6dB/octave. Similar circuits only use a first order filter so it may not be an issue but it is something to consider when utilizing the unused node.
 

EsquireBoy

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That’s actually how I had it set up before the PT failed. It would certainly be easier to wire that way.
Fortunately these components can all be mounted to the switch so I’ll have an experiment around when its together and see what works best. Doing it this way has the added advantage of being able to totally forget about the NFB loop until the rest of the amp is working correctly without worrying if the -ve feedback is actually +ve.
The parts were dispatched from Tube-Town today so I should be able to make a start soon.
I’ll be folding the chassis in work tomorrow when no one is looking!
Ive found/rescued a nice sized piece of ally that should be just the job!
Experimenting is always a lot of fun indeed!
Thanks for sharing with us, I’ll look for the next step. Good luck with the build.
 

Bitsleftover

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That is how I would wire the ground bus.

The Princeton Reverb has a node that is not used. There is a mod that connects the PI to that node (Stokes Mod).
I am with echuta13, IDK if providing a different node for the trem would make much of a difference. The two nodes, without a load in between, form a *second order RC filter*. It has a slope of 12dB per octave. A *first order RC filter has a slope of 6dB/octave. Similar circuits only use a first order filter so it may not be an issue but it is something to consider when utilizing the unused node.

Sorry LLC, just for clarity, are you saying the ground bus is looking ok now?

Im way out of my depth with regards to nodes if I’m totally honest.
In my paint by numbers style, I think I’m going to go with what I have at the moment.
It’s close to the EC Vibrochamp with an added tone control. It’s how my 5f2a ended up after I’d added the reverb and tremolo circuits into additional enclosures bolted to the ends of the chassis.
And, whilst the layout and noise floor left a bit to be desired, I think the overall concept was about right.
Although all these designs naturally morphed from one to the next, I suppose my goal is to build a 5F2a with added reverb and tremolo.
Unless anyone jumps I and says “NOOOOOOOOOO!” That is
 

Lowerleftcoast

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The ground bus looks OK. The 220k 6V6 grid leak resistor is the only part that I notice being out of place. It is associated with the next node over. It should be right there with the 6V6 cathode resistor/cap. Hard to say if it would cause any problem where you have it now. Most ground schemes don't keep the nodes together. Your scheme is way ahead of he game.
 

Bitsleftover

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The ground bus looks OK. The 220k 6V6 grid leak resistor is the only part that I notice being out of place. It is associated with the next node over. It should be right there with the 6V6 cathode resistor/cap. Hard to say if it would cause any problem where you have it now. Most ground schemes don't keep the nodes together. Your scheme is way ahead of he game.
Thank you. I’ll look at moving that. It makes sense to optimise where possible. Thank you for your help.
 

Bitsleftover

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Princeton Full Layoutl.png
 

Bitsleftover

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Ive been slowly chipping away at the layout.
Ive made quite a few changes. Some to acheive a more simplistic layout and some because when my components arrived...some were physically much larger than I expected.
The trem section still looks messy. Im hoping the 3rd dimension of reality will offer a little separation between wires.
Ive deleted the -ve feedback/V1B cathode bypass cap switch (for now) to avoid confusion. Ill add it back in once the amp is up and running correctly.
The Impedence selector Ive ordered from Tube-Town is much smaller than pictured, but I can't get DIYLC to reduce the size so it should be a bit tidier than that in reality.
Once the rest of the parts show up I'll do a trial fit to avoid any nasty surprises, then get stuck into it.


Tweed Prince Tremoverb the 2nd Layout.png
 

Bitsleftover

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The faceplate arrived from Tube-Town.
Very nicely done and a very easy process.
I drew up what I wanted in Inkscape then saved as a PDF.
A few days later it arrived in the post.
I even escaped paying import duty on this delivery!
My only gripe is that they only offer a Black text on Chrome option instead of White text.
I used some White acrylic paint and filled in the the gap left by the laser then carefully cleaned up all the edges.
I think it looks pretty good for €15.
Very happy with it.
F2915934-3401-44F8-8816-27B64C785289.jpeg
 

willholt92

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The faceplate arrived from Tube-Town.
Very nicely done and a very easy process.
I drew up what I wanted in Inkscape then saved as a PDF.
A few days later it arrived in the post.
I even escaped paying import duty on this delivery!
My only gripe is that they only offer a Black text on Chrome option instead of White text.
I used some White acrylic paint and filled in the the gap left by the laser then carefully cleaned up all the edges.
I think it looks pretty good for €15.
Very happy with it. View attachment 927985

That looks awesome mate.
I'm just about to finalise my artwork and send my JTM micro faceplates to tube town, hoping I might be able to swerve the import duty although I've had to go for a large size to get both plates on so the price is quite high so not holding much hope for it getting through without another payment.
 

Bitsleftover

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1E677D07-052B-4A60-8070-90BDAC0E311B.png
The ground bus looks OK. The 220k 6V6 grid leak resistor is the only part that I notice being out of place. It is associated with the next node over. It should be right there with the 6V6 cathode resistor/cap. Hard to say if it would cause any problem where you have it now. Most ground schemes don't keep the nodes together. Your scheme is way ahead of he game.

LLC, If I could pick your brains again please?
I’m trying to work out the best way to ground the Reverb tank without creating a massive loop via the send and return RCA sockets. I seem to have 3 options.
1/ Isolating all 4 sockets (the tremolo has to be isolated) from the chassis, then tying all 4 ground tags together with a single wire to the ground bus for that node?
(Possibly leaving the loop in place via the Reverb tank and cables, but grounded at the Ground bus rather than the chassis)
like this?
 
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Bitsleftover

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1948FD7A-4009-423B-88CC-7A29400074B2.png
Or option 2, leave the Return Non isolated.
The send signal through the reverb transformer will be kept away from the chassis and the unused non insulated return Jack will ground the tank chassis to the amp chassis. (Thats how im leaning)
 
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