5f1 with reverb

[pontiacpete]

I've been trying to add reverb into an 5f1 that i built, using the reverb part of a circuit sent to by, I think, tubenit. Of course, it's not working yet. I've tried quite a few different connections, there's something I'm doing wrong. There are a couple of questions, I'm trying to use the 9.25" tank sold by AES and used in fenders. will this work?
Next question, where do I put it, after the volume pot and before the PI grid?
Also, I added another filter cap on the rail, is that necessary?
thanks for any help.
pete

I attached the wrong schematic. please see the following post,

[pontiacpete]

here's correct schematic.

[tubeswell]

The 5F2A with 'verb has got enough gain stages to work good, but I wonder with an RT B+ of 250V, you might not have enough to drive the pan. (You need to hit the pan input transducer with heaps of current, which means (all other things being equal) a higher voltage of the RT primary side - so that it coverts to a higher current on the RT secondary side. So maybe try connecting the RT B+ to the same filter cap node as the OT B+

[pontiacpete]

thanks Tubeswell
I connected the primary of the RT to the first node and have about 400v. STill not working. It sounds more like an oscillator, a tremolo at this point. THere some connection problem here and I can 't seem to locate it..
My latest connection I have "RV" to a .02uf which is on the wiper of the volume pot...then the 220k to 'RV2' then to the PI grid pin 7.

[tubeswell]

What type of tank have you got? (Do you know what the input impedance is?)

[pontiacpete]

It's a P-R8EB2C1B . 800 ohm input and 2,575 ohm output.

[txstrat]

In the first half of V2 you use a 2.2 k cathode resistor. This will reduce gain considerable compared to the 1.5 K in tubenits schem. I'd try the smaller value to see if it changes something.
I'd also add a coupling cap in between the 470 K resistor (might reduce this to 330K) and RV2 and move the coupling cap from the grid of V2 before the dwell pot. All this to decouple the whole circuit from the rest.
Just my 2 cents.

[tubeswell]

Also having an 800 Ohm input would be giving the wrong reflected load with your RT (if it is one of those little fender RTs which are designed to give a 15k reflected load with an 8 Ohm pan input).

[pontiacpete]

In the first half of V2 you use a 2.2 k cathode r330K) move the coupling cap from the grid of V2 before the dwell pot. All this to decouple the whole circuit from the rest.
Just my 2 cents.

thanks txstrat,
do you mean remove this cap. the .001?

pete

[txstrat]

do you mean remove this cap. the .001?
pete

Not quite, remove the .001 from in between the pots wiper and the grid and put it in between RV and the pots input lug.
Also keep in mind what tubeswell said.
Tubenit uses this kind of reverb with a pan found in many Fender amps (e.g. Princeton reverb) - that would be the accutronics 4AB3C1B.
If you have a different pan it may not work as supposed.

[pontiacpete]

I took a few days off from this, but here is where I left off -
The tank I was using wasn't a 4AB3C1B, so I tried a working tank out of my SF princeton. Changed the location of the .001 and decreased the value of the 470k to 330k. Still not getting any reverb, no amplification of the pan at all. Still sounds more like vibrato when the pots are turned up...

I tried to draw what the circuit is looking like. (also, this is my first attempt at a schematic on the computer) It isn't complete, but this is the basic hook up.

[txstrat]

I'd still add a .02 cap (look at pic). But I doubt it would cure your problem. Have you checked your actual wiring in the amp over and over again?
Sometimes you have a schem and everthing looks like it, but actually isn't.
Hope this helps.

[Tubenit]

reverb

Have you tried a different tube, a different reverb tank?

Does the amp play fine without the reverb? If not, then the issue may be someplace else.

Double or triple check the component values and make sure you don't have a 10k where a 100k is called for (as an example).

I updated the schematic for you. It may need a dropping resistor between the reverb and V3. I'd probably try a 220k first?

I usually have around 300v on the reverb trannie and around 200v on the plate of the reverb recovery triode. (give or take 25-50v on each).

Hope you get it working! I think you will if you stay with it.

With respect, Tubenit

[pontiacpete]

thanks txstrat and tubenit,
I got the pan working, but I can't understand how this happened. I was connecting the output of the pan to the node @ the 220k and 500pf cap to pin 7. This clearly wasn't working, so I opened up the sf princeton and followed what that does, to the cathode pin 8 of the 12Ax7, I put the output of the pan to the 1.5k / 25/25v at pin 8 and it works. Why is this?
What is on the grid of my 2nd triode, only the the 220k and 500pf cap, no signal... mm?
Also It doesn't put out the amount of reverb the princeton does but the pan is definitely amplified. Is there anyway to increase it, or do I still have it wrong?
thanks for the help!
pete

[Tubenit]

reverb

That sounds really odd to me? Any way you can post some close up pictures of the reverb tube, RCA jacks, reverb pot, etc..... ??

You're saying there is NO signal going to the grid? Have you tried a different tube? And also look for tiny wires or something like that touching other pins. Such as a strand of stranded wire touching between pin 7 & pin 8. Also make sure the shielded wire from the reverb tank isn't shorting to ground. Such as a strand of the shield touching the inner signal wire.

With respect, Tubenit