Reverb question

[John]

Hi fellas, I'm building another amp for a buddy of mine. He wants spring reverb, not digital. I'll be using Doug's reverb tranny and Tubenit's 1-tube reverb. It's another SE build using 6SL7s if that matters.


My question is, Bruce (my buddy) is buying a 9" tank from Accutronics; we're limited on space or I'd just use Doug's tank. ANYWAY. Do I want the tank with the high impedance output? I looked at the tranny specs and it says secondary: 14.5K and so I would think I'd want the 12K tank. But, as this is my virginal trip into spring reverb, I thought I'd best ask. Below is the question he asked me.


"It is measured in ohms.  @ 1khz. Input range from 10 OHMS TO 1925 OHMS.
OUTPUT RANGE FROM 600 OHMS TO 12000 OHMS."

Thank you all!

[sluckey]

I looked at the tranny specs and it says secondary: 14.5K

Doug's reverb transformer has a PRIMARY impedance of 14.5K. The SECONDARY impedance is 4Ω. You will need a tank with a low input impedance and high output impedance, such as 1AB2B1B or 8AB2A1B.

[John]

Argh. With what I miss and mis-read, it's a wonder I'm still alive! Thanks!

[Willabe]

     me too!

[PRR]

> tank with the high impedance output?

Asked like that: Yes. The Tank Output should be high Z for best hiss.

However as Sluckey spotted, your question is about Tank INput, which should be similar to RT Output (secondary), which is 4-10 Ohms. Anywhere in that area is fine; a 600 Ohm Tank INput will not get much drive from a Fender-type 15K:4 RT.

[John]

Thanks again for the replies. Now, another question. I've googled and " heard it both ways. "  (Sean Spencer)


Is it okay to use the screen supply node to power the RT? Being this is a SE amp, will it have a much higher likelihood of hum? I typically use a 10 or 12K resistor at the power tube to get the screen voltage a little under the plate voltage, if that matters.


If I have to, I can squeeze another R/C filter in there, but if it's not necessary.....


I'm once again learning just how much I don't know. 

[sluckey]

Is it okay to use the screen supply node to power the RT?

Yes, Fender did.

[John]

Thanks!