Reverb Circuit from Marshall 8020 (schematic)

[blindsjc]

Is possible to make a reverb unit using this schematic?
http://server7.pictiger.com/img/382096/picture-hosting/8020-reverb-.gif

I just want to make a simple reverb unit, like used in
amplifiers like marshall 8020, maybe using same circuit
from C28 to C33. The schematics for reverb pedals are
full of things that I dont need.

PS: What does that SCN connection means? Is it a ground
for reverb chassis?

Thanks friends

[Mark Hammer]

The short answer is yes...provided you are using a tank similar to that used on the amp.  The principle reason is that the input transducer of the reverb pan is placed in the feedback loop of IC4B, in parallel to R35.  One assumes it is a reasonably high impedance (well, for a reverb pan) or else the circuit would not work very well.

There are plenty of decent spring reverb circuits posted around, none of which strike me as "less" than this one, and many of which allow a little more choice of which reverb pan to use.  I will also note that this circuit fragment assumes a certain degree of signal gain prior to IC3A and after IC4A, to which IC4B and 4A add.  That,s the thing about spring reverb; it's all about using gain and impedance-matching judiciously such that the springs receive and deliver a signal they can use and that can be used by the rest of the signal path.  What you show there may be incomplete, as far as providing that.

[blindsjc]

Thanks for your reply Mark

About your comments:
The schematic shows only a part of circuit, in fact, this fragment appears after
preamp and before power amp modules. I'm thinking about use it this way too.

The other reverb circuits which I found are really not "less" than this, they are
"more"... but I was searching for a simple reverb schem like this, just a knob
control to reverb level, my plan is use it at my homemade amp (LM3886).

Thanks man, I always learn a lot reading your posts.

[blindsjc]

Just thinking in a good opamp to use in circuit
cause I dont find this 1458 in my component
supplier. Any suggestion?

I get these values from my reverb tank:
28 ohms (input)
206 ohms (output)

[Mark Hammer]

Are those values the impedance or the resistance you have measured with your meter?  There is a difference.

[blindsjc]

Yes,
This reverb tank comes from a Crate amp
and it was working but the values appears
to be too low.