Anyone know what this is?

[Randall]

It came in plugged into the reverb jacks on a sliverface Princeton Reverb that the reverb was not working. Turned out to be a bad solder joint in the recovery section, so it was an easy enough fix, and happy the tank is not bad, because this amp is almost bone stock. I ran it by Nick at Magic Amps, but he says it is nothing of theirs. It measures 24 ohms tip to sleeve on the red dot side, and 1163 ohms tip to sleeve on the other side. Tip to tip is 1140 ohms.

What could it be?

[Enzo]

If I had to guess, I'd try it is a gadget to plug in place of the reverb pan, and it allows the reverb circuit to be used as a boost. SOme Fender models actually had such a thing wired in on a pull switch.. The low impedance on the red dot side suggests plugging it into the drive jack to match the low impedance of the reverb transformer.

[pdf64]

That kinda thing turns the reverb control into an overdrive. They were popular maybe 30 years ago.
Here’s the main brand back then
https://reverb.com/item/1405116-nos-...1978-and-after

[g1]

So did you remove this thing to reconnect the tank, or is the tank somehow hard-wired and both in use?

[Randall]

"So did you remove this thing to reconnect the tank, or is the tank somehow hard-wired and both in use?"

Oh, that came out in a New York minute, and stayed out.

[drewl]

Yes, used instead of the tank.

I modified the reverb circuit of my Marshall 2210 so it acted as a gain boost with reverb way back when.

Also made something similar without knowing people had already done the same.

[J M Fahey]

It even had its own name, was sold as "Ice Cube".
At least the original one.

[drewl]

Yeah, that's what the earliest one's I saw were called.

[Chuck H]

And, not yet mentioned,.. It doesn't make for a good distortion tone at all. Though that's subjective I suppose. But I sure didn't like the sound.

[drewl]

No it did not.
I tried various resistor and cap combinations before modifying the return stage for a gain/volume boost which sounded better.

[g1]

It doesn't make for a good distortion tone at all. Though that's subjective I suppose. But I sure didn't like the sound.

The SF Fenders with the pull 'boost' get it from the reverb drive. It sounds like crap as well.

[J M Fahey]

I never had the original ones to dissect , even less copies, so donīt know whatīs inside.

IF all they had was a resistor so 12AT7 driver was not unloaded (somebody above mentioned 24 ohm which sounds reasonable) , nothing else, and the whole couple Volts blasted the reverb recovery amp which expected, what? 20 mV? .... whatever the feeble recovery transducer puts out? .... then it would overdrive for sure but in an UGLY way.
Which I think to be the case.

NOW, if drive signal was clipped by a couple diodes, followed by some EQ, even if as simple as a Treble cutoff similar to RAT (fixed value of course) or even better similar to Big Muff EQ, preset to some tasty value reached at by ear, then result would be quite usable, similar to adding a reasonably good pedal in the effects loop.
Doubt anybody went that far though.

[Randall]

I have deduced why they were called the Ice Cube. It is surely because the shape and size of them is exactly that of a plastic molded ice cube tray, complete with tapered rounded bottom, and slightly concave top surface where the goop would have stuck to the edges a little. Cute.

[J M Fahey]

Yes

Maybe the inventor used some dyed black Polyester resin and a rubber cube tray as a container/mold
.