3 spring 10 ohm reverb tank, in a 8 ohm

[mikepukmel]

I have a 8 ohm reverb transformer for a Fender Ab763 Deluxe based amp.
I'd like to add a 3 spring tank with a dwell control to the amp.
If everything fits, will the circuit malfunction, or have some other problem with sound quality, if I use the 10 ohm
tank with the transformer that has a 8 ohm sec? 25% seems like a fairly big delta, even for the Fender amps.

[g1]

No problem.
Think how many of those amps are run with dirty connectors or disconnected so no load on those transformers. Yet they still rarely fail!

[mikepukmel]

Thanks! Im itching to add reverb to this amp, its going to sound like a stadium in my basement!

[Enzo]

Before you hack a hole in the amp for a dwell control, dummy up the circuit first. Most people who add dwell controls are at first interested, "Say, listen to that, I can turn it up and down", then they just turn it all the way up and go back to playing. A dwell lets you turn down the drive. Most of us don't need weaker reverb. We can turn down the existing control for less reverb.

Mike, never lose sight of this:

It is just a guitar amp, not lab equipment.


8 ohms, 10 ohms, the guitar gods and Leo himself don;t care.

An assignment: Look at amplifiers that used your 8 ohm pans and those with 10 ohm pans, and see if they used different transformers.

[mikepukmel]

Thanks, I get carried away sometimes.

[stokes]

Mike,most components in a tube amp have a +/- 10-20% tolerance.Add age to the formula and they can drift to 25% or more.So 9 times out of ten you can go with "its close enough for rock and roll".

[J M Fahey]

Just curious, how do you know itīs a "10 ohm reverb tank" ????

[g1]

A 4A* long type tank is designated as 8ohm input, whereas the type 8A* or 9A* short tank is designated as 10 ohm input. No idea why, unless the spring is the 'load' and is reflecting back a different impedance?

[stokes]

Spring Reverb Tanks Explained and Compared This link will explain the numbering system used in id'ing the various reverb pans/tanks.This one too http://amprepairparts.com/reverb_numbering.htm

[J M Fahey]

Thanks.
I am curious about how mikepukmel determined his tank is 10 ohms

[stokes]

He said he wanted to use a 3 spring tank in a circuit with a reverb transformer from a stock Fender that uses a 2 spring tank.The closest 3 spring tank has a 10 ohm input impedance.So I assume he bought the 3 spring tank and knows it is 10 ohm.A lot of people consider the 3 spring tank an upgrade in these amps.The 8 ohm/10 ohm mismatch is irrelevant.

[Enzo]

I am curious about how mikepukmel determined his tank is 10 ohms

Since there is no way to measure it, I'd have to assume he read the specs in the product description in the catalog.

[mikepukmel]

Yep, that's it. I read around here and there, and some folks liked the 3 spring 'deeper' (ok not correct term) 'bigger'? anyway, they liked the 3 spring tank, and I found a bunch of 3 spring tanks, 2 that are 10 ohm. Yes, read the specs on the various pages, I think the last one was on Antique Electronic Supply. I did start posting questions before buying, though, didn't want to buy something that wouldn't work,. and you guys would know best. the tank isn't all that much (20 to 40 bucks?) but didn't want to buy one if it would not work at all, and the Fender circuit is matched to the other side of the transformer, and I don't have the engineering chops to be able to swap that out.


There are a whole bunch of 3 spring tanks, with a few different impedances (10, 190, 310, 800, etc), no 8 ohm that I can find, but quite a few 10 ohm like this one:

Replacement Reverb Tank for 8AB3C1B
Solid, Sturdy Construction
Short (9-ž") 3 Spring Unit , Long Decay (2.75 to 4.0 seconds)
Input Impedance 10 Ohms, Output Impedance 2575 Ohms
Input Isolated/Output Grounded
Horizontal, Open Side Down Mounting Plane

https://www.tubesandmore.com/product...ronics-8ab3c1b

and people didn't seem to complain loudly about Accutronics.

[mikepukmel]

Just curious, how do you know itīs a "10 ohm reverb tank" ????

Just read it from the A.E.S. web page for the tank. There are a handful of 3 spring 10 ohm tanks they advertise.

[Enzo]

Watch out. The long full size pans come in two and three spring versions. The short pans are also three spring. Look at those three-spring 10 ohm guys and I think you will find them all shorties.

In my opinion the short pans do not have a nice a sound.

In the long pans, a three spring doesn't have more reverb, it just has a more complex sounding reverb.