Do Vintage Fender amps (AB763 type, etc.) all use the same reverb tank?

[waspclothes]

Happy 2023 everyone!

Looking at all of the classic-era Fender amps, the reverb driver and recovery schematics look identical. None of them show the reverb tank type, so I'm curious if the input and output impedance of the tanks are the same across all of these models?

I'm also guessing all of the modern reissues of those amps use the same impedance tanks as well?

[Chuck H]

As far as I know all the BF and SF guitar amps used the same tank. And as far as I know modern era reissues use the same specs too.

Original Accutronics model 4AB3C1B

Here's a site page with model numbering designations and specs https://www.amprepairparts.com/reverb_numbering.htm

[waspclothes]

Thanks Chuck! that's what I was thinking...

[mikepukmel]

If you happen to find a good sounding reverb tank, new, could you post the source? I went through 3 and none sound even close to what i remember the originals did, back in the day.

[g1]

I went through 3 and none sound even close to what i remember the originals did, back in the day.

What kind did you try?

[stokes]

I've had good results with these http://amprepairparts.com/reverb.htm

[xtian]

I’ve ordered several of the same model and they sound different!

[Chuck H]

I've had better luck both tonally and stability wise using the short three spring tanks. The long two springs seem aren't 3D enough in tone and are almost always too sensitive to microphonics. The short three spring tanks sound just as good or better than the long two springs and are more stable. They're also easier to shift around finding the quietest location because there's more wiggle room.

[Leo_Gnardo]

I’ve ordered several of the same model and they sound different!

You got good ears xtian. But we knew that!

Noticed this a long time ago - 1990's - back when I ordered a dozen at a time. Every one sounds different from the next! Some are exquisite, most OK, and some, well let's say they all eventually find a home. Hoping to perfectly emulate the sound of a tank that quit, or one in another amp, well good luck with that. Unless you order a dozen, or a hundred, and go through 'em one by one. Or toss in the towel, and go digital.

[Chuck H]

Every one sounds different from the next! Some are exquisite, most OK, and some, well let's say they all eventually find a home.

I had to audition three tanks for each of my last two builds with reverb. I had to buy one tank for the first of these and two tanks for the second. With a couple I had on hand still residing in the "eventually find a home" category. I fully expect I'll need to buy three tanks (at least) if I ever do another reverb amp. These last two builds were indeed long tanks (mojo for the customer). I've looked into the digital replacements. I think they they're called "brick"s in the genre. I don't know much about the offerings, implementation or tonal comparison but if mechanical tanks don't improve we may not have another option.

[Leo_Gnardo]

I've looked into the digital replacements. I think they they're called "brick"s in the genre. I don't know much about the offerings, implementation or tonal comparison but if mechanical tanks don't improve we may not have another option.

Trying to avoid going digital, but they don't CLANGGGG! when the amp gets knocked about, there's an irrefutable advantage. Some 30 years ago a customer asked "what if I patch my micro-verb into the Fender reverb jacks?" As long as the reverb is dialed full wet, no problemo. And it worked a treat, he put a couple brackets on the inner side wall of his Deluxe Reverb and afaik performs to this day with that setup.

As far as spring reverbs, I've had best luck with CE. AND in some cases I've found yes, a short tank sounds superior to all the long tanks I try. FWIW I studiously avoid long 3-spring tanks as the echo never seems to die off = way too long RT60 for you sound engine ears.

[The Dude]

FWIW: I've had good luck with Mod tanks.

[Chuck H]

Some 30 years ago a customer asked "what if I patch my micro-verb into the Fender reverb jacks?" As long as the reverb is dialed full wet, no problemo. And it worked a treat, he put a couple brackets on the inner side wall of his Deluxe Reverb and afaik performs to this day with that setup

.Did he load the output of the reverb transformer or pull the AT7 tube? I've experienced some Fender amps that generate unpleasant artifacts if the reverb tranny is unloaded. Then there's the safety of the little transformer and the tube driving it.

FWIW I studiously avoid long 3-spring tanks as the echo never seems to die off = way too long

Yep. Any time the long three spring tank is offered they seem to be of the long decay variety. I did use a medium decay three spring long tank in a dedicated reverb combo amp I built once. This thing filches power from the host amp to drive the tank and provide fifteen watts of reverb to the ten inch speaker. It worked great! But I had to wrap that three spring tank up like a sausage to keep it stable.

On a strictly pedantic note... The long "three spring" tank is actually six springs and the short "three spring" tank is three springs. While the long "two spring" tank is four springs and the short "two spring" tank is two. I like the short three spring tanks well enough. Sometimes if they don't sound right, not enough in the high or low frequencies, I'll modify them by either stretching a coil on the loosest spring (to add lower echo) or snipping a couple of coils off the tightest spring (to add higher echo). I did ruin a tank on my first attempt at this but it was a lousy sounding tank anyway so there was nothing to lose. I learned that the adjustments had to be smaller than what I did that first time. But it can work if you're judicious and careful.

[Chuck H]

FWIW: I've had good luck with Mod tanks.

I won't say I've had "good luck" but I WILL say I've had the least trouble with the MOD tanks. I also like the iso jacks and little jack boards in those tanks that make for easy ground modifications.

[The Dude]

The only trouble I've had is that occasionally the transducer coil isn't tight to the lamination and can resonate. We covered this in another thread a while back. It's easily fixed with a little rubber cement, silicon, or similar.