Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: simonallaway on June 02, 2015, 02:56:12 pm

Title: Reverb tank for '72 (ish) Fender Quad Reverb
Post by: simonallaway on June 02, 2015, 02:56:12 pm

I have a question about the 'correct' tank to replace one that has all the springs missing. It's an Accutronics 4BB3C1B which according to this:


http://www.amprepairparts.com/reverb_numbering.htm (http://www.amprepairparts.com/reverb_numbering.htm)


...has an input impedance of 150 Ohms and output impedance of 2250 Ohms.


If I buy one of Doug's

4AB3C1B tanks, with an 8 Ohm input impedance, will it work? Based on the condition of the rest of the amp I suspect the tank I found in there is wrong. Any thoughts?

Title: Re: Reverb tank for '72 (ish) Fender Quad Reverb
Post by: sluckey on June 02, 2015, 03:26:13 pm

4AB3C1B is the correct tank.

Title: Re: Reverb tank for '72 (ish) Fender Quad Reverb
Post by: PRR on June 02, 2015, 10:00:56 pm

> input impedance of 150 Ohms

Since it has the classic Fender transformer drive, the original part is surely a 4 to 10 Ohm input coil, not the 150 Ohm.

As Sluckey says, the second character should be "A", not "B".

> I suspect the tank I found in there is wrong.

Agree.

A 150 in a circuit that expects 4-10 will take only a fraction of the power it was designed to get, and deliver maybe a quarter of the "boing" that Fender decided was good for you. Full-up all-right, this reverb should drown you (and can be dialed-back to not-overwhelming). With the wrong impedance, it may be playable for many genres, but you can't do the Mr Dale surf-sound, and it may be hissy at part-surf setting.

> all the springs missing

Get the right part.

The springless tank housing might be useful as a cap-doghouse or a preamp chassis.

Title: Re: Reverb tank for '72 (ish) Fender Quad Reverb
Post by: simonallaway on June 03, 2015, 08:05:19 am

Thanks to both sluckey and PRR.


I understand now that this is an impedence matching issue. Obvious now that you spell it out.


When it comes to the Quad Reverb circuit, I'm refering to this one:
http://el34world.com/charts/Schematics/files/fender/fender_quadreverb_100w_nomstrvol.pdf (http://el34world.com/charts/Schematics/files/fender/fender_quadreverb_100w_nomstrvol.pdf)


Does this circuit have a name in the same way that we refer to AB763 or 5E3 ?

Title: Re: Reverb tank for '72 (ish) Fender Quad Reverb
Post by: Willabe on June 03, 2015, 09:02:09 am

Quad Reverb's are pretty much Twin Reverb's with 4x12" speakers. They are very loud!    :laugh:


                Brad     :icon_biggrin:

Title: Re: Reverb tank for '72 (ish) Fender Quad Reverb
Post by: simonallaway on June 03, 2015, 09:11:52 am

Very loud.


This one's in a bad state....no reverb (obviously)...a set of four completely different output tubes....a bent chassis....only two speakers work. Answers to the name of 'Lucky'


But it still sounds great. Loud and extremely strident.

Title: Re: Reverb tank for '72 (ish) Fender Quad Reverb
Post by: Willabe on June 03, 2015, 09:25:25 am

Blues men Freddi King and Albert Collins used to use them, Freddi played through 2!