Hoffman Amplifiers Tube Amplifier Forum

Other Stuff => Effects => Topic started by: bvdd on June 22, 2012, 02:42:36 pm

Title: Can't find a reverb tank w/ high output impedance
Post by: bvdd on June 22, 2012, 02:42:36 pm
Mods please move if necessary.

Hi all,

I have a Crate Vintage Club 20 and I'm replacing the reverb tank.

According to the Crate tech dept. the tank model is 2FC2A1B.

The letter 'F' refers to the input impedance at 1475 which is common.

But the letter 'C' calls for the output impedance to be 10k-12k and I can't find a
single tank with that spec .. Belton-Accutronics, Mod, or anything else.

Anyone know a source for these?

The closest tanks I've found have an output impedance of 2250 .. but I assume that's too far off.

Also, if any other VC20 owners out there have successfully replaced their tanks, give me a shout.

Great forum.
Thanks.
Title: Re: Can't find a reverb tank w/ high output impedance
Post by: HotBluePlates on June 25, 2012, 09:18:29 am
The number you cited is an old Accutronics part number. If you meant that you went to amp parts suppliers and couldn't find the tank, that's probably typical, as this tank had solid-state drive and recovery circuitry, and most buyers are looking to do a tube-driven circuit.

You used to be able to order from Accutronics, or they'd direct you to a distributor for a low-quantity order. I'd suggest visiting their website (http://www.accutronicsreverb.com/), and checking out the Ordering page. Worst case, you get referred to a distributor who actually stocks that tank. Or, they may make the tank for you to purchase (they used to do this via ebay for single-quantity orders).
Title: Re: Can't find a reverb tank w/ high output impedance
Post by: bvdd on June 25, 2012, 01:44:28 pm
The number you cited is an old Accutronics part number. If you meant that you went to amp parts suppliers and couldn't find the tank, that's probably typical, as this tank had solid-state drive and recovery circuitry, and most buyers are looking to do a tube-driven circuit.

You used to be able to order from Accutronics, or they'd direct you to a distributor for a low-quantity order. I'd suggest visiting their website (http://www.accutronicsreverb.com/), and checking out the Ordering page. Worst case, you get referred to a distributor who actually stocks that tank. Or, they may make the tank for you to purchase (they used to do this via ebay for single-quantity orders).

Thanks for the reply.

Just to make sure we have the facts straight .. this amp is a tube amp; 3 x 12AX7's and 2 x EL84's. Because of this I assumed it was a
tube driven reverb circuit but I could be wrong.

I tried calling Accutronics but the number isn't working for some reason and they have not answered my email.

Thanks again,
Bill
Title: Re: Can't find a reverb tank w/ high output impedance
Post by: sluckey on June 25, 2012, 03:16:33 pm
Can you post a schematic? It's possible that another readily available tank may work.
Title: Re: Can't find a reverb tank w/ high output impedance
Post by: bvdd on June 25, 2012, 03:22:24 pm
I split the schematic to try and see it better.
Title: Re: Can't find a reverb tank w/ high output impedance
Post by: HotBluePlates on June 25, 2012, 03:46:52 pm
Ah.. I couldn't find that schematic, and had to rely on a different model in the VC series. Unfortunately, that model was IC drive and recovery, where yours is tube-driven and solid-state recovery.

Give Accutronics (now Belton) a chance to respond; it might take a day or two. Or try one of their distributors. Otherwise, a lower impedance output should be just as happy in that circuit.
Title: Re: Can't find a reverb tank w/ high output impedance
Post by: bvdd on June 25, 2012, 04:04:24 pm
Thanks,

Actually, I used another tank to make sure the reverb was still working in the amp.

That tank has an output impedance of 2250 .. it works but the reverb effect is extremely weak and
can't be heard at all when I strum continuously, even at low volume.

So I'm assuming the issue is incorrect output impedance.
Title: Re: Can't find a reverb tank w/ high output impedance
Post by: HotBluePlates on June 25, 2012, 06:34:57 pm
I see.

Do you get proper d.c. voltages at Q1's collector and base? These are TP15 and TP16, and the voltages are listed in the schematic you posted.

I also did a quick check of available reverb tanks, and you're right. If Crate can't help you with a replacement, you'll need to buy it directly from Accutronics/Belton.
Title: Re: Can't find a reverb tank w/ high output impedance
Post by: Platefire on June 28, 2012, 10:08:30 am
About three years ago Accutronics worked worked with me in building a full size tank to replace a small inner chassis mounted tank for my Mesa Boogie. I just got around to installing it the other day but it works good. Platefire