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  • #1

    reverb tank questions

    I,m in the planning stages of a new project and need some info on the reverb section. This amp will be based on a deluxe reverb, single channel, no vibrato. I want to put it in a small cabinet that won't fit the standard 17' tank. can I use a 9" tank instead? The difference between the two is that the 17" is 8 ohm input and the 9" is 10 ohm input. what, if any changes will I have to make to the reverb circuit for this to work?

    17" #4AB3C1B, 9" #8AB2C1B

    Thanks, Rob.
    Tags: None
  • #2
    No changes are necessary.

    Comment

    • #3
      Thanks for the quick reply. That is good news too. Will the performance of the reverb suffer any because of the slighly higher input impedance? Like if I was going to use a medium decay tank, should I go for a long decay type? Rob.

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      • #4
        Decay has nothing to do with impedance anyway.

        IMpedances are frequency dependent, and nominal values at best. The small percentage change in impedance will not cause any trouble at all.

        The only differnce is that the smaller tanks have shorter springs in them and sound a little different. I think most of us prefer the sound of a long tank, but really it is not like night and day. And since you have no room for a long one, the point is moot.
        Education is what you're left with after you have forgotten what you have learned.

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        • #5
          Yes, most players feel the long tank is better sounding. On the up side the short tanks still do sound very good IME and are less prone to mechanical noise and breaking into feedback at higher volumes.
          "Take two placebos, works twice as well." Enzo

          "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

          "If you're not interested in opinions and the experience of others, why even start a thread?
          You can't just expect consent." Helmholtz

          Comment

          • #6
            Well, it seems that the tank I would like to use (8AB2C1B) is nowhere to be found. Could I use one with input and output grounded (8AB2A1B) as is, or modify it by lifting the ground at the input.

            Thanks, Rob.

            Comment

            • #7
              You are putting the cart before the horse. The input jack is insulated from the chassis for circuit reasons. If your circuit doesn;t require that isolation, then it becomes irrelevant. Since you have told us nothing of your circuit, it is hard to advise. COnsidering you are specifying an AB type pan, I must assume you are driving it with a transformer, so the grounding may not matter.
              Education is what you're left with after you have forgotten what you have learned.

              Comment

              • #8
                +1

                I did just what you are doing. I designed an amp and ordered a tank using what I considered a reasonable ground scheme... Only to find that the reverb tank presents it's own grounding gremlins. I ended up modifying the tank to isolate the output sleeve (more to save time on the project than to save $$$ on the tank). I understand ground schemes well enough. But when you add what amounts to another amplifier within the amplifier (and in my case on a different chassis) avoiding ground loops can become a Chinese puzzle. If I had it to do again I would get a tank with isolated grounds so that I could manipulate the grounds any way I wanted to in the event of a problem (unless I was cloning a proven design, which I never do).

                JM2C
                "Take two placebos, works twice as well." Enzo

                "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

                "If you're not interested in opinions and the experience of others, why even start a thread?
                You can't just expect consent." Helmholtz

                Comment

                • #9
                  Thanks for the replies.
                  I am going to be using a fender type reverb circuit, as used on a deluxe reverb ab763. So yes, it is driven with a transformer. This is the first build using reverb that I've attempted, so I don't have any experience with it. Thanks for the advice. I'll be asking a few more questions to be sure. Rob.

                  Comment

                  • #10
                    It's not hard to find the exact replacement tank or a layout for that amp. Be diligent and you can't miss.
                    "Take two placebos, works twice as well." Enzo

                    "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

                    "If you're not interested in opinions and the experience of others, why even start a thread?
                    You can't just expect consent." Helmholtz

                    Comment

                    • #11
                      A lot of reverbs with solid state drive circuits, even in tube amps, the drive can be solid state, the return on teh drive end is often not grounded because the circuit uses the return for sensing. Look at the common PV Classic 30 reverb as an example. On the drive side NEITHER side of the circuit goes to ground. It is not just a grounding scheme choice, the thing won;t work if grounded, no matter where you ground it.
                      Education is what you're left with after you have forgotten what you have learned.

                      Comment

                      • #12
                        It turns out that you can order directly from Accutronics in Korea. There is a link for ordering on their web page; payment via Paypal. They quoted $20 for a 8AB2C1B, plus $20 for shipping. Shipping cost can reduce depending on where it is going. That's a little higher cost than if you ordered from a US distributor, but if nobody has what you want, it's not a bad trade off. Just thought I'ld pass this along. Rob.
                        Here is the link:::::::::: Accu Bell Sound Inc :::::::::

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