Reverb tank question..does open side up or down really matter?

[ctcpete]

Hi Guys, Been a while. I have a Deluxe Reverb clone that I bought from a friend. It came with a NOS (made in USA I believe) 2 spring Accutronics tank. There is an ink stamp on top, 2nd character is smudged, best I can read it is 4?B2C1A. I was raised with old Fender amps and I love a little reverb. This amp was somehow lacking in that regard. I decided to try a 3 spring tank, a MOD 9AB2C1B. I did not like the results at all (way over the top for me) and reinstalled the Accutronics tank.

My question is, the last character indicates it is a "open side up" tank. My application has it open side down. I searched a little and found a few old posts (not here) that claim that does not matter much with regards to tone.

So what do you guys think? Am I wasting my time trying to get the vintage type reverb tone with a modern tank? Is the open side up/down deal critical and should I try a new one with the open side down spec? I'm tempted to leave well enough alone at this point (one screw is a pain in the butt to get to without pulling the speaker). I have also read that there is a wide variance in the performance of the new tanks even with the same model numbers.

Thanks!

[Tom Phillips]

For practical purposes mounting your tank open side up vs. open side down will not change the tone. It will slightly affect the mechanical spacing of the internal guts with respect to the outer metal housing. The matrix of holes in the outer housing where the suspension springs are attached are used to adjust the suspension positioning. I have never seen published data that shows the configuration for the various mounting positions. However, as long as your tank's inner chassis isn't crashing into the outer chassis during normal operation and the long reverb springs are not touching anything you are good to go. Just make sure that the open side is covered with a properly spaced piece so that the bag or anything else is prevented from touching the reverb springs. You can also experiment with the positioning of the suspension springs if necessary.

[Leo_Gnardo]

Haven't found much difference between tanks designated for open side up nor down. What Tom said ^^^. What should one do for those 60's Ampeg combos where the tank is mounted on the side of the box?

3-spring long tanks yes, over the top for most players. More is not better in this case. It seems the reverb never ends. Good for those who want an arena sized echo, which is nobody I've met. I avoid them.

Currently made MOD tanks sold by Antique/AmplifiedParts/CE work well for me. For long tanks I generally get 4AB1C1B which claims a short decay, still plenty enough for any Fender or similar amp. Short tanks, sometimes all that can be found are 3-spring units, the MOD tanks work fine for me in this instance. Sometimes I'll sub a short tank for a long one if I find it sounds better. Sound is what counts, I hope that's still true.

You'll also find Belton tanks, they bought Accutronics and set up shop in Korea about 15 years ago marketing Belton tanks. I see there are now tanks labeled Accutronics costing a few dollars more. Whether they're any different, any better, I dunno.

What is true though, is one tank sounds different from the next, even ones with identical parts numbers from the same manufacturer. I used to buy by the dozen. Out of each batch, a couple sounded fantastic, most OK, and typically there was a dog that was hard to get rid of but eventually found a home.

[Chuck H]

Same as above here. I read somewhere (from a source I had no reason to trust or question) that the actual transducers are specific to tank orientation to 'center' on the sag of the springs for best efficiency. I figured it to be hogwash considering the simple construction of the transducers. It's true that sometimes a tank oriented incorrectly will be more prone to "crashing" when the amp is moved around. This is surely about the location of the suspension springs that Tom mentioned. On my last reverb amp I had to put the tank on it's side to mitigate hum. That was a first. Not tonal change other than no hum, but the reverb is more prone to crashing when the amp is moved around because I didn't adjust the suspension springs. I told the guy not to move his amp while playing. Problem solved. Like Leo I can attest that a good sounding tank is hard to come by. And it seems to be getting harder regardless of additional manufacturers now. And I've tried them all. I bought three tanks for the last build, two for the one before that and managed to use one of those extra tanks effectively for something else. The other two are so bad I think they'd be more effective as wheel chocks. The common problems with new tanks are microphony, inaccurate delay and bad segmented tone. I've tried adjusting springs with limited success. I've done a lot of wrapping and padding too. Accutronics DID sound test and adjust their pans and had very specific spring tension combinations. If a tanks spring rows aren't compatible for delay, tone or reflection timing the tank just sounds bad. Proper damping is also critical. I read that Accutronics got out of the game partly because they could no longer get the specific and necessary material they used for dampers. And IMHO all the new tanks are more microphonic and don't sound as good as the old Accutronics tanks. Vintage tanks are out though because the damper DO eventually dry out and fail to perform. My go to tank is the short three spring model now from any of the makers. Decent depth and less horrifyingly microphonic.

[ctcpete]

Thanks very much for the replies. To be clear, my tank is spec'ed to be open side up as per the last character of the model #. I have it open side down as positioned in my amp, so I was just wondering if I should bother to get a tank spec'ed as an "open side down".

Mine is rated as a medium decay which may even be too much for me (I like a subtle bit of verb). I'd be tempted to try a short delay tank as Leo _Grande recommended one day.

One good thing is they are pretty cheap but I'd be willing to pay more for better and more consistent quality. I love the reverb in my early 70's Twin Reverb with original tank, I read that they are not made that way anymore. I bet there would be some market for reproductions of that quality. Thanks again.

If anyone is curious, I found this page useful for deciphering the model numbers spec wise:

Accutronics reverb tank numbering

[Chuck H]

If you like the tone of that tank at all, don't get rid of it before you find one you like better. Because you may not