How do Reverb Tanks Kill Amps?

Telfer

Member
Messages
235
In your case I'd suspect that the amp circuit expected a isolated input or a grounded input and the new tank was the opposite - result would be a short or near zero input impedance, which would stress the circuit and the amp would be damaged.
How do I tell the difference between an isolated/grounded input and an un-grounded input?

If the company Accutronics knew about this...wouldn't they state it clearly on their website that certain tanks wont work with certain Fender amp models?
 

Telfer

Member
Messages
235
Btw, the only time this amp makes a
post in the Amps/Cabs Tech Corner: forum you might get better help.
I didnt notice that corner...any moderator can feel free to transfer this whole thread if they think its appropriate.
 

swiveltung

Member
Messages
14,483
Tighten the cables and make sure they are correct. I had a fender amp once that I was having a terrible time with microphonics and noise and would stop completely. After a lot of fussing around I happened to touch the RCA jack to the tank and it went nuts. Cleaned and tightened the female and male side and all was solved. Go figure.
 

Telfer

Member
Messages
235
I had a fender amp once that I was having a terrible time with microphonics and noise and would stop completely. After a lot of fussing around I happened to touch the RCA jack to the tank and it went nuts. Cleaned and tightened the female and male side and all was solved. Go figure.

I have found the source of the problem...its microphonics as you mentioned. My RCA plugs are also rusty as you mentioned.

I found someone else with the same problem on another forum:

https://postimg.org/image/yzzx8vb8v/

Apparently, it has to do with the THIN sheet metal case on the Asian tanks...which vibrates too easily in a combo. The old Accutronics USA tanks are much thicker.

So, I turned on my amp and put my hand on top of the tank, pressing hard to dampen it...it worked...no more high-pitched feedback resulting in power circuit failure!

Now I just have to find a way to dampen it permanently...I could cover the top with a thick piece of rubber maybe???
 

Telfer

Member
Messages
235
Dio you have any foam or at least cardboard under the tank? Bag around it?
I installed the long 9EB tank the same way as the existing short 8EB tank...no foam, cardboard or bag.

Do all long tanks ship with a bag to insulate the case from vibration?
I never got one when I bought it....didnt even know they existed.

I should use a few rubber washers for the screws.
 

swiveltung

Member
Messages
14,483
All bf/sf fenders have a cardboard piece or other material under the tank and the vinyl bag around them. I used to think the bag was just for looks, but often wonder if it isn't for dampening also.
It's not my experience if everything is working properly that a bag or other is necessary though. How far up do you turn the reverb dial?
 

swiveltung

Member
Messages
14,483
Tighten the cables and make sure they are correct. I had a fender amp once that I was having a terrible time with microphonics and noise and would stop completely. After a lot of fussing around I happened to touch the RCA jack to the tank and it went nuts. Cleaned and tightened the female and male side and all was solved. Go figure.
I may have mis stated this instance, I was having not just trouble with microphonics, but runaway feedback also.
 

misa

Silver Supporting Member
Messages
3,682
If you need to dampen the tank, at minimum get some rubber grommets for direct mounting. I do think that tolex tank bags help. If you're simply placing the tank in a bag and then fastening the bag, taping up some cardboard underneath the tank helps. Parts

I feel like I've also experienced some new tanks "settling in." When first installed they seemed prone to feedback and a bit shrill, but over the course of a few days would be less so. With the system hinging on little metal springs with delicate connections, I feel there may be some physical truth to this.
 

Telfer

Member
Messages
235
All bf/sf fenders have a cardboard piece or other material under the tank and the vinyl bag around them. I used to think the bag was just for looks, but often wonder if it isn't for dampening also.
It's not my experience if everything is working properly that a bag or other is necessary though. How far up do you turn the reverb dial?
I'm thinking now that bags are necessary ONLY for long 16" tanks, because the top of the case vibrates more easily than a short case. The case is also supposed to be raised off the floor of the cabinet with rubber washers.

I get the squealing with the reverb control half way or more.
 

PremiumPlus

Senior Member
Messages
1,151
Glad to hear you got it working...I guess I misunderstood the original post, I thought you said that the amp made a high pitch sound and then went dead, no sound anymore. Whatever, good job!
 

swiveltung

Member
Messages
14,483
I'm thinking now that bags are necessary ONLY for long 16" tanks, because the top of the case vibrates more easily than a short case. The case is also supposed to be raised off the floor of the cabinet with rubber washers.

I get the squealing with the reverb control half way or more.
OK, yes, fender reverb gets noisy when up that far for sure. I agree about tank length. I have a couple home builds based on Fender design that I put the short tanks in, they are uncovered and one in a head cab not far from the tubes. No feedback issues on those.
 

Telfer

Member
Messages
235
Glad to hear you got it working...I guess I misunderstood the original post, I thought you said that the amp made a high pitch sound and then went dead, no sound anymore.
If I let the squealing grow in volume loud enough..somehow it shuts down the power circuit and the amp goes silent. I should have used the word 'coma' instead of 'dead'.
 




Trending Topics

Top Bottom