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Post by roly on Apr 26, 2021 21:42:18 GMT -5
I have an Acoustic Tube 60 on the bench and cant get the reverb to work.
I can extract signal from the reverb send and, although thin, it seems to be working.
I can inject signal into the reverb return and that works fine too.
I think the tank that came with the amp is not original. I have tried several tanks with different input and output impedances, but nothing works.
I can whack the tank and get the expected loud reverb noise.
So.....does anyone here know the correct input and output impedances for the tank?
I have found a more or less legible PDF of the service manual but the tank input and output impedances are not stated.
It is not a tube driven reverb send.
Standing by for advice.
cheers Roly
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Post by Leftee on Apr 26, 2021 22:23:21 GMT -5
Disregard...
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pdf64
Wholenote
Posts: 556
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Post by pdf64 on Apr 27, 2021 5:31:18 GMT -5
I can’t find a schematic for that model, but generally speaking, if there’s no transformer between the drive circuit and the tank input, then the input impedance will need to be much higher than otherwise.
So with a transformer, 8-10ohms is typical, whereas if no transformer, then it’ll need to be at least 1k, the higher the better really.
The tank’s output transducer almost always should be high impedance. Theoretically, a clever designer can use medium or low impedances to achieve lower noise, but reverb fx in guitar amps probably aren’t worth that degree of effort.
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Post by roly on Jun 20, 2021 23:01:36 GMT -5
Hi folks No interest regarding my reverb fix post, so it's time to move on. I need to figure out how to get rid of the ground switch and it's related cap. Here's a picture....the PT has dual primaries and there are three ceramic disc caps in the circuit.....one must be the death cap and I don't have a clue about the function of the other two. Anyone care to offer advice? cheers Hope this works ibb.co/3SrzVZd |
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Post by roly on Jun 20, 2021 23:04:21 GMT -5
Ground switch is top right....from the top down...grey yellow white.
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Post by Peegoo 🏁 on Jun 21, 2021 1:15:05 GMT -5
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pdf64
Wholenote
Posts: 556
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Post by pdf64 on Jun 21, 2021 3:43:12 GMT -5
Ground switch is top right....from the top down...grey yellow white. I wish you’d asked this 2-3 years ago, when I was fixing up the 100W version. Yes, the PT primary - mains input wiring is rather convoluted and confusing. And undocumented. Unfortunately I’ve forgotten the kind of detail needed to help out much here. I guess there’s a suppression disc cap across each primary winding, plus the death cap; all you can do is grit your teeth and trace it out. Failing that, I suggest to remove the death cap and leave the 2 suppression caps. As I recall, the mains input wiring was in the outdated arrangement, with the power switch on one side of the mains, the fuse on the other. The modern standard is live in direct to the fuse, then to the power switch. As you describe it, for your amp, then from the power switch to the PT primary mains voltage selector. Neutral in direct to the mains voltage selector. |
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