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Post subject: Princeton 65 reverb reissue noise on reverb
Posted: Thu Aug 05, 2010 5:12 am
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Hi there - I just prurchased a new Princeton 65 reverb reissue amp. I got a small problem. 2 days after getting the thing, I noticed a hum on the reverb line. It's a hum that has the same frequency as the tremolo, even if the tremolo is dialled all the way down to 1. It is there with all the dials set to 1, except the reverb. If you just turn up the reverb a bit, you hear the hum. If you switch 'Off' the reverb or the tremolo using the footswitch the hum is gone. If you turn up the volume on the amp, the hum does not get worse, it seems fixed by the Reverb level. If you remove the footswitch (ie unplug from the back of the amp) the hum problem is much less, but it's still there if you crank the reverb up past around 3 or 4.

I'm pretty sure there wasn't this issue when I tried the amp out in the shop - I would have noticed it. I called up the guitar shop and they suggest to try it in other locations in my apartment as this could be due to ground interference or something.

Anybody else had any similar issues - is this a known thing or is it a defect that needs fixing?


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Posted: Thu Aug 05, 2010 9:59 am
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Maybe try pulling the 12AT7 that drives the reverb circuit & if you have some contact cleaner spray the socket and tube pins. Re-insert. Do same with the 12AX7 that drives the vibrato section. And the plug for the footswitch.

Maybe, best to pull one tube at a time and clean them all. Along with footswitch plug. Use electrical contact cleaner.

HTH!


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Posted: Thu Aug 05, 2010 12:53 pm
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Thanks for the tip - but I don't have any such cleaner at home. And it feels strange if this was the problem as the amp is brand new. Basically it is fine without the footswitch attached, there is slight hum if you have the reverb and tremolo cranked up high, but I believe this is normal and is not an issue for me. But as soon as that footswitch is plugged in, it hums much louder when you turn up the reverb.

I'm going to take in the footswitch to get it checked out as a first step. The amp is a bit of a beast to get to the shop on the tube. Hopefully it's just an issue with the switch itself.


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Posted: Fri Aug 13, 2010 4:33 pm
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Are you trying to use a stereo headphone extension cable for the footswitch???? If so, that will ABSOLUTELY not work on this amp.....needs to be a balanced TRS cable. Believe me, I've tried it & Fender says the balanced cable is the only one that will work.


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Posted: Sun Aug 15, 2010 4:57 am
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i use the standard footswitch shipped with the amp. i took it back to the shop - there is an issue with the amp itself and it's being repaired. interestingly i have read a couple of other forums with people having a very similar sounding issue.


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Posted: Sun Aug 15, 2010 6:08 am
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I would recommand to go back to the dealer and ask for repairing, even the valves are under warranty (less than 3 months).



According to your description you could have a problem with the valve V4 or in the circuit, on the Princeton the tremolo is modulating the power stage by signal superposition of the bias voltage.

Please check the schematic:http://support.fender.com/schematics/guitar_amplifiers/65_Princeton_Reverb.pdf and tell me if your amp has the same schematic.

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