65 Princeton Reverb reissue feedback when reverb is turned above 4
Moderators: pompeiisneaks, Colossal
65 Princeton Reverb reissue feedback when reverb is turned above 4
This one has me stumped. Have tried replacing all tubes, reverb tank and cable. I've seen the D Lab video where he has a similar issue on a Super Sonic and it's the filter caps - that was not the issue either. Removed the tank and tried longer reverb cables to see if it was the proximity of the tank to the speaker - no luck there either.
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Stevem
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Re: 65 Princeton Reverb reissue feedback when reverb is turned above 4
Swap that 4th tube ( reverb return / mixer ) with the 12at7 PI/ output tube driver, does the issue lessen or go away?
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Re: 65 Princeton Reverb reissue feedback when reverb is turned above 4
Well, I stand corrected. I initially checked the filter caps on a handheld capacitance meter and they all checked fine. After exhausting what I felt was every other possibility, I removed them from circuit and checked them with my Sencore LC53 Capacitor-Inductor analyzer. They all checked fine UNTIL I tested them above 300 volts; at which point several started showing high leakage. I replaced all 4 with F&T 22uF/500V and the problem was resolved.
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Stevem
- Posts: 5144
- Joined: Fri Jan 24, 2014 3:01 pm
- Location: 1/3rd the way out one of the arms of the Milkyway.
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Re: 65 Princeton Reverb reissue feedback when reverb is turned above 4
There ya go, they where not uncoupling the gain stages from one another.
I am really surprised this does not happen more with Fenders because of all the channel preamp stages they feed off of one power supply node.
The golden rule of Thumb is to not have any more then two gain stages run off of any one filter node, so Fenders are a very bad ofender in that regard.
I am really surprised this does not happen more with Fenders because of all the channel preamp stages they feed off of one power supply node.
The golden rule of Thumb is to not have any more then two gain stages run off of any one filter node, so Fenders are a very bad ofender in that regard.
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
Not screaming like the passengers in his car!
Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!