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Hoffman Amps Forum image Author Topic: 1965 Princeton Reverb Trem very weak  (Read 2700 times)

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Offline jukelemon

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1965 Princeton Reverb Trem very weak
« on: July 12, 2013, 09:49:04 am »
Hi all.  Several years ago I built one into a P12N.  It has been such a great amp.  But the Trem never worked right.  Just weak.

I posted a few years back on this and got several good responses.  I cannot find those old posts.  Sorry.

I swapped tubes.  No change.

It is there and I can hear the changes in Speed, but it is just weak.

No loss of power.

It is like the Intensity of the effect is ~10% at full range if that makes sense.

I believe it is photo driven.  I wish I would have built to be bias modulating but...hindsight.

Any ideas?

Thanks

Juke

Offline sluckey

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Re: 1965 Princeton Reverb Trem very weak
« Reply #1 on: July 12, 2013, 09:56:16 am »
A stock PR is bias trem. Search this forum for weak tremolo.
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline tubeswell

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Re: 1965 Princeton Reverb Trem very weak
« Reply #2 on: July 12, 2013, 01:48:39 pm »
First thing to try is swapping the tube that contains the tremolo LFO stage.

Biasing the output stage cooler also helps increase the 'slam'.
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Offline tubenit

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Re: 1965 Princeton Reverb Trem very weak
« Reply #3 on: July 12, 2013, 03:08:55 pm »
Did you look in Archives?

http://www.el34world.com/Forum/index.php?topic=604.0

With respect, Tubenit

Offline jim

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Re: 1965 Princeton Reverb Trem very weak
« Reply #4 on: July 12, 2013, 03:59:01 pm »
Check the bug in a dark room. It could be leaking too much light. If the rest of the trem circuit is OK you should swap it out for a spare.  Jim
The music industry is a cruel and shallow money trench--a long plastic hallway where thieves and pimps run free and good men left to die like dogs.   There is also a negative side.

Offline plexi50

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Re: 1965 Princeton Reverb Trem very weak
« Reply #5 on: July 12, 2013, 04:32:25 pm »
Check the 25/25 cathode cap pin #3 on the LFO stage

 


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