Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Rascalrick on April 05, 2018, 09:28:42 am

Title: Princeton reverb no tremolo question
Post by: Rascalrick on April 05, 2018, 09:28:42 am

Hello.  I am planning a build of the Princeton Reverb with no tremolo, and am wondering if I can use a different power transformer.  I have a 580v 90ma power transformer with the standard 5v and 6.3v heater secondaries.  Would this work for the Princeton?  If so, would there need to be any component substitutions, or could it drop right in place of the standard 660v transformer?  I have built many amps, but don’t have a lot of tube amp design experience.

Title: Re: Princeton reverb no tremolo question
Post by: sluckey on April 05, 2018, 09:35:47 am

I think that will be fine if you use a solid state rectifier rather than a tube.

Title: Re: Princeton reverb no tremolo question
Post by: Rascalrick on April 06, 2018, 10:18:18 am

Thanks for the reply.  Is there a particular reason that I would need to use a SS rectifier?  The power transformer that I have has both 5v and 6.3v secondaries in addition to the high voltage secondary, so it seems that the tube rectifier would still work.  Is there something I don’t understand?

Title: Re: Princeton reverb no tremolo question
Post by: sluckey on April 06, 2018, 11:06:24 am

Quote from: Rascalrick on April 06, 2018, 10:18:18 am

Thanks for the reply.  Is there a particular reason that I would need to use a SS rectifier?  The power transformer that I have has both 5v and 6.3v secondaries in addition to the high voltage secondary, so it seems that the tube rectifier would still work.  Is there something I don’t understand?

A tube rectifier will work, but... Your transformer voltage is much lower than a standard PR. I suggested to use SS in order to get the B+ back up around 400vdc like the original PR. You could wire up a socket for the 5AR4. Then you could use either the tube or an octal SS plug-in rectifier. Hoffman sells both rectifiers.

Title: Re: Princeton reverb no tremolo question
Post by: Rascalrick on April 06, 2018, 11:15:07 am

Okay, makes sense.  I’ll probably do what you suggest and wire a socket to do both.  Thanks again!

Title: Re: Princeton reverb no tremolo question
Post by: jjasilli on April 06, 2018, 03:05:24 pm

Here's an outside the box alternative:  http://archive.ampage.org/threads/1/open/006188/Lower_power_octal_alternative_to_6V6_-1.html