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Topic: Circuit Modifications |
Gary Meixner
From:
New York, USA
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Posted 14 Jul 2011 7:39 pm |
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I would like to build another small tube amp and am considering using the Princeton Reverb circuit. I have always loved these amps but don't use the reverb or tremolo effects. Can the reverb and tremolo section be eliminated from the circuit design without effecting the overall tone characteristics of the amp. Looking at the schematic it seems fairly straight forward where to separated the sections - although my knowledge is limited. Does anyone have any thoughts or suggestions?
Thank you,
Gary Meixner |
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Tim Marcus
From:
San Francisco, CA
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Posted 14 Jul 2011 10:00 pm
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yup - you can rip them both right out of there. You'll have extra room to spare, so you may want to upgrade the phase inverter to a long tail
look at the trainwreck PR amps - they are basically this, with some tweaked values
I'd take it to the next level and cathode bias - that way you can put in larger transformers and run 6L6's if you need more pop from the amp
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Milkmansound.com |
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Mike Neer
From:
NJ
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Posted 15 Jul 2011 6:05 am
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No. The original Princeton amps sound different from the Princeton Reverb. There is an extra gain stage. A Princeton Rev has more growl, while a blackface Princeton is much cleaner.
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Tim Marcus
From:
San Francisco, CA
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Posted 15 Jul 2011 7:22 am
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Yeah, leave that third gain stage in there - that's what trainwreck does. If you use a Princeton reverb chassis, you'll have plenty of room. You'll waste half a tube but it's worth it!
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Milkmansound.com |
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J Fletcher
From:
London,Ont,Canada
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Posted 15 Jul 2011 9:17 am
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Hi Gary
No love for the reverb? I love my Princeton Reverb, and the reverb is part of the reason why. Love tremelo too, for that matter. I say build an amp with the reverb, you don't have to use it. Or just build a Princeton if you are certain you don't want rev....Jerry |
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Gary Meixner
From:
New York, USA
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Posted 15 Jul 2011 3:15 pm
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Hey Guys,
Thanks for your input. I have become a big fan of small, simple amplifiers. I have a Champ style amp and a Princeton 5F2A that I built. Both are single ended and sound great without any effects. I would like to get some of their tone in a slightly larger package. It seems that there is only so much I can expect from a SE amplifier and then need to switch to a push pull circuit. I do like reverb and trem but more often than not I don't use it. Since I am a novice amp builder I thought it would make sense to keep the construction as simple as possible. That being said it may be easier to build the amp as diagramed and just don't use the effects.
Thanks again,
Gary Meixner |
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Tim Marcus
From:
San Francisco, CA
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Posted 15 Jul 2011 5:02 pm
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If you build the amp without the effects, you'll notice an increase in gain.
If you want a champ style amp, but a bit louder, check out a Tweed Deluxe. Very simple amp - a hair louder than a Princeton - and sounds gorgeous with steel at low volume.
And, it's got perfect breakup for guitar over 5-6 on the volume knob.
Mine weighs about 15 pounds - another plus!
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Milkmansound.com |
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J Fletcher
From:
London,Ont,Canada
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Posted 16 Jul 2011 9:34 am
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Not sure where the increase in gain would come from if you omit the rev and trem circuits from a Princeton Reverb.
If you have built a Champ, then you can build the Princeton Reverb. More components for sure, but there isn't anything tricky to it, just more of the same...Jerry |
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Tim Marcus
From:
San Francisco, CA
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Posted 16 Jul 2011 10:44 am
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| Quote: |
Tremolo Mod
I replace the 50KRA Intensity pot with a SPST (on/off) switchable 50KRA pot. When the Intensity knob is clicked off, a 30% increase in volume and thus fidelity is observed. This is analogous to pushing in the loudness button on your home stereo. When the Intensity knob is clicked on, the tremolo circuit works the same as the stock factory setup. |
from: http://priceamp.home.comcast.net/~priceamp/mods.htm
this is a very popular mod - weber used to make a switched pot exactly for this. With the tremolo out of circuit the amp gets louder. Same with reverb - because you can then eliminate the 3M3 isolation resistor.
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J Fletcher
From:
London,Ont,Canada
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Posted 17 Jul 2011 7:44 am
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Hi Tim
The Princeton Reverb's trem circuit doesn't load down the audio path like say the Deluxe Reverb's does. The oscillator output is applied to the 6V6 grids through the 220k grid resistors. If you take the intensity control out of circuit, don't think there would be any effect on gain.
Yes, if you start reducing the 3.3 meg resistor's value you get an increase in gain. For that matter you could do that with the reverb circuit intact, though you would change the ratio of rev signal to dry signal. My comments were to the effect of, removing the reverb circuit doesn't increase the amp's gain. Naturally you can start changing values of resistors to get more gain, but that's a different kettle of fish...Jerry |
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Jay Fagerlie
From:
Lotus, California, USA
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Tim Marcus
From:
San Francisco, CA
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Posted 17 Jul 2011 9:36 am
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| J Fletcher wrote: |
Hi Tim
The Princeton Reverb's trem circuit doesn't load down the audio path like say the Deluxe Reverb's does. The oscillator output is applied to the 6V6 grids through the 220k grid resistors. If you take the intensity control out of circuit, don't think there would be any effect on gain.
Yes, if you start reducing the 3.3 meg resistor's value you get an increase in gain. For that matter you could do that with the reverb circuit intact, though you would change the ratio of rev signal to dry signal. My comments were to the effect of, removing the reverb circuit doesn't increase the amp's gain. Naturally you can start changing values of resistors to get more gain, but that's a different kettle of fish...Jerry |
I went back an looked over some schematics and you are right! Its totally different vibrato than a Deluxe reverb or a twin.
The trainwreck amps are very Princeton like, and do not have effects, and the 3M3 is removed from the design entirely. Thats gotta be a gain monster!
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Milkmansound.com |
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Gary Meixner
From:
New York, USA
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Posted 19 Jul 2011 4:31 pm
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Thanks for the comments and discussion. I have attached the address of an amp kit supplier who makes a stripped down version of the Deluxe in a single input, head unit. They also sell a repro Deluxe kit like many others do. I am considering giving the stripped down Deluxe kit a try. It is not a lot of money and kind of fits my aesthetic, which like my guitars, is home made. Take a look if you get the chance I would love to hear your thoughts.
http://www.stf-electronics.com/
Very best always,
Gary Meixner |
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J Fletcher
From:
London,Ont,Canada
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Posted 20 Jul 2011 1:37 pm
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| Well that tweed Deluxe type amp looks like it would get the job done. I personally prefer the Fender style amps with at least bass and treble controls. Need that sparkle...Jerry |
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J Fletcher
From:
London,Ont,Canada
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Posted 20 Jul 2011 1:38 pm
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| duplicate message erased |
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