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Topic: Red Rhodes modded Princeton reverb on eBay |
Brett Lanier
From:
Hermitage, TN
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Chris Boyd
From:
Leonia,N.J./Charlestown,R.I.
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Olli Haavisto
From:
Jarvenpaa,Finland
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Posted 17 Dec 2012 1:59 am |
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2 x6L6 and no tube rectifier. Hefty looking transformers, too...
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Olli Haavisto
Finland |
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Cartwright Thompson
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Posted 17 Dec 2012 4:09 am
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| RCA 6550's, it might actually be putting out 50 watts. |
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Tim Marcus
From:
San Francisco, CA
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Posted 17 Dec 2012 8:10 am
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might be - wonder if the phase inverter was switched out to a long tail?
I have a hard time believing that a cathodyne PI can drive those 6550's for a full 50
lots of tuna in that can!
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Milkmansound.com |
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Ken Fox
From:
Nashville GA USA
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Posted 17 Dec 2012 3:00 pm
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I agree, Tim. I had to change the P.I. in the Princeton Reverb I did with 6L6GC tubes. It would only put out about 14 watts with the original P.I. After deleting the tremolo I was able to do the long tail PI and get 45 watts clean out of the amp, using a Bassman power and O.T.
With 6550 tubes and the higher B+ voltages he might have got it to work. I can't see an extra preamp tube added and it stated the tremolo was working. Most interesting. |
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Tim Marcus
From:
San Francisco, CA
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Posted 17 Dec 2012 5:30 pm
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it can be done if he uses a single tube for reverb
the Milkman 5W is basically a princeton reverb with no phase inverter and a single power tube - if you ran that into a long tail pair and put in 2 6550's you could probably make it 50W
its an awesome idea, but in reality I think a princeton cabinet is way too small for a 50W power amp. Those tubes will really take a lot of vibration and rattle. Even a 15W princeton with a 12" speaker can rattle a tube and slide across the floor when you hit a low A.
Either way - its cool that someone did it! Cramming high power into small boxes is something I really respect.
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Milkmansound.com |
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J Fletcher
From:
London,Ont,Canada
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Posted 18 Dec 2012 6:24 am
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Be interesting to see a pic of the circuit board. You would likely have to make changes to the phase inverter to drive those 6550's, but a properly designed cathodyne circuit can do it. Lilely need another gain stage ahead of the phase inverter.
The Princeton Reverb circuit pretty much optimizes it's tube complement. You could use a 6FQ7 in place of the 12AT7, one section of that tube drives the reverb tank nicely, it is more or less equivalent to two sections of a 12AT7, and that would give you a triode section left over to tinker with.
That triode could be the phase inverter, and the 1/2 of a 12ax7 originally used as the phase splitter could then be used as a gain stage.
It's an interesting design problem..Jerry |
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Gibson Hartwell
From:
Missoula, Montana, USA
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Posted 18 Dec 2012 6:47 am
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| Interesting that he left the cutout at 10" and just installed mountings bolts to accept the 12" speaker. Besides maintaining the baffle so they could go back and remount a 10" speaker, is there any reason to do that? I have never heard of that before. |
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Stephen Cowell
From:
Round Rock, Texas, USA
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Posted 18 Dec 2012 9:20 pm
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Perhaps the baffle gets weak when the hole is cut that big... they're not supported at the top and bottom.
I have a Vibratone cabinet that has a 12" JBL E-type in it... the hole is still 10", works fine.
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Too much junk to list... always getting more. |
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