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Old 15th June 2006, 02:38 AM   #1
ttrentt is offline ttrentt  United States
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Default Mesa Dual Rectifier Mods...caps?

I just recently picked up a Mesa Dual Rectifier. I am looking for any information on mods for it, and had a couple general questions. When re-capping the amp, do people use Black Gates like they do in HiFi? I Also keep hearing about "orange drops" which were known in guitar amps.

Anybody have any good info or leads? I have done a lot of searching.
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Old 15th June 2006, 09:47 AM   #2
sreten is offline sreten  United Kingdom
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Hi,

I'd be tempted to leave well alone unless its had very hard use.
Unlike HiFi amplifiers, better components are not usually an improvement.
Obviously poor quality components are a bad idea, replace like for like.

Ugrading components will subtlely affect the sound, if you don't like
the sound I suggest you'd be better of looking for a different amplifier.

/sreten.


Quote:
SPRAUGE 'ORANGE DROP' 715P CAPACITORS Orange drops are made from polypropylene film and foil. They have many advantages over ceramic, tantalum or aluminium when used in guitar amplifier circuits. The offer a high pulse current rate and extreme stability. The have excellent current carrying capacity and offer extended high frequency response. They provide the sound and definition of the old capacitors that are found in vintage amplifiers and for this reason they have become the industry standard upgrade for all guitar amplifier circuits.
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Old 15th June 2006, 09:57 AM   #3
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Hi,

Those amps are very well respected and well made as they are.
Unless its got a problem, like sreten said, id stay away from its circuits and enjoy playing through it

Craig
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Old 15th June 2006, 01:53 PM   #4
amperex is offline amperex  United States
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I like Mallory 150M available at Antique Electronic Supply in Tempre, AZ. For musical & mild distortion, ceramic type coupling caps are hard to beat (not same as Mallory 150M). I always use one in the first preamp section- sweetens up that uninspiring Sprague Orange Drop sound..
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Old 15th June 2006, 05:41 PM   #5
ttrentt is offline ttrentt  United States
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Oh, don't get me wrong, I think the amp is great, just always looking to mod things myself.
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Old 21st June 2006, 08:53 PM   #6
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Cool A major upgrade to nearly every amp

There is one major upgrade to most amps: FRED-diodes.
If you have an amp with rectifier tubes in it, you have all you need. It you have an amp with FREDs allready in it, be happy. If you have an amp with the standard diodes in thre rectifier board (such like the 1N4006 or 1N4007 diodes) you should think about changing these to a setup with FRED-diodes. FRED means fast recovery epitaxial diode. The effect is, that you get all the punch, smooth and equally brilliant top end, better responsiveness that you would get with fully tube-featured rectifier (which was standard in the old vintage amps in the fifties and sixties). The standard diodes, which are used in 99% of the production amps bring a certain harshness into the sound and they lack punch and sensitivity. You get improvements with FREDs in tube-amps and solid-state amps. I just finished a general part upgrade (including FREDs) in an old MusicMan Bass Amp which is solid-state in the preamp and tube in the power-amp.
I also changed all coupling caps, all buffer and supply caps, most of the resistors and most of the OP-amps. The amp now performs and sounds better than ever before - possibly better than any MusicMan amp ever sounded. I use it mainly for bass, but have modified one channel for guitar and some people asked, if it was an all fully tubed vintage amp, because the clean and distortion was like that (remember it is a solid-state preamp with OP-amps and an integrated diode-distortion).
Part upgrades can really make a huge difference, but you should know, what you are looking for and which parts meet your purpose.

As regards you Boogie amp you can be shure, that the people at Mesa Boogie usually use good parts. replacement of the coupling caps might not be necessary - at least if the amp already features polypopylene caps. If not you might think about a replacement. Orange drops add a certain character, Xicon Polypropylene are more neutral and cost less. Another very good choice are Solen Fast caps, which might be able to add even more punch and sensitivity.

If the amp is a little older I would however replace the electrolytic caps (Sprague Atom for the big supply caps and for the caps at the cathodes of the tubes, there are some other good brands as well). The electrolytic caps age pretty fast and after some years a refreshment should be done.

If your Boogie Amp features the standard-diodes, you might think aabout a FRED-upgrade. But be carefull: You must be absolutely shure, what you are doing. If you mix the cathode/anode of the diodes you can imagine what happens, if you switch on the amp the next time which puts at least 400 V on the diodes. If you made a mistake it might kill the amp.
If you are familiar with high voltage and diodes, there is no problem.
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Old 22nd June 2006, 02:31 AM   #7
ttrentt is offline ttrentt  United States
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Default Re: A major upgrade to nearly every amp

Quote:
Originally posted by Doc Blues
There is one major upgrade to most amps: FRED-diodes.
If you have an amp with rectifier tubes in it, you have all you need. It you have an amp with FREDs allready in it, be happy. If you have an amp with the standard diodes in thre rectifier board (such like the 1N4006 or 1N4007 diodes) you should think about changing these to a setup with FRED-diodes. FRED means fast recovery epitaxial diode. The effect is, that you get all the punch, smooth and equally brilliant top end, better responsiveness that you would get with fully tube-featured rectifier (which was standard in the old vintage amps in the fifties and sixties). The standard diodes, which are used in 99% of the production amps bring a certain harshness into the sound and they lack punch and sensitivity. You get improvements with FREDs in tube-amps and solid-state amps. I just finished a general part upgrade (including FREDs) in an old MusicMan Bass Amp which is solid-state in the preamp and tube in the power-amp.
THank you very much for you post. I however do not think I have enough electronics genius to understand everything you wrote. I wouldn't even know what to look for to see if Mesa already uses those or what parts are needed to replace.

The Mesa Rectifier has a switch on the back that you can either use the tube rectifiers or the "hi-power silicon" diodes. I assume these are to which you are referring should get changed with FRED-diodes.

I need to do more research. Thank you

T
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Old 22nd June 2006, 12:06 PM   #8
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seems like disaster in the making if you want to mod something, but can't tell where the rectifier diodes are. please don't blow up a nice, epensive amp!
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Old 23rd June 2006, 01:22 AM   #9
ttrentt is offline ttrentt  United States
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Quote:
Originally posted by elementx
seems like disaster in the making if you want to mod something, but can't tell where the rectifier diodes are. please don't blow up a nice, epensive amp!

I am very new to this genre and have no problems learning.
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Old 23rd June 2006, 02:39 AM   #10
Enzo is offline Enzo  United States
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[Q]I just finished a general part upgrade (including FREDs) in an old MusicMan Bass Amp which is solid-state in the preamp and tube in the power-amp.
I also changed all coupling caps, all buffer and supply caps, most of the resistors and most of the OP-amps. The amp now performs and sounds better than ever before - possibly better than any MusicMan amp ever sounded. I use it mainly for bass, but have modified one channel for guitar and some people asked, if it was an all fully tubed vintage amp, because the clean and distortion was like that (remember it is a solid-state preamp with OP-amps and an integrated diode-distortion).
[/Q]

Just wondering, after changing this amp to FREDs and also all the caps and most of the resistors and op amps, how on earth could you decide what part of that improvement was due to the FREDs?
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