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Old 10th February 2007, 05:14 PM   #1
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Default Upgrading parts in an integrated amplifier

Im doing some repairs on my integrated amp, some parts in the power supply for the output stage went bad and took a few parts with them. So while I have it apart im thinking of doing a lttle upgrading and preventive maintenance, the amp is 15+ years old. Id like to replace all the lytic caps since they are getting up there is age. I did the 4 main power supply caps 4 x 10000uf about a year ago with some nice BHC Aerovox Als22. There are also a bunch of 10uf and 47uf Philips lytics, some are used for the LT317/337 voltage regs for the pre section and some are actually in the signal path which was surprising in an amp that cost around $1500 new. Id like to replace these but cant seem to find the original blue philips caps, I don't think Philips makes these parts anymore, I beleive Vishay took over some of their products though. So im thinking of going with mabe the elna silmic or nichicon muse, any recommendations?? Next there are a bunch of small styrene pf sized caps that are in the signal path, are these types still considered among the best or is there something better available now a days? I don't think film caps go bad with age like lytics so these will probably be left as is. Then there are some 1n4004 diodes that make up the rectifier bridge for the pre-amp section, would a fast diode like the UF4004 be a good upgrade over the standard diodes?? Other than that im going to add some nice binding posts to replace the banana plug sockets. Any tips or opinions please let me know.
thanks
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Old 10th February 2007, 05:40 PM   #2
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Hi imperfectcircle,
Leave the polystyrene caps alone. They are in the top two cap types you can use. Don't even resolder the leads as they have a low melting point.

For electrolytics, don't become enamored with product names. Just replace them with some good caps that are not the least expensive around. Work carefully.

-Chris
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Old 10th February 2007, 06:36 PM   #3
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What ate some good lytic caps?? I usually buy from digikey. They sell the Panasonic FC and Elna Silmic. Do you think its even worth replacing them?? im doing it more as a prebventive maintenance then to get better sound. Ive heard lytic caps start to go afte 15 years or so?? Also is it worth upgradinf the 1n4004 diodes for the pre section with the better uf4004 or maybe schottkys??
thanks
frank
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Old 10th February 2007, 06:43 PM   #4
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I would leave the diodes alone --

if you want to tweak you could bypass the power supply electrolytics with a polypropylene capacitor --

if you can manage to get your fingers in there -- try bypassing the LM317/LM337 adjust pin resistor with a 220uF or 1,000 uF capacitor.

you will find the FC electroytics are fine -- they are probably smaller than those extant so you could bet more milli-Farads on the power supply.
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Old 11th February 2007, 12:44 AM   #5
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Hi jackinnj,
Sage advice.

-Chris
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Old 11th February 2007, 01:49 AM   #6
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Very worth while rereading:

" Leave the polystyrene caps alone. They are in the top two cap types you can use. Don't even resolder the leads as they have a low melting point.

For electrolytics, don't become enamored with product names. Just replace them with some good caps that are not the least expensive around. Work carefully. ..."

I would only add to make sure you "oversize" any cap voltage ratings = to or >> ...
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Old 11th February 2007, 02:21 AM   #7
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You 'Seriously' want to improve yr Integrated? Disable the built in Pre and use somrething else, be it Direct input, Stepped attenuator or aGenuinely 'good' quality preamp.
Most All inty;s are simply a high Gain amp with a **** poor opamp riddled tone circuit posing as a Pre.
Defeating or bypassing this built in bottleneck almost universally gives significant 'improvement''.
Try It :-)
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Old 11th February 2007, 10:42 AM   #8
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My first question would be what integrated is this ??. There are many out there and while some can reap gains through some calculated mods some can be destroyed (sonically) by boutique misguided modifications. I used to own a rotel integrated and got the upgrade bug, i had made so many modifications with exotic parts that i ended up with an amplifier that essentially sounded worse than it did when it was new. your biggest returns will be in the signal path in an ac coupled design for a simple fix, if it is electrolytic throw it out and substitute a decent polypropylene. Being film you can use a value smaller than what was originally in the amp..I have not found special diode to make the gains that has been raved about, im sorry but we are not dealing with smitch mode power supplies for the most part and if you want to throw away hard earned money on exotic diodes feel free. ufsr diodes seem to be the rage in some groups but definately not in the nelson pass zone who speaks quite openly on slowing down even standard rat shack diodes.tweaking is a great start, even though eventually you may probably end up getting the nerve to jump into your own diy project which will sound better than what you are working with right at the moment ).
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Old 15th February 2007, 08:07 PM   #9
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Its an Exposure Xv integrated
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Old 15th February 2007, 10:44 PM   #10
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... like this? > http://202.186.86.35/audio/story.asp...996/8/01expoxv
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