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Old 3rd February 2007, 07:22 PM   #1
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Default Opinions on Ixys Fred rectifier in amplifiers?

Im doing a repair on my Exposure Xv integrated amplifier and ive descided while I have it apart that I will do a few upgrades. Im going to replace a few stadard grade Philips caps with some audio grade parts of the same value and add a pair of nice inding posts instead of he banana sockets. I also have some Ixys Fred rectifier bridges laying around and I was wondering if its worth replacing the stock bridge in my amp? The stock bridge is a wbpc2504 200v 25a part. And i have some of these Ixys FRED FBE22-06 600v 22a fast/soft recovery bridges. Will the 22amp part be sufficeint?? And will it really have any effect on the sound quality?? The amplifier is a fully regulated class B design putting out about 35wpc.

Ixys fred bridge

WBPC2504 bridge
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Old 4th February 2007, 03:38 PM   #2
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Can someone please tell me if can use the 22a part in place of the 25a one in my amp??
thanks
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Old 5th February 2007, 06:10 AM   #3
Stocker is offline Stocker  United States
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The engineers tend to rate parts as they do for a reason. Your 22A rated pieces may sound great until the advent of too-high inrush currents.





Then how will it sound


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Old 5th February 2007, 07:20 AM   #4
PWatts is offline PWatts  South Africa
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These rectifiers are always waaaay overspecified. Another reason is that the typical values are 15, 25 and 35A. 22A is unlikely to be a problem. Especially if it's a class-AB amp and rated so low, you've nothing to be afraid about. Most amps of those rating use those 8A inline things as found in PC power supplies - look at the standard power supply offered by Hypex for 2x UcD180 or 1x UcD400 as example.
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Old 5th February 2007, 07:24 AM   #5
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Imperfectcircle should read up on the designer of these amps, Mr Farlowe, to find what the last thing to expect an upgrade from is on an Exposure 15.

Hint: what a big Holden&Fisher resembling transformer for such a low output power integrated amp.
(even in 2007 the Brits cherish their Bananas)
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Old 5th February 2007, 09:01 AM   #6
PWatts is offline PWatts  South Africa
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Ugh yeah those speaker terminals look like they were sourced from a visit to a sweatswop in china. Rest looks quite nice though, esp the PSU caps.

If you really want the warm fuzzy feeling of swopping out stuff besides the electro's, you can have a go at the trimpots and volume potentiometer. If you don't use multiple inputs, hardwire the thing and bypass the unnecessary stuff. If you don't use the phono stage, disconnect its power.

Trying to solve jacco's puzzle but couldn't find any reference to it on Google.. but given the hint it may have something to do with increasing the bias, capacitance or somehow the voltage rails. In that case it may be wise to add some beef to the heatsink too..
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Old 5th February 2007, 09:33 AM   #7
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John Farlowe's view to amplifiers is/was that they're just tuned power supplies.

So his emphasis has always been on a large supply of electrical energy and extensive voltage regulation.
For a mere 35+35 watts amplifier the 15 has quite a big setup of transformer and capacitors.
Look closely at the board and you'll see ample voltage regulation sections.
The added amplifier circuitry is straight forward and hardly spectacular, DSelf will be proud.

Question yourself why Farlowe chose the blue Philips caps instead of something Limey.
PassLab products also carry those blue Philly things.
After 15 years it may be worthwhile to swap the caps, but what exactly does an "audio" electrolytic for this amp look like ?
AFAIK, Mr Farlowe used to be a power engineer, unlikely that you''ll beat him in clever PS engineering.
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Old 5th February 2007, 09:58 AM   #8
PWatts is offline PWatts  South Africa
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Well technically I'm a power engineer.. but 11kV AC-AC regulator technology is a bit hard to apply

The concept of a tuned power supply is even more so with class-D amplifiers which is just a DC-AC converter with the audio as reference signal.
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Old 5th February 2007, 10:29 AM   #9
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Sorry, Pierre.

I meant "you" as in Mr imperfectcircle
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Old 5th February 2007, 11:18 AM   #10
PWatts is offline PWatts  South Africa
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Hehe it was more tongue-in-cheek - I'm sure Mr Farlowe will still give me a run for my money when it comes to novel low-power PSU design..
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