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Old 9th June 2009, 08:03 AM   #1
Ziggy is offline Ziggy  Australia
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Question Bypassing electrolytics - GOOD or EVIL ?

I have done the following on a Kenwood receiver of 13 years of age :
1. replaced rectifier bridge with high quality IXYS bridge rectifier - instant improvement
2. removed the 2 standard Elna filter caps in the power supply(5600mf 63 volt).
3. soldered 4 wires of 1 foot length to where the capacitors were.
4. made a solid bees wax cast block containing the following: 2X Samwha 10,000mf ''for audio'' electrolytics (removed from their cases and wrapped in rice paper), bypassed by 27mf Solen polypropylene caps, bypassed again by 0.22 Sprague orange drops.This is in fact a double capacitor block as such(two polarised caps in a block of wax)
5. This block of wax was then paralelled by 4X large GE p.p in oil motor run caps each at 40mf (80mf per rail).

Thinking that I was probably and finally insane, the amplifier at first sounded warm and muddy.
After 3 days of constant run in(as most of the caps had not been used for years) the sound has completely trounced the original Elna standard caps - no harshness or electrolytic sound, very open, crystal clear and dynamic. Speed?......wow!!

Is this supposed to happen or have I just been lucky to not really make an abortion of the supply filtering?
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Old 9th June 2009, 08:09 AM   #2
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There is definitely some luck at work. IME random bypasses are mostly a shot in the dark and take too much time and auditions to be successful. Maybe the original ELNAs were easy to trounce even without the bypasses?
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Old 9th June 2009, 08:20 AM   #3
figge77 is offline figge77  Sweden
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hi

in my experience what happend is supposed to happen
ive been playing around with changing caps and bypassing and cant remember a time when it got worse than before.
improvements you do to the powersupply will generate better sound, thats if you stay on the sane side of things.

what i have not tried is the rectifier you mentioned. tell me more about that. never thought much about it.

nice touch with those motor run caps!
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Old 9th June 2009, 01:08 PM   #4
gareth is offline gareth  Wales
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Yeah, using smaller by-pass caps forces the larger reservoir caps to charge up quicker too, and it is probably this that you are hearing. I used to know the equation...

I think time=1.67 x voltage for DC or something like that.

I have always found that by-passing almost always improves the sound, and different brands have different 'sounds' too. Psychological?? Who knows on that one but I agree, by-passing is good. I tend to use small 0.022uF to 0.1uF by-passers but I always keep their voltage higher than the larger supply cap they are parallelled with.

ESR - Equivalent Series Resistance

Gareth

P>S> I would not have gone to the trouble of wrapping them in bamboo shoots and deep frying them though , but fair play to you
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Old 9th June 2009, 02:10 PM   #5
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I am unaware of anything that would make "caps charge up quicker" when they are bypassed. Actually if the capacitance is slightly higher, due to bypassing it ought to take longer to charge, as the time constant is slightly increased...

But since the ESR and DA are improved, the cap ought to work better at higher frequencies.

The beeswax deal is unlikely to have altered the sound. The removal of the aluminum can may have altered the performance of the cap, as the triboelectric effect becomes different.

But, as Count Basie said, "if it sounds better, it is better..."



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Old 9th June 2009, 02:21 PM   #6
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Default Re: Bypassing electrolytics - GOOD or EVIL ?

4. made a solid bees wax cast block containing the following: 2X Samwha 10,000mf ''for audio'' electrolytics (removed from their cases and wrapped in rice paper), bypassed by 27mf Solen polypropylene caps, bypassed again by 0.22 Sprague orange drops.This is in fact a double capacitor block as such(two polarised caps in a block of wax)

5. This block of wax was then paralelled by 4X large GE p.p in oil motor run caps each at 40mf (80mf per rail).

Very interesting..... So if I understand you correctly you have "encased" these caps in beeswax and formed a block of capacitors. What was the theory for this action? I'm thinking its for vibration damping which is a good thing. The Solen Polys are damn fast caps and I have also found that they work fine in a P/S bypass role, very nice.

#5, the oil motor run caps used in audio like you did is mainly using the oil as a damper. Same idea?
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Old 9th June 2009, 03:55 PM   #7
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Quote:
Originally posted by figge77
cant remember a time when it got worse than before.

You guys are so lucky you should play the lottery. Or maybe you do.

Most changes i make to my system, even if universally approved by tweakers, result in worse sound

Changing so many variables at one time: caps, skins, damping, bypassing is something i haven't done since my teens. Yup, i'm an old bore.
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Old 9th June 2009, 10:00 PM   #8
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Btw, hope you have that beeswax in a container of some sort for the hot summer days when the amp gets hot??

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Old 10th June 2009, 12:27 AM   #9
Ziggy is offline Ziggy  Australia
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Hi guys thanks for your interest and comments.
I will get the number/model of the IXYS hexfred rectifier bridge - this is a super mod.........amazing difference to standard bridge rectifiers(and alot more expensive ).

Encasing the paralelled caps in bees wax is mainly for vibration and to give the electros something different to a tin can for an enclosure.

The motor run caps seemed to add a bit of weight and smoothness........but I'm not dead certain of this.

All in all - a different sound was the end result.......BUT.........SOMETHING IS NOT RIGHT .........on large dynamics such as percussion music, closely miked kettle drums, I noticed some distortion coming in to the equation. Replacing the bypassed bank with a couple of 20, 000 uf Nippon Chemicon vintage caps, the distortion went away so it seemed. I let the Nippons break in overnight to re-form(if that's necessary?).
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Old 10th June 2009, 01:33 AM   #10
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Judging these sorts of mods without a scope is risky. I could make a convincing case (though possibly false) that to maintain super low impedance through the midband, you need a significant value film cap bypass. Motor run caps are ideal. Small value caps can't get the job done, so IMO bypassing with 0.1 films addresses very little.

OTOH

I could make just as convincing a case (maybe false as well) that super low impedance is risky and might cause instability and/or ringing. Super low impedance combined with a bit of lead inductance can give you a high Q tank, just what you don't want. Caps with a moderate and controlled ESR can be a good thing.

Usually, if you can definitely hear something, especially if it's bad, you'll be able to see it on a scope. It's more often a flaw than not. Circuit mods without a scope are hit and miss with the emphasis on miss.
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