Bypassing electrolytics - GOOD or EVIL ?

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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:bigeyes:
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?
 
hi

in my experience what happend is supposed to happen :)
i´ve 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!
 
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:D , but fair play to you
 
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..."

:D

_-_-bear
 
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?
 
figge77 said:
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 :dead:

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.
 
Disabled Account
Joined 2004
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:cannotbe: .........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?).
 
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.
 
All in all - a different sound was the end result.......BUT.........SOMETHING IS NOT RIGHT

Uh Oh......

.........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 always thought that the metal wrapper on an electrolytic is actually part of the unit and needs to be there for proper operation. Not to be confused with "nude" capacitors with the paper or plastic insulating wrapper removed. I still don't understand "nude" capacitors, what difference could it possibly make but I digress.

So putting back some "normal" caps made the nasties go away, I'm thinking you ruined a perfectly good set of caps. Try the same caps in there without removing anything and use the same bypass caps and listen to how it sounds. My curiosity is now fired up.
 
Disabled Account
Joined 2004
jwb.....thanks for the insult:cool: I can still hear to 16khz ,so I don;t think I'm deaf.
''High''............yeah.....................love to sniff that bees wax............mmmmmmmmmmmmmmmm.......beeeeeeeeeeeeswaaaaaaaaaaaaax........

I have heard the difference AS I ADDED EACH CAP BANK, so the wire inductance thing is B.S.

Tonight I am going to listen to some well run in 1000uf 50v Black Gate STD caps : 2,000mf only per rail. The other caps were disconnected and the B.G's wired in this morning. So, they'll have a 12 hour re-form by the time I listen to the amp tonight.

Bearing in mind that the original caps had 2X 5600uf, the 2,000mf per rail had absolutely no hum or noise when I listened briefly after connection. I would presume this amp has very good power supply rejection at such low capacitance?

Maybe there will be little or no bass?........or perhaps high speed transients?........or both?...........will report back.
 
Lumba Ogir said:
jrockhead,
all encapsulation materials, aluminum, plastic, beeswax, even the air have an electrical impact, causing distortion and coloration.


Interesting statement, Lumba. Can you point me to any articles or sites to further read up on this? During my great capacitor info hunt a few years ago I read a lot of stuff about different cap materials and how that makes a difference but not encapsulation methods or materials. Thanx.
 
Disabled Account
Joined 2004
O.K..........the Kenwood receiver truly has superb power supply rejection. The Black gates were as silent as first tried so you can go as little as 2,000mf per rail on this unit. But........bass seemed a bit flabby and I was only doing this as a quick test on P.S.R. and nothing else.

To my dismay, I realised that somewhere along the line, I had accidently switched the 8 ohm/4ohm switch at the back of the unit to 4 ohm:bigeyes: ............bad news as this is why the capacitor bees wax block and all those bypasses and even the larger Nippons to some extent, suddenly sounded lousy.

Looking at the circuit and measuring the D.C voltage at the caps shows that when switched to 4 oihm, the amplifier uses the lower voltage taps of the power transformer - 17 volts A.C per rail difference:confused: The difference to the sound is now dramatically better at the 8 ohm setting - no distortion,great dynamics and transparency. Better than it should be for a modest amp like this, even though it has been modded.

Can anyone care to comment on why Kenwood do this, and what it's supposed to achieve with lower impedance speakers?
 
jrockhead,
During my great capacitor info hunt a few years ago I read a lot of stuff about different cap materials
Of course, the dielectric materials overwhelmingly determine the characteristics.
Can you point me to any articles or sites to further read up on this?
Sorry, I cannot. However, in audio use, the often massive encapsulation is unfortunate.

Could we call this light encapsulation?
 

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Ziggy said:
Looking at the circuit and measuring the D.C voltage at the caps shows that when switched to 4 oihm, the amplifier uses the lower voltage taps of the power transformer - 17 volts A.C per rail difference:confused: The difference to the sound is now dramatically better at the 8 ohm setting - no distortion,great dynamics and transparency. Better than it should be for a modest amp like this, even though it has been modded.

Can anyone care to comment on why Kenwood do this, and what it's supposed to achieve with lower impedance speakers?

I think it's because a 4 ohm speaker requires more current for a given output, so the voltage has to come down so the power through the output devices stays within their rating.
 
A power amp designed to drive an 8ohm load is completely different from a power amp designed for 4ohm loading.

To get the most sales from a compromise that is affordable, they have used a dual voltage PSU. This helps overcome the major difference between the designs, the heat dissipated in the output stage.


I suspect that the reason for it sounding better is that the voltage amp stage and the PSU are optimised for 8ohm loading and that the 8ohm setting clips the transients less often.
 
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