The Workbench

Re: Capacitors

Die_Bogener — Mon, 06 Aug 2007 15:02:13 GMT

Yes, that's right. An electrolytic capacitor has the shortest lifespan of all electronic parts. 90% of all defects in a B&O tv is a defect of one of these capacitors.

The standard elko with 85 degrees specification survives just around 1000-2000 hours at 85 degrees environment. That's not very much... in a tv this temperatures are very common. Every 10 degrees more or less halfe or double the lifespan. Of course there are certain influences causing some more effects...

That's one of the reason why i like 105 degree types... they last around 4 times longer.

Re: Capacitors

yachadm — Mon, 06 Aug 2007 11:51:29 GMT

I'm not familiar with a B108, but a basic fact of life (electronically speaking), that of all electronic components, Electrolytic Capacitors have the shortest lifespan of all.

As an Electrolytic capacitor ages, the electrolyte dries out, or alters its consistency.

Thus, it loses its ability to "capacitate", and becomes a resistor, or in the worst case, becomes a "short".

The correct measure of a capacitor's health, is not its capacitance, but its ESR (Equivalent Series Resistance).

Generally, the older a capacitor, the more its ESR increases (while its capacitance may remain within acceptable limits).

There are only a few (relatively) inexpensive ESR meters made

http://members.ozemail.com.au/~bobpar/esrmeter.htm

http://ludens.cl/Electron/esr/esr.html

http://www.peakelec.co.uk/acatalog/jz_esr60.html

See any reputable capacitor manufacturer's datasheets regarding capacitor life.

Which means simply - buy only recent production caps, and never NOS units.

IMHO, I'm not aware of any exceptions to that rule.

Re: Capacitors

Friedmett — Mon, 06 Aug 2007 11:15:30 GMT

Never buy NOS Capacitors?

Some years ago I had a new reisue Fuzz Face (one of the first guitar overdrives) that needed a tuneup as it did not sound as good as my original 70s one.

There is only small printboard and 2 volume controls basically so I modified it with a Hendrix schematic and B108 capacitors which decide the output. I did mention the B108 capacitors to my repairman and the next time I met him he had a couple. How old I don't know.

The B108 needed to be mesured for the right value before soldering them on.

One of the problems with those FF pedals back in '66-'67 onwards were the capacistors value were night and day. So out of say 50 units 3 might sound good. As for Jimi he got them modified.

My modified FF sounds like the 70s one but less noise.

Re: Capacitors

Die_Bogener — Fri, 03 Aug 2007 09:15:09 GMT

We all know, that Hifi equipment and magic spells have something in common ;) A lot of dealers earn a lot of money with this equipment, not telling us everything where the parts come from and their production and the technical data..

I believe that the own ears are the best tool to decide wether the sound improves by a modification or not. I dont know how to measure "Sound". Measuring distortions, clitches or other things can show how good an amplifier can reproduce a CD, but i have the feeling that not always the most expensive thing is the best one... but a lot of dealers live from this idea.

We also know that even B&O has to earn money. And there are not only enginiers but businessmen ;) So often not the best part is used, but the cheaper one. And that's why we are here :)

Re: Capacitors

Puncher — Fri, 03 Aug 2007 06:03:39 GMT

I did not mean to give the impression that the type and quality of capacitor did not matter - the b******ks I was referring to was the over-hyped electrolytic parts from certain suppliers with supposedly exotic seperators and electrolytes etc for which hugely dubious claims are made regarding their abilities in an audio circuit.

As for parts for signal processing and conditioning then yes, it is important that the most approprate device is selected whose specifications best match the desired performance of the circuit - careful consideration of the parts data sheets is required.

Re: Capacitors

Dillen — Fri, 03 Aug 2007 05:28:44 GMT

I don't want to comment much in this thread but agree that
quality of capacitors matters.
Mainly in preamp, tonecontrol and other line-level (and below)
circuits where signals (and eventual noise/distortion etc.) are to be amplified.
Die_Bogener shows it perfectly in the mild rebuild of the
Beomasters and CD players in the workshop section.
This is not at all b*****ks, it makes perfect sense.
I've done a few myself and it does clear up things. Even better
is the opamp conversions he does but that's a different story.

The crossover capacitors (ROE type EN) are original and, I believe, bipolar ones.
I've seen several bipolar caps with polarity markings.
Also metal propylene caps as low as a few pF's can have
polarity markings.
The markings merely show which end is the shielded one (connected to the aluminum can or outer layer of metal foil).
In our world, dealing with low-impedance signals that needs no
further amplification, it doesn't make much difference as long
as the cans are not physically touching when mounted.

I agree with Puncher in that we have no need for "audio-grade" caps here.
The main problem is not the caps initial build quality but the degrading over time.
Any good quality bipolar cap will do fine and fitting components
of a bit higher voltage rating will ease the stress.
The readily available kits contain 100V components and it will be fine
for all standard setups without "overkilling".

Martin

Re: Capacitors

Eugenio Colazzo — Fri, 03 Aug 2007 03:48:07 GMT

Perfect!

Thanks a lot !!!

Now I have a Beocenter 7002 to repair and from this topic I discovered some important details, now is time to start changing capacitors and try some little modifications using different caps type. I don't want to transform my Beo to a Frank & Stain, this is a fix point!

Regards again

ciao ciao

Re: Capacitors

Puncher — Thu, 02 Aug 2007 18:32:31 GMT

wirralsimon:
Puncher:

As in all things HiFi there is a lot a bo**ocks talked about capacitors (similar to cables etc). I agree with yachadm in principal but I would be wary of some of the prices of some of the so called audio-grade caps - many are priced for selling to the cable brigade!
For a decent, unbiased read on the effects of various types of capacitor see HERE

Are we discussing two things here?

There are problems caused by capacitors if they deteriorate over time, am I right in thinking that this isn't a controversial area?

and

Whether or not buying high-end caps instead of ordinary ones makes an audible difference which is where I am guessing the controversy is.

Have I read it correctly?

Simon

Sorry - yes. there are two different issues. Yes electrolytic caps age and need replacing, but what with?? For crossovers then at least bipolar electrolyitcs, obviously rather than polarised, but most film caps would be better (if you can live with the size incease). The debate starts when replacing with bipolar electrolytics - how much better are the really expensive "Audio" grade caps than run of the mill bipolars?? My answer is that, for the same capacitance, if the voltage and temp ratings are OK, then negligable! The parasitic effects of electrolytic caps are well understood and if the design was properly dimensioned at the off then paying (vastly) over the odds for "specialist" replacements gets you exactly nothing!

There are those that will argue strongly but I will in turn ask for objective proof that these parts make better "pass through" elements than "standard " off-the-shelf bipolars from a reputable manufacturer, and when someone comes up with a scientifically sound answer then i will post her to alter my opinion. (I'll sleep soundly tonight)

Re: Capacitors

wirralsimon — Thu, 02 Aug 2007 14:04:33 GMT

Puncher:
As in all things HiFi there is a lot a bo**ocks talked about capacitors (similar to cables etc). I agree with yachadm in principal but I would be wary of some of the prices of some of the so called audio-grade caps - many are priced for selling to the cable brigade!
For a decent, unbiased read on the effects of various types of capacitor see HERE

Are we discussing two things here?

There are problems caused by capacitors if they deteriorate over time, am I right in thinking that this isn't a controversial area?

and

Whether or not buying high-end caps instead of ordinary ones makes an audible difference which is where I am guessing the controversy is.

Have I read it correctly?

Simon

Re: Capacitors

Die_Bogener — Thu, 02 Aug 2007 08:05:53 GMT

It's an article how to improve the BM6500 BM7000.

http://forum.beoworld.org/forums/thread/14361.aspx

Re: Capacitors

yachadm — Thu, 02 Aug 2007 07:12:31 GMT

Yes, I like Rod Eliott's website - lots of good, intelligent words there.

And yes, I agree that the best capacitor is the one that isn't there!

But if there needs to be, the right choice makes a big difference.

What is the BM7000 workshop?

Re: Capacitors

Die_Bogener — Thu, 02 Aug 2007 06:50:53 GMT

I think, the best capacitor is the one, that is not built in :)

All capacitors have an effect on sound, some more, some less.

If you look into the "BM7000 Workshop", more than 60% of all capacitors were eliminated, they were simply not necessary. And the effect on sound was great. Less means sometimes more ;)

I agree, Low ESR 105 are the best ones for power supplys.

Plastic types like MKP, MKT or Styrol are very good in amplifiers for the signal. Expensive, but at least neutral to sound.

The worst is a polarized elko, followed by a bipolar elko. They are the worst thing in an Hifi amplifier.

Re: Capacitors

Puncher — Thu, 02 Aug 2007 06:13:27 GMT

As in all things HiFi there is a lot a bo**ocks talked about capacitors (similar to cables etc). I agree with yachadm in principal but I would be wary of some of the prices of some of the so called audio-grade caps - many are priced for selling to the cable brigade!

For a decent, unbiased read on the effects of various types of capacitor see HERE

Re: Capacitors

yachadm — Thu, 02 Aug 2007 05:09:26 GMT

This is certainly the place for Martin to step in and clarify, but in my experience, I have always used Audio Grade capacitors in the Output Amplifier stages, and Low-ESR, High-Ripple-Stability 105* capacitors in the rest of the circuit.

Examples of Audio-Grade caps:

Nichicon Muse, BlackGate, Elna Silmic, Auricaps, Solen & Axon, Dynamicap

Check out www.percyaudio.com for Audio-Grade capacitors

Examples of High-Quality Low-ESR 105* Electrolytics at reasonable prices:

Nichicon HE or PW, Panasonic FM or EB

Check out www.mouser.com or www.digikey.com

It is important to buy from suppliers whose stock turns over rapidly.

All capacitors should have a date-code on them - buy only those manufactured within the last 2 years.

Never, never buy old (NOS) capacitors - at worst, they can damage your system.

Re: Capacitors

Eugenio Colazzo — Thu, 02 Aug 2007 04:00:24 GMT

Hello

It seems that you are speaking about capacitors , so this is the right place for a question that doesn't let me sleep...

I found AUDIO CAPACITORS (470uF 16V - 6,32 euro), so I'm wondering about their use in electronic circuits like amplifiers etc, it is right to change each capacitor with this AUDIO one or only in exact part of the electronic circuit like filter ?

How we can choose a capacitor (for example electrolyitic but not AUDIO) where there are tons of the same capacity and voltage but different prices? How is possible to choose the best one?

ciao ciao