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Low Loss capacitors

 
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Lee in Montreal
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PostPosted: Thu Oct 29, 2009 2:59 pm    Post subject: Low Loss capacitors Reply with quote

I replaced all caps on my 105/2 crossovers by Solen's caps, except for the four 120µF at the entry which were replaced by blue Bennics.

On the tweeter channel, there are two Low Loss 3,3µF caps. Did it matter if I used Solen's and what are the differences?
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Last edited by Lee in Montreal on Sat Oct 31, 2009 12:46 pm; edited 1 time in total
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ColinR
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PostPosted: Thu Oct 29, 2009 3:12 pm    Post subject: Reply with quote

Loss factor D in a reversible electrolytic is usually <0.1.

In a low loss elecrolytic D<0.05.

With Solens D varies from 0.0001 up to 0.001, so I don't think (apart from a slightly brighter sound) you've got a lot to worry about Very Happy .
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Lee in Montreal
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PostPosted: Thu Oct 29, 2009 4:12 pm    Post subject: Reply with quote

ColinR wrote:
Loss factor D in a reversible electrolytic is usually <0.1.

In a low loss elecrolytic D<0.05.

With Solens D varies from 0.0001 up to 0.001, so I don't think (apart from a slightly brighter sound) you've got a lot to worry about Very Happy .


Great. One thing less to worry about.

Now another question, and I am sure it could lead to a heated discussion. The long inductor coil wires in the bass channels are about 0.7mm. I am afraid that the size of the wiring is a restriction for the woofers (after all, the two leads from the board to the B300 are 0.95mm) and doesn't allow to bring all the dynamic the woofer has the potential for. I understand that on a production unit, there are some space and economic constraints, but here, it is a one-off. Am I wrong to think that using bigger wire in the inductor would improve the sound and dynamic of the B300?

On my experimental 105/2s (the other set I am building), I wish to use air core inductors with 14 gauge copper wire (1.63mm diameter - 540% increase in section), and the big inductors would be located on a different board. Resistance would be halfed by about 50%.

Am I crazy to think it would be bring a bit more dynamic on the woofer? BTW One set of 105/2 is used with stock, yet refreshed, crossovers, but the second set of 105/2 is for experimentation (both in cabinet and electronics).

http://www.solen.ca/pub/cms_nf_catalogue_niveau3.php?q=Jm5pdmVhdTE9MSZuaXZlYXUyPTQmc2VjdGlvbj0yJnNvdXNfc2VjdGlvbj00JmZ0PW5m

(Flame suit on)
Your thoughts Collin...
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TL 200
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PostPosted: Thu Oct 29, 2009 6:15 pm    Post subject: Reply with quote

Dear Lee,
i would never change the inductors of my speakers, CA TL 200 as you may already know.
Last week i spoke the shop-owner who reviewed them and i asked what he did to them before i bought them, about eight years ago now. He told me he rewired them and placed new, gold-plated, speakercable-connectors and he also replaced some bad capacitors.
When i asked about the inductors he told me they should never be replaced, unless broken, because it would change the sound of the whole system. The balance between the different speakers would disappear and you might not like it at all.
Off course you can always try but....remember i warned you. Wink
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ColinR
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PostPosted: Thu Oct 29, 2009 7:07 pm    Post subject: Reply with quote

Quote:
The long inductor coil wires in the bass channels are about 0.7mm. I am afraid that the size of the wiring is a restriction for the woofers (after all, the two leads from the board to the B300 are 0.95mm) and doesn't allow to bring all the dynamic the woofer has the potential for.



O.K. who's been at the "snake oil" then?

My comments.

1. The iron dust cored inductors used in the Ref. 105-2 were designed and are engineered appropriately for the job.

2. Iron dust cored inductors cost between 2.5 and 3 times the price of an air core.

3. You've just redone the capacitors, why do you want to downgrade the inductors?

4. Who's Collin?
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Lee in Montreal
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PostPosted: Thu Oct 29, 2009 7:30 pm    Post subject: Reply with quote

ColinR wrote:
1. The iron dust cored inductors used in the Ref. 105-2 were designed and are engineered appropriately for the job.

2. Iron dust cored inductors cost between 2.5 and 3 times the price of an air core.

3. You've just redone the capacitors, why do you want to downgrade the inductors?

4. Who's Collin?


All points taken

Lee
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Last edited by Lee in Montreal on Sat Oct 31, 2009 12:48 pm; edited 2 times in total
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T.O. Chef
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PostPosted: Thu Oct 29, 2009 7:41 pm    Post subject: Reply with quote

Nope. Never heard of him. Or Robert's. ;o)
For what it's worth to others considering mucking about in these waters, IMHO The 105 II bass from the B-300 in that cabinet, with that crossover is as good as anyone could ever hope to achieve. To quote another unnameable contributor: "it's likely the room that's the weak point in the chain".
Want slam? Try American.
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Lee in Montreal
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PostPosted: Thu Oct 29, 2009 8:53 pm    Post subject: Reply with quote

T.O. Chef wrote:
"it's likely the room that's the weak point in the chain".


And you are 100% correct. The positioning will make a difference, the width, height and depth ratio of the room will make a difference, where I stand in the room will make a difference, and the different textures in the room will also alter sound. Not to mention the sources: CD/vinyl, pre, power amps, cables, interconnects...

But, in my case, what motivates my questions is simply the quest for the ideal set-up. Wink
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TL 200
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PostPosted: Sun Nov 01, 2009 5:51 pm    Post subject: Reply with quote

Colin, i would like to hear/read your opinion about what i wrote:
"When i asked about the inductors he told me they should never be replaced, unless broken, because it would change the sound of the whole system. The balance between the different speakers would disappear and you might not like it at all".
Thanks, Bert.
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Lee in Montreal
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PostPosted: Sun Nov 08, 2009 11:06 pm    Post subject: Reply with quote

Here's a thought that T.O. Chief and myself are currently sharing after recapping our 105/2 crossovers, using Solen caps. We both find that "something" has happened, breaking the overall balance, especially in the mid range. Too much of it, and not as smooth as it should be.

By deduction, and citing Colin
"Loss factor D in a reversible electrolytic is usually <0.1.
In a low loss elecrolytic D<0.05.
With Solens D varies from 0.0001 up to 0.001, so I don't think (apart from a slightly brighter sound) you've got a lot to worry about Very Happy ."


It seems that on most caps (non-LL), loss factor goes from <0.1 to 0.001/0.0001, and on Low Loss caps (such as on the HF circuit), it goes from 0.05 to 0.001/0.0001... Meaning that the decrease in loss is more prevalent in the mid than the high drivers (LL in highs, standard in mids). Is that difference in loss factor a sufficient reason for the loss in smoothness and increased mid range level? Or are we chasing ghosts?
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ColinR
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PostPosted: Mon Nov 09, 2009 11:36 am    Post subject: Reply with quote

Quote:
Is that difference in loss factor a sufficient reason for the loss in smoothness and increased mid range level? Or are we chasing ghosts?


Ghosts Shocked no, if you look around www.diyaudio.com you'll find a couple of references to a suggestion by KEF that 0R1 (or something like that) be added in series per 10uF to remove the brightness of film capacitors.

The suggestion was pooh poohed by the diyaudio members, another reason why I don't favour them after, plagurising my pictures and schematics, plus constant demands form money when I registered to "police" the situation.
The demands kept on coming and the account never worked btw.

I tend to favour suggestions by KEF engineers over bulletin board contributors unless I know their individual backgrounds (designer/owners of speaker companies, ex-KEF employees, transformer designers, BBC engineers, etc) or which University Department they happen to lurk in!
None of the aforementined disagreed with the KEF advice btw.

I "avoid" the brightness you've found as I'm a poor oppressed Brit who parallels capacitors over 30uF with electrolytics using capacitance and ESR meters Rolling Eyes .

I do only one unit at a time and compare A to B until I get the sound I like which may or may not be the original.

Having "cloth ears" but I can hear a pin drop at 0.5 mile also helps Very Happy .


Problems with sound after replacing capacitors and adding resistors can be found in this diyaudio thread "celestion 66 needs Mid-range" as they don't do KEF.
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audiolabtower
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PostPosted: Sun Nov 15, 2009 12:55 am    Post subject: Reply with quote

[quote="ColinR"]
Quote:
if you look around www.diyaudio.com you'll find a couple of references to a suggestion by KEF that 0R1 (or something like that) be added in series per 10uF to remove the brightness of film capacitors.
The suggestion was pooh poohed by the diyaudio members.


I distinctly remember a thread there where the argument was with the suggestion that someone at Kef said use 1R per 10uF of elcap. Thus replacing a later series 900uF cap would require 90 ohms in series with the bass unit! Shocked
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audiolabtower
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PostPosted: Sun Nov 15, 2009 1:32 am    Post subject: Reply with quote

Lee in Montreal wrote:
Meaning that the decrease in loss is more prevalent in the mid than the high drivers (LL in highs, standard in mids). Is that difference in loss factor a sufficient reason for the loss in smoothness and increased mid range level? Or are we chasing ghosts?


My calculations and measurements when replacing my caps many years ago were that the low loss 3.3uF tweeter cap needed 0.5R. The mid section series caps needed 0.5R for the 30uF and 0.2R for the 100uF (my 105s are Mk1s).

Without these the speakers were rather "shouty" in the midrange and bright around the tweeter crossover thus seeming bass light (which they certainly should not be!), but if you had tone crontrols a boost of 2 db in the bass and cut of 2dB in the treble restored balance before the resistors were put in.

You can work out each "theoretical" resistor from R=d/2pifC where d assume<0.05 for low loss or <0.1 for ordinary elcap, f is crossover freq (400 or 2500/3000 etc) and C is obvious, a fixed resistor will not have the frequency dependence of original loss factor but nevertheless gives improvement.
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Thierry
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PostPosted: Thu Sep 16, 2010 3:40 pm    Post subject: Reply with quote

audiolabtower wrote:
Lee in Montreal wrote:
Meaning that the decrease in loss is more prevalent in the mid than the high drivers (LL in highs, standard in mids). Is that difference in loss factor a sufficient reason for the loss in smoothness and increased mid range level? Or are we chasing ghosts?


My calculations and measurements when replacing my caps many years ago were that the low loss 3.3uF tweeter cap needed 0.5R. The mid section series caps needed 0.5R for the 30uF and 0.2R for the 100uF (my 105s are Mk1s).

Without these the speakers were rather "shouty" in the midrange and bright around the tweeter crossover thus seeming bass light (which they certainly should not be!), but if you had tone crontrols a boost of 2 db in the bass and cut of 2dB in the treble restored balance before the resistors were put in.

You can work out each "theoretical" resistor from R=d/2pifC where d assume<0.05 for low loss or <0.1 for ordinary elcap, f is crossover freq (400 or 2500/3000 etc) and C is obvious, a fixed resistor will not have the frequency dependence of original loss factor but nevertheless gives improvement.


Hello,

I digged out this very interesting discussion and I came to the following remarks :

- ColinR points to the right direction when he says that one should work first on one loudspeaker speaker at the time and then compare with the other one.

- however this method is not quite the best one because the "reference" (i.e. the untouched one) loudspeaker capacitors may have drifted in value thus giving a false reference. That said, in many years of restorations I have done I very rarely came accross capacitors that had changed value a lot.

- last, but not least, I happen to practice a lot of RTA (Real Time Analyzer) on loudspeakers I build, test or listen to. The RTA method is by far the ultimate way to analyze the true response curve of a given system. Of course, you have to perform also Time Domain measurement. Back in the seventies those measurements took an anechoic room to be performed when the 105.2 were designed and not many manufacturers had one available. But today with a computer and a good dedicated software (see link below) anyone can have a rough idea of where a bump or a drop in the response curve happens.

From all the above I would suggest the following method in order to restore a crossover "the safe way" :

1) measure loudspeaker response curve before changing anything in the Xover because :

1a) you'll see if it's in line with manufacturer claims or specifications (thanks to KEF, they always specified it within a +/- x dB tolerance).

1b) if it's really that bad you will know where the problems have to be addressed

1c) if you are lucky because the speaker is within tolerance you will have the best possible reference available : the printed curve ! And you can really trust a printed down result, much more reliable than your ears.

2) once the above steps have been completed you can rework the crossover capacitors the way you want and you'll be able to verify the results against a real reference.

Sorry if it's unclear or if there are a lot of English language mistakes and improper use (I'm french), I'll be glad to clarify if there's a need.

Link to an EXCELLENT and FREE Real Time Analyzer :
http://www.libinst.com/SynRTA.htm

And a link to personal method for measurement http://www.dcx2496.fr/mesaudio3.php

It's written in french but you can use the Google translator http://translate.google.fr/translate?js=n&prev=_t&hl=fr&ie=UTF-8&layout=2&eotf=1&sl=auto&tl=en&u=http%3A%2F%2Fwww.dcx2496.fr%2Fmesaudio3.php&act=url )


I have compared my measurement results against IMF specifications for the Super Compact and I came to the conclusion that they were quite identical, which validates my own method. I saved building an anechoic room Rolling Eyes For even more accurate and reliable measurements I prefer to use time domain software (MLS impulses analysis) which gets you rid of room reflexions. RTA measurement is room dependent, although SynRTA elegantly addresses the issue (read the web page about it).


IMF SUPER COMPACT response curve, done by IMF Electronics




My own measurement of my IMF SCs - SynRTA - 1/12th octave
(the red circled area has to be discarded as it corresponds to room resonance)




Hope it helps,

Thierry
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