SpeakerTalk

[proffski]

_________________
I contend that for a nation to try to tax itself into prosperity is like a
man standing in a bucket and trying to lift himself up by the handle.
-Winston Churchill

[tancrède]

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Hi again folks

The crossover is very well glue to the bottom of the boxe. And there's not much place over there.

So how can i pull-it off so i can check the caps individually ?????

Thanks again

Tancrède

[tancrède]

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Ok I've have succefully pull them out

Tancrède

[tancrède]

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For those you are interest, I will try to understand this crossover.

For the moment, i know why my ohmmeter didn't see around 8 ohms. This crossover have a 600 microF at is end - opposite side of the frivers of course.

What is the use off those caps ? Maybe for the protection circuit ? Dont know yet.

I 've already check a few caps, and there is 2 of them that look like off of their farad limit value. Maybe that's explain why the tweeter are not so bright in high frequencies.

I dont have wave generator to see them work in a benchmark test
So, i think i will change them all. After 25 years, i think it's a logical move to do.


Tancrède

[proffski]

Series capacitors in sealed boxes offer improvement and or a tailoring of the LF response below f³.

This method can also be used in other enclosures but the loading will change from third, fourth to fifth order depending upon the configuration.
There is a penalty to pay as the obviously he dB/octave roll off will also change.

Then we have group delay and phase response to worry about.

Give me a well designed Sealed Enclosure any day for a crisp fast bass response!
Anyway, I'm getting out of my depth here, I'm sure that S.G. will elucidate further if he so wishes.
_________________
I contend that for a nation to try to tax itself into prosperity is like a
man standing in a bucket and trying to lift himself up by the handle.
-Winston Churchill

[tancrède]

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Hi

My schematic drawing of the 103.2 is the same that Colin Royle:

http://www.hifiloudspeakers.info/Anatomy/Crossovers/103.2/SP1144103.2CrossoverIndex.html

The protection circuit is a little bit hard to understand because some discret components are sealded by Kef

Nevertheless, after the 600uf (2 X 300) there is a R1 = 680 ohms. This R1 is bypass, in normal operation, by a normally close relay. But when the power is to high, the relay work and open the contact. So the signal audio will pass into the 680 ohms and the current will drop a lot to protect the drivers. But enough power to light the red light below in front of the speaker.

Well, i quiet sure that this is the way that work.

I find 4 capacitors off limit value (one crossover for the moment), not very much, but who knows what could be the change after changing them.

Tancrède

[ColinR]

[speakerguru]

[ColinR]

[proffski]

Must try harder...
_________________
I contend that for a nation to try to tax itself into prosperity is like a
man standing in a bucket and trying to lift himself up by the handle.
-Winston Churchill

[tancrède]

-----------

Thanks folks

I think there is a transisitor in that red sealed pack

Maybe one day, i will depack and draw the protection circuit. In case someone need to repair-it one day

But those protection circuit is good only if you have children around, in case.

Tancrède

[tancrède]

Hi

Solen, who is a specialist in Crossover and drivers in Quebec, told me that a coil with no core is better than one with.

The guy was talking about saturation and elimination of certain frequencies.

Exemple: B&W and other goods brands use coil with no core.

What does-it mean to you folks ?????

Thanks with anticipation of course.


Tancrède

[tancrède]

Hi

Long time i didn't play with cut frequencies calculation

About the crossover of the 130.2 at this adress:

http://www.hifiloudspeakers.info/Anatomy/Crossovers/103.2/SP1144103.2CrossoverIndex.html

For he HF, the Fc = 1/2 (6.29) (R) (C)

So, 1/ 2 (6.29) (220 ohms) (0.22uf) = 3.2 Khz

So the tweeter will produce everything above 3.2 Khz. And that's good

But in the vertical branch, going to the return wire, before the tweeter, there's a 2.2 uf and a 10 ohms

If we do again 1/2 (6.29) (10) (2.2uf) we have = 7.2 Khz
So everything higher 7.2 Khz will go thru this branch and not to the tweeter.

So, how can the tweeter can produce 7.21 Khz to 20 Khz ?????


Tancrède

[ColinR]

Add page 3 of the CS7 Constructor Series to your reading list, then write an essay titled "compare and contrast" .

At the bottom of the page it has some impedance plots; the schematic is at the top .


http://www.falcon-acoustics.co.uk/Archive/CS7-3.jpg
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This post or any other information supplied to this website or any other by myself is not available for any form of commercial purpose i.e. to hi-fi magazines or as sales and marketing material for sleezeBay or Audiodogging pimps and the like.

[tancrède]

Hi Colin

The Falcon page is allright for me, because the capacitor and resistance is not in parallel with the HF driver

But with the 103.2 it's not the same

I will change the 2.2uf because they're old. But i dont think it's gone change a lot.

I definitively find that those speakers have no high frequencies, and i think i understand why now.
Because they are cut at around 8000 hz

Or maybe there is something i dont understand over here


Tancrède