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Multi-Way Conventional loudspeakers with crossovers

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Old 26th August 2006, 10:11 PM   #1
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Default Student finds KEF drivers

Dad was a stickler for audio quality so I am assuming they are/were pretty good. I'd like some help from the forum in the following ways...

Please would you suggest a way to get started building the speakers. I am a physics student so dont have problems with the maths but I havent done much practical cabinet work before so the simpler the better.

In your opinion, knowing how difficult speaker design is and considering the quality of my drivers, can I build a pair of speakers worth the investment of time?

Do you know of any tried and tested standard designs with easy to follow guides... i assume these drivers were part of a DIY kit originally.

Thanks in advance for any help! I'm excited to hear your opinions.
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Old 26th August 2006, 10:15 PM   #2
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You might start by telling us what drivers you have. We then need the T/S parameters and what type of box you desire ie: sealed, vented etc.

Is there any crossover network?

Do you have pictures?
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Old 27th August 2006, 08:01 AM   #3
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Old Kef's are getting towards classic status so worth doing something with them
There is a specialist forum:
http://www.hifiloudspeakers.info/public_html/index.php
and falcon acoustics sell cross-overs for many of the Kef speaker combinations
But as Cal says more details would be helpful
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Old 27th August 2006, 09:34 AM   #4
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Hi sorry some of the information - including the driver descriptions - seem to have been lost in transit. These are the drivers...

2 x KEF B139
2 x KEF B110.A
2 x KEF T27

I do not have any crossover network.
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Old 27th August 2006, 10:30 AM   #5
Geoff is offline Geoff  United Kingdom
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Ah, the classic KEF drive unit combination!

Send me an email via the button below and I will forward the original KEF DIY enclosure designs for these drive units. The construction sheets also give the recommended crossovers but, as mentioned earlier in the thread, suitable crossovers can be obtained from:

http://www.falcon-acoustics.co.uk/

There are other designs around that use these particular drive units in a transmission line enclosure.

If you want datasheets for the drive units then I can send you these as well.

Geoff
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Old 27th August 2006, 05:46 PM   #6
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You thinking IMF there Geoff?

I can feel the bass already.
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Old 27th August 2006, 06:53 PM   #7
Geoff is offline Geoff  United Kingdom
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Quote:
Originally posted by Scottmoose
You thinking IMF there Geoff?

I can feel the bass already.
Actually, I was thinking of the Chris Roger's 'R50' equivalent published in Hi-Fi Answers back in August '73. Then of course there is Chris Roger's other design, the PRO-9TL. This originally used different mid and treble drive units but it could be adapted to be all KEF.

I still have a rather tatty drawing for another transmission line design that used the B139, B110, 2 x Celestion HF1300, T27 and an STC (Coles) 4001K super tweeter, but I forget what this design was called now.
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Old 27th August 2006, 07:10 PM   #8
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Are the drive units new and unused? They are all good units even today, but they command a premium on the market and I'm sure somebody would bite your hand off for new/unused ones.
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Old 27th August 2006, 07:42 PM   #9
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the state of the art has progressed since the Pro9-TL article was written - http://www.tech-diy.com/pro9.htm

the B139 has a very powerful motor (BL=12.3), low resonant frequency, Qt of 0.37, Re of 6.2 or so, but will only handle 100 watts -- if you do manage to fry the voice coil it is easily dissembled and rebuilt.
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Old 28th August 2006, 09:07 AM   #10
sreten is online now sreten  United Kingdom
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Default Re: Student finds KEF drivers

Quote:
Originally posted by edwardowen2


In your opinion, knowing how difficult speaker design is and
considering the quality of my drivers, can I build a pair of
speakers worth the investment of time?

Do you know of any tried and tested standard designs with easy to
follow guides... i assume these drivers were part of a DIY kit originally.

Hi,

The quality of loudspeaker design has moved on substantially
since the heyday of Kef kits, as has the quality of drive units
available to the constructor.

TBH you should sell the drivers to someone who seriously
wants to build one of the older designs, you should only
build one of these designs if you are seriously keen on
retro stuff, because whilst they are not that bad, they
are not that good either.

Some of the designs for the drivers are distinctly poor, I'd go
as far as saying oversimplifying to the extent of being wrong.

Original KEF drivers in good condition fetch a very good price.
You could then buy a very good second-hand pair of speakers
or choose a specific design suitable for your current purposes.

See how much you can get for the drivers and consider that
biulding something like this http://www.zaphaudio.com/audio-speaker12.html
and adding a subwoofer will not only be far easier than the
KEF TL designs, it will also sound much better (as long as you
do a good job on the mechanical behaviour of the cabinet.)

/sreten.
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