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mullmuzzler Introductory Contributor
Joined: 20 Sep 2005 Posts: 6
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Posted: Tue Sep 20, 2005 7:00 pm Post subject: KEF Constructor Series - Long time started, time to finish! |
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Hello!
I'm glad that I ran into this forum on hifiloudspeakers.info. I have my dad's DIY cabinets with KEF B110 and T27 units, but unfortunately, I don't have crossovers. The boxes were designed by my uncle and my father in the 80s for active amplifying, therefore the bigger boxes (rear part of the cabinet). Amplifiers are in *endless stand-by stage*, so, i need passive crossovers to complete the set so I can use them at home. I've found falcon-acoustics.co.uk sell crossovers for KEF, but I'm not sure what kit should I order... There is CS1 kit, and CS1A kit. Besides this, there is an option to buy the same kit, but with polyester capacitors.
I am new to this and everything sounds realy confusing... Could somebody help me out and point me in right direction, please?
Here are pictures of my speakers:
Thank you in advance,
mullmuzzler | OSSMT _________________ Chance favours the prepared mind. |
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ColinR Über Contributor 1000+
Joined: 31 Jul 2004 Posts: 1175 Location: Staffordshire
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Posted: Tue Sep 20, 2005 10:16 pm Post subject: |
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Remove a bass/mid unit and see which SP number is on the back or side of the magnet. 1057B's CS1, 1003A's Falcon 23aB and I've an alternative KEF (different solution to the target function) SP1057/T27 crossover design if you're into diy. |
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mullmuzzler Introductory Contributor
Joined: 20 Sep 2005 Posts: 6
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Posted: Wed Sep 21, 2005 1:19 am Post subject: |
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I did it. On the bass/mid unit says:
B110B SP 1057
and on the treble:
T27A SP 1032.
What kit do I need to order from Falcon?
Could you send me your design, ColinR?
mullmuzzler | OSSMT _________________ Chance favours the prepared mind. |
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ColinR Über Contributor 1000+
Joined: 31 Jul 2004 Posts: 1175 Location: Staffordshire
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mullmuzzler Introductory Contributor
Joined: 20 Sep 2005 Posts: 6
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Posted: Wed Sep 21, 2005 7:22 pm Post subject: |
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ColinR, I've sent you PM with my e-mail address.
Also, I have B139B (brand new). Is there some way to make a crossover for the bass unit to be used with my speakers - B110B+T27A x 2 (pictured aabove), and a single bass unit to be used as a sepparate speaker cabinet that I plan to build?
mullmuzzler | OSSMT _________________ Chance favours the prepared mind. |
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ColinR Über Contributor 1000+
Joined: 31 Jul 2004 Posts: 1175 Location: Staffordshire
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Posted: Wed Sep 21, 2005 11:33 pm Post subject: |
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You could steal the bass crossover design from the Cantata design as the B139's already attenuated slightly in it to match the B110B's higher output.
However running the speakers in series will present a 16 Ohm load, so you'll need a good amplifier.
Or steal the CS7 crossover design and insert a T27aB section in place of the T33 - change 3 components?
You could make a Bassett/Coffin transmission line sub - see t-linespeakers.org or dipole like this one http://mitglied.lycos.de/MundU/audio/dipolsubwoofer.htm |
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mullmuzzler Introductory Contributor
Joined: 20 Sep 2005 Posts: 6
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Posted: Wed Sep 21, 2005 11:58 pm Post subject: |
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The link doesn't work...
Any more suggestions, please?
mullmuzzler | OSSMT _________________ Chance favours the prepared mind. |
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ColinR Über Contributor 1000+
Joined: 31 Jul 2004 Posts: 1175 Location: Staffordshire
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SoundAsAnOldEngineer Introductory Contributor
Joined: 06 Oct 2005 Posts: 7 Location: Devon, UK
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Posted: Fri Oct 07, 2005 1:14 pm Post subject: |
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CS1A was the KEF design for a Ref. 101-like loudspeaker with front mounting B110B. CS1 was equivalent to LS3/5a with rear mounting B110A. I have the crossovers from CS1A, and I could sell you these if you want. However, I think you need to consider the size of the enclosures for the B110B units - they appear to be huge. The crossovers for Ref 101, LS3/5a etc. attenuate all of the audio range except for the bass. This accounts for the poor sensitivity (83 dB/W/m), and the relatively good bass extension. With your larger enclosures, this bass emphasis will be unnecessary, and will give the wrong response and unnecessarily low sensitivity. Also, don't use crossovers for much larger cabinets, because much of the crossover complexity is there to compensate for cabinet diffraction effects, and these depend critically on cabinet dimensions. |
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proffski Über Contributor 1000+
Joined: 22 Aug 2003 Posts: 1297 Location: Tewkesbury UK
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Posted: Fri Oct 07, 2005 7:29 pm Post subject: Re: KEF Constructor Series - Long time started, time to fini |
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Try Falcon Acoustics.
What is the internal volume of the box?
The 'Q' will be wrong if too large.
If I have the time I could run the predicted performance through my simulator programme if you like.
Must admit the boxes look nice, mine are about the same size, but internal volume has been kept down to about 8.5 litres by using lead sheet and bitumen layers. The whole thing is HEAVY!
Good Luck! |
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mullmuzzler Introductory Contributor
Joined: 20 Sep 2005 Posts: 6
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Posted: Mon Oct 17, 2005 3:45 pm Post subject: |
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They are bigger cause there was a plan to make active preamp for each of them, but that'a another story... I think that the volume is around 8.5 l, as you said... Here are the pics (sorry for the quality, it's my cell phone camera, my digital is not available at the moment)...
mullmuzzler | OSSMT _________________ Chance favours the prepared mind. |
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mullmuzzler Introductory Contributor
Joined: 20 Sep 2005 Posts: 6
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Posted: Mon Oct 17, 2005 3:48 pm Post subject: Re: KEF Constructor Series - Long time started, time to fini |
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proffski wrote: |
What is the internal volume of the box?
The 'Q' will be wrong if too large.
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What's 'Q'? Sorry for a probable beginner question... _________________ Chance favours the prepared mind. |
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proffski Über Contributor 1000+
Joined: 22 Aug 2003 Posts: 1297 Location: Tewkesbury UK
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Posted: Tue Oct 18, 2005 9:28 pm Post subject: Re: KEF Constructor Series - Long time started, time to fini |
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Oh my!
The dreaded Q parameters...
Q - Qtc - Qts.
Have a look here: http://www.geocities.com/kreskovs/Box-Q.html
The ideal Q for most enclosed loudspeaker designs is around 0.7 to 1.0.
I could fill several pages trying to describe as to what Q is.
Call it the "goodness" factor or resonant augmentation.
It is the resultant combination of all the parameters the enclosure will inherit once it is built regarding the characteristics of the driver, the enclosure size and the crossover ultimately.
Amplifier damping, but that can be ignored for the time being.
It is the total sum of the degree to which all the electrical, pneumatic and mechanical interact in the final resonance.
It would be easier to look it up on the internet via Google than let me try and explain it over the net.
Find a good graph showing the various levels of Q in a cabinet where the size is altered and observe the variance of the peak around the fundamental resonance of the system.
Ok, Qts, look at it this way, the resonance and the degree of damping, and the ability of the speaker to reach a particular SPL at the systems resonance.
In pictorial form it is not nearly so formidable! |
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