SpeakerTalk

cball · Posted: Tue Jan 09, 2007 9:47 pm Post subject: Rebuilding KEF CS project

Greetings everyone!
So glad to have found such a fountain of knowledge on Kef products. I'm new to this site and have little speakerbuilding experience. I have inherited what I believe is a CS5 project from my former longtime neighbor. It was a build he completed years ago but his custom cabinets have seen better days and one passive driver is unfortunately missing.

The parts list now consists of T33A-SP1074's, B200G-SP1075's, one BD139B-SP1082 and SP2016 crossovers.

My plan is to refurbish the cabs, locate a replacement BD139B passive driver (missed a pair on ebay recently for $11.50!) and reassemble his original project. In the meantime I have a pair of Energy Pro 22 cabinets that I've adapted to suface mount the drivers in a 2-way configuration for the time being. Because I'm lacking in the technical end of DIY I hope I can get some help fom you good people with a few initial questions as I proceed. I have tried the search function and come across a DEBUG error.

Questions:
1. The cabs for for the temporary 2-way are 24 1/2"x10 1/2"x11 3/4" in 3/4" particle board. What is the formula for finding total litres of volume and how suitable is that volume for this configuration?

2. The cabinet is vented and I wonder if it's ok to leave it so to gain some bass response missing without the passives, or is sealed more suitable?

3. At some point when they were stored in his workshop one of the tweeters looks like it picked up a lite coat of sawdust. I've tried to remove what's on the fabric dome with some adhesive tape with no success. I'm very wary about using anything that might cause damage on any future attempts so any knowledgeable suggestions would be great.

Any other opinions or suggestions would be greatly appreciated.

Regards,
George

ColinR · Posted: Tue Jan 09, 2007 11:20 pm Post subject:

I don't do woodwork Sad

, otherwise my collection would be much bigger Shocked

, but here are a few answers.

1. The CS3 desiign is on the web site, use it for the B200G & T33.

When you find another SP1082 you can cut a large hole in the base of the cabinet and convert to a CS5 by adding another box.

2. Lack of bass with a Caprice II which has the same crossover as CS3 but different topography and the Ref 103 which has the same totat bass section inductance but one resistor is different to CS3 in the treble section, is usually catered for with a sub woofer.

3. The fabric dome is not amenable to chemical cleaning, so if it doesn't come off with an old toothbrush, it's permanent
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cball · Posted: Wed Jan 10, 2007 5:27 am Post subject:

Thanks for the reply Colin.

Let me clarify my post:

1. I am actually cosmetically refurbishing an existing set of enclosures built for the CS5 setup and not building new as I am also not capable as such.

I'm temporarily using another set of cabs that are 24 1/2"x10 1/2"x11 3/4" in 3/4" particle board to house drivers in a 2-way CS3 configuration while I work the other issues for an indeterminate time.

What I was wondering was what's the formula to calculate the litre volume of a box of those dimensions, and if it is suitable for those drivers, or need to be modified.

2. Since the temporary cabs are a vented design, how will it affect the bass performance of these speakers? Should I go sealed instead?

3. I will try the toothbrush route. Any thoughts on alcohol or a damp wipe with plain water?

Thanks

speakerguru · Posted: Wed Jan 10, 2007 2:20 pm Post subject:

Multiply the three INTERNAL dimensions together to get the volume. Might be easier to convert the dimensions from inches to cm first (multiply by 2.54). The answer will then be in cubic cm (cc). Divide the cc by 1000 to convert to litres.

speakerguru · Posted: Wed Jan 10, 2007 2:28 pm Post subject:

Re toothbrush treatment, I wouldn't if it were me.

Don't touch the dome at all if you can help it. I assume the sawdust is very light and the problem is just a visual/cosmetic one. The dust won't affect the moving mass, but if you poke the dome around too much it will change the internal damping of the cloth and you run the risk of permanent damage to the cloth/voice coil joint. If you're really rough you could deform the coil out of round and then get buzzing.

cball · Posted: Wed Jan 10, 2007 6:37 pm Post subject:

Thank you for the formula and your take on the dome cleaning issue.
I have yet to determine if there is an audible affect on the sound, or if it's strictly cosmetic. I'm still in the process of getting them to the ideal state, by resolving the issue of volume and whether to seal the vented cabinet.

George