KEF B139

[TheBaronGroog]

Bought a pair of these on ebay and have finally gotten round to pulling the TS parameters off them using WT3 using the added mass method. Forgot to bring the TS spec in to work with me-doh, but did notice a few oddities:
One's impedence was about 15% higher than the other
The surround on both seemed to be a bit hit and miss where it was glued to the chassis-all glued solidly, just not uniformly, so the "bulge" of the suround is glued to the frame in some places-is this normal? If so I wouldn't say it spoke well of their construction quality!
Both of them ring like a bell if knocked with your knuckle-fundamental at about 250Hz, well out of the range I'll use them at but concerning none the less-anyone else noticed this? I'll proably just deaden them with some dynamat for peace of mind

I'm looking at running them isobarically so will build a baffle to go between them-wire the coils in parallel (as the drivers will be hooked to my amp) and re-measure to get the T/S as "one driver"-couldn't do this last night.

Anyone any ideas on whether it's worth trying to remove the souround and re-glue it? Looks like a bit of a PITA due to the deep outer flange on the basket.

[metako]

I would be interested in seeing the parameters you arrived at as I have these drivers too.

[soundalot]

Which sp# do you have? The t/s parameters are available from old KEF spec sheets.I am sure someone in diy audio has them. Hopefully the B 139 are sp1044. As usual it is best to get the t/s parameters yourself. I found an on line history of all sp# of KEF B139.Don't remember where.

[TheBaronGroog]

I'll check them tonight, I'm not sure they are the SP1044-I've had them close to a year and did try finding the specs when I got them and couldn't so purchased the woofertester in PE's Thanksgiving sale.

Looking at this link:
http://www.kef.com/Resources/KEFUnit...0Issue%202.pdf

I'm pretty sure my drivers are the earlier, unpictured, model. The have a round motor with the brass screws seen in the B110 type 6362 picture futher up the article.

I'll publish the specs I've pulled off them tomorrow

[planet10]

Originally Posted by soundalot

Which sp# do you have? The t/s parameters are available from old KEF spec sheets.I am sure someone in diy audio has them.

TL Links

As usual it is best to get the t/s parameters yourself. I found an on line history of all sp# of KEF B139.Don't remember where.

Typically taken with very low voltage they'll be different than factory (that typically use higher drive levels), you end up with another point on the T/S curve.

dave

[TheBaronGroog]

Originally Posted by planet10

TL Links
Typically taken with very low voltage they'll be different than factory (that typically use higher drive levels), you end up with another point on the T/S curve.
dave

Cheers, not the driver pictured there, mine has all round motor structure.

As I can't find sepcs on mine I'll just have to go with WT3's results

[planet10]

Originally Posted by TheBaronGroog

I'm pretty sure my drivers are the earlier, unpictured, model. The have a round motor with the brass screws seen in the B110 type 6362 picture futher up the article.

Thanx for that doc, haven't seen it before.

Both major types of B139 are pictured in the doc. The older ones have the non-sdonized racetrack frame. Newer ones have the black shaped frame.

dave

[planet10]

Originally Posted by TheBaronGroog

Cheers, not the driver pictured there, mine has all round motor structure.

You are going to have to post pictures.

dave

[TheBaronGroog]

No worries Dave,

So you'd say mine is the SP1044?

[TheBaronGroog]

Will take some snaps tonight