paper or plastic?

[CalgaryBlair]

Hello,

I have a 25 year old pair of Paisley Research speakers in need of repair. Paisley Research is the company formed by Ian Paisley who later went on to become one of the founders of Mirage. I have never been a big fan of Mirage but I do like my old Paisley Research speakers.

They are real wood veneer cabinets, SEAS dome tweeters and 8" Bextrene woofers (I understand Bextrene is no longer used)

One speaker has cracks in the cone while the other seems to be alright. I would however want to do both speakers as the new cone is likely not going to be Bextrene.

Some reconers have told me I should use a paper cone while others have said polystyrene. I am confused as to which way to go. One vendor even said he thinks he has a speaker but I am thinking with the speakers age I should just recone them both.


Your opinions would be greatly appreciated,

 

[annunaki]

Honestly, with the recent advancements in driver motor/suspension linearity as well as material improvement, you would be best served by using a proven DIY design with new enclosures or purchasing new ones.

Trying to rehab an old speaker when recone or replacement drivers are available is one thing, but when the components are no longer available it is time to throw in the hat (assuming you are after their original sound). Sorry.

 

[TLS Guy]

Hello,

I have a 25 year old pair of Paisley Research speakers in need of repair. Paisley Research is the company formed by Ian Paisley who later went on to become one of the founders of Mirage. I have never been a big fan of Mirage but I do like my old Paisley Research speakers.

They are real wood veneer cabinets, SEAS dome tweeters and 8" Bextrene woofers (I understand Bextrene is no longer used)

One speaker has cracks in the cone while the other seems to be alright. I would however want to do both speakers as the new cone is likely not going to be Bextrene.



Some reconers have told me I should use a paper cone while others have said polystyrene. I am confused as to which way to go. One vendor even said he thinks he has a speaker but I am thinking with the speakers age I should just recone them both.


Your opinions would be greatly appreciated,

If you recone with different material, the cone will have a different weight, and the suspension have a different comliance and the T/S parameters will be different. The speaker will then be in the wrong box. The frequency response of the drivers will also change, and so the crossover would then be wrong. If you carry out this plan your speakers will sound dreadful.

Your only hope is finding an original driver in good condition. I bet the woofer was made by Audax. It might be KEF, but most OEM Bextrene drivers were made by Audax. Look at the back for the model number and see if there is a replacement somewhere. If it is Audax, chances are good you will find a replacement, as they made a lot of them. The only problem is that I think Audax had close to a 100 different Bextrene drivers, so finding the right one might be a problem.

Post the numbers on the back and I will see what the driver was. I think all those Audax Bextrene drivers started with HD. This is a typical Audax number: - HD13B25H2CP12.

If it is KEF the number will start with SP or B.

As far as I know only KEF and Audax made Bextrene coned speakers.

If you can't find a driver, then those speakers have reached the end of the road.

 

[CalgaryBlair]

Yikes, not the response I was hoping for. They were honest however which is what I wanted.
One of the stores told me that if I were to use thier paper cones they would sound better. I found that hard to believe especially since he had never heard them.

Another told me they would sound good although somewhat more lush sounding.

I hate the idea of scraping them as they were in my opinion very good speakers. $800.00 a pair 25 years ago. I am going to pull the driver and post some pictures of the speakers.

What a fantastic resource this place is, thanks for your input!

 

[TLS Guy]

Yikes, not the response I was hoping for. They were honest however which is what I wanted.
One of the stores told me that if I were to use thier paper cones they would sound better. I found that hard to believe especially since he had never heard them.

Another told me they would sound good although somewhat more lush sounding.

I hate the idea of scraping them as they were in my opinion very good speakers. $800.00 a pair 25 years ago. I am going to pull the driver and post some pictures of the speakers.

What a fantastic resource this place is, thanks for your input!

Pictures won't help much, numbers will.

 

[CalgaryBlair]

The markings on the driver are: PL2B2 BM OB25G.

 

[irishtom]

Glue the cracks in the cones and keep on going with them.

 

[TLS Guy]

Glue the cracks in the cones and keep on going with them.

Actually that is probably the best advice if you want to keep them in service.

However be careful, as Bextrene is dissolved by a lot of glues. Bextrene is not actually a plastic.

That number has the right sequencing for the Audax Bextrene cone drivers, but I can not cross reference it. I suspect it was some type of custom OEM driver.

Bextrene was developed by BBC engineering to overcome the day to day variation of Paper cones. The first Bextrene speaker was built for them by KEF. It was the KEF B110. The date was 1967. The BBC/Rogers LS 3/5a was the result. Although this speaker had, and still has a fanatical following, the fact is Bextrene is a lousy material for a speaker cone.

The material is synthetic, but like Polystyrene an acetate polymer. It is related to wood. It has to have a doping coat to help damp it. It was produced by the Bakelite corp, later acquired by BP chemicals. They canned production as they could not justify producing such small quantities.

By 1978 the BBC had patented and developed polypropylene which is a far better cone material.

The advantages of Bextene were that it is more consistent then paper.

Disadvantages are many. It is heavy and the sensitivities of the drivers are in the very low 82 to 84 db range.

The substance resonates violently at 1.5 KHz with a very high Q. This resonance requires a steep 6db notch filter in the crossover. There are multiple resonances in the top end of the pass band and above the pass band. These are too numerous to notch and so steep order crossovers are mandatory, but do not completely solve the problem. All of this results in Bextrene drivers having a peculiar "quack" to their sonic signature.

I gave up on the KEF Bextrene drivers very quickly, and never fell victim to the enthusiasm for them.

I think you would do yourself a favor and audition some current speakers. In my view any speaker using Bextrene coned drivers is going to be outclassed by even fairly inexpensive modern speakers.

If the glue job fails, it is time to go auditioning.

 

[irishtom]

Interesting post TLS.

Many years ago I played around with the Audax bextrene woofers, I think I bought them from SRC in Dallas. I'd just read an article in Audio about first order crossovers and the extended response of the Audaxes seemed to make them a likely suspect for a project using such a crossover, I was unaware of course of the driver's resonance problems.

Anyway following Berenek's Law they were pretty good sounding speakers.

 

[CalgaryBlair]

Bump (to get to 5 posts so I can post a picture link

 

[CalgaryBlair]

woohoo last bump I can post now

 

[CalgaryBlair]

Thanks for the informative post TLS!
You can view the speakers and the driver here:
http://s492.photobucket.com/albums/rr284/calgaryblair/

I am going to attemp to glue them as suggested. I don't have anything to lose by trying.
In actual fact I will still be in the market for new speakers as I would like a 5.1 system. I likely would not find a timbre matched center to what I have currently.

Thanks again for your input!

 

[Milesrunsdownthevoodoo]

Hello,

I have a 25 year old pair of Paisley Research speakers in need of repair. Paisley Research is the company formed by Ian Paisley who later went on to become one of the founders of Mirage. I have never been a big fan of Mirage but I do like my old Paisley Research speakers.

They are real wood veneer cabinets, SEAS dome tweeters and 8" Bextrene woofers (I understand Bextrene is no longer used)

One speaker has cracks in the cone while the other seems to be alright. I would however want to do both speakers as the new cone is likely not going to be Bextrene.

Some reconers have told me I should use a paper cone while others have said polystyrene. I am confused as to which way to go. One vendor even said he thinks he has a speaker but I am thinking with the speakers age I should just recone them both.


Your opinions would be greatly appreciated,

Despite all the naysayers I believe bextrene is a very good speaker cone material. Those Paisley's are great sounding speakers with the original drivers. I have owned over 50 pairs of speakers in my 75 years and I love the sound of well designed speakers with bextrene drivers. My favorite speakers are KEF, IMF and RAM speakers, all with Bextrene drivers. As a pianist they sound very natural to me. I also like some Kevlar and a few pulp drivers. I do not care for the sound of most Polycarbonate drivers and find most to be overdamped and lifeless. I really can't stand those very underdamped Injection molded graphite or metal cone speakers.