Steve I could use some help...

7V,

Can I ask you a little favour?

 

Steve,

Don't go way... I think you can give me some specs that I am looking for...

 

Of course you can, BD.





...Is it a secret?

 

Of course not...

Since you use Bandor drivers in your designs I was wondering if you could give me the Bandor-300 specs (8 ohm) because they are not disclose in Bandor's website and I've got no answer from them to my email yet...


Thank you Steve!

 

I'm afraid that Bandor's response to emails is very slow. I'm hopeful that the changes that I'm currently discussing with Bandor will improve communications in the very near future.

The Bandor-300 is still under development. Specifications are not available yet. Some of the components are having to be re-sourced as they were just too expensive to make the driver marketable.

I have seen the prototypes and they look very impressive. They are 15" diameter so strictly speaking it's a Bandor-375. They have a spun aluminium cone (like other Bandor units) and have a very large maximum cone excursion.

I'd like to get my hands on the new drivers as much as anyone and will keep everyone posted as I get more information.

 

Steve,

They already have answered me, I'm waiting for the specs. Once again thank you.

Bendor's website mention a 300 mm cone... and I just need a 300 mm metal cone...

 

So Vasco, the paper cone on the Yammies not good enough? Oops, I forgot. Only speakers with all metal cones can sound good

Michael.

 

Very good, Michael... but good metal cones will always be better... I hope I can show you the difference between them with the Yammies... in a double blind test, that is.

"Sound good" is a very, very little ambitious expression...

My car stereo sounds good...

 

But they do need to be coated in C34 first

 

My tweeter and midrange domes are pure Beryllium...

I wish making a 300 mm Beryllium cone wouldn't be so expensive...

 

... Or C32, if C34 is unavailable.

By the way BerylliumDust, why not buy some powdered Beryllium and get it spun into a cone yourself? It's less than a dollar per gram and you wouldn't need that much. Buy a 300mm drive unit, use the existing cone as a former and there you go.

Alternately, what are the actual requirements for your bass driver? What is the cut-off frequency and slope for your midrange dome?

 

Maybe I'll give a call to Yamaha to tell them these...

500Hz @ 12dB/oct. No problem for Bandor's I believe, as they are very wide bandwith... One problem though, I'll need 90dB sensitivity and I am not sure if Bandor's 300 can cope with that.

 

90dB won't be a problem for the Bandor 300. The problems may be:

a) the diameter will be 15" (measured to half of the rubber surround) so they'll actually be Bandor 375s.

b) they're not yet available and I don't know how long it will be before they're on the market.

Unless you're really in no hurry you'd be better off looking elsewhere.

 

Steve,

If you say that the diameter will be 15", it won't do it for me...

Can you please indicate me a 300 mm metal cone (8 ohm) as an alternative... because I cannot find any, and I've been looking...

 

Sorry. I've had a brief look too but all I've found so far are some aluminium car subs that will only go up to 150Hz (which seems a bit strange).

Taking a hi-fi 300mm, if you're only going up to 500Hz, you may find that the material isn't as important as you're probably operating solely as a piston anyway.

Why is a 15" no good? What size and type of cabinet are you using?

 

Steve,

Those that I've found either don't have 8 ohm nominal impedance or don't have the necessary sensitivity...

Steve,

That would only happen if we were talking about stationary signals... we must account for the impulse response. The woofer may need to go from rest position to maximum excursion (and vice-versa) very, very quickly, and must do it so without bending and as quicker as possible...

I don't want to make any drills...