Is anybody familiar with volt B220SS 8" woofer

[jez]

Hi all,
I have just been given some home made PA type speakers of unknown origin which seemed incredibly heavy for their small size, the woofers (2 per cabinet) looked to me to be more like hi-fi drivers than PA types as they have long throw roll surrounds. Anyway, I decided to strip them down and found , to my surprise and delight, that they are indeed hi-fi drivers, Volt B220SS 4Ohm to be precise, which I believe are quite high-end drivers. I rang volt loudspeakers, who were very helpful, and confirmed that they are for hi-fi applications but that they no longer make them , they told me the most important of the TS parameters over the phone but can no longer supply data sheets/full specs for them...
Can anybody tell me a bit more about what exactly I have here?,
has anyone used these themselves?, do they have a good reputation?, does anyone know of any published designs/projects using them?.
It could be interesting to build a pair of cabs for these using them in D'Appolito form, active, with an amp for each driver but allthough I am an audio electronics engineer, my experiance is in amp design and I've never tried to design a speaker before I would wish to avoid spending loads of time/money on something that turns out to be awfull !, so any info from you more experianced types would be great

[ShinOBIWAN]

All I can say is, lucky bas***d!

The B220.2 is the direct descendant and modern equivalent of your B220SS.

The B220SS is a well respected speaker although its design must be nearing at least 20 years old, this doesn't matter though, the tannoy red & golds are proof enough.

The only advice I can give you is that they must be used in ported enclosure. Virtually all Volts have this requirement and to use them in a sealed one is a waste of driver.

How many of these do you have? Is it 2 or 4, if it is 4 then re-read the first sentence in this post

[pinkmouse]

You lucky ^%$&(*&^*&!

Do some reading on Transmission Lines, they are perfect for the Volts.

[jez]

Yes I have four of them ! one appears to be newer than the others and so I assume it has been a replacement at some time but beggers can't be choosers eh!?......just wish I knew a bit more about what to do with them, I reckon I'll have to re-read that Vance Dickason book I bought a few years back

[ShinOBIWAN]

As PM has said, look closely at transmission lines.

PMC use volt drivers in some of their TL subs and speakers.

Also take a look at Martin King' MathCAD worksheets which allow accurate simulartion and modelling of TL enclosures. A google search will come up with the goods.

Once you've decided on an enclosure come back here with some proposed designs and something more specific. If you do model the TL lines get some grabs of the output graphs from the worksheets so we can tell you if your on track or not.

I'd model one for you now but I don't currently have MathCAD installed. If you get really stuck give me a nod and I'll knock up something rough for you.

BTW: My suggestion would be to house the volts within their own enclosure and then build a book shelf model to sit ontop of this.

[KBK]

I've got a pair I've been trying to dump..and nobody wanted them.

[jez]

Hmmm...transmission lines?, I have never liked the sound of them, based upon my recollection of IMF's and even TDL's they have a slow bass, although not boomy or anything, the extension is impressive, but the bass doesn't seem to be from the same track as the rest of the song!
Apart from that, there is the fact that I have never tried to build a speaker cabinet before and doubt that I have the woodworking skills to build a TL. Also I dont have mathcad and wouldnt know what to do with it if I did!, like I said, I'm an absolute beginer with loudspeakers.
Having looked at the spec sheet for the more modern B220.2 it seems to suggest that they are only suitable as a fundamental bass driver and not as a bass/midrange unit, is that the case?.
My favoured bass type is infinate baffle as this seems to give the tightest most natural bass and appeals on an engineering basis (I've always been amazed that reflex speakers can sound as good as they do...), Volt say that they are suitable for a sealed box of 15 litres with plenty of foam stuffing in them and that this gives -3dB @50Hz with a Q of 0.5, could I therefore put two of them in a 30 litre box for greater extension with similar Q or am I just showing my lack of knowledge here
If it has to be reflex then Volt suggest a 30 litre cabinet with a 5 x 9 cm port, lightly stuffed, should give -3dB @ 40Hz (no Q given) which sounds useful. Again, what about two drivers in one cab?, if this is feasable how do I work out port size?.
The only data I have for the units is as follows: 88dB/W, resonant F = 26Hz, frequency range=26Hz-1.8KHz, Qe=0.27, Qa=1.45, Qt=0.23, Vas=93litres, Xmax=4.75 mm, Re=3.2 ohms
these figures are apparently for the 8Ohm version but the chap at Volt said the 4Ohm units I have should be virtually identical.
I would prefer to use them as bass/midrange drivers as I don't have any midrange drivers to hand and don't relish the thought of trying to get the crossover right for a 3 way, even though they will be active.