Transmission Line with 8" Bass Driver?

[TLS Guy]

TLS Guy, I was just about set on using SEAS CA22RNX as my bass unit, then I saw that the distributor for SEAS here also carries Volt, which is what PMC uses in their larger monitors. Can you offer any advice on this front? I've played around with the idea of using one of the 8-10" units as my bass driver, possibly using the 8" midbass in a two way, or even going crazy and using the ribbed 12". They seem to have a very good reputation, but so does SEAS.

Volt drivers are not well know here, but they are in Europe where they are held in high regard.

If you want a 10" volt driver then this is the only one suitable from Volt.

For 8" then this one will work, or better this one.

The Usher could work, but it has a high Vas, so you will have a large enclosure. As Fs goes down, and Vas goes up, your enclosure size will go up.

Another thing you have to understand, as Fs goes down which allows deeper bass, you often have to use two drivers, as you can't make a practical line without using two drivers to keep Vas in line.

I use two of these in my deep bass lines. T/S parameters are perfect. The lines take a lot of real estate as you can see in my signature. Also these drivers have a very difficult acoustic response to work with. However the crossovers involving these drivers are active, which makes tailoring the response much easier.

The other issue in using a larger driver, is that you end up with a wide cabinet. In order to overcome the problems created you end up with a very complex design and difficult build, again as you will see in my signature.

Funnily enough for your purposes, the very best driver is a vintage one, the KEF B139. The parameters are perfect and you can you can use one or two. Since the drivers are oval you end up with a narrow cabinet. For your purposes this driver is better than all those mentioned above, unless you want a no holes barred design like mine.

Here are KEF B 139s in my rear dual lines.

The front mains are also dual lines.

It would be helpful to know how big and enclosure you are prepared to tolerate.

 

[hulminator]

As big as it needs to be. I have 7 x 4 sheets of mdf, but can get bigger if necessary.

edit: also, the Volt links are dead

 

[TLS Guy]

As big as it needs to be. I have 7 x 4 sheets of mdf, but can get bigger if necessary.

edit: also, the Volt links are dead

The Volt links work for me. I have no clue why they don't work for you.

 

[its phillip]

The volt links all link to their "about us" page, not any specific driver information. I think that's what he means by them being dead.

 

[hulminator]

They all just link to the "about us" page. Another question; as I've been pondering the designs, it seems that many of the drivers have quite low resonances. Do I have to tune the QWT to the resonant frequency of the speaker, or could I go a little higher to get more output in the musically "useful" range

 

[TLS Guy]

They all just link to the "about us" page. Another question; as I've been pondering the designs, it seems that many of the drivers have quite low resonances. Do I have to tune the QWT to the resonant frequency of the speaker, or could I go a little higher to get more output in the musically "useful" range

So, they do.

You need to look at the Ls 201 for 8" which is the best bet or the BM 220.8.

For the 10" the B250.8. For 12" the RV 3143. Fs is only 34 Hz though, so you will need a sub for the deep stuff, like the PMC has to have. If you don't want to have to use a sub, then the SEAS I use and referenced above is your driver. You can get to 23 Hz with a couple of those drivers and in fact with room gain F3 is 20 Hz. I can assure you, no sub required!