[versus rider]

Hi all, having run my open baffles for some time now and now added compression driven horns for mid and hf, or as I prefer to call it high and ultrahigh, that is from 1KHz - 5KHZ and 5KHZ up. I now want to improve what I call my mid driver, a direct radiator from 200Hz - 1KHz. I was interested in Scanspeak drivers but the qts is only around  0.33. Is that high enough or do other factors come into play to make a driver suitable for open baffle.

[JohnR]

I'd suggest downloading Unibox and putting the driver's parameters into it. Use a closed box with a very large volume (e.g. 10,000L) to see the response in a very large (in effect) baffle.

The Edge will tell you what the effects of your actual baffle are. Combined you should get a fairly good idea of how the driver on the baffle will behave. Enough to decide on whether to go with a particular driver anyway.

Whether or not you intend to use EQ will play a part as well.

[versus rider]

thanks John, I am reluctant to download any more software as my pc already has far too much. I am running a DEQX so eq will certainly be used. Just some basic parameters that tend to work in ob will suffice, i.e qts etc

[mcgsxr]

If you search this circle, you will come across some discussions from the past around parms for good subs for OB, but I don't recall a midrange discussion.

For subs, a focus on the combinations of low FS, QTS near 0.7, and decent XMAX are the usual.

For mids, I would think you would want efficiency similar to your tweeters unless you intend to biamp.  The FS would not be critical, as I am sure it will fall well below your 200Hz target.

[JohnR]

thanks John, I am reluctant to download any more software as my pc already has far too much. I am running a DEQX so eq will certainly be used. Just some basic parameters that tend to work in ob will suffice, i.e qts etc

Which driver is it that you're looking at?

[versus rider]

I have been leaning towards Scanspeak drivers, they have a very flat response in the band I wish to cover but a low qts  around 0.34. They don't show xmax. I am tri-amping and running DEQX. Here are the parameters for one particular driver: Scanspeak 22W/8534G
8 Ohm, Re: 5.8, Le: 0.71, fs: 26, qms: 5.04, qes: 0.37, qts: 0.34, Bl: 8, Mms: 24.7, sd: 235, vas: 118.
most of these figures are very close to the supravox 215GMF, that I believe is good for ob.

[JohnR]

Hi, here's the modeled response of that driver in a large sealed enclosure -



Since you are crossing at 200 Hz, the low Qts really looks like a non-issue. However at 200 Hz and the rated 70W power you are driving it to around 1mm excursion - I can't help wondering if you might want to look into drivers with a higher Fs/sensitivity.

[versus rider]

thanks John, yes the spl is 88.8 not that sensitive and when combined with horns of 118db and 113db you are no doubt right. Although that is not such an issue as the DEQX and tri-amping sorts that. Actually yesterday I had a day of listening before working last night and the system was sounding very good indeed even with rock. Which I had felt before wasn't really suited to rock. But then I had another play with the DEQX, thought I had cocked it up, but set a new configuration with different crossover points but find the original crossover points better as I think I have used different slopes this time. Still really trying to get to grips with the software. Maybe I just need to listen to music for a while and stop messing with it. 

[panomaniac]

FWIW, the Seas Prestige A26RE4 10" makes a great midrange on OB.  Easy to do crossover, too. (like none, at the simplest)

A fairly expensive driver, but a very clean one.  Very easy to use and get great results.  Worth a look.  See it in action here near the bottom of the page:
http://www.hifizine.com/2010/06/lone-star-audio-fest/