[2litre]

Hi all,

I was tinkering with Xbaffle the last couple of days.
How well does it model driver characteristics?

I plugged my system into it, uuggh, horrible! But the darn things sound nice.
I put the SI's and Augies into, super nice response curve! I thought "Does it really sound like it looks here? Am I really missing ALL OF THAT in my system!?"

Anyway, specifically the "Frequency Response (one woofer)" chart or screen.
Does this screen accurately display the frequency response relationships, like when comparing a driver of say .37 Qts to the SI Augies with their .92 Qts? Now the exact points might be different I know, but the graphical representation is correct?

So one could look at this screen and say "If I had a .92 Qts driver I would be up +6db at 40Hz as compared to what I've got now" and have it be real close to true when implemented.

R/

Jim

[hurdy_gurdyman]

Hmmm, I don't know anything about Xbaffle, but I do know the SI/Augie combo (when properly hooked up), on a 24 inch wide by 36 inch tall baffle, will get a pretty flat bass down to around 30 Hz.

Dave

[2litre]

I realize that it's a projection but if the projections are fairly close it makes a great tool.
Its inner workings are locked with the roll off slope set at 2nd order (I guess to correctly model roll off below baffle support).

I used the advertised data along with the Qes and Qms Darrel provided in a post on the Hawthorne Forums.
It graphs the SI beginning to roll off at 60Hz and the Augie beginning to roll off at 40Hz. It also only graphs a less than 1db Qts hump for the octave above Fs. And it graphs the SI down -3db at 35Hz and the Augie down -3db at 25Hz.

That sounds pretty close to what you're experiencing Dave.

When I modeled one of my two systems (don't have any idea the T/S of the other mutts drivers) it showed me a roll off point of just under 300Hz and a -3db point of 65Hz, hence the comment "Am I really missing ALL OF THAT in my system". And as bad as that sounds, the system actually is very pleasing to listen to.

But what if...........

R/

Jim

[hurdy_gurdyman]

I used the advertised data along with the Qes and Qms Darrel provided in a post on the Hawthorne Forums.
It graphs the SI beginning to roll off at 60Hz and the Augie beginning to roll off at 40Hz. It also only graphs a less than 1db Qts hump for the octave above Fs. And it graphs the SI down -3db at 35Hz and the Augie down -3db at 25Hz.

That sounds pretty close to what you're experiencing Dave.

I have a room problem that causes a bit of suck-out at 40 Hz where I have my baffles located, so makes my coaxial weaker there than it should be, thus the 50 Hz roll-off I've mentioned. Your figures are probably close to right-on. Individual rooms, of course, will have differing effects. The SI OB 15 Coaxial, by itself, is impressive. I've tried moving it around and once measured -3 dB in the mid to upper 30 dB's. Unfortunately, it was not a good spot to put a speaker (I wish to remain married, so chose to move it.) It sounds and measures best well out into the room. This is best with bigger rooms. Smaller rooms are a compromise, though may improve with the right room treatment, but they still sound quite good. I'm real happy with mine, though I do have some corner treatment in mind.

Dave

[Rudolf]

I was tinkering with Xbaffle the last couple of days.
How well does it model driver characteristics?

Hi,
nice to see the usual suspects all meeting in this place too. 
While it´s questionable whether we need another loudspeaker forum for discussion, this seems to be the first one exclusívely committed to OBs. So maybe it is a good choice to concentrate that issue in this place.

Let me jump right into the pool:
I have compared the same OB with the same driver in Xlbaffle and in MJKs OB worksheet. The OB is presented in www.dipolplus.de/thema9.htm#03 . Driver is the Ciare 250 with the specs from the Ciare home page. Because Xlbaffle does not account for listening distance, I put that in the worksheet to 10 m. The distance from OB to front wall is 50 cm. Since MJKs worksheet doesn´t expect any side wall, I put the side wall distance in Xlbaffle to 10 m.



While Thorstens Xlbaffle has been a great help in the past, he would readily admit that MJKs worksheets are quite more sophisticated.

To give you a guideline how big the influence of front wall reflections is, I have simulated the same OB with (blue) and without (red) those reflections:



The boundary conditions are different for this sim (more front wall distance, less listening distance). So don´t get disturbed by the different FR curve.

Adding everything up - MJKs OB worksheets are some big improvement on that XLbaffle.xls

Rudolf
www.dipolplus.de