Isobaric horn + Hornresp

[Mr Evil]

How would I account for two drivers in isobaric configuration in Hornresp? Usually it's simply half Vas, leaving everything else alone, but Hornresp takes no account of Vas directly. My instincts tell me that Bl and Mmd would double, but I'm not sure.

If the answer to that is not forthcoming, perhaps someone would at least know if two isobaric drivers would increase or decrease the overall required size of the horn, or if there is any other configuration of two drivers that might decrease the horn size, or at least not increase it (I have two drivers and don't want to leave one unused).

[Brett]

Originally posted by Mr Evil
How would I account for two drivers in isobaric configuration in Hornresp?

Why would you want to? The load on each driver would be quite a bit different I would think.

(I have two drivers and don't want to leave one unused).

It's hard enough to design really good sounding horns with one driver. Practice with that first.

But to directly answer your question, go to Professor Leach's site and download his spreadsheet, that'll give you more info to load into Hornresp.

[Mr Evil]

Originally posted by Brett
Why would you want to? The load on each driver would be quite a bit different I would think.
It's hard enough to design really good sounding horns with one driver. Practice with that first.

But to directly answer your question, go to Professor Leach's site and download his spreadsheet, that'll give you more info to load into Hornresp.

I have no idea why I would want to horn load an isobaric pair of drivers, that's why I want to find out what will happen

I had a quick look at Prof. Leach's site but couldn't find any spreadsheets.

[AndrewT]

Hi,
you could shorten your horn by using the two drivers in parallel. but your back box now needs to be twice the size. Total volume might end up the same or worse.
regards Andrew T.

[thylantyr]

A long long time ago I bought sixteen 18" woofer (Eminence clones) do create an isobaric folded horn for a van but I never completed the project. I did a test box with two woofers (isobaric/horn) and it worked. Satisfy your curiosity and build a test box out of cheap wood to see what happens.

[Mudge]

Bizarrely I'd not looked at the forums for awhile, but was looking into the theory behind Tom Danley's new APB design. The APB is a very small (by horn standards) twin bass horn. The basic design is a very short conical horn, with a small mouth and throat far below Sd. Two of these horns are paired in one enclosure and both drivers use the same rear chamber.
Just for kicks I used the LAB12 parameters, 80L rear chamber, combined mouth size of 600 sq cm, 37cm path, 10:1 Sd:Throat ratio, drivers wired in parallel. The impedance curve doesn't drop below 5.5 Ohms (despite the parallel wiring) and the sensitivity stays above 95dB/2.83V till below 30Hz
The only problem is that rear chamber size, I'm going to look at other popular high X-max drivers to see what else is possible.

[gatedriver]

Mudge,

do you have more info on the APB-1 ?
I took a look at the servodrive site and at prosoundweb but didn't find anything..

i'll try to duplicate your simulation when i have time

Regards

[Mudge]

This thread on the SPLBoard discusses the APB . Other than this I have no knowledge of the APB. I have to give full credit to Tom, he is a genius, he figures out ways to use horns that most of us would never come up with

EDIT: My sims use the LAB12 parameters as provided by Eminence. I use Hornresp to simulate a single driver with a 300 sq cm mouth, then use the multiple horn option to simulate the effect of two close coupled.