Comments on bass horn sim in horn response

[mike.e]

Thats still a large horn slowmotion : Id consider one with half the mouth area,and correspondingly less path length.

The beta8 is probably quite cheap too!

Otherwise id go car audio 10"

[paulspencer]

The biggest problem I'm having is IMO "compression ratio!" The designs seem to call for a very small throat, ie 10% of SD, which is a compression ratio of 10 right? As far as I'm aware, this is too high! Make it closer to SD and the response is no longer flat!

How high can I go in compression ratio?

What are the problems if I go too high?

[slowmotion]

Hi

Originally posted by mike.e
Thats still a large horn slowmotion : Id consider one with half the mouth area,and correspondingly less path length.

You'd get a smaller horn, but also more ripple.

Originally posted by paulspencer
The biggest problem I'm having is IMO "compression ratio!" The designs seem to call for a very small throat, ie 10% of SD, which is a compression ratio of 10 right? As far as I'm aware, this is too high! Make it closer to SD and the response is no longer flat! :

Huh?
SD on the Beta 8 is 214 and the throat in the example is 100. That's not what I would call high compression ratio.

cheers

[paulspencer]

Jan, I was referring more to the results I get from the "Hypex designer" feature. I tend to find better simulated results also from a high compression ratio. I'm trying to find out what my limits are here ...

even the example you gave has a compresssion ratio greater than 2 which I thought was considered a safe limit, unless I got it wrong.

[slowmotion]

Hi

Paul, then I misunderstood

Re the "Hypex designer" feature, well,
better to start from scratch when designing horns, I think....


cheers

[paulspencer]

Jan, so how do you "start from scratch?" Do you have some rule of thumb guidelines to start out?

[GM]

Greets!

10:1?!!!!! Altec compression drivers are this high and look at the construction/horn size required to get a 500 Hz/2nd order Fc. Extrapolating to 40 Hz would require a motor hoist to put in position and turn a large personal fortune into a small one to make.

In the 'good ol' days', horn drivers/lens were initially designed as theoretically ideal full size exponential since sound pressure is exponential (1/f) and if it was acoustically long enough it generated a smooth response over the desired BW with a second order roll off at both ends once reactance annulled. If it was too long or there wasn't a suitable driver or it had too much gain and/or BW for the app, a 'slice' of it was used that best met the performance goals with the desired driver(s), ergo the early truncated designs from Altec, etc..

Anyway, in today's 'techo world' Leach's math will give you your answers. Remember, any driver can be optimally horn loaded over some BW at some efficiency, so the main question is, does its specs meet the needs of the desired performance goals? If not, use his math to find the ideal driver and if it doesn't exist in this reality, then find the closest to it and sim how much it compromises your goals, etc.. At least you won't have to actually cobble together/measure an old chicken coop full of proofs-of-concepts like I did to get yours.

GM

[slowmotion]

Hi Paul, all

Here's a link to a webpage by John Sheerin:

http://ldsg.snippets.org/HORNS/design.html

The page has further links to Leach's page.

cheers

[mike.e]

Its interesting how the equations reccomend often,a high compression ratio which isnt normally practical.

Biggest basshorns
http://www.geocities.com/xobt/bassho...rns.htm:smash: