DIY upper-mid horn design help.

[turk 182]

not quite sure what all your doing but gaining spl @ 1kz while increasing the rate of roll off above that sounds correct.
i thought you wanted a higher frequency not more spl?

 

[klampykixx]

yes i do. i cant seem to improve upon the upper extension. ive played with all the dimensions now and i can get it quite peaky, but cant get it to rise above the 1k mark. the 2k mark is 6db down at best.

i just checked the specs on my tweeter, which is a selenium D220ti, and they claim to have a response of 1k-21k.

ill post a pic of what i have in a sec.

 

[klampykixx]

here is what im working with atm.

 

[klampykixx]

the two different black lines represent one woofer, vs two and then the tweeter.

the cabs are dual woofer cabs, so i figured id put both up.

 

[turk 182]

the traces aren't labelled so which one is which?is the one with the narrower bandpass the single or the double?

 

[klampykixx]

Same sim just one driver vs two.

 

[turk 182]

so which has the narrower bandwidth one driver or two?

also in doubling the drivers is there a partition between the two drivers?

 

[klampykixx]

Lower line is one driver. Top line is two drivers

 

[klampykixx]

I was told by Mr mcbean that if I simulate the horn and then mark it as two drivers in parallel that the response would be as if two horns exist and are measuring the total response.

 

[turk 182]

thank you for clarifying the trace confusion.

so in doubling or "marking as two drivers" does hornresp assume one larger horn or that there's a divider between the two parallel stacked horns? i'm trying to envision the construction of this mt 130 with 2 12's

 

[klampykixx]

just to clarify further, this isnt my MT130 in question.

its an all new box to fill the gap between my MT130 and my tweeters. hence upper mid.

i have settled to let the MT130 be, as its satisfactory, i just need a couple more.

 

[turk 182]

ok got you not an mt 130.

 

[David McBean]

just playing with hornresp at the moment. playing with the VTC measurement, ie: increasing it, ive actually gained output upto 1000hz, but the dropoff is steeper. what am i actually changing there?

The throat chamber acts as an acoustical low pass filter.

Increasing the volume Vtc will lower the upper rolloff frequency. Try doubling Vtc from 120cc to 240cc in your design, to see the effect.

 

[David McBean]

Lower line is one driver. Top line is two drivers

Not sure how you generated the lower trace, but just to clarify - the top trace shows two SPEAKERS in parallel, not two DRIVERS.

 

[David McBean]

I was told by Mr mcbean that if I simulate the horn and then mark it as two drivers in parallel that the response would be as if two horns exist and are measuring the total response.

For the case you are referring to, I actually said speakers, not drivers .

http://www.diyaudio.com/forums/subwoofers/119854-hornresp-304.html#post3286857

It is important to distinguish between multiple drivers and multiple speakers, as defined in Hornresp.

One horn loudspeaker with multiple identical drivers - multiple drivers.
Multiple identical horn loudspeakers - multiple speakers.

Note that each of the multiple horn loudspeakers can also contain multiple drivers, if required.

 

[David McBean]

so in doubling or "marking as two drivers" does hornresp assume one larger horn or that there's a divider between the two parallel stacked horns? i'm trying to envision the construction of this mt 130 with 2 12's

"Two drivers" in Hornresp means that the specified horn has two drivers.

"Two speakers" in Hornresp means that there are two of the specified horns in close proximity to each other.

 

[turk 182]

thanks for the clarification.
i'm by no means a hornresp ninja.

 

[klampykixx]

Thanks for the clarification David.

I'm at the point of trying to work out how to plot out the physical horn.

So far I've got throat dimensions, horn length and mouth dimension. Can't for the life of me work out how to plot out the curve when the top n bottom are flat but tapered, and then also having a phase plug in the center.... Do I just run a straight square post right to the mouth or go pyramid or something different... I'm a little lost on this step.

I read that a typical expo horn is at y=2x but I couldn't put that on paper while accounting for the other two parameters.

 

[turk 182]

well i'll be following along cause i need to figure out how to do this in hornresp as well...

 

[klampykixx]

Can a phase plug be constant size and run right to the mouth of the horn?