horn loading project

[mazurek]

I just finished my active crossover speakers, and will be writing a brief report soon.

Anyhow, yesterday some guys came over to play speakers. This onen fellow brought over some large diameter full ranges that imaged real well compared to mine, but required a very small listening area.

I was wondering if horn loading might aid in my imaging abilities. I left a space for a notch filter in my crossover, and was thinking about horn loading the tweeter. I have an mcm horn.

It would help me experiment much faster if I could order parts and try, I'm getting from zaph's measurements that I would need a notch with Q=0.8, fo=2500 Hz, and -6dB. This is just from his graphs.

Also, am I on base by thinking a waveguide will enhance stereo imaging?

[Carl V]

I dunno about the 'enhancing the imaging....it is supposed to enhance
directivity amongst other electro-acoustical properties. I own some SP
Tech speakers AV-2 Presence (large MTM stnd mount, two different XOs).

I have found that directivity & set-up are different than many other
MT & MTM speakers that I have or had. Mostly positive. These paticular
speakers have nice imaging, good lateral sound staging somewhat foreshortened stage depth...that 'U' shaped sound stage...those elusive
back square corners aren't as noticable.

I've heard Summa speakers on two occassions. Imaging was good as well.

An aquaintance has some pretty Zingali speakers....Horn/guide. Forward soundstage with tight imaging.
He also has some Triangle (tweeter in a shallow guide) Imaging is good.

[mazurek]

Thanks for the reply Carl. That reinforces my suspicions this would be a worthy project, at least to try.

My speakers image pretty well, and the crossover is in phase, but I figure horn loading will both better control directivity, and allow me to use a shorter analog allpass delay (shorter allpass delays have less phase effects in the crossover region).

I'll try and post more info to this forum later regarding my projects, seemingly to share my experience, but with the selfish intent of making my system better from feedback.

[BobEllis]

Were your friend's speakers placed the same as yours? If not, you might try treating the wall to control the first reflection. I discovered the effect of a too close first reflection quite by accident and controlling it really tightened up the imaging.

I'm also about to embark on a Zaph-esque waveguide tweeter active XO project. Instead of a notch, I plan to use a 6 db shelving high pass filter. Like baffle step compensation on the other end of the spectrum, it will boost the top end to compensate for loss of waveguide loading above 4kHz. See Linkwitz for the schematic and equations. It's easier to calculate and has a lower parts count.

[mazurek]

Thanks for the reply Mr. Ellis. You know I think we are working along very similar lines judging from our projects. Sorry about faking you out about my power supply, I'm slightly afraid to post it because the collaboration went sour. However, check out the muting circuit I'm using which is pop free, can hard switch the power on or off:

http://www.diyaudio.com/forums/showthread.php?postid=964538#post964538

BTW-please tell me if cross linking is frowned upon.


Thats clever to use a shelving filter instead of a notch. I remember last time I did a notch filter it had some simulator effects outside of its band I think due to the opamp capacitor inductor. Must be nice to be you with all your modular crossover boards, I have to use a notch. Have you added a spot for a muting relay yet, I'm using the Omron G6K, its super-small and works quite well.

The room placement was different for our speakers. I'd like to design some which are fairly room placement independent, I'm trying to design stuff that myself and regular people can live with comfortably without changing the room much. I was thinking horns might help.

Also, evidently I have some issues with the bass in my room. I will be going from one 12 per speaker to two 10's. Will it excite less room modes if I place them closer to the floor. I guess the answer from the people that know better on this forum would be dipoles with horn loaded tweeter a la AJInFLA.