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In the Forum: Horn-Loaded Speakers
In the Thread: Good midbass is complicated, if not unobtainable.
Post Subject: Midbass HornPosted by Jorge on: 9/7/2013
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Hi Gera
"Has anyone done this and what were the observations of comparing different topologies."
I have done just what you propose, I tried the JBL2490 compresion driver with a 3" mouth in a 110 hz horn well made, MDF round tactrix horn, it goes nicely down to 200 hz, I run a couple of test tones with no xover and the most the horn would load it was to 200hz, I was looking mainly for a response to match the compresion driver on top, crossing at 500-800 hz, The sound in that frequency was clear and transparent, not as dynamic as I would have expected, which could be a good thing. The tone of the lowest frequencies it made was not too full or rich, it was actually pretty bland, I had to cut the bass drivers a little higher to fill out the response. If you play it without a woofer under it you will clearly miss part of the music, even a string quartet it will sound thin.
Certain female voices were phenomenal.
I had tried before that a lot of 8 inch to 10" paper cone drivers in a similar horn, round tactrix 110 hz MDF horn with recalculated throats for each driver. The difference was obvious, the compression driver was more detailed but would go no lower, the paper cone driver would go much lower, down to 110-120 hz: Now the difference between 120 hz and 200 hz is a big one (even 150hz) there are so many thing happening at that range that most instruments and voices get "cut" in their response and the lower registers have to be played by the woofer. This creates a step in which the horn is playing one part and a woofer solution, which ever you have, will play the rest of it ussualy with a very different tone and speed (if I may use the term). You can tell. Now if your horn makes it down to 120-110 hz this small diffference makes for most of the instruments and voices to be played more by the horn, the step gets minimized and the performance is much better.
Then I tried the Studio 8M, it is the best of both worlds, it plays clearer and more transparent than the compression driver (2490) and it goes even lower than any other paper cone driver I tried, with a great tone.
I tried an coupple of arrays. One had 16 woofers, 4" aerogel small woofers per side in a sealed cabinet: The sound is indeed very strong and punchy, the efficiency goes pretty high to the point that I was moving them with a 1.5 watt amplifier, but it did better with more watts. This array would go lower down to around 70 hz. The quality of the sound, to non horn user was amazing (a close friend kept them for himself) but when comapred to a "well made horn" it became slowish, undefined with a darker tone. When I changed to the 120 hz horns it was like turning the lights on.
I also tried a bigger array of 5 woofers per side each being 10". It would not compare to any of the above at the 500 hz frequency. I finally had it playing from 27 hz down in a Infra sub configuration with a Marchand active xover: WOW! that was very nice...
All the Best
Jorge
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