mike_nz wrote on Tue, 05 October 2004 22:28 |
Problem!-Using generic designs for any driver doesnt guarantee good results!Especially with horn loaded enclosures!This was the whole point of the labhorn-To design the best driver possible for the required horn.
Playing with hornresp for 2minutes youl realise this.
Problems 1-Long rear loaded scoops have the inherent 'echo'delay from the two acoustic outputs 2-Lack of subsonic filtering 3-Lack of linearity due to no sealed box rear chamber-relies on driver spider(cms) linearity 4-Reactance annulling is impossible 5-Longer horn required for the same cutoff compared to Front loaded rear sealed horn.
Ofcourse a HPF deals with reducing the low freqs-but not with the linearity.
For Measurements on B1/Bzero/Labhorns see- http://homepages.paradise.net.nz/sbk1/so/ssi.htm With associated link.
Cheers!
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Hi Mike,
When I went to your link I see you say you could not find the original site for the shootout. (And yes some of the files are BIG
The original Michigan subwoofer shootout page was hosted by John Sheerin. When he graduated he lost his website and Mattie Bien was kind enough to host it.
Here is the current address-
http://shootout.mattiebien.com/As to the problems caused by combining the front wave and back wave in a sub enclosure there are some compromises made to gain the extra energy, but some people like the result.
The Bassmax speakers are easy to criticize when looking at both the impulse response and the frequency response (The hole caused in the high bass from cancellation), but when listening they sound very nice. I just sold some home speakers that use a 7" Peerless in a TL (Transmission Line) that have the same symptoms, but people love the way the bass sounds. This TL is very close to the Bassmax in some respects.
The main similarity is that the bass output from the back of the driver is a significant distance from the output on the front of the horn, never mind the length of the horn. Just looking at the actual exit points where it enters the room.
If you take those two sources and measure the cabinet at different places (an off axis polar pattern for instance) you will find that hole in the response changes to a peak, flat and then back to a hole depending on where you measure from. So the averaged "power response" to the room may be much smoother then it that one measurement shows. It certainly sounds like it when you listen in a room.
I personally still liked the LAB sub's sound better then the Bassmax. To me it sounded tighter and clearer. To the owners of the Bassmax speakers it sounded a little to sterile or as they put it The LAB sub has the "closed box" sound.
OTOH considering I was listening in a room with a fairly low ceiling and sidewalls causing lots of room modes I wonder if could really overcome my prejudice toward something I worked on and helped create.
In the end the only thing I can point to with certainty is the LAB subs went a little lower and a little louder down at its cutoff, while the Bassmax has a bump a little higher up.
For the people there anyone who could not do the woodwork to build a LAB thought the price and performance of the Bassmax was a worthy choice.