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High Efficiency Speaker Asylum Need speakers that can rock with just one watt? You found da place. |
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In Reply to: Re: Horn stuff and a post back for Tom posted by Wayne Parham on July 8, 2002 at 02:21:20:
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[about the "LAB" horn]>> With that design, as it is so small acoustically even a large pile
>> has little directivity. Not caring about that, I used a hyperbolic
>> flare.That's Bruce Edgar's favorite for bass horns as well.
-----------Indeed, the LAB horn is a DIY design which is very closely related to the BassTech 7 shown on our website. The difference with these sound reinforcement designs is that they plan for a proper sized mouth, and higher compresion ratios, where the boxes are intented to be coupled together to provide the proper mouth area.
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Do you mean the woofer system or the woofer motor? I assume you mean the BT-7, which I also assume is a Servodrive bass subsystem cabinet, yes?
-----------The LAB Bass Horn is a new project which can be found at www.live-audio.com The BassTech 7 (BT7) is a ServoDrive product which has been in use for I believe about 15 years, with some related previous ServoDrive designs before that. Obviously the claim above was with the ServoDrive BT7, as this LAB subwoofer didn't exist then.
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But with an Eminence woofer, right? I like Eminence products, and they are more popular by far than my more expensive product offerings. But have you considered using any other motor for the LAB device? I am very aware that there is an intimate relationship between the motor, diaphragm and system. But there are some pretty good existing systems using significantly more expensive components. Do you really think it will be a "fair fight?" Are comparisons really warranted?
-----------While there are certainly more exotic woofer designs, the issue is that Eminence modified an existing design a good bit to allow more ideal matching to this specific horn which employs a 2:1 compression ratio and ~28Hz flare. The drivers can handle a fair amount of power, and have linear excursion past 14mm. Since the horn is folded in a snail shell manner, much of any distortion products will be acoustically low-passed by the bends in the horn. By employing a pair of drivers, power handling is quite good. By comparison, the ServoDrive motor allowed Tom to design a 3.4:1 compression ratio with a pair of 15" driven cones in the BT7. The models and initial measurements indicate that the horn should in fact mostly match the capabilities of the BT7, with some increase in distortion and power compression at higher power levels. This should still be leaps and bounds beyond what most "subs" are doing in the pro market. The low frequency extension alone puts it in scarce company, and the efficiency of 4 or more boxes will match or best most anything I know of presently on the market.
Other OEM's may in fact make a driver of their own, but the only real area to improve on is at the upper end of the power and output levels. Thermal power handling will be the biggest limiter, followed by nonlinear distortions at high excursions, which won't be seen very often in this box in sound reinforcement applications.
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Not if the performance of my device were up to it. Again, you said that you were planning to use a motor that is likely very good but that is also probably somewhat average in terms of distortion performance. There are several more expensive motors that will outperform it, and that are designed for horn loading.
-----------In actuallity it is the horn design, and PROPER parameters of the driver which make it so potent, not the driver itself. Creative design will outclass fancy parts any day. Unfortunately there are NOT many drivers with appropriate parameters for properly loading a BASS horn. Most are suited to midbass loading, or reflex use. The point is that most are scared because there are no other boxes aside from ours which have performance up to the task.
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>> why don't you think I couldn't push the envelope with an Eminence driver?I like Eminence, and particularly for their price. I think performance is quite good. But I don't think their best motors rise to the level of a comparible JBL Professional motor.
-----------The driver is of good quality. Not exotic, but very good quality, which was not readily available say 5 years ago. Both Eminence and other companies could certainly push the performance a little further in terms of power compression and maximum linearity. There was no justification for this in the context of this project, and the benefits would be relatively small where costs would more than double.
Mark Seaton
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Follow Ups
- LAB Bass Horn project - Mark Seaton 13:24:52 07/09/02 (1)
- Re: LAB Bass Horn project - Wayne Parham 17:28:10 07/09/02 (0)
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