Clever sub idea

[Dennis H]

I hate to admit it but it looks like John K has come up with an original idea for a sub. No details yet but it sounds like it has two woofers mounted to the front and back of a box with built-in electronics. With a switch, you can choose monopole, dipole or cardioid operation. An electronic delay and two drivers will give you a true cardioid, unlike the pseudo-cardioid of his NaO.

http://www.musicanddesign.com/craw.html

[Davey]

Dennis,

SL outlined essentially the same thing (if I'm interpreting it correctly) a few years ago.....A front/back woofer configuration with controlled time delay to one of the drivers to "reconfigure" the polar patten

http://www.linkwitzlab.com/H-U%20woofer2.htm

(near the bottom)

Davey.

[ThomasW]

I hate to admit it but it looks like John K has come up with an original idea for a sub

Ok, ok, lets not get carried away until we see some solid info.... :wink:

[Dennis H]

Davey,

I've seen SL's description before and I'm sure John has too. The novel thing is including circuits for the 3 modes of operation. I think it's actually pretty cool to be able to flip a switch and change it from monopole (bipole) to dipole to cardioid, presumably with appropriate EQ for each mode. Of course that's not totally new. (Is anything?) Some surround speakers have a switch for bipole/dipole operation.

[Davey]

Yeah, I'll be interested to see more information on the CRAW when John publishes it. It wouldn't appear to be too difficult to apply the appropriate time-delay/EQ for each mode of operation. Another job for the versatile Behringer DCX me thinks.

Cheers,

Davey.

[AJINFLA]

Original?

Um, it may not be a bad idea, and I don't want to sound like Mac :B , but "original" might be a stretch. Now granted the Meyer can't switch to bipole, but there is a slight resemblance. Again NOT bashing John. His design's have merit. But you guys might want to stray out of the "Home" audio realm once in a while, into the world of "Pro" or even car for that matter. There's some wonderful stuff out there. I plan to use both in my next design.

http://www.meyersound.com/products/concertseries/psw-6/

Cheers

AJ

p.s. - I actually like Mac - he's cool with me

[RonS]

Yeah, I'll be interested to see more information on the CRAW when John publishes it. It wouldn't appear to be too difficult to apply the appropriate time-delay/EQ for each mode of operation. Another job for the versatile Behringer DCX me thinks.

Cheers,

Davey.

Davey, I was thinking the same thing, that the DCX would do this easily. John mentions that the woofer system will have a built in 250 watt amp, which leads me to believe that it will be a plate amp. So either he has 2 of them in each woofer system (one for each woofer) or he's doing something else. Somehow the rear woofer needs a delay for cardiod. This could be done with an all pass filter, but how to do it with 1 plate amp?? I guess we'll have to wait until he releases more details :wink:

Cheers,
Ron

[Davey]

Ron,

Yep.

Also, AJ made an excellent point on the MAD forum regarding the logic of box mounting two woofers....and all the stuffing/size/construction/complexity concerns. Since the dipole configuration is probably the superior one in most instances why would a person want to do that when the elegantly simple "H" configuration exists? I don't quite see the point.

I think John K. revels in the technical challenges of projects like this, but tends to lose site of practicality often times.

Davey.

[Jim85IROC]

A few weeks ago a friend and I went to DIY NE at John K's house. After everybody else left, my friend was discussing an idea he had for a time-delay subwoofer.

A few weeks later, John K has the CRAW.

[AJINFLA]

Oh no

Good lord Jim, I hope Mac doesn't see your post 8O ! Fuel for the fire if you know what I mean

AJ

[Mark Seaton]

Ken Kantor's last company had a product using 2 or 4 12" drivers and some front end measurement and processing gear to determine the best polar pattern for the placement in the room. I recall it allowing bipole, dipole and cardioid capabilities and of course points along the curve inbetween those. I would have to check my other computer for the link, but it was something that started with an "I..." I think.

[RonS]

Mark, is this it?

http://www.arsenal.net/speakers/IAS/Road-Trip%20to%20IAS.htm

That's all I could find. I sure would like to know more about this speaker, but it doesn't look like it ever got anywhere (couldn't actually find the company on the web).

Cheers,
Ron

[Mark Seaton]

That is the design I was referring to. I'm not sure if they sold the concept/company or if it just faded out, but Ken Kantor is now off working on new driver technologies as part of another company that is now part of D-S-T.

[john k...]

A few weeks ago a friend and I went to DIY NE at John K's house. After everybody else left, my friend was discussing an idea he had for a time-delay subwoofer.

A few weeks later, John K has the CRAW.

(JPK) Yes, It was nice haveing you all over and I remember that discussion. Ovbiously none of these ideas in and of themselves are new, not dipole, cardioids or U-frames. I've tried to bring this to light on my web page where relevant. The unique feature of the CRAW is the user selectable radiation pattern and retension of the same on axis anechoic response in each configuration. As I recall I believe part of the dicsussion with your friend was also directed at why I went with a U-frame instead of a front driver and rear driver with dealy. The reason for that which I alluded to was that with a U-frame the additional driver get's you another 6 dB is SPL, or similar SPL with a single driver.

With a true cardioid design the rear driver is just doing what the rear radiation from the damped U-frame with a single driver is doing. So the benefit of the U-frame is the added SPL. The benefit of the dual driver +delay cardioid is that there is no 1/4 wave resonance to worry about and therfore no degradation of the response cancellation to the rear as the frequency rises.

I think it was Davey above who suggested that this could be done with a DCX. Sure, or Sound Easy's Digital Equalization/ Filters. But it requires 2 amplification channels if everything is done at the line level.

John k...