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[Peter Sylvester]

Still somewhat a work in progress, but heres a compact "trap" type top design indended to compliment the lab sub, for smaller venue usage...

http://home.comcast.net/~labhorn/traps/

--Peter

[ChainedDragon]

Thank you

[Chris Parsons]

Looks great, i'm very excited!

So how many of these per lab do you think?  What's the exstimated building costs per cab?

Thanks for your time and energy!

-Chris Parsons

[Peter Sylvester]

Chris,

I have 2 LABs, and 4 of these tops, and it seems like a good combo for the type of work I do.  But I don't operate at real high volumes, and the LABSs are not even stressed, even with some heavy EQ, so I think you could throw even more tops (say pairs of double 12s or 15s each side) into the picture.

The Magnum 12HO drivers are really heavy, and not as efficient as I'd like so I am going to be trying out some B&C drivers shortly.

As to cost, its all in the drivers, and I leaned towards the better stuff on these, so they are not exactly cheap. You can lower costs by going with cheaper components and moving down to a 1" horn.

As with anything there are some compromises going on here. You need to cross the LABs over at around 100Hz minimum, as the bottom starts to drop off after that on these tops.


--Peter

[raj]

The best Top for the Lab Sub would be one which has the same deley as the Lab Sub , then both could be paired without adding any digital deley in the tops .
I hope some loudspeaker guru will design such a horn loaded top .

[Geri O'Neil]

raj wrote on Thu, 07 October 2004 23:16

The best Top for the Lab Sub would be one which has the same deley as the Lab Sub , then both could be paired without adding any digital deley in the tops . I hope some loudspeaker guru will design such a horn loaded top .

Not necessarily. Digital speaker processing is pretty much the norm these days and highly advisable when using high-performance cabinets such as the LAB sub. There's many advantages to using DSP such as the needed delay that you mention, parametric EQs on each bandpass output plus input parametrics, and limiting for driver protection, a must these days. For the time and effort it takes to make the Lab sub, I cannot understand using an analog crossover for this purpose. Okay, maybe a money thing, but we all pay to play, right?
It's my understanding that the LAB sub is flexible enough to used with most any good top cabinet with a little help from a measurement program such as SmaartLive.

Geri O

[Alan Searchwell]

Raj,

I do not know that it would be possible to build a good sounding top based on your criteria. The effectiveness of a horn is based on a relationship between the wavelength of the lowest frequency you want to reproduce, the length of the horn and the mouth area. For a more thorough discussion see:

http://melhuish.org/audio/hornshape.html

That is the reason the lab sub is so big, that is, to achieve the over 10 foot horn path and reasonable mouth area necessary for the horn to be effective at the long wavelengths desired. As we go up in frequencies, the wavelengths get shorter and the circumstances change. I read somewhere about a relationship of the radius of a bend to the shortest wavelength that can effectively travel around it. The long and short of it is that to quote a page on the EAW "the expanding sound wave front does not maneuver well through the corners above certain frequencies, reducing output and increasing distortion through air turbulence" (taken from http://www.eaw.com/technology/nonproprietary/basshorn.html). Therefore the best horns for the shorter wavelengths are straight horns and to achieve time alignment with a lab sub, such a horn would have to be around 10 feet long! That's just not practical.

[raj]

Hi Guys ,
You are RIGHT ,
I had a thought , and if it is NOT practical it is not .

Cheers

Rajeev

[raj]

Hi Peter ,
In  your reply to Chris on 7th instant ,
You said you operate with four tops and two  lab subs , are two labs enough for small programmes , I think I had read somewhere that a minimum of four labs are required to get good results ??
Regards
Rajeev

[Peter Sylvester]

Rajeev,

Yes, you are better off with 2 LABs per side or more, to acheive the design mouth size, But if your needs are modest you can get away with one per side and hit it with some EQ to flatten things out.

See some examples (single cabinet) here:
http://home.comcast.net/~labhorn/rta/index.html

I typically use the "aggresive single notch filter" version, but at -6dB, which seems to sound pretty good.

--Peter