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[raj]

HI
I am quite amazed after going through BHFProfessional,s post , I also visited Bill Fitzmaurice,s site ,
This Tuba 24 seems to be a  LITTLE MONSTER ,
BHFProfessional also writes
"  Bill Fitzmaurice says that his Tuba 24 horn, loaded with a HL-10 getting 300w, can be used to replace a dual-18" bin getting 1000w, in terms of output. So for those looking for a smaller alternative to something as big as the LAB sub, the Tuba 24 (because its external dimensions are 24"x24"x24") with the HL-10 should fit the bill nicely as a SR sub."

Also regarding DR12  Bill Fitzmaurice says ;-
"The DR12 loaded with a premium driver, such as an EV DL12X, will produce an average SPL of 109dB/1watt/1 meter from 100 to 5kHz; no other loudspeaker of its size and weight, not to mention cost, comes even close. Want proof? Look at this response chart:
The DR12 gives mighty strong competition to the $5,800 EAW ™
KF-850, despite being only 2/3 its size."

I am wondering CAN THIS ACTUALLY BE TRUE??

Just  for  information I would like to know  , can a number of  Tuba 24,s equal one lab sub , say if we do not go below 35 to 40 hz.

Regards

Rajeev

[[x]]

I wonder if, when loaded into the Mini Horn sub, you would find that the cone and surround would be bumping into that first board below the woofer hole, damaging it. With an Xmech of 36mm (one way, I assume) I would expect that the cone and surround would go right through that hole (25mm) and then cram itself right down onto that board, over time destroying the woofer. I'd add an extra spacer to the woofer mounting so that it doesn't destroy itself.

[Gary Perrett]

HI,
After seeing this I checked out the site and had an email discussion with Bill here is his response RE: "the use of the HL 10 Eminince driver in the Tuba 24":

The destructive Xmax of the HL10 is moot; the useful Xmax is 11mm one way, and
the box design limits throw to that excursion at full power, 300 watts input.
The cone is not going to hit anything. Additional driver spacing is not
required. This box was tested at 300 watts input of a pure 40Hz sine wave,
which represents far more stress than it would ever encounter with musical
program material.

Gary

[[x]]

I was actually referring to Cowanaudio's Mini Horn Sub, not the tuba 24. As you can see, it looks like the cone and foam edge will bottom out on the piece that is below the driver hole, at the throat of the horn. Bill Fitzmaurice's design, on the other hand, has plenty of room for the HL-10 to do its thing.

I'm in the process of designing my own HL-10 horn (The BHFProfessional G-Horn 10) using the excellent Hornresp program. It will use a single HL-10, and I am trying to get it to extend to 45 Hz anechoic. Right now, it looks like the finished design will be 16" wide, 32" deep, and 32" high. It should give good performance with two per side instead of requiring 4. I wouldn't want to move and setup eight boxes if I could do the same job with 4. Also, the BillF design isn't satisfactory to me because while it is short, it is as wide as it is tall, and so it will claim a lot of real estate whereas my own design aims to get that performance with a smaller frontal width. I still have some bugs to work out, because my design currently has a larger compression chamber and rear chamber than I'd like, and I think that may be what's causing me to have a low sensitivity, around 108dB 1w/1m. I still have a lot of playing around to do.

[[x]]

I remember that with the LAB subwoofer, there have been issues with the screws holding the access plate. After some hard shows, they would begin to come unscrewed, and develop leaks. Then people's drivers would begin to overexcursion and you'd get things like torn surrounds and cones and glue joints. In short, the woofers would self-destruct. I'm looking into a way that, for my own design, the rear chamber can be sealed. That way, the driver will always have some support behind it. Also, I think I'll try and make a way to have the magnet facing out into the horn (cone facing into the rear chamber), to prevent the "hot oven" effect where temperatures build up inside the small rear chamber and the voice coil burns up.

[Mark Seaton]

BHFProfessional wrote on Tue, 05 October 2004 11:27

I remember that with the LAB subwoofer, there have been issues with the screws holding the access plate. After some hard shows, they would begin to come unscrewed, and develop leaks.

Your mention is the first I've heard of.  So long as you are building with quality materials like Baltic Birch or using T-Nuts and machine screws, there should be no problems like you describe.

Note that while everyone always seems to ask and worry about thermal handling of subs, once the sub doesn't compress as badly as many common ported designs, most (not all, but most) failures are due to over excursion or running out of amplification.  Without some intelligent limiting or similar it is very easy to ask a sub to respond to huge peaks.  It's an interesting case where once you have clean output, it is very easy to use lots of it.  Very few actually take any representative measurements of what they are listening to or pushing into their subwoofers, where a very small push of a fader can send 2-4 times the power.  Getting some reference as to what you are used to or what you want to hear is very important in understanding what you really need a subwoofer to do for you.

[[x]]

Give me a moment and I'll go search for the post. I think it's a page back, where the one guy ripped 4 LAB drivers, and then people asked about his access panel screws, and talked about having to periodically retighten screws after long shows, sometimes as much as a full turn, and they explored the possibility that a leaky side access panel can cause the driver to over-excursion, especially with the power people are putting into these things.



---Well, I tried to find the post, but it's not there. I guess I may have just jumped to that conclusion from reading a bunch of posts and then they all run together in my mind. Oh well. I've jumped to stranger conclusions before.

[ChainedDragon]

BHFProfessional wrote on Wed, 06 October 2004 22:34

Give me a moment and I'll go search for the post. I think it's a page back, where the one guy ripped 4 LAB drivers, and then people asked about his access panel screws, and talked about having to periodically retighten screws after long shows, sometimes as much as a full turn, and they explored the possibility that a leaky side access panel can cause the driver to over-excursion, especially with the power people are putting into these things. ---Well, I tried to find the post, but it's not there. I guess I may have just jumped to that conclusion from reading a bunch of posts and then they all run together in my mind. Oh well. I've jumped to stranger conclusions before.

http://srforums.prosoundweb.com/index.php/t/2037/3213/?SQ=5a fdfc8c17087c929e65c065f64b0c96

i think he took the pics out

[Too Tall (Curtis H. List)]

Mark Seaton wrote on Wed, 06 October 2004 08:12

BHFProfessional wrote on Tue, 05 October 2004 11:27 I remember that with the LAB subwoofer, there have been issues with the screws holding the access plate. After some hard shows, they would begin to come unscrewed, and develop leaks. Your mention is the first I've heard of.  So long as you are building with quality materials like Baltic Birch or using T-Nuts and machine screws, there should be no problems like you describe. Snip- .

Hi Mark,
   Al is constantly having screws back out. Mostly on all the handles (they are on T-nuts) and I believe also on the access plate. It's something he has to check every time. As to the construction, you saw and heard his boxes pushed past 135dB at about 2 1/2 meters with not a single rattle so I believe they are constructed correctly.

Too Tall

[Mike MacWillie]

[quote title=Too Tall wrote on Sat, 09 October 2004 07:25
Hi Mark,
   Al is constantly having screws back out. Mostly on all the handles (they are on T-nuts) and I believe also on the access plate. snip
[/quote]

Have you guys given loctite a go on the bolts? I've used it on acess panel bolts on my own horns (not labs though..) and they're staying tight as they were when I put them in