jbell's set of four tapped horns

[contour]

Hello,

Yes, I think the tapped horn variant with the driver close to the mouth is very similar to a 'classic' back loaded horn. I think the main advantage of the tapped horn is the ability to fill up the dip at around 80-120Hz which normally occurs with a back loaded horn because the direct radiating driver and mouth are out of phase.

As for stacking, I think Jbell will get the best results with the mouths of the cabinets as close to each other as possible. So virtually creating one very big horn mouth.

Best regards,

Walt

[davygrvy]

Where'd Jim go?

[HK26147]

Don't Know - figured he would have been here by now.

I know these TH's are for a permanent install.
If they were to be moved frequently I would be concerned about the vulnerability of the exposed drivers to being poked...
An open grille perhaps...

It looks like it would NOT be possible to mount them reversed ( magnet in ) because of space limitations and the influence of the volume of the woofers frame & magnet structure on the horn throat?.
At least without a redesign?

[littlemike]

The orientation of the driver was discussed somewhat, Jim elected to reverse-mount them. That bit of our discussion may have gotten lost in the other noise though - we probably exchanged 30 emails during this design, let alone the forum posts.

Anyhow - a driver flip complicates the construction a little bit and makes the cabinet slightly bigger due to some wasted space, but it certainly could be done.

Make the initial leg (L12) a rectangular section with depth sufficient to hide the magnet and basket. Use a side baffle (or two) in this rectangular section to get the taper you need.

Just don't ask me to draw it - my CAD skills suck.

[jbell]

you were talking behind my back...

However, I did achieve 114db/10m/20v/40hz.

I was impressed.

and yes, the cabinets have to be like the pic above in the install, and bass steering does work.

more later

[davygrvy]

Jim,

Tell us about the space this will be used in, too.

[jbell]

It's use is for a football stadium sound system, on top of press box. That's why bass steering is important. I need to be able to spread wide the bass, without killing people right in front. (and split subs, with cancellations is not for me)

For anyone who wants to replicate this (not sure if anyone does) It's 46x36x25.5 wide. (because I used 3/4" 7ply arauco)

Points of interest in plan layout:
1st point is 10.75 down from top, 8.5 from front.
2nd point is 12.25 from top, 14.25 from back
3rd point is 18.5 from bottom, 16.25 from back.

Those are the horn fold (toward outside) measurements.

The front panel is 25.25 long, and the throat is exactly 4".

From that and the pic above showing the fold, you can get to everything needed.

Hornresp params are 600cm throat, 3000mouth, 16.9,235,16.9

I will be the first to say, this is nothing special. However it fulfills a need that none of the BF cabinets that I was working with at the time would.

If 40hz is your low frequency that you need for your PA, that efficiency at that freq sets the overall response you can achieve, as it's the hardest to reproduce and most power intensive frequency in the PA power band. (which we obviously know) A sub that's 13db more efficient at 100hz vs 40hz, helps little. If I need more 100hz out of a sub, I'll eq it in. However, If I need more 40hz... there's only one way to get that, big power and big excursion, and that limits the overall spl you can get out of your cabinet.

So.. this sub is very efficient at 40. 102.5@2.83volts according to hornresp, and it measured spot on. +-1db up to 100hz. Good enough for me. It actually measures +1 at 100hz, with 103.5. and yes, that's outdoors, over grass measurement, static test tone, calibrated spl meter, and voltmeter measurement... not an INDOOR fairy tale measurement... like some others...

anyway, I digress.

set up on a dcx2496, LR48@38hz high pass, LR24@90hz low pass, into a EP2500 really puts on a show on the cheap.

These use eminence 3015lf drivers, just under 2 sheets of 7ply 3/4" plywood per cabinet, a dcx, and a ep2500. All 4 cabinets were built in a day. They are brain dead simple to build. Yea, they probably could use some more bracing. And if built with 1/2" would require significant bracing everywhere. My tradeoff was the 3/4 was heavier, more expensive and needs less bracing, and allowed me to build super fast. So it was a good trade. Mouth doesn't vibrate, most vibrations I feel are in the front panel (no bracing... should have put some in)

This is a huge system on the cheap, so I guess that's it's value here.

oh, and yes, they'll be grilled, to keep the bugs out.

[davygrvy]

Ahhh.. I had wondered about that football stadium setup and how you were going to solve it. The DRs are going on the roof, too? Nothing hanging from the light poles then?

[jbell]

Yes, everything on pressbox.
My tops aren't dr's. They are my own designed slot loaded dual 10's with 18" long horn paths. I found the OT had too much boxy 250-500 sound and not enough mid-bass, and the longer horn path moved that cabinet gain down into the frequency range I really needed outdoors.

The only eq I 'have' to have is the 8.5khz piezo eq, to get rid of that spike. (-3db q10) The 1025's are just much better controlled than the 1016's.

This whole stadium project was an exercise in trying to get cabinets (tops and subs) to really provide the most output at the hardest to reproduce frequencies, knowing that everything else can be accomplished with a little eq.

[davygrvy]

Post some pix showing us the mounted stuff when you get there