515 with papersurround

**Old Guy** · August 27th, 2006, 08:04 PM

Originally posted by Dave H.:
A 20Hz bass horn is an impressive item as a horn that low is usually huge and difficult to incorporate into most homes. Do you have to compensate for the delay with the rest of the system? Would sure like to see a pic of them. Thanks.[/QB]

<font size="2" face="Verdana, Helvetica, sans-serif">It's actually a 35 hz or so horn, with usable response to an octave below. Below cutoff the drivers act as direct radiators just as in the Altec mid bass horns. It's built in modules, requires 3 modules to make a systm. Finished system to be approximately 36x36x60. (3) 20 inch modules.

Very ugly prototype of one module done. It's based on Bill Fitmaurice' Tuba 36 design, I've been playing with mods to chamber volume.

I'm using Oberton drivers made in Bulgaria, I like their BL product. That may or may not be the finished driver. Precision devices looks good, I may even give 515 g's a try but some of the 515's specs aren't right. Still. the proof of the pudding... And the 515G WAS designed as a horn driver. It's BL product (essentially motor strength) is way lower than the above mentioned drivers.

If you want, I'll post links to the forum where guys talk about these, and to the drivers I'm using. There are lots of tests and graphs there of guys who built different versions. Most are using Eminence drivers.

I like the idea of a movable module.

The 8 ohm driver becomes a 12 ohm or so across the 20-100 hz range due to the horn loading. 3 units becomes a 4 ohm load. And 3 units reaches the necessary mouth area, with a perimeter of some 16 feet.

Let me know if you want the links , I don't have them handy but would just take a few minutes to dig for them.

**Old Guy** · August 27th, 2006, 09:26 PM

Addendum- I misposted. I s******* the 20" module and a m now working at 24". The stack (actually sideways stack is how I plan to use them) becomes 72" instead of 60" with a perimeter of 18 ft.

Horn path is some 11 or so feet with a flare rat around 30 hz.

My apologies. the project I posted first has been discarded, I just didn't like the simulations in the program I run. I had actually cut wood for it but was able to salvage some of the panels for the current prototype.

Not my intent to ever mislead, just jump tracks sometimes. Unfortunately it seems to happen more often lately...

**Old Guy** · August 27th, 2006, 09:28 PM

This board is just plain weird sometimes. It censored s-c-r-a-p-p-e-d.

I understand when I used the word with the "s" left off.

But that's just plain silly.

**dhook17322** · August 28th, 2006, 04:22 AM

That sounds like a fascinating project, yet a manageable size as well. I have been toying with a few ideas after seeing another project that was a large folded bass horn that was 8'x8' but only 24" in width and assembled in 4 modules. I forgot who was working on it, but it was designed to use about 8 sheets of plywood complete. If you get a chance, please do post the links to the site. Thanks much - love to hear that monster.

**sguttag** · August 29th, 2006, 03:53 AM

It has been a while since I've ordered any Image parts but their number was 1-800-552-1639. The 515 cone was the W-5200.

Steve

**just me now** · August 29th, 2006, 01:51 PM

I would love to read up on the tuba mods that you are doing....

I know some guys on the east coast that are using multiple Tuba 36s; they say with great results...

**Old Guy** · August 29th, 2006, 02:05 PM

Originally posted by louped garouv:
I would love to read up on the tuba mods that you are doing....

I know some guys on the east coast that are using multiple Tuba 36s; they say with great results...

<font size="2" face="Verdana, Helvetica, sans-serif">Give me a day or so- I'm just playing with the rear chamber volume to optimize for the driver...

The designer recommend 4 boxes in a stack. I'm trying to work around 3 because with the 12 ohm effective impedance 3 is a 4 ohm load.

4 would be a 3 ohm load. Not so much a problem at home but I'm also wondering about the uses of these for SR.

My SR systems all have the amps wired to4 ohms but the amps are 2 ohm capable. Drop a channel and I can just double up.

I haven't dropped an amp channel on a job in over ten years. But I am still paranoid about it.

The cabs are definitely more effective built at 30"
again not so much a problem for home. For SR there are some place that barely goes thru doors. So I'm investigating the 24". I may build both just to see if the extra few percent is worth the hassle.

There is a point of diminishing returns, where improvement isn't worth the effort. Especially in SR. No way I would carry 80 pound power amps again. My back still hurts from 20 years ago. forums