Go Back   Home > Forums > Loudspeakers > Full Range

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 11th June 2006, 05:37 PM   #1
diyAudio Member
 
Join Date: Apr 2004
Location: Costa Rica
Send a message via AIM to johninCR Send a message via MSN to johninCR Send a message via Yahoo to johninCR
Default Tombstone RLH

I've been having trouble visualizing how to make a good looking RLH with the added "supra baffles". I understand the need to get the "baffle action" down to where the "horn action" falls off. I can also easily foresee a lot of work going into this added baffle, so I thought "Why not incorporate it into the cab itself?". I'm calling it the Tombstone RLH.

I'm no horn designer, so I want to copy the critical horn dimensions from an existing design such as Ron's A126. The following is what I came up with. Note that the added volume directly behind the CC can be used to vary the CC size. It obviously isn't drawn to scale, but the layout is flexible enough to scale the basic folding approach to almost any horn, and get the added benefit of horn pathways that are closer to square than typical constant width RLH's while keeping the construction fairly simple.

Does anyone see any pitfalls that I may not be considering? Is there anything inherently wrong with bifurcating the first 2/3rds of a horn?

Click the image to open in full size.
__________________
Everyone has a photographic memory. It's just that most are out of film.
  Reply With Quote
Old 12th June 2006, 11:36 PM   #2
jamikl is offline jamikl  Australia
diyAudio Member
 
Join Date: May 2005
Location: Melbourne
Interesting idea John. I would like to know how it works out if you build it. Hasn.t created any response - I don't know why. the famous Klipsch corner horn was bifurcated for about two thirds of its length. I had a copy fo the papers he wrote about the design and he didn't seem to think that splitting it caused any problems. I think Dinsdale or one of the other British designers did an ugly looking one that was bifucated in the sixties or seventies. One speaker rear lodaded for the bass with an upward firing mid horn on the other side of the speaketr. I think it was in Wireless World. Designer may have been Crabbe. Hope this helps you make a decision.
jamikl
  Reply With Quote
Old 13th June 2006, 03:59 AM   #3
diyAudio Member
 
Join Date: Apr 2004
Location: Costa Rica
Send a message via AIM to johninCR Send a message via MSN to johninCR Send a message via Yahoo to johninCR
jamikl,

Thanks for the input. I put some dimensions to paper and with a horn somewhere in between the Frugal and A126 horns, I end up with exterior dimensions for the main panel of 80cm high, 22cm wide at the base, 30cm wide at the maximum near the top, and 8cm thick. The mouth will add about 20cm to the back, and the overall size should remain a cute little high WAF horn.

The only change I've made in my plan is to eliminate the triangle centered at the top. I think it would only lead to a less than perfect bifurcation and be more likely to guide HF content into the horn.

I'll report back once I build a pair. My only horn for comparison is the Fostex cab for the 108, which I like alot, but I feel the front mouth is detrimental because it's HF content detracts from the point source sound.
__________________
Everyone has a photographic memory. It's just that most are out of film.
  Reply With Quote
Old 13th June 2006, 04:22 AM   #4
GM is offline GM  United States
diyAudio Member
 
GM's Avatar
 
Join Date: Jun 2003
Location: Chamblee, Ga.
Default Re: Tombstone RLH

Greets!

Most of the BLH designs of the 50s, 60's were split, not to mention W.E.'s fabulous 1920's 16A 'pancake' compression horn and all the 'W' bins that followed.

Anyway, the quality of the bends determine how much HF the horn will pass as well as how much gets reflected back to the throat, modulating the driver, so its HF corner needs to be fairly low to keep folding simple.

GM
__________________
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
  Reply With Quote
Old 11th October 2006, 11:51 PM   #5
diyAudio Member
 
Join Date: Apr 2004
Location: Costa Rica
Send a message via AIM to johninCR Send a message via MSN to johninCR Send a message via Yahoo to johninCR
Tombstone prototypes are under construction. Note that I've gotten away from the original plan of a rear firing mouth and will use the perimeter of the front section to form the mouth.

The basic idea is to take the Frugelhorn and add an extension to greatly enlarge the mouth, similar to the effect of the Frugel deflector, but probably more controlled. To retain the overall theme of efficiency in size most of the perimeter of the main cab will be part of the panels forming a horn mouth greater than 3000 cm2 (up to 4k cm2 if I ignore edge diffraction, which I might be able to get away with to some extent since the baffle is 11" wide). These cabs shouldn't suffer ill effects too much with near wall, corner, or placement well into the room due to the mouth size and orientation.

The guts of front section are pictured below. Note that a small panel to prevent interference between the operation of the 2 throats isn't installed. To give you an idea of scale, they are 90cm x 28cm x 9cm (3ft x 11" x 3.5") externally. The back plate will increase the width and height, but they are prototypes. In shareable form I'll be able to shrink the height quite a bit by using some of the CC which is way too large right now at about 3.5L.

Note the ease of construction so far, and I'll probably mod the layout to minimize angled cuts when I shrink the height, leaving only a few angled cuts to form the rear segments, or at least focus on standard 90's and 45's.

Also, these are looking way too much like tall skinny baby coffins, so I need another name to avoid the negative connotations. Any input is welcome. In the meantime, my fingers are crossed regarding the sound. While I've covered a lot of bases in theory, as Ed always reminds me, good sound means a lot more than theory.

Click the image to open in full size.
__________________
Everyone has a photographic memory. It's just that most are out of film.
  Reply With Quote
Old 12th October 2006, 07:20 AM   #6
diyAudio Member
 
Scottmoose's Avatar
 
Join Date: Mar 2005
Location: UK
I take it that engraved brass name-plates & carrying handles are out then? They remind me of the sarsens in megalithic stone circles, so how about Henge Horn? Rolls off the tongue nicely, and if you got some stone-effect spray paint out, you're just about there.
__________________
Community site www.frugal-horn.com Commercial site www.wodendesign.com
  Reply With Quote
Old 13th October 2006, 12:59 AM   #7
diyAudio Member
 
Join Date: Nov 2005
Location: NorCal
As long as they are large enough that they aren't in danger of being trampled by a dwarf!
  Reply With Quote
Old 13th October 2006, 01:05 AM   #8
diyAudio Member
 
Join Date: May 2005
Location: Buenos Aires
To get rid of the nasty implications, just make them rectangular, leave the bends as internal and fill the voids with sand.
If you paint them jet black, you can call them Monoliths... not original but it could work wonders with ape-like friends
Hope it works well. I'm in the search of new homes for my 108s too...

Gastón
  Reply With Quote
Old 13th October 2006, 06:41 AM   #9
diyAudio Member
 
Join Date: Oct 2004
They look fantastic John!
and maybe not so hard to build. I have some FE126e's which could work. keep us posted.

I'd love to make a tastless dead baby joke...but i probably shouldn't.

Could be made to look a bit like Zu duids maybe as per ghpicard's suggestion. I think the shape looks like a skate or surfboard.

Regards Philip
  Reply With Quote
Old 13th October 2006, 07:48 AM   #10
diyAudio Member
 
Join Date: Apr 2004
Location: Costa Rica
Send a message via AIM to johninCR Send a message via MSN to johninCR Send a message via Yahoo to johninCR
Thanks Philip,

These are just first tries, so I'll probably go shorter and closer to rectangle when I use some of the CC for early portions of the horn. I'm going to finish the 2 out differently to see which works best, the original plan (rear exit) or the mouth(s) around the cab, and compare them to my Frugels and Fostex's.

I think I can finish out the horns no problem. My biggest sticking point now is how to deflect/dissipate HF in the CC with using absorbant in order to prevent reflections back at the cone. This is very problematic in the Fostex cab with flat service behind and close to the driver. In my Frugels I solved the problem very well with deep V shapes behind the driver, but I had excess depth to work with there. With these I don't have much depth to work with, so I'll probably have to use a circular plate behind the driver with bevelled edges to deflect them away and dissipate them using V shapes elsewhere in the CC. I have over 1.5 liters to fill up anyway.

I've read repeatedly that absorbant in the CC is harmful to a horn's sound. I think the resulting change in the compliance of the air/absorbant combo is harmful to the horn's function. I've long speculated that the sonically destructive HF bouncing around in the CC can be dissipated using rigid surfaces in special shapes. That way the air volume in the CC retains its normal compliance. The results I'm getting with my Frugels supports this theory.
__________________
Everyone has a photographic memory. It's just that most are out of film.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



New To Site? Need Help?

All times are GMT. The time now is 06:23 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2