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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => SR Forum Archives => LAB Subwoofer FUD Forum Archive => Topic started by: Antone Atmarama Bajor on May 27, 2006, 02:51:40 pm

Title: Hornresp 80Hz Candidate
Post by: Antone Atmarama Bajor on May 27, 2006, 02:51:40 pm
     Ok I have come up with a 80Hz Horn Design Candidate, I would like to get some feedback and ask some questions.

    A question arose when looking at the Lab v3 Vs Lab "v2".

    What are the implications of having a Hyperbolic Sine Horn (expansion rate greater than 1).  That apears to be how the Lab v3 was built.

    I am asuming that the LAB subs where designed with a Size Factor of 4?

    How flexible are the mouth dimensions for a size factor 2 Horn?

    Would optimal be either a circle of appropriate radius/ square that is the sqr(area).  I'm wondering this since the Labs only have an expansion on one axis.  

    Could a rectangular mouth that expands on one axis (and meets all of the area requirments be as usefull in a size factor of 2 horn?

    When I exported the data from the horn flare, it gave me grayed out symetrical dimensions.  If I just keep the height constant what can I expect good performance If I just accept the single axis expansion (say if I stack them 2 High?)

    Any how here is one of the horns I am modeling.

Its a segmented aproximation of a Hyperbolic expansion rate of .55.

    Using exponential or conical sections in the model don't seem to make much difference.

index.php/fa/4907/0/

Antone-
Title: Re: Hornresp 80Hz Candidate
Post by: Antone Atmarama Bajor on May 27, 2006, 02:53:43 pm
Here is predicted response of 2 half space with 1 in gray.

index.php/fa/4908/0/
Title: Re: Hornresp 80Hz Candidate
Post by: Antone Atmarama Bajor on May 27, 2006, 03:41:45 pm
Ohh PS the drivers are JBL 2225's
Title: Re: Hornresp 80Hz Candidate
Post by: peter.golde on May 27, 2006, 04:09:20 pm
Why 1/2 space? Will these be sitting on the ground?
Title: Re: Hornresp 80Hz Candidate
Post by: Jeff Robinson on May 28, 2006, 02:31:51 am
Hi Antone

I've been shooting for 100Hz with less than 1 meter of throat length.

So far this is the best I've modelled in Hornresp.
4 Pi space load but note the T/S parameters are for dual EVM10M driver source.

Please excuse the cobbled together graphics.

index.php/fa/4910/0/

I think for ground stacked subs 1/2 space is right,
but for midbass in mobile PA you ought to allow for use of singles in free air.

I think Dwg86 models ok for 3 or 2/cluster and even 1 doesn't look bad considering the 1 meter throat length constraint.

The problem will be the tight spacing from the phase plug to the boundary wall.

My thanks to Bill Geiger for suggesting the dual driver format as a means of shortening the horn.

Jeff Robinson

PS; The most compact graphics file format I've found is png, I'll see your 200KB and raise you 16KB.
Title: Re: Hornresp 80Hz Candidate
Post by: Antone Atmarama Bajor on May 28, 2006, 04:51:43 am
Sometimes they will be on the Ground yes.

    The rest of the time they will be on top of BT7's.

I have yet to find anything that models well in Free space unless I want to build a horn of Size Factor 1.

Antone-
Title: Part 2
Post by: Antone Atmarama Bajor on May 28, 2006, 03:05:13 pm
     Ok I tried Changing the Chamber Volume a bit since that seemed to effect my performance a bit.

    This should perform in free space like 1 in half-space.

Yet another hyperbolic approximation 122 cm long flare .55 80Hz.



index.php/fa/4919/0/

Antone-
Title: Re: Part 2
Post by: Antone Atmarama Bajor on May 28, 2006, 03:12:41 pm
Here are the numbers.

Question:

    If you have to consider cone volume when solving for Throat chamber.  Why does Hornresp try to override it when you are trying to use its hypex calculator?

    Wouldn't that mean you have to stick a mass between the cone and throat to take up the cone area?

index.php/fa/4920/0/

Antone-
Title: Re: Hornresp 80Hz Candidate
Post by: Bogdan Popescu on May 30, 2006, 02:47:07 am
Isn't this DDS horn not the perfect candidate ?
I am considering it for my midbas.

http://www.ddshorns.com/catalog.php?page=DVB15NPro

Bogdan
Title: Re: Hornresp 80Hz Candidate
Post by: Antone Atmarama Bajor on May 30, 2006, 04:50:19 am
     I seriously doubt the DDS horn has much effective loading down bellow 200Hz with those dimensions.  It will probably behave just like normal direct radiator in a sealed or vented enclosure below horn flare and length.

   I would think this would work only for Low Mid not Mid Bass.  You can't cheat physics.

Antone
Title: Re: Hornresp 80Hz Candidate
Post by: Bogdan Popescu on June 01, 2006, 04:37:04 am
Yeah, i wonder too, but i always tought DDS are one of the best horn manufacturers. Are they cheating?

I would love to hear from DDS. I write them a mail and never got any answer...

Bogdan
Title: Re: Hornresp 80Hz Candidate
Post by: Antone Atmarama Bajor on June 01, 2006, 12:58:12 pm
     I have heard that the original designer for DDS is no longer there, and its a small 2 man type of opperation these days.  So it may be hard to get ahold of someone there.

Antone-
Title: The Correct design for the Job
Post by: Antone Atmarama Bajor on June 01, 2006, 04:41:34 pm
      Ok so this looks prety reasonable to me.

Building it into a Straight horn seems impractical.

    What are the pitfalls of doing a W bin/Vs Snail.
Whats the critical Wavelength relation ship of the folds to keep in respect to HF performance.

    A lot of W bins I have seen are sort of like two halves of a snail horn where the flairs meet in the center instead of expanding outwards.  That seems wrong to me since this doesn't create a complimentary horn mouth but maybe it doesn't matter?

 Would it be better to do a Wbin "reentry horn" (Like a megaphone?)  How do either effect polar up in the High range????

    If I don't fold the Horn the Length without the driver/compression chamber attached is 4'.

    Any help on the topic would be greatly appreciated.

If I did a Phase plug in the throat to improve polar  I'm guessing that I need to keep the throat area the same as it would be across the flair as if there was no plug there?

 Or do I need to pay for this information as no one seems to have any comments?

    Thanks.

Antone-
Title: Re: The Correct design for the Job
Post by: peter.golde on June 01, 2006, 08:14:00 pm
The first rule of horns is don't fold them. But hey, Paul Klipsch did it. To get MF through a fold, they must be rounded. 1/4" Baltic Birch bends nicely, both sides of the fold must be rounded, and preferably closer to the driver, and since you are going higher in freq, the top and bottom can't be paralell or cancellation will happen. Hey that sounds like a DR300.
Title: Re: The Correct design for the Job
Post by: Antone Atmarama Bajor on June 02, 2006, 02:07:30 pm
     I haven't ruled out the DR300 as an option.

The only problem Is I already own the JBL 15's I would like to use them the DR300 Is designed to use 12's.

    I have no idea where the Xover frequencies are but, smoothness of the bends is not the only thing that will determine HF performance.  Wavelength relationships of bends will also have and effect as well as throat area.  The vertical expansion of the DR 300 only occurs in the first several inches then stays constant.  I imagine that will cause a HF problem as well.  

I know I wouldn't have to mount horns in it but.  Having both horns radiation patterns overlapping like that is not very good.  They may sum coherently in their low end but will interact badly as frequency increases.

    I'm still wondering about having the flairs expanding to the center making a non complimentary horn mouth.  

     Its a cool design for sure, but Unless someone wants to swap my 2225's for some of the Eminence Definimax 12's I'll have to seek out another design.

Antone-
Title: Re: Hornresp 80Hz Candidate
Post by: Tracy Sherwood on June 03, 2006, 12:25:15 am
Hello Antone,
The DVB-15N horn flare only offers pattern control to 190hz and will provide loading to the specified 80hz only in a properly designed ported enclosure. There is a compresion factor introduced to the cone and not all 15" speakers are up to the task.
   The specifications may seem confusing in that regard, they were published by the original founder of the company Robert Rice and may need to be re-evaluated/clarified. DDS recently relocated into a larger facility and is phasing out direct sales to contractors in general due to pressure from OEM clients.

-Tracy Sherwood, Primary, DDS LLC.
Title: Re: Hornresp 80Hz Candidate
Post by: Antone Atmarama Bajor on June 03, 2006, 03:56:16 pm
     I was close.
It sorta reminds me of the old JBL 15 half horn half relex idea.

   Thats to bad that you are stopping selling dirrect I can't find anyone that carries the CFD-1-100 or 1-110.

Antone-
Title: Re: Hornresp 80Hz Candidate
Post by: Bogdan Popescu on June 07, 2006, 03:39:50 am
I did write a mail to DDS about a possible colaboration. Can i please have some feedback on that ? I might be also interested in OEM

Bogdan
Title: Re: Hornresp 80Hz Candidate
Post by: Too Tall (Curtis H. List) on June 14, 2006, 02:41:43 pm
Antone Atmarama Bajor wrote on Sat, 27 May 2006 14:53

Here is predicted response of 2 half space with 1 in gray.

index.php/fa/4908/0/


First thing that bothers me is the lack of any high end at all. You would need the biggest high frequency horn DDS makes to reach down to where it rolls off.

I know nothing of horn modeling so perhaps this can be taken cars of somehow???



For an 80Hz horn I have direct experience using straight horns, both made by Community.

My first PA used a Community FRC/B with a single 15” woofer.

I was talking it over with AL Limberg and best we can guess is the horn mouth was 42” wide by 32” high by 36” deep.

This put out 80Hz, but not one cycle lower. When I pushed it running full range below 1200Hz I had to use double gaskets on the 15” to keep the surround from striking the horn throat.

From 80Hz up it was one of the most efficient, punchy and just plain nice to listen to speakers I have ever used. With a sub under and a 2” compression driver over very few 3-way designs could touch for volume without distortion. It lost favor because it was not arrable and just plain too big, thought it was very light in weight compared to what it put out.

Next is the Community “Boxer” flare.
The original design was a flair that held dual 15” (or dual 18”). The flare was 28.5” wide by 48” high by 36” deep. This slipped into a box that was the same width, but 60” high and 45” deep. You put the flare in the middle giving you a 6” by 28” port above and below. The rest of the box volume left over from the flare was used for a ported solution. There were curved ribs on the sides, top and bottom for bracing. Some really big panels to brace.

Al built a box only 48” and made a very small sealed volume the drivers shared.

This measured dead flat from 80Hz to 1200Hz and sounded wonderful with LAB subs below and M-4 midrange above. For lighter gigs he ran it all the way down to 40Hz with EQ, but you had to be careful. (One of the advantages of a sealed vs ported design.)

If I had to make a serious mid-bass this is it. Just curve the sides of the flare with some bending plywood or carbon fiber if you are fancy.

A smaller mouth or less depth is a real compromise, not that we don’t do it every day…

Title: Re: Hornresp 80Hz Candidate
Post by: Phil Pope on June 14, 2006, 03:34:53 pm
I don't think you can get very far modelling a midrange horn with constant directivity assumed. unfortunately hornresp will only give response at a specified angle for a single one segment horn. Antone, you should approximate your horn to a single segment exponential and model between 0 and 90 degrees as the effect upon the response above 200Hz is quite dramatic.

Phil
Title: Re: Hornresp 80Hz Candidate
Post by: Stephen Kramer on April 16, 2007, 09:40:21 pm
Hello, I've come across a pair of these and would appreciate some professional help on designing the cabs for them.

http://www.users.uswest.net/~ddshorns/dvb15n.htm

sorry to bump an old post, but I came across this on a search:
Quote:

Hello Antone,
The DVB-15N horn flare only offers pattern control to 190hz and will provide loading to the specified 80hz only in a properly designed ported enclosure. There is a compresion factor introduced to the cone and not all 15" speakers are up to the task.
The specifications may seem confusing in that regard, they were published by the original founder of the company Robert Rice and may need to be re-evaluated/clarified. DDS recently relocated into a larger facility and is phasing out direct sales to contractors in general due to pressure from OEM clients.

-Tracy Sherwood, Primary, DDS LLC.


Any info on the cab specs and drivers to achieve these specs would be of great help.

Thanks,
Steve