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Author Topic: Direct versus Folded Horn Sub enclosures  (Read 47858 times)

Tom Young

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Re: Direct versus Folded Horn Sub enclosures
« Reply #10 on: December 14, 2011, 09:42:31 PM »

It depends on the freq in question, the size of the cabinet etc.

And how much is a "huge" difference?  6dB 10dB 20dB?

There can be some directivity-depending on various factors.

Remember that large waveforms are harder to "control" than smaller waveforms.

I would add that at 80Hz (the most common ballpark crossover frequency for subs) and below the wavelengths are 14' and longer. It is hard to imagine a typical folded horn being capable of containing these long wavelengths.

I've mixed more than my share of monitors while behind the FOH stacks and I don't recall the folded horn systems being any less loud than the DR's back there  :(
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Rory Buszka

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Re: Direct versus Folded Horn Sub enclosures
« Reply #11 on: December 14, 2011, 11:46:32 PM »

Don B. Keele has a paper comparing low-frequency horns to direct radiators based on volumetric efficiency, wherein he finds that for a given amount of cubic volume, direct radiating speaker systems produce more output than comparable horn-loaded systems. Per-driver, horns are the most efficient. However, per cubic foot of tractor-trailer space, vented systems are the way to fit the most bass into the least space (hey, that rhymes -- I should be in marketing). This research effort took place during the development of the first JBL VerTec line array systems.

http://www.xlrtechs.com/dbkeele.com/PDF/Keele%20%281976-05%20AES%20Preprint%29%20-%20Efficiency,%20Horns%20vs%20DR.pdf
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George Dougherty

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Re: Direct versus Folded Horn Sub enclosures
« Reply #12 on: December 15, 2011, 01:43:00 AM »

Don B. Keele has a paper comparing low-frequency horns to direct radiators based on volumetric efficiency, wherein he finds that for a given amount of cubic volume, direct radiating speaker systems produce more output than comparable horn-loaded systems. Per-driver, horns are the most efficient. However, per cubic foot of tractor-trailer space, vented systems are the way to fit the most bass into the least space (hey, that rhymes -- I should be in marketing). This research effort took place during the development of the first JBL VerTec line array systems.

http://www.xlrtechs.com/dbkeele.com/PDF/Keele%20%281976-05%20AES%20Preprint%29%20-%20Efficiency,%20Horns%20vs%20DR.pdf

The caveat is that you also trade up in terms of power input requirements.  For larger shows with big generators that's not a huge issue.  For some of the smaller non-profit stuff I've done where I'm handed a 3000W genny or a 15 amp circuit, that can make the difference between constant breaker trips or an uninterrupted show.

In regards to horns sounding "woofy", driver quality and EQ can make a big difference.  The pressure in a horn puts far more strain on the driver so you need something that can hold up and do it accurately.  I use the larger BFM Titan48's and their natural rising sensitivity means you need to EQ the top end above 80Hz down to flatten their response otherwise they sound boomy due to the over-emphasis in that range.  OTOH, folded horn paths filter out much of the harmonic distortion that DR subs produce and tend to produce cleaner output as a result.  Some like it, others don't. 
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Roland Clarke

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Re: Direct versus Folded Horn Sub enclosures
« Reply #13 on: December 15, 2011, 08:45:38 AM »

My experience with horn subs, has never been great, the move to direct radiating subs has (IMHO) been a blessing for live sound.  I was never a lover of bandpass boxes either, again far too coloured and a real tendency towards one or two note bass.

I am still waiting to see someone instigate a really good example of truncated transmission line.  In my experience I have found good TL designs to offer really great extension and an ability to "fill the room" even with limited numbers/size of speakers, albeit at low SPL's (bearing in mind to my knowledge no examples exist in the professional sound reinforcement market.  In the past most TL design has been of the "rule of thumb" type with extensive testing and tweaking to achieve desired results, however, George Augspurger and Martin King have in very recent years both produced reliable, mathmatical models, Auspurger via an electrical model and King via a mechanical model, interestingly both's work arrive at similar results and conclusions.  From what I remember I believe that Martin discarded the long held belief that stuffing slowed the speed of the air within the line, he further tested this to prove it was indeed the case and built his model from there.  My understnading means that transmission lines can very succesfully be produced with much shorter lines than previously thought.  Bing that most subs now are crossed over at around 80hz (possibly a little higher) the damping of the ripples should prove less of an issue.

I'd be very interested in your thoughts Tom.

My appologies for drifting way off topic, however, with Tom posting on the thread I couldn't resist!
« Last Edit: December 15, 2011, 08:48:50 AM by Roland Clarke »
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Tom Stone

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Re: Direct versus Folded Horn Sub enclosures
« Reply #14 on: December 15, 2011, 09:48:31 AM »

It depends on the freq in question, the size of the cabinet etc.

And how much is a "huge" difference?  6dB 10dB 20dB?

There can be some directivity-depending on various factors.

Remember that large waveforms are harder to "control" than smaller waveforms.

Okay just remember seeing a band with folded horn and every time I went to walk to the side of the subs you could hear a huge difference in volume loss on the kick and bass but once you got back in front they would hit you hard. Keep in mind this was many moons ago like back in the 90's I can't even remember hat subs they had just remember they were folded horn design and huge and look like you needed a forklift to move them around.
All thought the band was kick ass hair metal type.
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George Dougherty

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Re: Direct versus Folded Horn Sub enclosures
« Reply #15 on: December 15, 2011, 10:01:32 AM »

My experience with horn subs, has never been great, the move to direct radiating subs has (IMHO) been a blessing for live sound.  I was never a lover of bandpass boxes either, again far too coloured and a real tendency towards one or two note bass.

What models of bass horns do you have experience with?  There are a number of more modern designs that IMO do quite well. I wholeheartedly agree that band pass subs have no place in the world of audio.

I've noticed some directionality with my Titans as well, especially outdoors without boundary reflections.  I'd guess the longer horn path controls more of the upper end of their range which can impact some of the punch feel.  It may also have something to do with placement and alignment of the subs.
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Roland Clarke

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Re: Direct versus Folded Horn Sub enclosures
« Reply #16 on: December 15, 2011, 12:42:12 PM »

What models of bass horns do you have experience with?  There are a number of more modern designs that IMO do quite well. I wholeheartedly agree that band pass subs have no place in the world of audio.

I've noticed some directionality with my Titans as well, especially outdoors without boundary reflections.  I'd guess the longer horn path controls more of the upper end of their range which can impact some of the punch feel.  It may also have something to do with placement and alignment of the subs.

Many over the years, initially the first I encountered were the Martin "w" bins, IMHO truly awful "boink" boxes, no bottom end at all.  Others that spring to mind are Turbosound, Court Acoustic W bins (they had the advantage of porting to the front that gave the impression of more bass, Martin Wavefront folded horn boxes, none of these ever did it for me, have been using direct radiating boxes for last 15-18 years so I am probably not qualified to talk about anyone's latest developments in "horn" loaded boxes, that being said, I can't see how anyone has overcome the physics to give you a "true" bass response, outside of electronic jiggery.

Just as an afterthought, I am talking about horn's with no direct radiation, not semi hybrid designs.
« Last Edit: December 15, 2011, 12:44:56 PM by Roland Clarke »
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Tom Stone

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Re: Direct versus Folded Horn Sub enclosures
« Reply #17 on: December 15, 2011, 01:04:54 PM »

 Here ago about these sub which is neither FH or DR, but coaxial
http://www.youtube.com/watch?v=Q5S_DIEDMOs

I know their for stage wedges but thought they looked cool and all the different ways you can stack them. I'm with the OP on the quasi Yorkville design pretty cool design.
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Stu McDoniel

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Re: Direct versus Folded Horn Sub enclosures
« Reply #18 on: December 15, 2011, 01:28:03 PM »

Thanks again to all of the knowledgeable people who unselfishly share their knowledge and experience.  I am looking at buying subs for my classic rock band PA.  "Back in the day" all of the high end subs were in folded horn or other type of enclosures "tuned" to amplify lower frequencies.  Now it seems that half of the high end subs are in direct radiator cabinets.  The direct radiator subs would certainly be easier to transport and store, but I would not want to sacrifice a significant amount of sound quality.  What are the pros and cons of sub enclosures?
Back in the day Crown, Phase Linear etc had max of 200 to 300 per channel
into 8 ohms..  Thus efficiency was the "horn loaded subs and cabs
As Tom stated you can go with Lab Grupens and Itechs and have 1500 per channel or more into 8 ohms real easy and the loudspeakers can take a lot more power as well and are more efficient in the 1w per 1m spec. 
Space is an issue as well...I do remember the Floyd tour having something like 24 semi loads of gear back in the Animals tour in 77.
Horns are big...horns are well..just plain Fu#king cool but not optimal in this day and age.  I have a bunch of old horn loaded cabs and I just cant get myself to burn them.
They sit and take up space in my storage.    One day I will burn them...I just know it
:)
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Tom Stone

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Re: Direct versus Folded Horn Sub enclosures
« Reply #19 on: December 15, 2011, 03:37:48 PM »

Back in the day Crown, Phase Linear etc had max of 200 to 300 per channel
into 8 ohms..  Thus efficiency was the "horn loaded subs and cabs
As Tom stated you can go with Lab Grupens and Itechs and have 1500 per channel or more into 8 ohms real easy and the loudspeakers can take a lot more power as well and are more efficient in the 1w per 1m spec. 
Space is an issue as well...I do remember the Floyd tour having something like 24 semi loads of gear back in the Animals tour in 77.
Horns are big...horns are well..just plain Fu#king cool but not optimal in this day and age.  I have a bunch of old horn loaded cabs and I just cant get myself to burn them.
They sit and take up space in my storage.    One day I will burn them...I just know it
:)

Seen the Animals tour in 78  great concert.
Back then before the arrays the SE's didn't mix a giant roar mix like today's rock concerts.
AC/DC nice pretty roar  :P
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Re: Direct versus Folded Horn Sub enclosures
« Reply #19 on: December 15, 2011, 03:37:48 PM »


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