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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 Lounge FUD Forum Archive => Topic started by: [x] on October 13, 2004, 07:59:28 pm

Title: 21" Cones - Why Not?
Post by: [x] on October 13, 2004, 07:59:28 pm
I see a lot of people using single and dual 18" boxes. It's like the industry standard or something, for pro sound companies to have a large inventory of dual-18" enclosures. But what I'd like to know is, why aren't 21" woofers like this one (see picture) in wider use?

P-Audio SD-21 http://www.paudio-europe.com/products/foto/foto_sd-21.jpg

This has a 6" Voice Coil (!) and extends down to 30 Hz. It also handles 1000w per driver RMS, 2000w max. A dual-12" cabinet could handle 4000 watts with just one unit.
Title: Re: 21" Cones - Why Not?
Post by: Dietrich Sider on October 13, 2004, 11:30:52 pm
Any product decision in Live Audio will be made for the following reasons (not necessarily in order of importance): size and weight, cost, reliability, performance.

Why aren't 21" drivers used more often for subwoofers?

1) size and weight - 21" loudspeakers are HEAVY and need a bigger, stronger box - this impacts load crew and truck pack. The  one you show from P-Audio weighs in at 68 lbs just for the driver - about double the weight of most 18" speakers

2) they cost significantly more than the 'industry standard' 18" drivers or boxes.

3) reliability? couldn't tell you as I've never owned one - maybe someone else has some facts and figures or a personal experience. I would have to say though that they have yet to prove themselves in the market.

4) performance - I've heard several people argue that 21" subs are not the nicest sounding boxes - they lack clarity or punch. Sure, they go low, but they don't give the sound that most live audio engineers are looking for.

There ya go . . . Very Happy
Title: Re: 21" Cones - Why Not?
Post by: Graeme Goodacre [Centauri on October 14, 2004, 08:03:12 am
Would echo dsider's comments and add that this particular speaker mentioned doesn't model very well either.  Doesn't seem to like going low in any cabinet and its 5mm Xmax limits it to about 300W at 30Hz.  Maximum output is around 115dB at 30Hz - would do better with a Labsub with less power and less $ outlay...

You also mention 18s as "industry standard" - this only comes about from the thinking that "bigger must be better (deeper)" and is actively encouraged by speaker manufacturers marketing departments.  EAW's top performance sub uses 12s....

Cheers
Title: Re: 21" Cones - Why Not?
Post by: Mike {AB} Butler on October 14, 2004, 11:45:50 am
BHFProfessional wrote on Wed, 13 October 2004 16:59

I see a lot of people using single and dual 18" boxes. It's like the industry standard or something, for pro sound companies to have a large inventory of dual-18" enclosures. But what I'd like to know is, why aren't 21" woofers like this one (see picture) in wider use?




Simple answer. Transient response. An 18" woofer is commonly considered the largest size woofer that will effectively reproduce transients. The larger the cone surface area, typically thicker material is required to make the cone rigid enough to withstand the immense push of the voice coil.
EV had their 30" woofer 20+ years ago (Mitsubishi and possibly others had King Size woofers as well), and it put out some IMPRESSIVE low end. But no punch. Notice it isn't widely used or available anymore?
It IS possible that through new materials that these guys have overcome this issue - but I don't believe it..
Regards,
Mike
Title: Re: 21" Cones - Why Not?
Post by: Jim Brooks on October 14, 2004, 12:40:45 pm
I'm not saying I'm into 21" speakers,
But there is an awful lot of
Turbosound TSW-21 cabinets out there
for something that 's not supposed to work so well.

Just a thought,
Jim Brooks
Title: Re: 21" Cones - Why Not?
Post by: John Roberts {JR} on October 14, 2004, 02:03:52 pm
21" will work OK within their bandpass but you will probably use another smaller woofer above them.

JR
Title: Re: 21" Cones - Why Not?
Post by: Mikael Holm (the old one) on October 14, 2004, 07:14:41 pm
JR wrote on Thu, 14 October 2004 21:03

21" will work OK within their bandpass but you will probably use another smaller woofer above them.


Up to 150Hz w/ Flashlight and 180Hz w/ Floodlight. OTOH Turbo recommend TSW-718 (double 18") w/ Floods because of the upper limit of the bandpass horn.

Title: Re: 21" Cones - Why Not?
Post by: Mikael Holm (the old one) on October 14, 2004, 07:18:05 pm
jbrooks wrote on Thu, 14 October 2004 19:40

But there is an awful lot of
Turbosound TSW-21 cabinets out there
for something that 's not supposed to work so well.


I remember seeing a figure of over 3000 Turbosound Flashlight TFS-780H sold so there must be AT LEAST 3000 TFS-780L boxes laying around somewhere. Add to that the sister box TSW-721 (without flyware) and we are counting some huge numbers of 21" drivers being in use today.

Title: Re: 21" Cones - Why Not?
Post by: Tim Padrick on October 14, 2004, 09:16:50 pm
Quote:

Mike AB wrote on Thu, 14 October 2004 10:45
Simple answer. Transient response. An 18" woofer is commonly considered the largest size woofer that will effectively reproduce transients. The larger the cone surface area, typically thicker material is required to make the cone rigid enough to withstand the immense push of the voice coil.
EV had their 30" woofer 20+ years ago (Mitsubishi and possibly others had King Size woofers as well), and it put out some IMPRESSIVE low end. But no punch. Notice it isn't widely used or available anymore?
It IS possible that through new materials that these guys have overcome this issue - but I don't believe it..
Regards,
Mike


Nope.  The rise time of the signals produced by subs is very long (in other words, the signals are "slow").  Driver speed is just not an issue.  If subwoofer 'A' "sounds faster" or "has more punch" than subwoofer 'B', it is almost certainly because of one of the following:

'A' is producing more distortion than is 'B'.  The distortion products are more audible than the fundamental frequency.  Most PA subs are junk - 40Hz in at a decent level gives as much 80Hz and 160Hz out as 40Hz out.  (Many Hi-Fi subs aren't a lot better.)

'A' has better phase/time alignment to the rest of the system than does 'B'. Owing to the various box designs and the crossover and EQ filters, subs require that the top boxes be delayed to the subs to align the boxes properly.  (My subs are front loaded, and I have to delay the tops 12.5 feet to line them up.  It makes quite a differenc.)

'B' has a badly tuned port (or a badly designed horn) and is resonating excessively (it is 'ringing' or has a lot of 'overhang').



Title: Re: 21" Cones - Why Not?
Post by: Scott Shaw on October 14, 2004, 11:19:21 pm
While I'm certainly no expert on this subject, or any other in pro sound, I would think the mechanical damping of a speaker that size would be a factor. I prefer 10's over 15's or 18's on my bass rig because of their abilty to produce very tight response. Each speaker size seems to have it's own characteristics.

Scott
Title: Re: 21" Cones - Why Not?
Post by: Baron Gray on October 15, 2004, 05:46:49 am
Yup and that's why guitar players seem to go for the old 12" and Bass players opt for the 8 or 10s in their quad or octa boxes.

It is all about personal preference and I like my bass tight and punchy and all the 12s I have tried sounded a bit fuzzy around the edges compared to the 10s.

Baron
Title: Re: 21" Cones - Why Not?
Post by: David A. Parker on October 15, 2004, 08:44:34 am
Ah, the KF940 Supersub. I experienced those once, it was unforgetable. It was an outside festival, I parked a half mile from the stage, and the bass was tight when I got out of the car. A quote from the eaw website

Description
The KF940 portable horn-loaded subwoofer system, otherwise known as the "Super-Sub," has created a new level of sub bass performance by loading two specially designed 12 in woofers with a horn with an exponentially expanding throat that is over 13 ft long. Great care has been taken to create woofer cones that could withstand the force of being loaded with such a large horn. As an impedance matching device, the horn brings the 1 watt @ 1 meter sensitivity of the system at 100 Hz to 113 dB SPL.

Note the 113 DB sensitivity at 1w/1m. BUTTT!!!!! You need a forklift with each cab weighing 360# !!!! AND!! EAW sells a lot more double 18's, THE INDUSTRY STANDARD (for whatever reason), than the KF940's.
Title: Re: 21" Cones - Why Not?
Post by: David A. Parker on October 15, 2004, 08:56:41 am
But then what the audience actually hears, coming from the mains, is coming from a combinations of drivers, usually starting with 18's. So, what you are hearing onstage from your 10's can never be exactly what the audience is hearing. I am a sound man and bassist, and I believe one of the advantages of the bassist having 10's onstage is that the 10's are easier to hear up close. A bassist standing near his stage rig cannot hear the lower freqs an 18 puts out. They develop out farther in the room and the sound guy has to deal with them. 10's do this too, but not nearly as bad. One thing I noticed early on in this business is that to satisfy the bassist onstage, (me included), the stage rig will be pretty much filling the room with bass. AND, it doesn't matter if the bassist doesn't have a rig onstage, if he only has wedges, when I get the wedges cranked enough to make the bassist happy, the wedges are filling the room with bass.
Title: Re: 21" Cones - Why Not?
Post by: Elliot Thompson on October 15, 2004, 10:14:43 am
BHFProfessional wrote on Thu, 14 October 2004 00:59

I see a lot of people using single and dual 18" boxes. It's like the industry standard or something, for pro sound companies to have a large inventory of dual-18" enclosures. But what I'd like to know is, why aren't 21" woofers like this one (see picture) in wider use?

P-Audio SD-21 http://www.paudio-europe.com/products/foto/foto_sd-21.jpg

This has a 6" Voice Coil (!) and extends down to 30 Hz. It also handles 1000w per driver RMS, 2000w max. A dual-12" cabinet could handle 4000 watts with just one unit.



21" woofers are limited in selection. Beyma, Precision
Devices, and, P Audio, are the only companies (To my
knowledge) that make 21" tranducers.

The Beyma is designed for a Reflex Cab {QTS 0.43}

The Precision Devices is designed for a Horn-Loaded Cab. {QTS 0.19}

The P Audio is designed for a Horn-Loaded Cab. {QTS 0.22}

So, IMHO if the QTS was around 0.3 - 0.35, you would see
Dual 21's popping up. For the extension, of a dual 18 cab,
will require a very large box, for the Beyma, and, for a
21" horn, the cabinet size will be too large, using the P
Audio, and, Precision Devices.


Best Regards,
Title: Re: 21" Cones - Why Not?
Post by: Chris Cowley on October 15, 2004, 12:47:15 pm
At Plasa a few weeks ago I hear the Void Static system. This used an 15" horn on bass, with 21" bandpass below it.

This was one seriously kickass rig, the best I have heard in a longtime (it looked cool as well).

I was was designed by Rog Mogale (www.speakerplans.com) who is bit of genius.
Title: Re: 21" Cones - Why Not?
Post by: Dave Barnett on October 17, 2004, 11:02:37 am
Mike AB wrote on Thu, 14 October 2004 10:45



Simple answer. Transient response. An 18" woofer is commonly considered the largest size woofer that will effectively reproduce transients.


What kind of transients make it through a low-pass filter?????
Title: Re: 21" Cones - Why Not?
Post by: John Roberts {JR} on October 17, 2004, 11:13:23 am
Dave Barnett wrote on Sun, 17 October 2004 10:02

Mike AB wrote on Thu, 14 October 2004 10:45



Simple answer. Transient response. An 18" woofer is commonly considered the largest size woofer that will effectively reproduce transients.


What kind of transients make it through a low-pass filter?????

Very large ones ....   Smile  

JR
Title: Re: 21" Cones - Why Not?
Post by: bgavin (Bruce Gavin) on October 18, 2004, 11:20:49 am
Looking over the numbers on the SD-21, the BL:MMS ratio (motor strength to total cone mass) is right there with the better 18" drivers, i.e. Eminence Magnum, JBL, B&C, Beyma.

However, this ratio is only half of that for high quality 15" drivers, which are reputed to have more punch.

A higher motor strength relative to cone mass provides tighter control over cone acceleration, especially for transients.  The ability to accelerate the cone faster translates into "punch" in my mind.  Hence, bass players and their love for 10" drivers.  

It would be interesting to see this on a scope.
Title: Re: 21" Cones - Why Not?
Post by: Greg Bass on October 18, 2004, 08:41:03 pm
A club I work at regularly has some old Turbo stuff -early 80's maybe late 70's.  Two of the subs have 21" or 24" drivers and the other two have 15"'s I believe. All in horns. Substantial low end.

Cheers1

Scred
Title: Re: 21" Cones - Why Not?
Post by: Noel Bennett on October 18, 2004, 09:46:00 pm
A friend of mine has a single P Audio 21 in a bandpass box that is significantly smaller than any 2x18 sub I have ever seen . They are in an instillation with one sub a side with 2x 15 and 2coaxial P audio mid highs powered by lab gruppens and believe me this little rig rocks
Title: Re: 21" Cones - Why Not?
Post by: Noel Bennett on October 18, 2004, 09:49:12 pm
Only 360 lbs  an S4 weighs in at nearly 500lbs didnt stop people using them
Title: Re: 21" Cones - Why Not?
Post by: bgavin (Bruce Gavin) on October 19, 2004, 02:08:35 pm
The T/S data for the SD-21 indicates it is a typical high efficiency sub, small box, with a high F3.

Title: Re: 21" Cones - Why Not?
Post by: Mikael Holm (the old one) on October 28, 2004, 11:15:50 am
Old thread, yadda yadda but...

D. Parker wrote on Fri, 15 October 2004 15:44

Note the 113 DB sensitivity at 1w/1m. BUTTT!!!!!


As was said that sensitivity is at 100Hz. They are 8dB down from that at ~30Hz. It's useless to quote the sensitivities outside the bandpass they are used.

Title: Re: 21" Cones - Why Not?
Post by: Mikael Holm (the old one) on October 28, 2004, 11:48:23 am
D. Parker wrote on Fri, 15 October 2004 15:56

I believe one of the advantages of the bassist having 10's onstage is that the 10's are easier to hear up close.


Yup and that is because smaller cones usually have better response where it really counts iow. in the 1kHz and up range (definition is in the 2-5kHz range).

Quote:

A bassist standing near his stage rig cannot hear the lower freqs an 18 puts out.


BS. It's because they have it directed to their legs. In the 2-5kHz range they have serious directivity and that's why they must be cranked higher.

Quote:

They develop out farther in the room and the sound guy has to deal with them. 10's do this too, but not nearly as bad.


Nope. A soundwave does not need any distance to develope. See above for the explanation. 10" woofers has less directive response at upper frequencies so you don't have to turn then so loud.

Besides quad 10" cabinets are not that better than very large woofers. They have serious directivity and destructive interference up where the definition is -> bassplayer turn them louder. That's the real reason why FOH engineers have hard time with bassplayers.

Quote:

One thing I noticed early on in this business is that to satisfy the bassist onstage, (me included), the stage rig will be pretty much filling the room with bass. AND, it doesn't matter if the bassist doesn't have a rig onstage, if he only has wedges, when I get the wedges cranked enough to make the bassist happy, the wedges are filling the room with bass.


It's about the feel. Boost HF and see what happens.

Title: Re: 21" Cones - Why Not?
Post by: AxeSlash on October 29, 2004, 08:07:10 pm
Thought this might be of interest; Adamson are developing a new 21" kevlar coned sub to complement the Y18 (SX subs aren't man enough for the job)...don't know much about it, I'm just hoping it'll be better than their kevlar 18s are. One to keep an eye on I think just to see what it's capable of.