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Author Topic: Weekend Warrior Cover Band Needs New Speakers... But What?  (Read 1255 times)

Phil Schrantz

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Re: Weekend Warrior Cover Band Needs New Speakers... But What?
« Reply #30 on: Yesterday at 11:18:05 AM »

Related question:

As noted, my current subs are JBL PRX815XLF. As I think about logistics (and my aging body) I find myself wondering if I could accomplish my goals by adding another pair of 15Ē subs. I could then bring additional subs in spaces I need more bottom. But I donít really understand the physics with this approach. Air is air, after all, and has to be moved. Would that approach produce a result similar to a pair of single 18s? How important would it be for the subs to be matched?

Thanks for smartening me up!
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Scott Holtzman

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Re: Weekend Warrior Cover Band Needs New Speakers... But What?
« Reply #31 on: Yesterday at 01:32:52 PM »

Related question:

As noted, my current subs are JBL PRX815XLF. As I think about logistics (and my aging body) I find myself wondering if I could accomplish my goals by adding another pair of 15Ē subs. I could then bring additional subs in spaces I need more bottom. But I donít really understand the physics with this approach. Air is air, after all, and has to be moved. Would that approach produce a result similar to a pair of single 18s? How important would it be for the subs to be matched?

Thanks for smartening me up!
I would dump the 18 and get another pair of fifteens so that she got 4 15ís I think you would find your best performance that way.


If I were you, thereís so well, balanced, and easy to move. I would look really really hard at the JTR double 15 box. Its output per pound is amazing.


Sent from my iPhone using Tapatalk
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Scott AKA "Skyking" Holtzman

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Dave Garoutte

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Re: Weekend Warrior Cover Band Needs New Speakers... But What?
« Reply #32 on: Yesterday at 01:44:21 PM »

I would dump the 18 and get another pair of fifteens so that she got 4 15ís I think you would find your best performance that way.


If I were you, thereís so well, balanced, and easy to move. I would look really really hard at the JTR double 15 box. Its output per pound is amazing.


Sent from my iPhone using Tapatalk

Just add wheels.
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Art Welter

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Re: Weekend Warrior Cover Band Needs New Speakers... But What?
« Reply #33 on: Yesterday at 05:41:46 PM »

Related question:

As noted, my current subs are JBL PRX815XLF. As I think about logistics (and my aging body) I find myself wondering if I could accomplish my goals by adding another pair of 15Ē subs. I could then bring additional subs in spaces I need more bottom. But I donít really understand the physics with this approach. Air is air, after all, and has to be moved. Would that approach produce a result similar to a pair of single 18s? How important would it be for the subs to be matched?

Thanks for smartening me up!
Air is air, and there is no replacement for it's displacement at low frequencies.
Low frequency speakers are governed by Hoffman's Iron Law: Efficient, Low, Small, pick any two.

Matching the phase response of additional speakers is important, if not close (within 90 degrees) the different speakers can reduce output.  Even if the cabinets are nearly identical, the DSP processing in different powered speakers could result in cancellation of output.

The JBL PRX815XLF uses a 15" 2275 driver, which has an Xmax (linear excursion) of +/-8mm.
There are subs available using drivers with double (or more) displacement than the 2275, such as JTR, Bassboss, DSL etc. Doubling displacement gives +6dB more low frequency output, but requires two to four times (+3 to 6dB)more power.
The JTR Captivator 215PRO drivers have 19mm Xmax and 30mm Xmech (60mm peak to peak).

Unfortunately, like most speaker specifications, Xmax can be calculated many different ways.  JBL is pretty consistent, though mistook Xlim/Xmech (mechanical limit or failure) for Xmax on some past data sheets for the 2268 used in the SRX series.
Xlim/Xmech should be about double Xmax for pro woofers, though gets less with longer excursion to keep the surround a reasonable size.

Finding specifications with Xvar, which is 70% Bl motor strength is a more reliable figure.
Driving a driver past Xmax can increase harmonic distortion from around 10% to 100% or more. As anyone hearing a guitar amp knows, more distortion sounds louder..

Doubling cabinets and power results in +6dB level (if the output coherently couples), which sounds about twice as loud to our hearing/feeling in the low end.
-6dB is equivalent to doubling the distance from the source outdoors.
A sub system that is +6dB will sound as loud at 20 meters (65 feet) as the weaker one at 10 meters (32.5 feet).

An 18' of the same excursion in the same size cabinet with the same low frequency box tuning (Fb) will be capable of about 3 dB more output than a 15". That said, larger drivers generally require larger cabinets for the same low frequency corner.

Horn speakers like the DSL TH-118 "tapped horn" are as much as +6dB more sensitive than a (smaller) bass reflex, so can do more with less power, but are larger. The DSL-118 uses a driver with an Xvar of 16mm and over double the power handling, so could have more than 12dB more output than the PRX815XLF.

This calculator is useful for getting a rough idea of what a driver of a given Xmax can do assuming a sealed box or infinite baffle alignment:

http://www.baudline.com/erik/bass/xmaxer.html

Bass reflex can add 3-6dB around the tuning frequency (Fb), large horns 6-10dB across the entire sub range.

Art
« Last Edit: Yesterday at 06:42:59 PM by Art Welter »
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Chris Hindle

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Re: Weekend Warrior Cover Band Needs New Speakers... But What?
« Reply #34 on: Yesterday at 11:29:03 PM »

Because they're giant and heavy as shit?  :-\
naw. that's what 850's are for.... 8)
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Ya, Whatever. Just throw a '57 on it, and get off my stage.

Tim McCulloch

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Re: Weekend Warrior Cover Band Needs New Speakers... But What?
« Reply #35 on: Today at 12:11:59 AM »

naw. that's what 850's are for.... 8)

Those "one of the happiest days of my life was...."

The day the last Soundcraft mixer left our shop to never return

The day the last MAC 2000 left our shop to become someone else's problem.

But I was not around for the day the last 12 KF850 finally shipped.  >:(
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Scott Bolt

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Re: Weekend Warrior Cover Band Needs New Speakers... But What?
« Reply #36 on: Today at 08:49:47 AM »

Air is air, and there is no replacement for it's displacement at low frequencies.
Low frequency speakers are governed by Hoffman's Iron Law: Efficient, Low, Small, pick any two.

Matching the phase response of additional speakers is important, if not close (within 90 degrees) the different speakers can reduce output.  Even if the cabinets are nearly identical, the DSP processing in different powered speakers could result in cancellation of output.

The JBL PRX815XLF uses a 15" 2275 driver, which has an Xmax (linear excursion) of +/-8mm.
There are subs available using drivers with double (or more) displacement than the 2275, such as JTR, Bassboss, DSL etc. Doubling displacement gives +6dB more low frequency output, but requires two to four times (+3 to 6dB)more power.
The JTR Captivator 215PRO drivers have 19mm Xmax and 30mm Xmech (60mm peak to peak).

Unfortunately, like most speaker specifications, Xmax can be calculated many different ways.  JBL is pretty consistent, though mistook Xlim/Xmech (mechanical limit or failure) for Xmax on some past data sheets for the 2268 used in the SRX series.
Xlim/Xmech should be about double Xmax for pro woofers, though gets less with longer excursion to keep the surround a reasonable size.

Finding specifications with Xvar, which is 70% Bl motor strength is a more reliable figure.
Driving a driver past Xmax can increase harmonic distortion from around 10% to 100% or more. As anyone hearing a guitar amp knows, more distortion sounds louder..

Doubling cabinets and power results in +6dB level (if the output coherently couples), which sounds about twice as loud to our hearing/feeling in the low end.
-6dB is equivalent to doubling the distance from the source outdoors.
A sub system that is +6dB will sound as loud at 20 meters (65 feet) as the weaker one at 10 meters (32.5 feet).

An 18' of the same excursion in the same size cabinet with the same low frequency box tuning (Fb) will be capable of about 3 dB more output than a 15". That said, larger drivers generally require larger cabinets for the same low frequency corner.

Horn speakers like the DSL TH-118 "tapped horn" are as much as +6dB more sensitive than a (smaller) bass reflex, so can do more with less power, but are larger. The DSL-118 uses a driver with an Xvar of 16mm and over double the power handling, so could have more than 12dB more output than the PRX815XLF.

This calculator is useful for getting a rough idea of what a driver of a given Xmax can do assuming a sealed box or infinite baffle alignment:

http://www.baudline.com/erik/bass/xmaxer.html

Bass reflex can add 3-6dB around the tuning frequency (Fb), large horns 6-10dB across the entire sub range.

Art
Great post!  I have said much the same thing on multiple occasions, but generally peoples eyes glaze over when I start trying to explain xmax ;).

Do you happen to know the xmax on the RCF 8003 and 9004 drivers?  I looked, but couldn't find the spec anywhere.  I know they perform relatively well (compared to SRX, DSR, etc), but thought they may fall short of JTR xmax which seems to be industry leading.

Thanks.
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Mike Monte

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Re: Weekend Warrior Cover Band Needs New Speakers... But What?
« Reply #37 on: Today at 09:51:15 AM »

I'm old
 Venues range from the neighborhood bar with 100 people to local "music in the park" outdoor shows to small festivals. We all go to FOH and all use IEMs. As we've grown, our modest PA speakers (JBL PRX612M tops and PRX815XLF subs)
are starting to show their age.

Well, as others have suggested (and re-stated) you would probably be best to rent a rig for your larger venues/outdoor concerts and be done with it.
When I was contracting my club/wedding/GB band we used a modest PA that was easy to load in/out/set up/strike.

We gigged the above-listed circuit and it worked well for us....then I got the "upgrade bug" which led to bigger/heavier/louder gear for-the-same gigs that we were doing.....plus the-few outdoor gigs....set up / strike time got longer and gigging became less-fun for me....(be careful, it's a slippery slope).

IMO: a modest rig that is easy to lug (transport, schlepp, etc) playing at 7/8 out of 10 on most of your gigs is better than a larger PA rig that can play 2x as loud (but you attenuate it at 4 out of 10... for the same venues)...
 
^^^Your back will tell you this.^^^

"starting to show their age" suggested to me that you may be getting some dings in your grills - Why not get new grills and paint the cabs?

The gear that you currently have seems adequate for your current indoor applications however
if you are looking to add a bit more "umph" to your indoor rig, get an additional pair of like subs....adding more subs will fill-out your rig's sound quite a bit.





 
« Last Edit: Today at 01:26:28 PM by Mike Monte »
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Bob Stone

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Re: Weekend Warrior Cover Band Needs New Speakers... But What?
« Reply #38 on: Today at 12:49:32 PM »

Those "one of the happiest days of my life was...."

The day the last Soundcraft mixer left our shop to never return

The day the last MAC 2000 left our shop to become someone else's problem.

But I was not around for the day the last 12 KF850 finally shipped.  >:(

Oh come on now, I loved old analog Soundcraft mixers (and still do)...I know mixers shouldn't "sound" different, but there is a warmth in Soundcrafts that I haven't quite heard in other mixers.
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Art Welter

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Re: Weekend Warrior Cover Band Needs New Speakers... But What?
« Reply #39 on: Today at 05:42:39 PM »


Do you happen to know the xmax on the RCF 8003 and 9004 drivers? I looked, but couldn't find the spec anywhere.  I know they perform relatively well (compared to SRX, DSR, etc), but thought they may fall short of JTR xmax which seems to be industry leading.
Don't know what drivers are used  in the 8003 and 9004, but both the RCF Neo and ferrite 4" voice coil drivers they sell separately list 9mm Xmax.
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Re: Weekend Warrior Cover Band Needs New Speakers... But What?
¬ę Reply #39 on: Today at 05:42:39 PM ¬Ľ


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