No. 20 meters is a long distance . Average mid-price active 2 x 15" or even 2 x 18" will not cut it. You will need big man subs with big man amps behind them, minimum 4 x 18". 4 tapped horns or scoops, or 4 - 8 high grade bass reflex loaded 18". Or a stack of front loaded or bandpass horns.
Edit: for techno, a horn stack might be the best option
Thanks bob for the honest answer.. I’ll be looking for 18inch subs then and try to get 2x18 if possible.
I’m back again with another probably dumb question:
I saw that doubling a set (for example going from 2 RCF708A to 4 RCF708A) makes you gain 3db.
So, taking as a basis a DZR15 from Yamaha which has 139spl max and an RCF708A which has a 127spl max.
Does it mean that if I put the DZR15 at its maximum, I hear as much sound as 16 (!!) RCF708A together at their maximum too ???
As 2 RCF = 130db max, 4 RCF = 133db max, 8 RCF = 136db max and 16 RCF = 139 db max...
I’m back again with another probably dumb question:
I saw that doubling a set (for example going from 2 RCF708A to 4 RCF708A) makes you gain 3db.
So, taking as a basis a DZR15 from Yamaha which has 139spl max and an RCF708A which has a 127spl max.
Does it mean that if I put the DZR15 at its maximum, I hear as much sound as 16 (!!) RCF708A together at their maximum too ???
As 2 RCF = 130db max, 4 RCF = 133db max, 8 RCF = 136db max and 16 RCF = 139 db max...
No. Here's an article I wrote on the subject: Spec Wars: Looking Inside Loudspeaker SPL Specifications - ProSoundWeb
Chris
Chris
The basic arithmetic is right, but as Chris pointed out, the specs are not directly comparable. You CAN do such a comparison, if you look at the spl graph, and take power levels into account as well. But even then, some guesswork and error margin involved.
Ok I see, not as simple as I thought it was haha
Thanks for pointing that out..
By the way, I read across the forums that bass reflex subs are more suitable for outdoors (lot of people etc), is there a reason for that ?
I never got to experience of sound between a bass reflex and a bandpass sub..
Thanks for pointing that out..
By the way, I read across the forums that bass reflex subs are more suitable for outdoors (lot of people etc), is there a reason for that ?
I never got to experience of sound between a bass reflex and a bandpass sub..
Bandpass can sound just fine, so long as it's well designed. My first PA sub was a Tannoy T40, and recently I made a 4th order 2x18" which also sounded decent.
Bass reflex cabinets are commonly used because they're a good balance between enclosure size, LF extension, and output.
Good cabinets don't have a "sound" of their own. They just play the music.
Chris
Bass reflex cabinets are commonly used because they're a good balance between enclosure size, LF extension, and output.
Good cabinets don't have a "sound" of their own. They just play the music.
Chris
I have one 2x18 6th bandpass sub too. Great for indoors but not so good for outdoors (very omnidirectional).
They aren't really more suitable for outdoors... horns works best there, but they are more popular right now. The reasons for that are multiple...
- amp power is cheap and plentiful
- Reflex are the most compact PA sub design
- Reflex subs are a real swiss army knife.. they can handle all kinds of different music genres
- reflex subs scale up well from 1 to as many as you like.
- It's relatively easy to build cardioid arrays with reflex subs.
Thank you for the infos!
Now I understand why reflex subs are best for my use, as I’m playing the music outdoors, and would like to add subs gradually.
After all your advices, I think I’m going to buy the RCF 905 AS-II as it has all the caracteristics I need:
-bass reflex sub
-15 inch so more punchy and not too big for my « small » tops (RCF 708 and 712)
-same brand as the tops so not risky
-133 spl max and 1100W RMS so looks to be quite powerful
Now I understand why reflex subs are best for my use, as I’m playing the music outdoors, and would like to add subs gradually.
After all your advices, I think I’m going to buy the RCF 905 AS-II as it has all the caracteristics I need:
-bass reflex sub
-15 inch so more punchy and not too big for my « small » tops (RCF 708 and 712)
-same brand as the tops so not risky
-133 spl max and 1100W RMS so looks to be quite powerful
Just one thing, I saw this Meyer Sound HP-600 sub (2X15 inch sub with 2200W RMS and 138 spl max).
Basically, if I get two RCF 905 AS-II at full sound (one sub is 15 inch, 1100W RMS and 133 spl max), I will get the same power in my ears at a few meters as with the Meyer sub ?
Or a 2X15 inch sub like the Meyer will be more powerful itself than the two RCF ?
By the way, when I mean « more powerful », I mean the one that can produce the higher level of sound without starting to clip (red limiter button lighting up).
Basically, if I get two RCF 905 AS-II at full sound (one sub is 15 inch, 1100W RMS and 133 spl max), I will get the same power in my ears at a few meters as with the Meyer sub ?
Or a 2X15 inch sub like the Meyer will be more powerful itself than the two RCF ?
By the way, when I mean « more powerful », I mean the one that can produce the higher level of sound without starting to clip (red limiter button lighting up).
Needbass,
The answers to your questions go back to chris661 "Spec Wars".
1) The Meyers spec is a very short term peak in the upper range. As a comparative example, the 2x18" Meyers 650-P is rated as a "Maximum SPL 136dB @ 1meter", 2 dB less than the 2x15" 600-HP.
On 10/3/2009, got to do a side by side gig with my system ground stacked next to a flown Vertec 4889 system, 8 per side with 4 Meyers 650P subs on the ground per side.
16) 18” cones, 9920 watts ”burst capability”, 140 cubic feet of truck space, 1768 pounds of cabinet weight.
Headliner frequently pushed the 650P subs into “TPL” (TruPower limiting) and “Excursion limit”. The spectrum was 60 Hz boom-boom, about 6 dB more 60 than 40 Hz. At FOH, about 125 ft out, the system was hitting 108 dBC, the hard limit, no extra VU swing resulted in any more low frequency output, though it did sound crunchier..
My stage was doing dance groups with recorded music and one live act. On the last dance group, with some fairly heavy LF content, my 4)WS 2x12” front loaded ported subs using LAB 12s were hitting 104 dB, spectrum looking pretty equal from 40-80 Hz. 8)12” cones, 3600 watts (2 Crest CA-9), 31 cubic feet of truck space, 400 pounds of cabinet weight. Their output was +2 dB at 40 Hz, -4 dB at 60 Hz. Not bad compared to sixteen 18".
Since the ratio of Meyers to WS was 2/1, my cabinets were capable of 6dB more output to keep up- giving them somewhere around 142dB "peak" rating!
That said, I'd rate them at 125dB by their excursion limit.
2) As you can see by #1, peak specs may not relate well to real world output, though the RCF specs are probably far less inflated. Considering the drivers used in the RCF likely have considerably more excursion capability than the Meyers, and similar Fb, safe to say that a pair of the RCF 905 AS-II would have more output than the HP-600.
Attachments
Yeah I had understood what Chris said, I know I can’t really relate to all the specs mentionned by the brands, I got it that some inflate quite a bit their spl max or watts
I was trying to compare the two subs, taking into account no « lies » by both brands, as I wanted to know what would be most powerful between a 2X15 or two 15 side by side..
But obviously, with what you said now I understood that a pair of RCF subs will go higher than the 2X15 mentionned here.
However, as a 18 sub can go deeper and replicate lower frequencies, would it be a good idea to incorporate a 2X18 sub with my two 15inch subs already in place ?
So every frequencies could be replicated, punchy thanks to the 15inch subs and deeper thanks to the 2X18 sub..
Or it would make a complete mess ?..
It would make:
-Tops: 2XRCF 712A and 2XRCF708A
-Subs: 2XRCF 905 AS-II and a 2X18 active sub
By the way, I only use active speakers/tops with a mixer, so no equalizer etc.
I was trying to compare the two subs, taking into account no « lies » by both brands, as I wanted to know what would be most powerful between a 2X15 or two 15 side by side..
But obviously, with what you said now I understood that a pair of RCF subs will go higher than the 2X15 mentionned here.
However, as a 18 sub can go deeper and replicate lower frequencies, would it be a good idea to incorporate a 2X18 sub with my two 15inch subs already in place ?
So every frequencies could be replicated, punchy thanks to the 15inch subs and deeper thanks to the 2X18 sub..
Or it would make a complete mess ?..
It would make:
-Tops: 2XRCF 712A and 2XRCF708A
-Subs: 2XRCF 905 AS-II and a 2X18 active sub
By the way, I only use active speakers/tops with a mixer, so no equalizer etc.
Unless you really know what you're doing with a measurement mic and DSP, keep all your subs to the same make and model.
The whole 18" is deeper than a 15" thing is largely a myth. It depends on a lot of factors. If you were to compare the B&C 18SW115 vs the 15SW115 and give the 18" a bigger cabinet tuned lower, then yes it might well have a bit more LF extension.
However, if you put the B&C 15" against an old-school 300W RMS 18", the 15" will demolish the 18" in terms of LF extension and output.
FWIW, I did this: PA system check at Batley Rugby Stadium - YouTube
With a total of 4x 15" subs.
Chris
The whole 18" is deeper than a 15" thing is largely a myth. It depends on a lot of factors. If you were to compare the B&C 18SW115 vs the 15SW115 and give the 18" a bigger cabinet tuned lower, then yes it might well have a bit more LF extension.
However, if you put the B&C 15" against an old-school 300W RMS 18", the 15" will demolish the 18" in terms of LF extension and output.
FWIW, I did this: PA system check at Batley Rugby Stadium - YouTube
With a total of 4x 15" subs.
Chris
Just looked at the video of the Pa system you made in the stadium, very impressive.. I didn’t know 15 inch subs could cover such a large area..
I get it, I’ll go with the same brands for subs and tops, I just thought it would be nice to add that 2X18 sub to go extra deep but now I understand I might just regret it very rapidly.
I just have another question: I have two RCF712A at the moment which I’m using. And I also have two RCF708A somewhere else which would take some time to get them back.
I tested both models and I can tell the RCF 712A are more powerful but not THAT much.
However, I never had the opportunity to test all 4 speakers together and before I might go get the 708 back, do you think it’s a good idea to put all 4 speaker together for a large event ?
Or the sound won’t be good because of the diference between woofer’s sizes (8 inch for 708A and 12 inch for 712A).
Basically, is a woofer difference between two pair of speakers a problem when it comes to putting them side to side for an outdoor sound systemb?
I get it, I’ll go with the same brands for subs and tops, I just thought it would be nice to add that 2X18 sub to go extra deep but now I understand I might just regret it very rapidly.
I just have another question: I have two RCF712A at the moment which I’m using. And I also have two RCF708A somewhere else which would take some time to get them back.
I tested both models and I can tell the RCF 712A are more powerful but not THAT much.
However, I never had the opportunity to test all 4 speakers together and before I might go get the 708 back, do you think it’s a good idea to put all 4 speaker together for a large event ?
Or the sound won’t be good because of the diference between woofer’s sizes (8 inch for 708A and 12 inch for 712A).
Basically, is a woofer difference between two pair of speakers a problem when it comes to putting them side to side for an outdoor sound systemb?
Ive DJ'd at a smallish club in Poland that had a pair of RCF 8003 ASII subs. I have to say they performed pretty well. I was also playing techno and those things responded pretty well to tracks with 40-45hz kicks and bass lines. Paired with 2 yamaha dsr15s the system went loud and sounded pretty decent.
For that sort of music you need to look at the frequency response of the sub you are looking at. They may have a peak spl of 135db or whatever but that is no good if they drop off by 10db at 40hz. That might be Ok for house music but definitely not OK for techno.
For that sort of music you need to look at the frequency response of the sub you are looking at. They may have a peak spl of 135db or whatever but that is no good if they drop off by 10db at 40hz. That might be Ok for house music but definitely not OK for techno.
Hello, I’m coming back because I just bought the RCF 905 AS-II but still don’t have the opportunity to test it..
Just some things I don’t understand about it:
-there is a « delay » mode which goes from 0,1m (meters) to 20 and I don’t know on what should I set it ? I just want to have the same delay as a classic active subwoofer.. nothing complicated
-there is an « input gain reduction » mode and I don’t really know what it stands for either..
Thanks for your help..
Just some things I don’t understand about it:
-there is a « delay » mode which goes from 0,1m (meters) to 20 and I don’t know on what should I set it ? I just want to have the same delay as a classic active subwoofer.. nothing complicated
-there is an « input gain reduction » mode and I don’t really know what it stands for either..
Thanks for your help..
Delay should probably be set to zero - you usually need to delay the main speakers to match the subs IIRC, but a lot will depend on physical positioning.
Input gain reduction is likely an LED to tell you that the limiters are engaging.
Chris
Input gain reduction is likely an LED to tell you that the limiters are engaging.
Chris
Input gain reduction is exactly that- a reduction of the input gain, also known as attenuation (up to 99dB), or a volume control/fader/knob/potentiometer...
When setting it, the left hand indicator light illuminates.
When setting the delay, the center indicator light illuminates red, when set it indicates green when signal is present.
When the soft clipping circuit is active (the limiters are engaging), the right hand LED blinks red.
From Page 7 of the RCF 905 AS-II manual:
"Pushing the rear encoder, it is possible to select the following three functions: - input gain reduction - speaker delay setting - selection of a speaker preset. Pushing once the rear encoder the gain reduction LED will light up. Now rotating the encoder counter clockwise, it will be possible to reduce the input gain. The gain reduction will be in steps of 0,1 dB for the first 10 dB and then in 1 dB steps. The maximum reduction is 99 dB."
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