@wae
yeah my cabs would be about 30 kilos. Hey we work in the music industry lugging around equipment all the time. Any of us should be able to lift 30 kilos. Not that I want to though.
Anyway, your idea is very interesting. Let's see a sketch.
yeah my cabs would be about 30 kilos. Hey we work in the music industry lugging around equipment all the time. Any of us should be able to lift 30 kilos. Not that I want to though.
Anyway, your idea is very interesting. Let's see a sketch.
Hi Crahspc,
Thanks for the reply. We don't aim and home usage, but want to design and build a compact HIFI DIY PA. So, we thought of a Sub and a separate Satellite / Top cabinet. MUST be compact and handle a band. A sub usually is crossed somewhere between 80 - 120 Hz, so I choose 120 Hz for various reasons, one "most" important, I DON'T want large drivers in the Tops.
Hmm, what about this.
I compared 4 x 12" with 2x 18". You would expect the 18" to just walk all over the 12", would you?
Well, I compared B&C 12TBX100 with B&C 18SW115. The 18" is an animal, so must be the winner then. Some facts;
2 x 12" Sd = 1 x 18" Sd (90- 95 %)
2 x 12" Pe = 2000 Watt, 1 x 18" Pe = 1700 watt
Now 80 liters is even smaller to your "tiny" 15", so I put 2 x 12" in push Pull config in an 80 Liter bass reflex and compared it to 1 x 18 " in bass reflex. Based on the facts, it would result in kind of the same. So, here's what I did, I ran a quick config in BB 6 Pro, I used:
2 cabinets of the 2 x 12" push pull bass reflex config in 80 Liters = 160 Liters,
2 Cabinets of the 1 x 18" bass reflex config in 80 Liters = 160 Liters
and loaded it with 2000 watt. Is used: F3 @ 35 Hz, same cabinet volume, same Power applied, same bass reflex tuning, same DSP setting.
Now that would be fair, would it?
Look at the graph attached. the YELLOW = 2 x 12", the BLUE = 1 x 18". Both feel at home in this config.
Kind of the same isn't it? The slight valley of the 12" is typical for this 12", using a Faital Pro 12" would NOT give this valley. The 120 Hz cross-over makes this valley almost disappear and it would be hard to hear this.
I would opt for the 2 x 12" cabinets, because;
1 - the push pull config greatly reduces distortion
2 - a 12" conus don't break-up that easy compared to 18"
3 - 2 voice coils would have a less hard time (less heat compression) compared to the 18".
4 - You spend the same money on 2 x 12" compared to 1 x 18" in most cases.
Same story for the 10", but you would need 3 or 4 x 10" versus 1 x 18".
Price wise, almost the same, the 18" may win if you would need 4 x 10" by a few euro's / dollars. But the 10" is even better in distortion reduction and cone break-up.
For the Tops, the idea that a 6" would not work well below 250 Hz sounds strange to me, do you have a explanation for this statement (of course depending on the driver). I've used 6" in column arrays and they nicely roll off at 120 Hz in sealed enclosures, the Faital Pro 6FE100 I used handles 100 Watt easily in a 10 Liter enclosure and rolls off at around 120 Hz. RCF, JBL and others use 6" a lot, must be a reason I guess 🙄.
kind regards,
Frans Wessels
Thanks for the reply. We don't aim and home usage, but want to design and build a compact HIFI DIY PA. So, we thought of a Sub and a separate Satellite / Top cabinet. MUST be compact and handle a band. A sub usually is crossed somewhere between 80 - 120 Hz, so I choose 120 Hz for various reasons, one "most" important, I DON'T want large drivers in the Tops.
Hmm, what about this.
I compared 4 x 12" with 2x 18". You would expect the 18" to just walk all over the 12", would you?
Well, I compared B&C 12TBX100 with B&C 18SW115. The 18" is an animal, so must be the winner then. Some facts;
2 x 12" Sd = 1 x 18" Sd (90- 95 %)
2 x 12" Pe = 2000 Watt, 1 x 18" Pe = 1700 watt
Now 80 liters is even smaller to your "tiny" 15", so I put 2 x 12" in push Pull config in an 80 Liter bass reflex and compared it to 1 x 18 " in bass reflex. Based on the facts, it would result in kind of the same. So, here's what I did, I ran a quick config in BB 6 Pro, I used:
2 cabinets of the 2 x 12" push pull bass reflex config in 80 Liters = 160 Liters,
2 Cabinets of the 1 x 18" bass reflex config in 80 Liters = 160 Liters
and loaded it with 2000 watt. Is used: F3 @ 35 Hz, same cabinet volume, same Power applied, same bass reflex tuning, same DSP setting.
Now that would be fair, would it?
Look at the graph attached. the YELLOW = 2 x 12", the BLUE = 1 x 18". Both feel at home in this config.
Kind of the same isn't it? The slight valley of the 12" is typical for this 12", using a Faital Pro 12" would NOT give this valley. The 120 Hz cross-over makes this valley almost disappear and it would be hard to hear this.
I would opt for the 2 x 12" cabinets, because;
1 - the push pull config greatly reduces distortion
2 - a 12" conus don't break-up that easy compared to 18"
3 - 2 voice coils would have a less hard time (less heat compression) compared to the 18".
4 - You spend the same money on 2 x 12" compared to 1 x 18" in most cases.
Same story for the 10", but you would need 3 or 4 x 10" versus 1 x 18".
Price wise, almost the same, the 18" may win if you would need 4 x 10" by a few euro's / dollars. But the 10" is even better in distortion reduction and cone break-up.
For the Tops, the idea that a 6" would not work well below 250 Hz sounds strange to me, do you have a explanation for this statement (of course depending on the driver). I've used 6" in column arrays and they nicely roll off at 120 Hz in sealed enclosures, the Faital Pro 6FE100 I used handles 100 Watt easily in a 10 Liter enclosure and rolls off at around 120 Hz. RCF, JBL and others use 6" a lot, must be a reason I guess 🙄.
kind regards,
Frans Wessels
Attachments
Last edited:
Hey.
I cannot agree on your thought process. I would, if I wasn´t there before with 12"s. Not anymore. At any point in my life, I´m not going back to 12"s. Propably not even 15"s.
I would not only expect 18" to walk over it. I experienced it in real life.
Used 12", when I begun to like loud music. 🙂. I had the chance to listen to some 2x12" setups, and even 3x 12"s (for example this one: Megaton DS312 lak - DAS12G | Reproboxy - Pasivní reproboxy - Subwoofery | PRODANCE). No matter what parameters it has, it all sounds either weak or with no low bass, If you don´t load the cone of small cone area speaker accoustically in BandPass, or some kind of horn. That´s why I´m going 21" after my 18SW115, which plays by me right now.
For theory of bassreflex boxes, here is how it goes. "Displacement volume is all that matters". To a point of course. Bl power has its word too.
18SW115 is in the same price ballpark as 2x 12TBX100 or 12NW100 to keep the game light and "neo", so lets take these.
Displacement volume of two 12NW100s is 0,955l. Displacement of 18SW115 is 1,69l. How do you expect those drivers to play as loud low, when they have "nothing in their hands" to move the air? That displacement difference is like 4-5db difference in capabilities. For Xvar parameter, we´re approaching 6db according to the displacement volume. That I would say, is significant. Okay, these small drivers have more normalized BL power on hand, but for what use? Cone control and damping, but that´s not really what you need at 30-60Hz anymore.
So lets break down your points:
1 - the push pull config greatly reduces distortion
True. The same as newer, better optimized driver capable of higher cone excursion in linear fashion. I highly recommend you seeing Clippel measurements of linearity. Those newer drivers are really something.
The question is if good PA driver has so much distortion that you must chase this on purpose and sacrifice possible power output. I would say you don´t.
Once you hit the wall of small speaker capabilities, you´ll get into very nasty pushing and distortions, while at the same output level, the large driver will go 6db under its maximum.
2 - a 12" conus don't break-up that easy compared to 18"
True, but again, not rellevant for bass content. Seriously... Cone breakup is in 1,5-2kHz range, and we´re playing 100Hz here...
3 - 2 voice coils would have a less hard time (less heat compression) compared to the 18".
True. Coil area of the 18SW115 is 124cm2. Coil area of two 12NW100s is 157cm2.
That is roughly 25% more power handling for 12NW100s. But for what use? Those drivers might work cooler, but what difference is that for us 100°C or 125°C. No difference really. I highly doubt that 18SW115 will run out of thermal capabilities in bassreflex box when driven properly. Very unlikely. If you put 1000W into the 12NW100, it isn´t going to look well, and the sound will will not be good either. Had both 12TBX100 and 12PS100, had a listening session with 12NW100.
4 - You spend the same money on 2 x 12" compared to 1 x 18" in most cases.
True. It´s cool that the size of the driver scales so well with price.
If we threw in 21DS115 with three 12", it would be very similar situation. How cool is that.
Smaller drivers usually don´t do the same cone excursion. You have to load them more for less excursion, or they fail you miserably. Then we might get to horn-bassreflex or bandpass comparison, comparison, which is not what we discuss here.
For 6"s, its like I like to buy more expensive powerfull drivers, and those are usually very sensitive in the upper range, and not sensitive under 250Hz. You can EQ it back, of course....
So my sincere recommendation for you is to go larger. It won´t be worse, it propably won´t be even the same. It should be better.
I cannot agree on your thought process. I would, if I wasn´t there before with 12"s. Not anymore. At any point in my life, I´m not going back to 12"s. Propably not even 15"s.
I would not only expect 18" to walk over it. I experienced it in real life.
Used 12", when I begun to like loud music. 🙂. I had the chance to listen to some 2x12" setups, and even 3x 12"s (for example this one: Megaton DS312 lak - DAS12G | Reproboxy - Pasivní reproboxy - Subwoofery | PRODANCE). No matter what parameters it has, it all sounds either weak or with no low bass, If you don´t load the cone of small cone area speaker accoustically in BandPass, or some kind of horn. That´s why I´m going 21" after my 18SW115, which plays by me right now.
For theory of bassreflex boxes, here is how it goes. "Displacement volume is all that matters". To a point of course. Bl power has its word too.
18SW115 is in the same price ballpark as 2x 12TBX100 or 12NW100 to keep the game light and "neo", so lets take these.
Displacement volume of two 12NW100s is 0,955l. Displacement of 18SW115 is 1,69l. How do you expect those drivers to play as loud low, when they have "nothing in their hands" to move the air? That displacement difference is like 4-5db difference in capabilities. For Xvar parameter, we´re approaching 6db according to the displacement volume. That I would say, is significant. Okay, these small drivers have more normalized BL power on hand, but for what use? Cone control and damping, but that´s not really what you need at 30-60Hz anymore.
So lets break down your points:
1 - the push pull config greatly reduces distortion
True. The same as newer, better optimized driver capable of higher cone excursion in linear fashion. I highly recommend you seeing Clippel measurements of linearity. Those newer drivers are really something.
The question is if good PA driver has so much distortion that you must chase this on purpose and sacrifice possible power output. I would say you don´t.
Once you hit the wall of small speaker capabilities, you´ll get into very nasty pushing and distortions, while at the same output level, the large driver will go 6db under its maximum.
2 - a 12" conus don't break-up that easy compared to 18"
True, but again, not rellevant for bass content. Seriously... Cone breakup is in 1,5-2kHz range, and we´re playing 100Hz here...
3 - 2 voice coils would have a less hard time (less heat compression) compared to the 18".
True. Coil area of the 18SW115 is 124cm2. Coil area of two 12NW100s is 157cm2.
That is roughly 25% more power handling for 12NW100s. But for what use? Those drivers might work cooler, but what difference is that for us 100°C or 125°C. No difference really. I highly doubt that 18SW115 will run out of thermal capabilities in bassreflex box when driven properly. Very unlikely. If you put 1000W into the 12NW100, it isn´t going to look well, and the sound will will not be good either. Had both 12TBX100 and 12PS100, had a listening session with 12NW100.
4 - You spend the same money on 2 x 12" compared to 1 x 18" in most cases.
True. It´s cool that the size of the driver scales so well with price.
If we threw in 21DS115 with three 12", it would be very similar situation. How cool is that.
Smaller drivers usually don´t do the same cone excursion. You have to load them more for less excursion, or they fail you miserably. Then we might get to horn-bassreflex or bandpass comparison, comparison, which is not what we discuss here.
For 6"s, its like I like to buy more expensive powerfull drivers, and those are usually very sensitive in the upper range, and not sensitive under 250Hz. You can EQ it back, of course....
So my sincere recommendation for you is to go larger. It won´t be worse, it propably won´t be even the same. It should be better.
To really look in the power strain issue, we should compare impedance curves, thus efficiency. That would tell us more...
Hi Crashpc,
So we agree on most points and I take what you write, there isn't much to disagree here.
I think the starting point, can we make REAL small subs for a DIY compact PA got mixed up with "not being able to grow" the current setup of "Borg Audio". SO, we got into the "lets make a VERY small component Line Array".
When we would start with 18" or eve 21", we don't have the option to start REALY small anymore. I like to be able to put a simpel PA set in a standard car, not using vans or trucks.
Thanks for your input, much appreciated.
kind regards,
Frans
So we agree on most points and I take what you write, there isn't much to disagree here.
I think the starting point, can we make REAL small subs for a DIY compact PA got mixed up with "not being able to grow" the current setup of "Borg Audio". SO, we got into the "lets make a VERY small component Line Array".
When we would start with 18" or eve 21", we don't have the option to start REALY small anymore. I like to be able to put a simpel PA set in a standard car, not using vans or trucks.
Thanks for your input, much appreciated.
kind regards,
Frans
Wow, how small do you need the smallest building block be?
18" in 100l looks like it can be put in the car easily.
Some time ago, I could take two 18" in 60*60*90cm (288l outer volume) box each, and 15" tops in my european sized car for four-five people 🙂
Anyway I wish you best luck. Your project looks abicious, and I will look around how it goes. Thanks for good discussion.
18" in 100l looks like it can be put in the car easily.
Some time ago, I could take two 18" in 60*60*90cm (288l outer volume) box each, and 15" tops in my european sized car for four-five people 🙂
Anyway I wish you best luck. Your project looks abicious, and I will look around how it goes. Thanks for good discussion.
Attachments
Hi Crashpc,
Well, I thought to aim at 40 - 50 liters per sub and 20 liters per top. Weight should be around 15 kilo's for the sub and around 8 kilo's for the top. Maybe sounds a bit stupid to start with size and weight, but we already "know the rest", must be able to compete we the commercial bigger stuff, without the need of trucks and road crews.
I know it is a bit ambitious, but hey, what's the point in designing what's already there. 😀
I already have a PA set for pubs, it's 2 x 10 or 2 x 12 subs and 2 tops (4 x 4"), NO monitors, PA is behind the band. Musicians love it, once they've used it.
This would be the "next size" PA, just a bit bigger and targeted at large pubs and venues til around 400 - 500 people, like most bands will have at it's max.
Love to see you around,
kind regards,
Frans Wessels.
Now we´re talking 🙂
Look how 10x10" has significantly more cone area, and even displacement volume. That goes hand in hand with efficiency, maximum power output, and that would certainly "do the business". Except for price and real box size comparison ratio :-D :-D
That´s awesome. If you come with something crazy like that, I´ll certainly bow to you. Noone does that!
Look how 10x10" has significantly more cone area, and even displacement volume. That goes hand in hand with efficiency, maximum power output, and that would certainly "do the business". Except for price and real box size comparison ratio :-D :-D
That´s awesome. If you come with something crazy like that, I´ll certainly bow to you. Noone does that!
Hi Frans,
My apologies - I didn't mean to send the thread off on a tangent, just thinking out loud.
I have always liked the idea of multiple small subs, but on paper the displacement volume Vd never seems to compete with fewer large diameter drive units. There are, of course, the ridiculous car subs with 50mm Xmax but I really don't think these are appropriate to any speaker with sound quality in mind. There is also little I have heard to sway me from the idea that it is far, far better to move a lot of air gently, rather than a small amount violently.
There is no doubt a number of small subs with produce good quality bass at volume, it will just have a fairly high rolloff. Possibly the question that has not been well enough pursued is how low do we need to go.
Cheers, Carl.
You can run some tracks through a spectrum analyser and find out. Looking at the popularity of 12" THs with the pop-DJ crowd, it looks like something that kicks hard around 55Hz is enough for a good portion of music.
I find advantage in going to 40Hz. Most tracks have some content down there, and the lower cutoff makes the system sound more powerful. 35Hz is starting to get good for dubstep/electronic stuff, and 30Hz will cover 90% of that pretty well. The last bit of electronic stuff needs more like 25Hz extension. 20Hz and below is almost exclusively for movies. There are examples of music that goes that low, but they're quite rare and most people wouldn't be able to sing along.
Of course, getting the next 5Hz in extension requires exponentially more cone area to achieve at PA SPLs. If your regular clients are the extreme dubstep sorts, you'll do well aiming (and marketing for) 25Hz extension, with all the 21" THs you'll need for that. If you're doing a couple of weddings a week, and they're often in difficult locations, a couple of 12" 55Hz THs will be plenty.
Chris
Hi, very late to thread but I like the concept of frans faitalpro fe32 column speakers, I'll run them off Crown XLS1502, 525 w/ side 4 ohms,they are 30w RMS and 60 peak, , so not running full tilt.. So I'm looking at 8 per side I reckon for live band use, paired to MTH sub crossed at about 180hz, running of separate amp, about 1000w bridged, is this practical do you think? I may port the boxes possibly, going to play with win isd, worried in sealed box they may cook a bit, some gigs can be long....like the idea of thin speakers, and driver cost makes for a budget experiment... If not enough sparkle maybe add tweeter, is this a bollocks idea..!?
Hi ALt,
Well, i've found it a VERY practical and workable solution, so I would support your setup.
Few remarks on my experience with this setup for the last 4 years I've been using and selling this setup:
- I DID start with the XLS1500 for the tops (mostly with 4 4FE32 units per side) but found that you run out of power in venues over 200 people.
- I DID accidentally almost cook the 4FE32's on my first live gig, when the cross-over for some strange reason (maybe as the result of some experiment the day before the live gig) was set at 120Hz. this resulted off-course in the subs NOT to go much higher than 120 Hz and with the tops NOT being able to produce below 180 Hz in a closed box (which is the fall of frequency so to speak), I had a gap in low-mid and kept pushing harder using the EQ's around 150 Hz, pushing more and more power into the poor 4FE32's. I found that looking at the mixing desk and noticed ALL channel EQ's where lifting low-mid. YES, it's useful to now and then look at the complete mixer to note strange settings over all channels, which may point you at your PA not setup correctly.
After the last set of the gig, which did go remarkably well, I smelt the drivers from a few meters distance and the complete top cabinets were HOT (Yes HOT wood).
NONE of the Faital's give in an inch, so much for quality. (Although I would expect some power draining occurring).
So bottom line, 180HZ is the best to work with, your OK.
I was thinking of porting the Top's, while driving back home that evening and did build a test set. That did not go very well, the 4FE32 struggled with not being in a closed box. We did a later experiment with 16 4FE32 in a bass reflex cabinet and that worked out quite OK as a music reproduction set, both for home use AND small venues.
- I also found that having an amp with more power than required (I use XLS2500 on both Top and Sub) actually make the complete setup running more relaxed sounding without EVER having the driver blow-up or cook. YES, the Top's can get a bit warm during long gigs, but never to an unacceptable level.
- I have build some TH's (12") but never used them live, they are just to big for the "fits in the booth of a car" marketing hype I forced myself into😀. They will out perform my bass reflex version but at almost 1,75 times the size, i did not go that way yet, again because of the same marketing.
So bottom line YES, certainly 8x 4FE32 per side is absolutely spot-on, use bigger amps then your current idea, you won't kill the drivers when used sensible (right cross-over settings and NOT drive your amps into klipping).
- TWEETER's ? NO NEED to have them. I found that the 4FE32 have enough to offer in the high range, you SHOULD correct the bubble around 8 - to 10 KHz (around 2 - 3 dB correction) to make them sound smooth. I even found out it sounds more natural then adding a tweeter if your high's slowly roll-off.
So , Your fine I would say.
kind regards,
Frans
Well, i've found it a VERY practical and workable solution, so I would support your setup.
Few remarks on my experience with this setup for the last 4 years I've been using and selling this setup:
- I DID start with the XLS1500 for the tops (mostly with 4 4FE32 units per side) but found that you run out of power in venues over 200 people.
- I DID accidentally almost cook the 4FE32's on my first live gig, when the cross-over for some strange reason (maybe as the result of some experiment the day before the live gig) was set at 120Hz. this resulted off-course in the subs NOT to go much higher than 120 Hz and with the tops NOT being able to produce below 180 Hz in a closed box (which is the fall of frequency so to speak), I had a gap in low-mid and kept pushing harder using the EQ's around 150 Hz, pushing more and more power into the poor 4FE32's. I found that looking at the mixing desk and noticed ALL channel EQ's where lifting low-mid. YES, it's useful to now and then look at the complete mixer to note strange settings over all channels, which may point you at your PA not setup correctly.
After the last set of the gig, which did go remarkably well, I smelt the drivers from a few meters distance and the complete top cabinets were HOT (Yes HOT wood).
NONE of the Faital's give in an inch, so much for quality. (Although I would expect some power draining occurring).
So bottom line, 180HZ is the best to work with, your OK.
I was thinking of porting the Top's, while driving back home that evening and did build a test set. That did not go very well, the 4FE32 struggled with not being in a closed box. We did a later experiment with 16 4FE32 in a bass reflex cabinet and that worked out quite OK as a music reproduction set, both for home use AND small venues.
- I also found that having an amp with more power than required (I use XLS2500 on both Top and Sub) actually make the complete setup running more relaxed sounding without EVER having the driver blow-up or cook. YES, the Top's can get a bit warm during long gigs, but never to an unacceptable level.
- I have build some TH's (12") but never used them live, they are just to big for the "fits in the booth of a car" marketing hype I forced myself into😀. They will out perform my bass reflex version but at almost 1,75 times the size, i did not go that way yet, again because of the same marketing.
So bottom line YES, certainly 8x 4FE32 per side is absolutely spot-on, use bigger amps then your current idea, you won't kill the drivers when used sensible (right cross-over settings and NOT drive your amps into klipping).
- TWEETER's ? NO NEED to have them. I found that the 4FE32 have enough to offer in the high range, you SHOULD correct the bubble around 8 - to 10 KHz (around 2 - 3 dB correction) to make them sound smooth. I even found out it sounds more natural then adding a tweeter if your high's slowly roll-off.
So , Your fine I would say.
kind regards,
Frans
Hi Frans,
Thanks for taking the time to help me out! I reckon Ill get ordering some drivers. I get what you say about using reflex, for this kind of tops it makes way more sense than the tapped horn. It should just about get up to 180hz but im guessing it may sound a bit weird, ill be able to test in next few days. Good to see you are selling these cabs, its generous of you to share the design to the DIY community. Seem to me like a very good concept. I hope mine turn out looking ok! Will post review once I get them going ! Cheers man, Al
Thanks for taking the time to help me out! I reckon Ill get ordering some drivers. I get what you say about using reflex, for this kind of tops it makes way more sense than the tapped horn. It should just about get up to 180hz but im guessing it may sound a bit weird, ill be able to test in next few days. Good to see you are selling these cabs, its generous of you to share the design to the DIY community. Seem to me like a very good concept. I hope mine turn out looking ok! Will post review once I get them going ! Cheers man, Al
That's OK, I've learned a lot here and that's what this forum is all about.
PM me if you have any questions / issues. The build took some challenges, you could bypass them if needed.
p.s. A Tapped Horn may still be an option, although 180 Hz is a bit on the high side. They pack considerable more punch which may support you to decrease the number of subs. I also wanted to test alternative sub placement (can't remember how the principle was called) but did not find the time yet. It is based on 3 sub locations inside a venue.
1 - A Sub near the tops
2 - A sub in the corner at the opposite wall
3 - A sub in the middle of one of the side walls.
As alternative (which i've used in a number of fixed installations) you could place 2 tops (holding 4 drivers each) at the stage and 2 tops at the opposite wall. Kind of a surround sound approach. I LOVE the overall effect, the even spreading of the level of sound and a nice stereo image. Combine that with the alternative sub placement will give you a very pleasant soundscape, people will not likely forget. It provides almost even loudness at any position in the venue with lower SPL levels and nice imaging. The owner was very happy with the end result.
Any way, give it a go.
PM me if you have any questions / issues. The build took some challenges, you could bypass them if needed.
p.s. A Tapped Horn may still be an option, although 180 Hz is a bit on the high side. They pack considerable more punch which may support you to decrease the number of subs. I also wanted to test alternative sub placement (can't remember how the principle was called) but did not find the time yet. It is based on 3 sub locations inside a venue.
1 - A Sub near the tops
2 - A sub in the corner at the opposite wall
3 - A sub in the middle of one of the side walls.
As alternative (which i've used in a number of fixed installations) you could place 2 tops (holding 4 drivers each) at the stage and 2 tops at the opposite wall. Kind of a surround sound approach. I LOVE the overall effect, the even spreading of the level of sound and a nice stereo image. Combine that with the alternative sub placement will give you a very pleasant soundscape, people will not likely forget. It provides almost even loudness at any position in the venue with lower SPL levels and nice imaging. The owner was very happy with the end result.
Any way, give it a go.
with regards to front and rear speakers, wont there be weird delays going on with people sitting 1/4 and 3/4 of the way back? The sound guys tried doing something similar at a festival I was helping out at last year. They billed it as "quadraphonic setup" but they gave up because it just sounded rubbish in a lot of areas due to delay.
Hi Damo s
Well, their is not a simple answer, but yes, you have a point.
Having said that, I can safely state that we won't have that effect in our situation. Let me try to explain.
Our brain (that's where it all starts) "samples" sound in fragments and works out what we here. When there is a time difference between chuck of sound we here, like a person talking or a drummer playing, we start hearing it as "new" sounds when the time difference gets bigger then the sample time. We start translating that in our brain as reverb until the time difference gets big enough for our brain to hear it as echo.
If we have a loudspeaker in front of us, we are standing in front of the stage we have just one sound source so we will never get a second "identical" sound to start the reverb / echo issue. If we are inside a room, the sound from the loudspeaker arrives at our ears but also travels through the room, hits the wall, bounces back and that "second" (identical) sound arrives the travel time later at our ears. We will hear that as reverb or echo.
Having a second pair of speaker at the other side of the room works kind of the same so we hear the sound 4 times (2 times direct sound and 2 times reflected sound. Now you would expect that this will become a mess inside our brains, BUT it depends on the sound travel time if we still experience it as ONE sound OR work it out as reverb / echo.
The model to figure that out becomes very complex because the following (most important) phenomena are at play here;
- The speed of sound
- The reduction of sound level traveling through air
- Our brain sampling the sound
- Phasing issues of sound waves from one source arriving at our ear from various directions (speaker, wall, ceiling, back wall).
To nail it down (and why we should not care) is the following (and presented at very simple level) principle:
- If sound travels at 340 meter per second and we are standing at 3,4 meters from the loudspeaker, we will here the sound after 1/100 of a second.
- It is at around 2/10 of a second that we start experiencing reverb effects to kick in. 2/10 of a second sound travel time is 68 meters distance. So if we are at 1 meter from the stage AND we use 2 sets of speakers AND the room length is 68 meters we will experience reverb and delay effects. This however is a a VERY large venue and we do not have the PA intended for this application. We are in an average (15 x 30 meters at max venue).
The model above only takes time distance into account, but sound levels reduce while traveling through air. For every doubling of the distance, sound level reduces by 6dB.
SO, 120 dB at 1 meter, will be 114 dB at 2 meters, 108 dB at 4 meters, 102 dB at 8 meters, 96 dB at 16 meters etc. If we would take the 2/10 of a second situation, we are talking about 76 dB of sound from the rear speakers versus 120 dB from the front speakers. The sound level difference is that big that it will become "neglect-able" for our brain.
For the room we are in (15 x 30 meters max) we would have 120 dB (front speaker at 1m from us) versus 90dB (rear speaker) which is clearly noticable. BUT the time for the sound to travel 30 meters (from the rear speaker to our ears is 1/10 of a second, meaning we will NOT perceive this as delay but as ONE sound. Standing in the middle of the room, we will here both sources at the same time at the same level, so there is no issue at all. In all other locations it's a combination of time and sound level reduction. BUT still one sound at 2 levels where our brain will say, OK I understand what's going on, I am kind of in the middle and that's fine (psycho acoustics).
When walking through the room front to back, we WILL here a shift of sound source from front to back, BUT we are not walking around during a concert ALL the time. Since we will never be in a position that sound travel time is large enough, we will NEVER experience reverb / echo.
BOTTOM line, YES we can here that there are 2 sources (one louder than the other) BUT not with at big enough time difference.
What you described is obvious, the distance between sound sources becomes big enough to here these sources all independently, resulting in a mess because they almost all arrive at a different time, depending on where you are standing. In the middle of the 4 sound systems, there will be no issue, any other locations will be experienced as reverb to delay, phasing / cancelation of frequencies etc. That will be NOT be a nice experience, since our brain is trying to order this mess but will never be able to work it all out (because the sound keeps changing al the time, except when it is ONE note for a long time seconds to minutes to hours) which is not nice to be in for a long time. Using delay towers (which is common in large concerts) is kind of a cure, but they ALL point away from the stage. The speaker at the largest distance will be the "null" counting back in adding delay with the end result "no matter where we are, it's one sound. But THAT is not quadro phonic. The other "cure" may be to use lots of speakers around the field, but still, reverb delay will be present.
OK?
Well, their is not a simple answer, but yes, you have a point.
Having said that, I can safely state that we won't have that effect in our situation. Let me try to explain.
Our brain (that's where it all starts) "samples" sound in fragments and works out what we here. When there is a time difference between chuck of sound we here, like a person talking or a drummer playing, we start hearing it as "new" sounds when the time difference gets bigger then the sample time. We start translating that in our brain as reverb until the time difference gets big enough for our brain to hear it as echo.
If we have a loudspeaker in front of us, we are standing in front of the stage we have just one sound source so we will never get a second "identical" sound to start the reverb / echo issue. If we are inside a room, the sound from the loudspeaker arrives at our ears but also travels through the room, hits the wall, bounces back and that "second" (identical) sound arrives the travel time later at our ears. We will hear that as reverb or echo.
Having a second pair of speaker at the other side of the room works kind of the same so we hear the sound 4 times (2 times direct sound and 2 times reflected sound. Now you would expect that this will become a mess inside our brains, BUT it depends on the sound travel time if we still experience it as ONE sound OR work it out as reverb / echo.
The model to figure that out becomes very complex because the following (most important) phenomena are at play here;
- The speed of sound
- The reduction of sound level traveling through air
- Our brain sampling the sound
- Phasing issues of sound waves from one source arriving at our ear from various directions (speaker, wall, ceiling, back wall).
To nail it down (and why we should not care) is the following (and presented at very simple level) principle:
- If sound travels at 340 meter per second and we are standing at 3,4 meters from the loudspeaker, we will here the sound after 1/100 of a second.
- It is at around 2/10 of a second that we start experiencing reverb effects to kick in. 2/10 of a second sound travel time is 68 meters distance. So if we are at 1 meter from the stage AND we use 2 sets of speakers AND the room length is 68 meters we will experience reverb and delay effects. This however is a a VERY large venue and we do not have the PA intended for this application. We are in an average (15 x 30 meters at max venue).
The model above only takes time distance into account, but sound levels reduce while traveling through air. For every doubling of the distance, sound level reduces by 6dB.
SO, 120 dB at 1 meter, will be 114 dB at 2 meters, 108 dB at 4 meters, 102 dB at 8 meters, 96 dB at 16 meters etc. If we would take the 2/10 of a second situation, we are talking about 76 dB of sound from the rear speakers versus 120 dB from the front speakers. The sound level difference is that big that it will become "neglect-able" for our brain.
For the room we are in (15 x 30 meters max) we would have 120 dB (front speaker at 1m from us) versus 90dB (rear speaker) which is clearly noticable. BUT the time for the sound to travel 30 meters (from the rear speaker to our ears is 1/10 of a second, meaning we will NOT perceive this as delay but as ONE sound. Standing in the middle of the room, we will here both sources at the same time at the same level, so there is no issue at all. In all other locations it's a combination of time and sound level reduction. BUT still one sound at 2 levels where our brain will say, OK I understand what's going on, I am kind of in the middle and that's fine (psycho acoustics).
When walking through the room front to back, we WILL here a shift of sound source from front to back, BUT we are not walking around during a concert ALL the time. Since we will never be in a position that sound travel time is large enough, we will NEVER experience reverb / echo.
BOTTOM line, YES we can here that there are 2 sources (one louder than the other) BUT not with at big enough time difference.
What you described is obvious, the distance between sound sources becomes big enough to here these sources all independently, resulting in a mess because they almost all arrive at a different time, depending on where you are standing. In the middle of the 4 sound systems, there will be no issue, any other locations will be experienced as reverb to delay, phasing / cancelation of frequencies etc. That will be NOT be a nice experience, since our brain is trying to order this mess but will never be able to work it all out (because the sound keeps changing al the time, except when it is ONE note for a long time seconds to minutes to hours) which is not nice to be in for a long time. Using delay towers (which is common in large concerts) is kind of a cure, but they ALL point away from the stage. The speaker at the largest distance will be the "null" counting back in adding delay with the end result "no matter where we are, it's one sound. But THAT is not quadro phonic. The other "cure" may be to use lots of speakers around the field, but still, reverb delay will be present.
OK?