As for time-domain, many experts say it doesn't matter up until 1/2 of the wavelength. That's a minimum of 10' that the subs can be from the mains, without your brain detecting a difference. I'm not so sure, but it's definitely one major theory.
One of these days I have to actually test this, but I've seen some churches that had floor subs, with the mains 30' in the air. No digital time compensation. Sitting in the first row, that puts the subs 20' closer, yet cd's sounded fine on playback.
Putting all the subs together is a trade-off. In a really bad room, this will actually accentuate the nulled areas. It can be brutal. Having them separate will create some semi nulls in the middle, but even-out the room as a whole. So, it depends on the room.
Good stuff. Just a got a system for the first time. Phase discrepensies. Reminded me of StarTrek, but here I actually learned something.
By the way is it the way to place these things on the floor? I have a thin carpet tiled floor and concrete under. I always feel I need to place my speakers on a foam surface (basically like the stuff that comes packed with the sytem) for better sound...
You're always gonna have critics that don't appreciate what you're doing but it seems the majority of us appreciate your time and knowledge. Keep it up
I actually went to your website and saw your videos... some top advice my friend. Knew some stuff, learnt more stuff. All good. Just wanted to stop by and say thanks!
hi Jeff, i love all your video..it help me alot also, please can you draw a diagram, i'm confused about what you are saying...., so instead of placing my full range tower on the sub as i usally do, i should combine the sub and place it in the middle of the stage???, and put the full range tower on the edge?? further out next the crowd?? away from stage? Is this correct??? Please response back, thanks you so much
Thanks for the reply. I do use 1 speaker per chanel. The set up i got was 2 Omnitronic 750w rms 8ohm speakers 1 a side and 1 skytec 1500w rms 4ohm amplifier so i plug one speaker to each side. i don not use an electronic crossover i just simply plug my laptop into my 3 chanel mixer my iphone into another chanel and my mic into the third, then straight from the mixer to the amp then amp to speakers via speakon but after an hour or so it may cut out. sometimes it lasts longer sometimes it doesnt.
Hi you look like you know what your talking about so i have a question. I have a 4 Ohm Amplifier and 2 8 Ohm speakers this came as a pack so i thought that they would run smoothly together but every single gig ive gone to the amp seems to cut out and i have to take time plugging in my new one ect and face embarresment. What do you think the problem is and how can i solve it? i thought i may have something to do with the OHM's?
I think what you may running into is the amplifier. Just because an amplifier is "rated" at 4 ohms doesn't mean that it can actually handle 4 ohms.
But first,,, are you using an electronic crossover? If not you may be actually down closer to 2 ohms on the full range of speakers. Speakers impedance changes with the frequency and the inductive resistance of the speaker movement.
First I would try to see if the situation happens with only one speaker...
@motojeff hey jeff thanks for ur advice i was wonderin if its ok to put my subs in front of my mixin desk side by side and then two tops right and left of the mixin desk?its just that its just that my cables are only 10m long.
@motojeff thanks for the advice jeff is it ok to put my 2 subs side by side in front of my mixin desk and my2 tops left and right of them its just that my cables are only 10m long some more advice would be great thanks
@jonnyshaw1989 He dosn't know what he's talking about. It actually takes about 30 to 40 feet for low end to develop and double the volume is 3db not 6db. Are you you're speakers in series or parallel. If you're running in parallel you're closer to 4 ohms if you're in if you're running in series you're closer to 8 ohms.
@crashdog5866 Johnny, I appreciate the feedback. But I think you are the one who isn't understanding electrical theory. And sound theory. Two 8 ohm speakers in parallel makes 4 ohms. Two 8 ohm speakers in series makes 16 ohms. Double the volume and double the signal are different. 3db is double the signal voltage, 6 db is double the sound pressure. and since the human ear is inefficient 10 db is perceived as double the volume. Sound measurement is logarithmic ,
@crashdog5866 Oh ,,, and use basic speed of sound to figure out a wave form. if sound is traveling at 1030 fps. Then a 1000Hz signal takes 1ft to complete. A 100 Hz Signal takes 10 feet to form. a 50 Hz signal takes 100 feet. But there are such things as quarter and half waves, if a sub is using the floor as a carrier you can reduce the distance for the wave by 1/2...
@motojeff Ok, First of of all sound travels 1130 FPS not 1030 and you're not calculating the full period of the wave. a 1/4 and 1/2 wave are not fully developed. If you're using a floor as a carrier you still need the wave to fully develop in the air or you will have phasing problems. That 's why in a typical line array the sub is flown. Finally 6db is not double the sound pressure. You're getting to very complex sonic theories confused. Every time you double the distance from you're source
@crashdog5866 yes sometimes subs are flown but if you use ground stacked subs you just simply need to time align your flown speakers to your ground stacked subs. but what your saying in theory is correct.
@motojeff (continued) you loose 6db. It's not half the volume it's just 6db less. 3db pan law if you pan a signal to one side it's necessary for the volume to increase 3db because you're loosing the opposite side. It needs to be twice as loud because 1 speaker is now needing to do the same amount of work as 2.
@crashdog5866 Ok,,, you are being petty here. 1130, 1030. Here in Colorado with an altitude density less than at sea level the speed of sound is actually slower. And I see that you are into recording, I am talking about live sound, not what is on a CD or a controlled media device. Your twice as loud at a mere 3db voltage reduction in signal... Anyways, I have been doing sound for 20 years. I had over 100 full live gigs in 2010.
@crashdog5866 You do not have to agree with me , but if you tell people I do not know what I am talking about while stating incorrect information (like your ohms law mistake) expect me to respond. I have been working with small and large events for a long time and have learned from all people in the field. Everyone has something to offer, I know you are young and still new in the field. But many people like myself who have sound companies look more for a learning spirit than proclaimed expert
thanks for the tip but i cant see as the bass frequency starts creating at 10-15 feet because when ur stood infround of a big stack with your head in a bass bin then it is fucking out outragous mate even more outrageous than when your stood 15 feet away !!!! but i spose these rules aply for a mobile dj set up and not a rave haha i will take it in consideration nice one butt
iv allways been interested in how sound waves actually travel and the different ways you can use your speakers in order to get a different sound and ways you can increse bass. will you post a video explaining this in an advance way and maybe do a diagram of how this works and i will try to understand :P
Bravo for finally getting out some good information in a sea of misinformation.
I see too many people with the subs split on either side of the stage. Do a web search using "Power Alley PSW" for more information on why a single point source sub placement is better. The other ticket is to run a dedicated sub if you can. Running two "full range" cabs on sticks has the same effect as separating the subs.
Thanks for the comment, hopefully people will try this. If mains on sticks are cut off at a low frequency like 100 hz then there really is little cancellation.
I have 2 15" top cabs and 2 15" subs and all of them are passive speakers.I also run them on 1 800 watt amp. At this point I daisy chain amp-sub-top cabs. And yes they are on poled sub-top cab 1 on each side. I can put the top cabs on stands, but should I place the subs about a foot away from the wall with the speaker facing the wall? I was told I could also 90 the speakers facing the wallabout a foot away. Is that a true statement also? Thanks for any and all help!
I have a few suggestions,first make sure that the subs have a crossover in them. If not you need to get one or get an electronic crossover and run the amp in stereo mode with one side running both mains and the other side running the subs. This would be ideal actually as you could better tailor your sound.
As far as pointing the subs at the wall, this is a bad attempt at trying to make a folded horn. The bass will form closer to the speaker for sure but you will lose sound pressure further away from the speaker. I really think youll get better results by getting your subs together. Try the different things at home and see what works best- and please write back on your findings.
Im mixed on self powered speakers. I think that the simplicity of them is awesome. But from what I have heard, unless you get the $1200 each speakers - they just dont have good sound quality or volume. I only run speakers powered by amps, it gives me more flexibility I think. But I sometimes do live bands as well. The best QSC powered sub is 400 watts.... I run 1200 watts into each of my speakers with a QSC RMX 2450 in bridged mode.
I wasnt clear on that, the best self powered QCS is putting out only 400 watts from the woofer. Less through the other 2 drivers. Thats not that much.
I personally would pick a dual 18" sub box. Its easier to work with because its only one unit. Most of those are 4 ohm which means you could use one amp in bridged mode. But do remember that you need to use a crossover on the sub- otherwise it will sound muddy. The built in passive crossovers dont do that good of a job. Peavey Kosmos and BBE Sonic Maximisers both have a crossover for the sub in them. I really like the Kosmos for DJing- it adds a lot of boom.
Geat tip. Question. If you have say X2 15" 400watt mid range speakers what type of sub or subs would be best to run with these? 1-15, 2-15s what wattage? 1-18 2-18s??????
As for time-domain, many experts say it doesn't matter up until 1/2 of the wavelength. That's a minimum of 10' that the subs can be from the mains, without your brain detecting a difference. I'm not so sure, but it's definitely one major theory.
One of these days I have to actually test this, but I've seen some churches that had floor subs, with the mains 30' in the air. No digital time compensation. Sitting in the first row, that puts the subs 20' closer, yet cd's sounded fine on playback.
cableaddict 9 hours ago
Putting all the subs together is a trade-off. In a really bad room, this will actually accentuate the nulled areas. It can be brutal. Having them separate will create some semi nulls in the middle, but even-out the room as a whole. So, it depends on the room.
cableaddict 9 hours ago
Good stuff. Just a got a system for the first time. Phase discrepensies. Reminded me of StarTrek, but here I actually learned something.
By the way is it the way to place these things on the floor? I have a thin carpet tiled floor and concrete under. I always feel I need to place my speakers on a foam surface (basically like the stuff that comes packed with the sytem) for better sound...
Thanks.
seafireliv 1 month ago
You're always gonna have critics that don't appreciate what you're doing but it seems the majority of us appreciate your time and knowledge. Keep it up
EveRyan2003 1 month ago
AWESOME TIP!
Singhka8 9 months ago
Thanks for your video's Jeff. they have helped me tremendously.
scusmcsgt 1 year ago
thanks mate,very helpful
antztudio 1 year ago
It kills me when bands are placing sub cabs on either side of the stage. correcting people's bad habits is hard, when they are stubborn.
SophicMedia 1 year ago
Good information on the do's and dos and don’ts or pros and cons. Subs do indeed sound better located in the middle least the feel of it does.
EmpireLS56KW 1 year ago
Hey Jeff,
I actually went to your website and saw your videos... some top advice my friend. Knew some stuff, learnt more stuff. All good. Just wanted to stop by and say thanks!
Keep it rocking!
Ankur
thepandefamily 1 year ago
hi Jeff, i love all your video..it help me alot also, please can you draw a diagram, i'm confused about what you are saying...., so instead of placing my full range tower on the sub as i usally do, i should combine the sub and place it in the middle of the stage???, and put the full range tower on the edge?? further out next the crowd?? away from stage? Is this correct??? Please response back, thanks you so much
guitarpikz 1 year ago
Thanks for the reply. I do use 1 speaker per chanel. The set up i got was 2 Omnitronic 750w rms 8ohm speakers 1 a side and 1 skytec 1500w rms 4ohm amplifier so i plug one speaker to each side. i don not use an electronic crossover i just simply plug my laptop into my 3 chanel mixer my iphone into another chanel and my mic into the third, then straight from the mixer to the amp then amp to speakers via speakon but after an hour or so it may cut out. sometimes it lasts longer sometimes it doesnt.
jonnyshaw1989 1 year ago
Hi you look like you know what your talking about so i have a question. I have a 4 Ohm Amplifier and 2 8 Ohm speakers this came as a pack so i thought that they would run smoothly together but every single gig ive gone to the amp seems to cut out and i have to take time plugging in my new one ect and face embarresment. What do you think the problem is and how can i solve it? i thought i may have something to do with the OHM's?
jonnyshaw1989 1 year ago
I think what you may running into is the amplifier. Just because an amplifier is "rated" at 4 ohms doesn't mean that it can actually handle 4 ohms.
But first,,, are you using an electronic crossover? If not you may be actually down closer to 2 ohms on the full range of speakers. Speakers impedance changes with the frequency and the inductive resistance of the speaker movement.
First I would try to see if the situation happens with only one speaker...
motojeff 1 year ago
@motojeff hey jeff thanks for ur advice i was wonderin if its ok to put my subs in front of my mixin desk side by side and then two tops right and left of the mixin desk?its just that its just that my cables are only 10m long.
maxair43 1 year ago
@motojeff thanks for the advice jeff is it ok to put my 2 subs side by side in front of my mixin desk and my2 tops left and right of them its just that my cables are only 10m long some more advice would be great thanks
maxair43 1 year ago
@maxair43 You can certainly do that, and it's and ideal setup. However you may be deaf from the bass by the end of the night. :-)
motojeff 1 year ago
@motojeff thanks iv being doin it wrong for years!
maxair43 1 year ago
@jonnyshaw1989 He dosn't know what he's talking about. It actually takes about 30 to 40 feet for low end to develop and double the volume is 3db not 6db. Are you you're speakers in series or parallel. If you're running in parallel you're closer to 4 ohms if you're in if you're running in series you're closer to 8 ohms.
crashdog5866 1 year ago
@crashdog5866 Johnny, I appreciate the feedback. But I think you are the one who isn't understanding electrical theory. And sound theory. Two 8 ohm speakers in parallel makes 4 ohms. Two 8 ohm speakers in series makes 16 ohms. Double the volume and double the signal are different. 3db is double the signal voltage, 6 db is double the sound pressure. and since the human ear is inefficient 10 db is perceived as double the volume. Sound measurement is logarithmic ,
motojeff 1 year ago
@crashdog5866 Oh ,,, and use basic speed of sound to figure out a wave form. if sound is traveling at 1030 fps. Then a 1000Hz signal takes 1ft to complete. A 100 Hz Signal takes 10 feet to form. a 50 Hz signal takes 100 feet. But there are such things as quarter and half waves, if a sub is using the floor as a carrier you can reduce the distance for the wave by 1/2...
motojeff 1 year ago
@motojeff Ok, First of of all sound travels 1130 FPS not 1030 and you're not calculating the full period of the wave. a 1/4 and 1/2 wave are not fully developed. If you're using a floor as a carrier you still need the wave to fully develop in the air or you will have phasing problems. That 's why in a typical line array the sub is flown. Finally 6db is not double the sound pressure. You're getting to very complex sonic theories confused. Every time you double the distance from you're source
crashdog5866 1 year ago
@crashdog5866 yes sometimes subs are flown but if you use ground stacked subs you just simply need to time align your flown speakers to your ground stacked subs. but what your saying in theory is correct.
yoyomann86 1 year ago
@motojeff (continued) you loose 6db. It's not half the volume it's just 6db less. 3db pan law if you pan a signal to one side it's necessary for the volume to increase 3db because you're loosing the opposite side. It needs to be twice as loud because 1 speaker is now needing to do the same amount of work as 2.
crashdog5866 1 year ago
@crashdog5866 Ok,,, you are being petty here. 1130, 1030. Here in Colorado with an altitude density less than at sea level the speed of sound is actually slower. And I see that you are into recording, I am talking about live sound, not what is on a CD or a controlled media device. Your twice as loud at a mere 3db voltage reduction in signal... Anyways, I have been doing sound for 20 years. I had over 100 full live gigs in 2010.
motojeff 1 year ago
@crashdog5866 You do not have to agree with me , but if you tell people I do not know what I am talking about while stating incorrect information (like your ohms law mistake) expect me to respond. I have been working with small and large events for a long time and have learned from all people in the field. Everyone has something to offer, I know you are young and still new in the field. But many people like myself who have sound companies look more for a learning spirit than proclaimed expert
motojeff 1 year ago
thanks for the tip but i cant see as the bass frequency starts creating at 10-15 feet because when ur stood infround of a big stack with your head in a bass bin then it is fucking out outragous mate even more outrageous than when your stood 15 feet away !!!! but i spose these rules aply for a mobile dj set up and not a rave haha i will take it in consideration nice one butt
dropboxcox 2 years ago
Thanks for the tips
yurbrotha 2 years ago
nice tip, but it would be better if you put some detailed visual aid even hand sketch for easy understanding.
but that was a good tip.
I think indoor set up has a less problem comapred to the outdoor set up.
Any tip? Example if you have an area of at least 100 x 100 feet for example.
gentri80y 2 years ago
this guy looks like steve jobs :)
goran2009 2 years ago
thanks soo much for this vid!
iv allways been interested in how sound waves actually travel and the different ways you can use your speakers in order to get a different sound and ways you can increse bass. will you post a video explaining this in an advance way and maybe do a diagram of how this works and i will try to understand :P
thanks again
rob
robjcrowston 3 years ago
Your very welcome, Ill post more when I get some time.
motojeff 3 years ago
nice.
davehikah 3 years ago
Bravo for finally getting out some good information in a sea of misinformation.
I see too many people with the subs split on either side of the stage. Do a web search using "Power Alley PSW" for more information on why a single point source sub placement is better. The other ticket is to run a dedicated sub if you can. Running two "full range" cabs on sticks has the same effect as separating the subs.
RubiconDave 3 years ago
Thanks for the comment, hopefully people will try this. If mains on sticks are cut off at a low frequency like 100 hz then there really is little cancellation.
motojeff 3 years ago
How true! Good job!!!
itsj1train 3 years ago
You know much about home theater setups??
dragon79rider 3 years ago
I have 2 15" top cabs and 2 15" subs and all of them are passive speakers.I also run them on 1 800 watt amp. At this point I daisy chain amp-sub-top cabs. And yes they are on poled sub-top cab 1 on each side. I can put the top cabs on stands, but should I place the subs about a foot away from the wall with the speaker facing the wall? I was told I could also 90 the speakers facing the wallabout a foot away. Is that a true statement also? Thanks for any and all help!
djcuda2005 3 years ago
I have a few suggestions,first make sure that the subs have a crossover in them. If not you need to get one or get an electronic crossover and run the amp in stereo mode with one side running both mains and the other side running the subs. This would be ideal actually as you could better tailor your sound.
motojeff 3 years ago
As far as pointing the subs at the wall, this is a bad attempt at trying to make a folded horn. The bass will form closer to the speaker for sure but you will lose sound pressure further away from the speaker. I really think youll get better results by getting your subs together. Try the different things at home and see what works best- and please write back on your findings.
motojeff 3 years ago
Cool thanks for the info. Also what your thoughts on selfpowered systems (tops & bottoms)????
DjTRex08 3 years ago
Im mixed on self powered speakers. I think that the simplicity of them is awesome. But from what I have heard, unless you get the $1200 each speakers - they just dont have good sound quality or volume. I only run speakers powered by amps, it gives me more flexibility I think. But I sometimes do live bands as well. The best QSC powered sub is 400 watts.... I run 1200 watts into each of my speakers with a QSC RMX 2450 in bridged mode.
motojeff 3 years ago
I wasnt clear on that, the best self powered QCS is putting out only 400 watts from the woofer. Less through the other 2 drivers. Thats not that much.
motojeff 3 years ago
I personally would pick a dual 18" sub box. Its easier to work with because its only one unit. Most of those are 4 ohm which means you could use one amp in bridged mode. But do remember that you need to use a crossover on the sub- otherwise it will sound muddy. The built in passive crossovers dont do that good of a job. Peavey Kosmos and BBE Sonic Maximisers both have a crossover for the sub in them. I really like the Kosmos for DJing- it adds a lot of boom.
motojeff 3 years ago
Geat tip. Question. If you have say X2 15" 400watt mid range speakers what type of sub or subs would be best to run with these? 1-15, 2-15s what wattage? 1-18 2-18s??????
You sound like you have a glue Cheers:)
DjTRex08 3 years ago