Hi! I just registered here, after countless hours searching the web and reading forums and articles. I arrange techno clubs and have recently bought a new soundsystem (we used to rent). We got a really good deal, but there is a lot about the operation that i dont understand. I hope that you can help me straighten out a few questionmarks!
The system consist of:
Amps:
2 x alto mac 2.4 Link
1 x alto mac 2.3
Speakers ( homebuilt, seemingly good carpentry):
4x passive 12" monitors
4x 15" bases - JBL 2225H Link
4x 12" + horn - P. Audio C12 Link
Misc:
Mixer
3way splitting filter
Compressor
EQ
Currently the smaller amp drives the monitors. So far, so good. Here the confusion starts. Reading some articles about power, i come to the conclusion that the amps are way oversized. Reading others, i get the impression that i im way underpowered. I cant make heads or tails of the numbers here. Ohms, RMS, EIAJ, continous program power, program powre and sensitivity.
If someone can tell me how these specs of the speakers relate to the rateings of the amplifiers, i would be very grateful!
The other question i have is regarding expanding the system. Our Idea is to sell the monitors, and get one active monitor. Than use the smaller amp to power the tops, use the 4x 15" speakers to run lower mid, and build a subbase (double 18" perhaps?) to be run by the second big amplifier. What do you think of this idea?
I realise an active system would be better matched to our skill, but its a question of money, and also of wanting to learn.
Thanks so much for taking your time to read this, and i hope i made myself atleast somewhat understood
The system consist of:
Amps:
2 x alto mac 2.4 Link
1 x alto mac 2.3
Speakers ( homebuilt, seemingly good carpentry):
4x passive 12" monitors
4x 15" bases - JBL 2225H Link
4x 12" + horn - P. Audio C12 Link
Misc:
Mixer
3way splitting filter
Compressor
EQ
Currently the smaller amp drives the monitors. So far, so good. Here the confusion starts. Reading some articles about power, i come to the conclusion that the amps are way oversized. Reading others, i get the impression that i im way underpowered. I cant make heads or tails of the numbers here. Ohms, RMS, EIAJ, continous program power, program powre and sensitivity.
If someone can tell me how these specs of the speakers relate to the rateings of the amplifiers, i would be very grateful!
The other question i have is regarding expanding the system. Our Idea is to sell the monitors, and get one active monitor. Than use the smaller amp to power the tops, use the 4x 15" speakers to run lower mid, and build a subbase (double 18" perhaps?) to be run by the second big amplifier. What do you think of this idea?
I realise an active system would be better matched to our skill, but its a question of money, and also of wanting to learn.
Thanks so much for taking your time to read this, and i hope i made myself atleast somewhat understood
Matching amplifiers to speakers is a complicated issue but the bottom line is if you can get the SPL you want without overdriving the amplifiers or damaging the speakers then you're good. Your plan is also fine but I'd suggest not using the compressor as it won't do anything useful and could actually increase the potential to blow drivers. If you want to add some protection then sell off the mixer, compressor, and EQ and buy a Behringer DCX, this unit has all those functions plus adjustable limiters.
Assuming you have one channel of amplifier for one channel of speaker - be it a two or three way with a passive crossover, you have no big problems except one. That problem is the potential of running too much power to your speakers.
Paralleling IDENTICAL speakers per channel of amp is ok, IF the lowest impedance does not drop below 4 ohms IN REALITY - not just based on some label.
Different speakers ought not be paralleled on any channel of any amp, especially at high power levels.
There is a practical SPL limit for the speakers, and that limit is WRT to some power level that they can handle. You have to set the power limit to LESS than the max for the "weakest link", that being the speaker that can handle the least power (after taking into account things like pads and attenuators in a xover).
Then the way to keep from blowing up speakers is with a soft knee limiter where the output level from that unit is NEVER CHANGED, set up properly and drives the amps directly. Pro audio companies frequently put covers over level pots on amps, to keep idle hands off them. To be clear that level out needs to be such that it drives the speakers to just under their max long-term power limit... speakers get hot over time and blow up. Some technical ability is required to do this, but it's not that difficult.
There's another trick that uses a light bulb for protection of mostly tweeters and high mids, you can read up on that here and elsewhere on line.
Also you can not get the full power out of those amps by using an extension cord off a 15amp 120vac plug in some random room/club. Btw.
The amps on paper have more power than the speakers can handle.
Maybe a wiring diagram, some pix of the speakers, the xovers, and the like would help to give you better information...
Btw, beware of EQ, in particular BOOSTs eat up a lot of power and headroom.
Keep in mind that just a 3dB boost = 2x the power!! 6dB= 4x and 12dB = 16x!!
_-_-bear
Paralleling IDENTICAL speakers per channel of amp is ok, IF the lowest impedance does not drop below 4 ohms IN REALITY - not just based on some label.
Different speakers ought not be paralleled on any channel of any amp, especially at high power levels.
There is a practical SPL limit for the speakers, and that limit is WRT to some power level that they can handle. You have to set the power limit to LESS than the max for the "weakest link", that being the speaker that can handle the least power (after taking into account things like pads and attenuators in a xover).
Then the way to keep from blowing up speakers is with a soft knee limiter where the output level from that unit is NEVER CHANGED, set up properly and drives the amps directly. Pro audio companies frequently put covers over level pots on amps, to keep idle hands off them. To be clear that level out needs to be such that it drives the speakers to just under their max long-term power limit... speakers get hot over time and blow up. Some technical ability is required to do this, but it's not that difficult.
There's another trick that uses a light bulb for protection of mostly tweeters and high mids, you can read up on that here and elsewhere on line.
Also you can not get the full power out of those amps by using an extension cord off a 15amp 120vac plug in some random room/club. Btw.
The amps on paper have more power than the speakers can handle.
Maybe a wiring diagram, some pix of the speakers, the xovers, and the like would help to give you better information...
Btw, beware of EQ, in particular BOOSTs eat up a lot of power and headroom.
Keep in mind that just a 3dB boost = 2x the power!! 6dB= 4x and 12dB = 16x!!
_-_-bear
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Thank you for your replies. I will ignore the smaller amp and the monitors, since we are planning on selling those.
My wiring is as follows:
SL2442FXPRO mixer to
Samson s-3way splitter to
-> Low signal R+L (<900hz) -> amp -> 2 paralell bases for each chanel.
-> Hihgh signal R+L -> amp -> 2 paralell tops for each chanel.
The speakers are identical. They are connected paralell with two to each channel, thus giving a total resistance for each chanell of 4 ohm i think. The amplifiers are rated on the website as such:
Stereo Mode:
2 x 1800 Watts @ 2 Ω (EIAJ)
2 x 1100 Watts @ 4 Ω (EIAJ)
2 x 910 Watts @ 4 Ω (RMS)
2 x 670 Watts @ 8 Ω (EIAJ)
2 x 560 Watts @ 8 Ω (RMS)
My interpetation of this is that the amplifier can deliver 910w to a pair of paralell speakers. The tops are rated 600w program, and the bases at 400w. This is confusiong to me, because i had the impression that the jbl bases were the better speakers here. But atleast the tops then should be fine running with the amp almost at clippping evels, and the bases somewhat lower?
I also suspect that there is something fishy going on with the specs here, orr rather, my understanding of them. It would seem that the amp could deliver 1800w per chanell at 2ohm, which i believe would be four paralell speakers. That cant be right?
As for the power issue, im in sweden with 16a/230v in the socket. This would ofcourse no be enough in theory, but hopefully in practice.
I dont have the speakers here, but the next time im where they are, i will get some pictures. They are however just black, homebuilt boxes. What should the wiringdiagram contain? And what is an xover?
As for compression, we are at the moment not using any, since we almost only play already mastered music which shouldnt have a lot of peaks. Or is this faulty reasoning?
My wiring is as follows:
SL2442FXPRO mixer to
Samson s-3way splitter to
-> Low signal R+L (<900hz) -> amp -> 2 paralell bases for each chanel.
-> Hihgh signal R+L -> amp -> 2 paralell tops for each chanel.
The speakers are identical. They are connected paralell with two to each channel, thus giving a total resistance for each chanell of 4 ohm i think. The amplifiers are rated on the website as such:
Stereo Mode:
2 x 1800 Watts @ 2 Ω (EIAJ)
2 x 1100 Watts @ 4 Ω (EIAJ)
2 x 910 Watts @ 4 Ω (RMS)
2 x 670 Watts @ 8 Ω (EIAJ)
2 x 560 Watts @ 8 Ω (RMS)
My interpetation of this is that the amplifier can deliver 910w to a pair of paralell speakers. The tops are rated 600w program, and the bases at 400w. This is confusiong to me, because i had the impression that the jbl bases were the better speakers here. But atleast the tops then should be fine running with the amp almost at clippping evels, and the bases somewhat lower?
I also suspect that there is something fishy going on with the specs here, orr rather, my understanding of them. It would seem that the amp could deliver 1800w per chanell at 2ohm, which i believe would be four paralell speakers. That cant be right?
As for the power issue, im in sweden with 16a/230v in the socket. This would ofcourse no be enough in theory, but hopefully in practice.
I dont have the speakers here, but the next time im where they are, i will get some pictures. They are however just black, homebuilt boxes. What should the wiringdiagram contain? And what is an xover?
As for compression, we are at the moment not using any, since we almost only play already mastered music which shouldnt have a lot of peaks. Or is this faulty reasoning?
A 900hz crossover between the bass and mids seems unnecessarily high, I'd suggest you lower that to about 500hz. Don't get too hung up on the rated power handling of the drivers, suffice it to say they will be fine with the amplifiers you have especially after you balance(blend) the output from each section to sound natural, the mids and highs will be turned down relative to the bass and subs. So for example if you had the same amplifiers powering all drivers the sub amp would be the only one to reach full output, all the others would run at incrementally lower levels.. probably 3dB less for the bass and 6-9dB less for the mid-highs, and that is because human hearing is more sensitive to mid and high frequencies, because it takes more power to reproduce lower frequencies, and because modern music is recorded with a hugh sub/bass boost.
That is another area with direct math does not apply, music is not a sine wave so you can't compare AC wall power directly with music power. In practice the ratio will vary but even for heavily compressed music it could be 2 or 3:1
Crossover = Frequency Dividing Network
That is another area with direct math does not apply, music is not a sine wave so you can't compare AC wall power directly with music power. In practice the ratio will vary but even for heavily compressed music it could be 2 or 3:1
Crossover = Frequency Dividing Network
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One way to balance the speakers by ear is to run some pink noise through them, and adjust them so that the sound from the different speakers is more or less indistinguishable, that is nothing sounds louder than the other... it should sound more or less like a powerful waterfall - but watch ur levels.
xover = crossover, btw.
unless you need to recover some money, keeping the other amp around is a good plan.
worst case you have a backup if the main one smokes!
The alleged power handling ratings are likely not accurate, since even pro compression drivers are limited to <100watts max. With a crossover and pad, higher of course.
So, your "splitter" is the crossover.
You're better off with a more sophisticated unit, even a Behringer, that does EQ in the passband, delay and probably limiting... yes, limiting is a VERY good idea... if for no other reason than it will protect ur speakers against a stupid move and/or a fault in the signal chain.
Oh and yes, minus losses and IF the amp is capable of delivering current then power doubles as the impedance is halved (with a low output Z amp, aka a solid state amp - not a tube amp)
xover = crossover, btw.
unless you need to recover some money, keeping the other amp around is a good plan.
worst case you have a backup if the main one smokes!
The alleged power handling ratings are likely not accurate, since even pro compression drivers are limited to <100watts max. With a crossover and pad, higher of course.
So, your "splitter" is the crossover.
You're better off with a more sophisticated unit, even a Behringer, that does EQ in the passband, delay and probably limiting... yes, limiting is a VERY good idea... if for no other reason than it will protect ur speakers against a stupid move and/or a fault in the signal chain.
Oh and yes, minus losses and IF the amp is capable of delivering current then power doubles as the impedance is halved (with a low output Z amp, aka a solid state amp - not a tube amp)
Yes that would be 4 speakers in parallel but there is something telling in those specs.. notice there is no RMS spec for 2ohms. That is not surprising to those in the know because building an amplifier that will happily deliver that amount of power into 2ohms continuously is expensive, and these aren't expensive amps so the only conclusion is that the amp won't really drive 4 speakers per channel for any useful period of time before going into protection.
Okay, so you have 4x 1x15" subs, and 4x 1x12"+horn tops, and a pair of fairly powerful amplifiers.
Here's how I'd go:
Set the crossover for, say, 150Hz.
Use one amp for your left side, one for your right. 2x15"s on one channel, 2x12"s on the other. This keeps your speaker cable runs short. Should be 4ohm on each channel of the amp, which is fine. I wouldn't trust these amps at 2ohm, but there's very few that I would.
The 15" JBLs may be the weak link here, depending on what sort of music you'll be playing. Most bass is fairly peaky, so you'd have to be pushing really hard to burn the drivers. If it'll be EDM and dubstep, you're gonna need some good limiters, since they can approach sine-wave-like content, which kills drivers very quickly unless you can cut back the power. Either way, make sure the subs do not receive signals below the tuning frequency of the cabinet. Its very very easy to do mechanical damage when there's no highpass filter in place.
Chris
Here's how I'd go:
Set the crossover for, say, 150Hz.
Use one amp for your left side, one for your right. 2x15"s on one channel, 2x12"s on the other. This keeps your speaker cable runs short. Should be 4ohm on each channel of the amp, which is fine. I wouldn't trust these amps at 2ohm, but there's very few that I would.
The 15" JBLs may be the weak link here, depending on what sort of music you'll be playing. Most bass is fairly peaky, so you'd have to be pushing really hard to burn the drivers. If it'll be EDM and dubstep, you're gonna need some good limiters, since they can approach sine-wave-like content, which kills drivers very quickly unless you can cut back the power. Either way, make sure the subs do not receive signals below the tuning frequency of the cabinet. Its very very easy to do mechanical damage when there's no highpass filter in place.
Chris
Hang on... there are "horns" that load some 12" drivers made by "P Audio" for the highs?
No HF horns or other HF drivers??
How low the crossover can be set will be determined by the lowest usable frequency of the 12" horn loaded drivers, in the horn. Without knowing what those are, it is impossible to set the LF xover point for them.
Probably that accounts for the "900Hz" crossover frequency.
And, yes a HP filter on the bass set just below or at the -3dB point of the bass enclosures is a very good idea.
Again, something like one of the Behringer boxes (cheap, especially used) has that sort of feature.
Agree, do not attempt "2 ohm" operation, ever...
Think you may be in need of some HF speakers - although excessive HF in PA/SR can sound very annoying, imo. Maybe you want to hold on to the smaller amp for running the HF?
It's not that difficult to put together a good HF array, DIY... could be done fairly inexpensively for a system of this size and power...
No HF horns or other HF drivers??
How low the crossover can be set will be determined by the lowest usable frequency of the 12" horn loaded drivers, in the horn. Without knowing what those are, it is impossible to set the LF xover point for them.
Probably that accounts for the "900Hz" crossover frequency.
And, yes a HP filter on the bass set just below or at the -3dB point of the bass enclosures is a very good idea.
Again, something like one of the Behringer boxes (cheap, especially used) has that sort of feature.
Agree, do not attempt "2 ohm" operation, ever...
Think you may be in need of some HF speakers - although excessive HF in PA/SR can sound very annoying, imo. Maybe you want to hold on to the smaller amp for running the HF?
It's not that difficult to put together a good HF array, DIY... could be done fairly inexpensively for a system of this size and power...
I assumed "12+horn" meant a traditional 2 way PA box with a high frequency compression driver, you could be right but since this was apparently a complete working system it would be strange if it didn't include any high frequency components.
So much good help, i can hardly keep up!
The tops consist of a 12" drive + a hornloaded HF drive. There is also some kind of passive limiter at the back of the speaker to the HF drive, which i usually put as low as -12db in order to not get "sharp" soundiing music that hurts my ears. what this is a symptom of i dont know, but since i can get decent sound out of it, im happy.
As for the crossover at 900hz, i also thougth that this was very high. But turning it lover, i seem to loose something in the music. We will get acess to our new place in about a weeks time. I will do the sugested testing with pink noise then.
We play almost exclusively Techno, DJs, but also live. This is the compressor we have, and this is the EQ. Your sugestion is to replace these to guys with a more advanced limiter?
The enclosures are homebuilt by someone, there is no information on them at all. And what is the -3db point of an enclosure. There is a 30hz low cut-off on the amps.
The tops consist of a 12" drive + a hornloaded HF drive. There is also some kind of passive limiter at the back of the speaker to the HF drive, which i usually put as low as -12db in order to not get "sharp" soundiing music that hurts my ears. what this is a symptom of i dont know, but since i can get decent sound out of it, im happy.
As for the crossover at 900hz, i also thougth that this was very high. But turning it lover, i seem to loose something in the music. We will get acess to our new place in about a weeks time. I will do the sugested testing with pink noise then.
We play almost exclusively Techno, DJs, but also live. This is the compressor we have, and this is the EQ. Your sugestion is to replace these to guys with a more advanced limiter?
The enclosures are homebuilt by someone, there is no information on them at all. And what is the -3db point of an enclosure. There is a 30hz low cut-off on the amps.
Could be a lot of things causing that like no internal crossover or a really poor quality HF driver. You may have to look deeper into this as it has been my experience that those adjustable potentiometers don't last in pro audio applications, sooner or later it burns up and that often spells the end of the HF driver too
Can you post a link to this unit too, sounds like something isn't connected or setup correctly.
the -3dB point is also known as the tuning frequency or the box, for a reflex design(front loaded driver with ports) this is roughly where you want the low cut filter set as below that the driver is unloaded from the enclosure and easily damaged. The 30hz low cut on the amps is a good starting point, make sure these are always engaged. Finding out what frequency your enclosures are tuned to isn't that hard, you need to measure the internal volume and also note the dimensions of the port or ports, both diameter or cross sectional area and depth. These numbers can then be used to determine tuning.
If you don't mind making a bit of noise, you can play test tones and see when the cone stops moving. Start at 30Hz and move upwards. At first, it'll flap around with little sound. Be careful, start with the volume low or you risk damaging your drivers. Take it up to 31Hz, 32, 33, etc. As you move up, you'll see the cone excursion reducing, and almost stopping when you're at a particular frequency. When you move past, you can see the cone moving again. That particular frequency is the port tuning frequency, and you want to cut off any bass below that.
Measuring ports is okay, but watching speakers flap around is more fun.
Chris
Measuring ports is okay, but watching speakers flap around is more fun.
Chris
Samson — S-com plus That one has the limiter function.
Again, Behringer may be better for your uses... a bit more sophisticated in what it can do.
Pictures will tell a lot about what you have... hardly worth discussing the particulars without at least the pix to start.
Use the 30Hz filter on the amps. Use it.
The thing on the back of the tweeter is likely a level control, not a limiter.
It has to match the output level of the mid driver, so likely it needs to be set low.
You can also likely dial in a "roll off" on the Samson that drops the highs above 8-10kHz by as much as -6dB @ 20kHz and like the sound "more better". Like turning the treble control down, except that instead of the treble control starting to work at 1kHz it starts more like 8-10kHz...
The Behringer EQ also has a LF cut, use it too. Two cuts, one on the amp, the other on the EQ.
So to do the HF roll off with the Behringer, (unless it is easy with the dial on the Samson) you'd take the fader to the right and set it down to -6dB, maybe 8-10dB, the next one below, a bit less cut, the one below that a bit less, until you get to the one that says some number between 8kHz and 10kHz, that one would be "flat" aka "0" or maybe just a tad below zero.
Keep in mind that if you do NOT NEED to EQ something, don't!
Moving the sliders UP is usually bad.
Moving them down, universally safe.
Most users do not realize that you can get the SAME CURVE by going "minus" as you can by jacking the sliders UP (positive).
Positive uses amplifier power, a lot of it. If you have a limiter in, then you will slam the limiter with the jacked up EQ energy.
The knobs on the mixer do the same thing - boost eats power. And they are usually very broad tone controls - a little often
goes a long way...
(department of free advice, send check or paypal...)
_-_-bear
Again, Behringer may be better for your uses... a bit more sophisticated in what it can do.
Pictures will tell a lot about what you have... hardly worth discussing the particulars without at least the pix to start.
Use the 30Hz filter on the amps. Use it.
The thing on the back of the tweeter is likely a level control, not a limiter.
It has to match the output level of the mid driver, so likely it needs to be set low.
You can also likely dial in a "roll off" on the Samson that drops the highs above 8-10kHz by as much as -6dB @ 20kHz and like the sound "more better". Like turning the treble control down, except that instead of the treble control starting to work at 1kHz it starts more like 8-10kHz...
The Behringer EQ also has a LF cut, use it too. Two cuts, one on the amp, the other on the EQ.
So to do the HF roll off with the Behringer, (unless it is easy with the dial on the Samson) you'd take the fader to the right and set it down to -6dB, maybe 8-10dB, the next one below, a bit less cut, the one below that a bit less, until you get to the one that says some number between 8kHz and 10kHz, that one would be "flat" aka "0" or maybe just a tad below zero.
Keep in mind that if you do NOT NEED to EQ something, don't!
Moving the sliders UP is usually bad.
Moving them down, universally safe.
Most users do not realize that you can get the SAME CURVE by going "minus" as you can by jacking the sliders UP (positive).
Positive uses amplifier power, a lot of it. If you have a limiter in, then you will slam the limiter with the jacked up EQ energy.
The knobs on the mixer do the same thing - boost eats power. And they are usually very broad tone controls - a little often
goes a long way...
(department of free advice, send check or paypal...)
_-_-bear
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This is the unit. I realised though that it was propably how i tested that gave those results. I Had the xover at 900hz, and then set the volume for the bases and tops to get a good mix. Then turning down the xover to lower hz, the tops had to take more of the output with the same power, thus giving a decrease in volume from the tops. maybe.
I tried to see at what point the cone stopped moving using a tone generator online. but honestly, i didnt really see it move at any frequency. Meassured it instead:
Height: 51,5 cm
Width: 50 cm
Depth: 44 cm
port heights: 4,5 cm
depth of "port roof": 8 cm
Depth of port separator: 20 cm.
What now to do with this information? This seems like very useful knowledge for the upcoming subconstruction project!
So far ive only used the eq on the mixer to dampen the nasty sharp frequencies a little. I shall connect the behringer eq then as well and turn on the HP on it.
Still trying to stay as far away from costs as i possibly can. I notice that the compressor unit actually also says limiter. Does this mean i can use this unit for protection against peaks in the music?
For some reason i cant upload pictures to the forum, but i uploaded them here
I am sorry about the quality, only have a very old cellphone for camera.
Ignore EIAJ ratings, only "true" ones for a Pro setup is RMS, so you have a 2 x 900W@4 ohms amp and another doing 500W @ 4 ohms.
Use the large one to drive the 4 x 15" ones , 2 per side.
Use the medium one (wouldn´t call it "small" ) to drive the 4 x 12" , again 2 per side.
Get a small amp, say 80 to 100W per channel into 4 ohms to drive the horns.
You need a 3 way active/electronic crossover to send whatever´s best to each amp and speaker type.
As a rule of thumb suggestion, what you can get asking in a Forum, crossover the 15" to the 12" between, say, 200 and 300Hz.
As of the horns, whose specs you don´t state here, and again as a time tested rule of thumb, read datasheet to get frequency range, say "800Hz to 18kHz" and cross them over one full octave *above* the lower limit, in this case 1600 Hz.
This is done, mainly, not because of frequency response considerations but to reduce average program material sent to them.
Then you need to setup low/mid compressors tolimit power *just* below clipping; if those amps have built in limiters activate them, this will simplify your job because they auto detect clipping .
Set limiters on the horns to hard limit at, say, 30 to 40W RMS.
This way you will have a LOUD CLEAN SAFE system.
Get an extra small amplifier for monitors, problem there is not raw power but feedback, you´ll set them up only as loud as to allow performers start hearing themselves and not much more, just in case one of them walks all over the stage microphone in hand .
Use the large one to drive the 4 x 15" ones , 2 per side.
Use the medium one (wouldn´t call it "small"
) to drive the 4 x 12" , again 2 per side.Get a small amp, say 80 to 100W per channel into 4 ohms to drive the horns.
You need a 3 way active/electronic crossover to send whatever´s best to each amp and speaker type.
As a rule of thumb suggestion, what you can get asking in a Forum, crossover the 15" to the 12" between, say, 200 and 300Hz.
As of the horns, whose specs you don´t state here, and again as a time tested rule of thumb, read datasheet to get frequency range, say "800Hz to 18kHz" and cross them over one full octave *above* the lower limit, in this case 1600 Hz.
This is done, mainly, not because of frequency response considerations but to reduce average program material sent to them.
Then you need to setup low/mid compressors tolimit power *just* below clipping; if those amps have built in limiters activate them, this will simplify your job because they auto detect clipping .
Set limiters on the horns to hard limit at, say, 30 to 40W RMS.
This way you will have a LOUD CLEAN SAFE system.
Get an extra small amplifier for monitors, problem there is not raw power but feedback, you´ll set them up only as loud as to allow performers start hearing themselves and not much more, just in case one of them walks all over the stage microphone in hand .
no performers, looks like he does DJ with this rig...
to upload pix you go to "Go Advanced" instead of "Quick Reply" and then use the upload manager below the main text area...
Pix of the speakers is what is needed...
If you place a bit of tissue paper hanging over the port area, taped above and free to flap, you can find the resonant frequency of the PORT when it moves the most.
Unfortunately that does NOT tell you if the driver is properly matched to the volume of the box and the port frequency. If it is homemade, it may not be correct at all.
The other way to do the xover frequencies is to run the sections separately, one at a time and see where they sound right and handle level properly. I'd run the low woofers alone, and then the mid boxes alone, moderate levels and adjust the xover frequency with music and then pink noise running... some EQ may be required to make each sound balanced as the xover point shifts... etc. The mid boxes ought to work to 200-300Hz, but if there is a problem doing that, then you'd have to discover why...
_-_-
to upload pix you go to "Go Advanced" instead of "Quick Reply" and then use the upload manager below the main text area...
Pix of the speakers is what is needed...
If you place a bit of tissue paper hanging over the port area, taped above and free to flap, you can find the resonant frequency of the PORT when it moves the most.
Unfortunately that does NOT tell you if the driver is properly matched to the volume of the box and the port frequency. If it is homemade, it may not be correct at all.
The other way to do the xover frequencies is to run the sections separately, one at a time and see where they sound right and handle level properly. I'd run the low woofers alone, and then the mid boxes alone, moderate levels and adjust the xover frequency with music and then pink noise running... some EQ may be required to make each sound balanced as the xover point shifts... etc. The mid boxes ought to work to 200-300Hz, but if there is a problem doing that, then you'd have to discover why...
_-_-
This really is th e running point here i think. All would propably be easyer with a system where qll the spec are known. However, that would only be half as fun. Not even that actually, because we wouldnt have anything.
I do however feel much more prepared for setup in our new venue next week now, than i did a few days ago. I also feel less prepared to build a subbase. So much to consider.
Here are pictures! Again, almost useless camera.
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No I suspect the crossover isn't setup correctly. First thing you need to do is make sure the crossover mode switch is set for 2-way stereo, and then connect the low outs from the crossover to the amp driving the 15s and the high outs from the crossover to the amp driving the tops. Then on the front panel of the crossover you will only have to adjust 1 frequency control on each channel to change the crossover frequency, make sure the range switch on that control is set correctly to allow the crossover frequencies you need. Now as you take away frequencies from the 15s the 12's will pick them up and vise versa. If you turn off the amp driving the 15s and listen to the tops alone as you change the crossover frequency you will better hear where response begins to fall off.. As the freq control is moved lower there will be point below which these boxes just don't perform very well. That may be pretty low as in close to 100hz but that doesn't mean you want them operating that low, at higher power you want the 15's carrying the low frequency load but to maintain a wide coverage angle you also don't want the 15s operating above about 800hz so your ideal crossover will be somewhere in that range.
Are those internal cabinet dimensions or external?
If that is external and the boxes are constructed with 3/4" (18mm) plywood then I guesstimate an internal volume of 81L after subtracting volume displaced by the port and driver. That produces a box tuned to 62hz using a handy program called WinISD Pro.. http://www.linearteam.dk/default.aspx?pageid=winisdpro with this you can model driver response in a given or theoretical enclosure.
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