What happens when Flint makes a Line Array?
- Thread starter Flint
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Razz,
For the 16 drivers alone...
That would give 128 ohm load (assuming they are all in series) - which is kinda non-standard as far as finding an amp to drive them.
If wired in parallel you would get a 0.5 ohm load - which would also be tough to handle.
Hence the combination of series / parallel to get the "standard" 8 ohm load.
Jeff
For the 16 drivers alone...
That would give 128 ohm load (assuming they are all in series) - which is kinda non-standard as far as finding an amp to drive them.
If wired in parallel you would get a 0.5 ohm load - which would also be tough to handle.
Hence the combination of series / parallel to get the "standard" 8 ohm load.
Jeff
If the speakers were wired in series as your depiction indicated the impedance would multiply 8ohms x 16 speakers for a total of 128 ohms, Jeff's math.
If they were all wired in parallel the impedance would be lowered, you would divide 8 ohm / 16 speakers for a total of .5 ohms, Jeff's math.
Both of those loads would be really difficult for an amp to handle, so the combination of wiring them in series and parallel gives the 16 speakers a total nominal impedance of 8 ohms or a fairly normal load for most amps.
Razz
Well-Known Member
Thanks Randy,
I don't understand how the loads work. (I don't get the basics)
To me I just see one amp powering 16 speakers no mater how it's wired (again, I don't get the basics)
I know it's more than a simple explanation and would/should be discussed in an entirely different thread. But thanks for helping, you too Jeff.
Flint, just send more pics.. we all agree on those.
oh, your diagrams are cool too.
I don't understand how the loads work. (I don't get the basics)
To me I just see one amp powering 16 speakers no mater how it's wired (again, I don't get the basics)
I know it's more than a simple explanation and would/should be discussed in an entirely different thread. But thanks for helping, you too Jeff.
Flint, just send more pics.. we all agree on those.
oh, your diagrams are cool too.
If 16 speakers, 8 ohms each, were wired in parallel, the loads on the amp would be 0.5 ohms and few, if any, amps could handle that at all.
As for the wiring and resulting load on the amp, when I was first making the purchase of these speakers I took into account the sub-eight foot limit on height AND having an easily divisible number of drivers so I could use a series/parallel wiring scheme to get a reasonable load on any amp. So, with these speakers, I could have gone with as many as 17 drivers, but there was no easy way to combine them with a series/parallel wiring scheme since I want an equal voltage to go to each driver and thus need equal sized sub-groups 17 is a prime number and thus no divisible into equal subgroups.
I could have gone with 15 drivers and wired them sets of three in series and all five sets wired in parallel resulting in a 4.8 Ohm load using 8 Ohm drivers.
But, I'd rather have more drivers than fewer, so 16 was easier for me. I wish I could have fit 18 drivers easily into the 8 foot height limit, then if I wired them in sets of three in series than six sets in parallel resulting in a 4 Ohm load on the amp. That would've gotten me more drivers (thus louder and better bass), but I would have to mount the drivers touching edges and still would have a minimum height of 94.5 inches, which is just not enough wiggle room for a pragmatic project.
So, I went with 16 drivers. The speakers are still huge and based on my listening experiences thus far it appears they play louder and deeper than I could have ever imaged.
I could have gone with 15 drivers and wired them sets of three in series and all five sets wired in parallel resulting in a 4.8 Ohm load using 8 Ohm drivers.
But, I'd rather have more drivers than fewer, so 16 was easier for me. I wish I could have fit 18 drivers easily into the 8 foot height limit, then if I wired them in sets of three in series than six sets in parallel resulting in a 4 Ohm load on the amp. That would've gotten me more drivers (thus louder and better bass), but I would have to mount the drivers touching edges and still would have a minimum height of 94.5 inches, which is just not enough wiggle room for a pragmatic project.
So, I went with 16 drivers. The speakers are still huge and based on my listening experiences thus far it appears they play louder and deeper than I could have ever imaged.
Technically, 18 is a more mathematically flexible number.
16 can be divided into groups of eight, four or two.
18 can be divided into groups of nine, six, three or two. That's more options.
Understood, I got ya!
I haven't done sensitivity measurements, yet. That will come when I am ready to measure the speakers to design a passive crossover (as I have to know if I need a pad for the highs or lows and the amount of dB reduction that pad needs to be designed to do).
But, in general, since I am wiring the speakers in a series/parallel fashion, the power going to each speaker will be significantly lower compared to a single speaker wired to an amp. Since the resulting impedance of my 16 driver array is the same as a single driver (4x4 wiring array), then the output from the amp for a given voltage will be the same power as a single speaker. So, at 2.83V, one watt into one driver will also be one watt into this 16 driver array, so each driver is getting 1/16th of a watt. So, any increase in SPL in the room will be the result of acoustic characteristics of the large baffle.... HOWEVER, there are also rampant nulls and modes caused by the variation in distance from the listener to the various speakers. That means that at low frequencies where the wavelength is longer than the listening distance the output is working in unison to retain the SPL which one speaker would generate. But at midrange and higher frequencies where the difference in listening distance is as great as the wavelength, the comb filtering affect will reduce the overall apparent output in that range.
So, it is quite complicated to predict without some pretty advance software, really. But, when I measure the system at a reasonable listening distance (in this case about 14 feet), the output above 600Hz is about 3dB to 5dB lower than the output below 600Hz. I think I can work with that.
The tweeters, however, I was hoping to get the same beaming effect as the woofers, the same room dispersion characteristics, and a higher power handling solution than a single cheap tweeter could manage. Plus, they just look cool.
I should add, with my tweeter array I have 6 speakers which means the resulting impedance after wiring as 3x2 series/parallel will result in a higher impedance than one. So, the power feeding the tweeters will be lower, so the resulting sensitivity should be slightly lower than with a single driver.
So, at 2.83V the a single 4 ohm speaker will receive 2 watts and at 6 ohms that same voltage will generate 1.33 watts. That's a drop of about 1.8dB... so, based on the rated 94dB SPL sensitivity, the array's sensitivity at 2.83V at 1 meter should be about 92.2 dB SPL.
So, at 2.83V the a single 4 ohm speaker will receive 2 watts and at 6 ohms that same voltage will generate 1.33 watts. That's a drop of about 1.8dB... so, based on the rated 94dB SPL sensitivity, the array's sensitivity at 2.83V at 1 meter should be about 92.2 dB SPL.
