Chris,
I agree with you regarding the 2225 H, though a check on what they would do in ported cabinets should be done as a comparison, and since vc08 is using them for home use, SPL requirements presumably would not be as much as typically used by djs or live.
As far as mains wiring in a typical venue provide some RMS limiting, I would not count on it, my tests with a NU4-6000 with two bridged mono pairs each driving four ohm loads just below the illumination of the clip/limit light each put out 85.5 volts at 60 Hz (1828 watts), 84.6 volts at 30 Hz (1789 watts), dropping the mains voltage on a 100' 10AWG 120V line from 118.1 volts down to 107.2 volts, drawing 31 amperes, that would definitely cook an 18SW115-4 voice coil before the breaker would pop.
A Crest CA9, bridged into a 4 ohm load dropped the mains to 99.6 volts, drew 37.8 amps and put out 80 volts (1600 watts). The NU4-6000 put out more power, and drew only 50% of the power from the mains compared to the CA9.
The new owner of the original pair of Keystones burnt one of the B&C18SW115-4 out using a bridged CA9 with live music. With the kind of low crest factor "test tracks" recently posted, I expect to hear of more scorched coils from those that have not set RMS limiters to around half the AES power rating
.Art
Chris,
I agree with you regarding the 2225 H, though a check on what they would do in ported cabinets should be done as a comparison, and since vc08 is using them for home use, SPL requirements presumably would not be as much as typically used by djs or live.
As far as mains wiring in a typical venue provide some RMS limiting, I would not count on it, my tests with a NU4-6000 with two bridged mono pairs each driving four ohm loads just below the illumination of the clip/limit light each put out 85.5 volts at 60 Hz (1828 watts), 84.6 volts at 30 Hz (1789 watts), dropping the mains voltage on a 100' 10AWG 120V line from 118.1 volts down to 107.2 volts, drawing 31 amperes, that would definitely cook an 18SW115-4 voice coil before the breaker would pop.
A Crest CA9, bridged into a 4 ohm load dropped the mains to 99.6 volts, drew 37.8 amps and put out 80 volts (1600 watts). The NU4-6000 put out more power, and drew only 50% of the power from the mains compared to the CA9.
The new owner of the original pair of Keystones burnt one of the B&C18SW115-4 out using a bridged CA9 with live music. With the kind of low crest factor "test tracks" recently posted, I expect to hear of more scorched coils from those that have not set RMS limiters to around half the AES power rating
Art
According to what you just said one iNuke 6000 would be able to power even two 18sw115-8 each side with that crest factor, with a limiter set to 850 watt per driver (half aes rating). The 18tbw100-8 would then be even more on the safe side(half aes at 750 pulling 1500 watt from the amp each side at 4 ohms)
Otoh bjones claim his 18tbw100-4 wants a amp of more than 2500 wRMS for heavy EDM music, 3-4 times the power you recommend so my thought is he did not try this over an extended period of time... kinda confusing.
How it would sound without any peak power headroom is another question(maybe no worries as the music lack big peaks aswell) but I've done similar stuff with an old peavey ipr 1600 and it really rocked the house, but house a little shy of 1/3rd the power compared to the iNuke 6000
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As mentioned, the voice coil will generally burn long before the breaker pops.
TH BC 8 ohm drivers sims are comparable to the 4 ohm sims other than the obvious need for more voltage to achieve the same excursion & SPL.
Thanks! I see you use Zmin to calculate at what given voltage excursion limits are reached, I can only find how to calculate Zmax on the interwebz, is the Zmin simply the "minimum impedance" spec from b&c specsheet? The reason I'm asking and hesitating is because the minimum impedance of the 18tbw100-4 from the b&c specsheet is the same(4 ohm) as the nominal impedance while it's lower on the 8 ohm models(6.5 ohm minimum, 8 ohm nomimal)
I use Hornresp and actual measurements to see what the excursion is at a given voltage.
The voice coil's DCR is generally identical (or within a tenth of an ohm) to the impedance minima in a tapped horn, you can look at the Hornresp impedance chart to see what the impedance looks like, or measure.
If you play really heavy edm/rap and don't wanna burn your coils go for 50 volt, with a zmin of 3.3 ohm this will give the driver 750 volt continuous at it's lowest impedance, half the aes power as recommended by Art(for LOW crest factors). If you have higher crest factors you can offc give it more voltage
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I'll post the plans soon
In centimeters
for 21" sub
I use Beyma 21SW1600
It's insane
Here's a pic, horizontal (ground extension) position:
https://instagram.com/p/6HmWvcA9uO/
Mouth is below the big black "S"
I'll have to a/b test with different mouth plates.
I think without plate or flat plate in front will win.
I didn't figure out how to sim this in hornresp, too many horn sections!
So I'll just build another one
By the way:
Placing two subs in stereo like it seems that most people do i really crappy, a lot of you probably know this.
I did an install with subs 4 meters apart, no 40 hz at all!
I convinced them to put subs on a lin and BOOM!
$$Maan,
I would not want to peddle that rig uphill...
Did you experiment to find the optimum "ground extension" height vs. output, or was it simply determined by axle height?
Any measurements of your 21" Keystone in the upright vs. "ground extension"?
Art
It has an electric motor, easy to bike, and by the way: Copenhagen is all flat, -like the nederlands...
I didn't do any real experiments yet, as my plan is to first build the second one and test.
I am able to sim the bike without the front plate, but still not perfect.
At first I planned a completely different build with another fold, but it turned out to be too tall no matter what I tried, so instead, in last minute, I just did a big version of the keystone sub.
All my first sims (of different tapped 21" designs) takes the air below & around the bike into account, I even did a spreadsheet that calculates the cross sectional areas (S5) as a function og axle height, box size & lenght (from mouth).
It showed that the speaker has a gain nor only from the air below the bike, but all around the bike to the top!
Further interesting experiments would be directivity, as in having more direction to the mouth (now it sits in front) or experimenting with cardioids
I didn't do any real experiments yet, as my plan is to first build the second one and test.
I am able to sim the bike without the front plate, but still not perfect.
At first I planned a completely different build with another fold, but it turned out to be too tall no matter what I tried, so instead, in last minute, I just did a big version of the keystone sub.
All my first sims (of different tapped 21" designs) takes the air below & around the bike into account, I even did a spreadsheet that calculates the cross sectional areas (S5) as a function og axle height, box size & lenght (from mouth).
It showed that the speaker has a gain nor only from the air below the bike, but all around the bike to the top!
Further interesting experiments would be directivity, as in having more direction to the mouth (now it sits in front) or experimenting with cardioids
So you've had issues with running the Keystone 4meters apart with the main sitting on top?? are you recommending couple the subs in the centre with the mains sitting left and right ?
Have other people had this issue?? I was going to use my two Keystone to sit my mid and high boxes on sitting either side of the DJ, so 1 either side, so probably 4 metres apart also.
http://www.voidaudio.pl/attachments/article/147/A Practical Guide To Bass Arrays (angielski).pdf
Take a look at page 8 specifically. That shows you what it'll do to your dispersion.
Cool, I'd already read something similar and when I've run systems in the past I've coupled the ported subs in the middle but it causes all sort of issues for the DJ if they are close to the subs.
From the previous comments I was wondering if tapped horns affected this more so.
I should have everything finished and ready for a outdoor party in October so I'll play round with different config. just need to build something to put my mids and highs on.
Tapped horns exhibit higher directivity in general. So you start with a slight to moderate degree of front gain and rear reduction that approaches zero as you go down in frequency.
Direct radiator ported boxes will still have some directivity, especially in the midbass if you're low passing them fairly high (2-300hz) to reach midtops as some people do. But in the lower octaves they tend so exhibit so little they're nearly omnidirectional unless you start building stacks of them.
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Less so, due to increased directivity of a tapped horn. So, I'm in agreement with zettairyouiki.