Keystone Sub Using 18, 15, & 12 Inch Speakers

Yeah, but that's somewhat missing the point. YOU are functioning as the limiter now. And while obviously having some knowledgeable person overseeing the equipment at all times and doing the job of a limiter manually is preferable, it's not practical.

Some people are interested in idiot-proofing the subs so they are protected from any kind of possible input signal, from 40hz sinewaves to pink noise to massively clipped program material. And while it's easy to set a peak limiter so low that the amp simply can't pass enough power to cook the driver, you've just eliminated tons of headroom.

Hence why having 2 (or more) different limiters is appealing for people who have equipment being used in potentially abusive environments without wanted to constantly supervise it.

Yes, now you are the limitter, but if you know you have a stupid ads DJ, you better stay next to him and smack the snot out of him if he is constantly keeping the overload led turned on. Because it is your equipment, your reputation and you are right and they are not, so they better learn.
 
Semi related. Had the opportunity to run my Keystone Lite (LAB15-4) for a homecoming dance that a friend's son DJ'd. We experimented with a few setups and ultimately went with a horizontal mounting center stage. For giggles we put it against the back wall of the stage room on a 30deg angle or so like a horn expansion and we were blown away but it didn't carry into the dance area/main gym as well. For a minute, we had some very physical bass that I had not experienced in some time. It was very interesting how directional the bass was with various setups. At this point, however, I am somewhat convinced to blast into the main dance area regardless of the benefits of boundary gains etc. In addition, horizontal seems my favorite too.

Kinda shocked to read of the battles between soundguys and DJs. I get it, but when I played/DJ's if you broke it you bought it and that kept it pretty real. I spent time dialing in the gain so that he couldn't do too much damage but felt a bit better engaging the amps soft limiter. Better than nothing I thought.
 
Semi related. Had the opportunity to run my Keystone Lite (LAB15-4) for a homecoming dance that a friend's son DJ'd. We experimented with a few setups and ultimately went with a horizontal mounting center stage. For giggles we put it against the back wall of the stage room on a 30deg angle or so like a horn expansion and we were blown away but it didn't carry into the dance area/main gym as well. For a minute, we had some very physical bass that I had not experienced in some time. It was very interesting how directional the bass was with various setups. At this point, however, I am somewhat convinced to blast into the main dance area regardless of the benefits of boundary gains etc. In addition, horizontal seems my favorite too.

Kinda shocked to read of the battles between soundguys and DJs. I get it, but when I played/DJ's if you broke it you bought it and that kept it pretty real. I spent time dialing in the gain so that he couldn't do too much damage but felt a bit better engaging the amps soft limiter. Better than nothing I thought.


Agreed. I have never met a Dj which showed signs of being that irresponsible for me to worry about my gear, and if something breaks I would blame myself in most cases for not properly setting up the system. It requires rather drastic measures to actually harm a balanced gain stage with proper filters/limiter, even with only long term voltage limiter engaged.

Hope your stone is very rewarding for your gigs!
 
Has the 'B-low' version of keystone been posted?
..if not, anxiously awaiting...

Thanks Art, this is a great thread..:)
Wreckingball,

No, been rather busy cleaning up after Matthew's visit, have not got to them yet, still have a few more projects in the que before the "B-Low" will "B-Dun" ;).

Art
 

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Yikes, what a mess. Hope no-one was harmed.

I was going to delete my post, but woke up on the couch 6 hrs later to a no-can-do situation. :eek: It was just laziness, so now I've subscribed.

Taller with (slightly lower) output down to the high 20's sounds like something I'd be very interested in, completely understand these things take quite some time, I'll just keep an eye on the thread. Thanks.
 
Yikes, what a mess. Hope no-one was harmed.

I was going to delete my post, but woke up on the couch 6 hrs later to a no-can-do situation. :eek: It was just laziness, so now I've subscribed.

Taller with (slightly lower) output down to the high 20's sounds like something I'd be very interested in, completely understand these things take quite some time, I'll just keep an eye on the thread. Thanks.
As far as I've heard, only one lady was killed when a branch fell on her while she was feeding her animals, died on the way to the hospital. Considering the amount of huge water oak trees dropping like flies all around here, I am just amazed there were so few casualties.

I was lucky that my rental house has an attic, a branch dropped about 50' and pierced the roof just a few feet from my desk, it was LOUD, and then the power went out. I shut down the computer and my two battery back up power supplies, and ike a dumb-***, went outside to see what happened. There was almost no wind, but my neighbor had another huge branch drop on the power lines at the same time, which resulting in the power outage.

Art
 
I have simmed the B&C 21DS115. It looks rather nice except for gracefully downward slope in dB from 37hz to 98Hz of 2dB. However this driver can handle 1700+ watts (116v) with an xmax @ around 14mm. Delivering 130dB plus and has still 1mm xmax to spare.

sD: 1680
Re: 5,10
fs: 30Hz
Vas: 268,84
Qes: 0,24
Qms: 10,00
Le: 4,60
Pmax: 1700w
Xmax:15mm


What do you guys think?
BC-21DS115-displacement.JPG

 
I have simmed the B&C 21DS115. It looks rather nice except for gracefully downward slope in dB from 37hz to 98Hz of 2dB. However this driver can handle 1700+ watts (116v) with an xmax @ around 14mm. Delivering 130dB plus and has still 1mm xmax to spare.
USRFobiwan,

With 116V into the 5.1 ohm impedance minima of the B&C 21DS115 in the Keystone, it would be drawing 2638 watts into a smaller diameter voice coil rated for less power, pushing a cone with less mass (stiffness) than the BC21SW152-4.

It looks to be no more sensitive than the BC21SW152-4, which simulates as 131.6 dB over the pass band of 35 to 100 Hz, using 92 volts into 3.4 ohms, 2489 watts.

Art
 
Playing around with time alignment between my Keystones and some 15" x 2" (Fulcrum DX1565) tops....crossed over at 100hz on Jupiter 8 running FIR...so some latency added there.

If I do the old play a 100hz tone and flip polarity and listen for null - I get about 1.5 to 2ms as best.

Using REW I find around 7ms gives a nice smooth transition and sounds even better.

Does that seem reasonable?
 
Playing around with time alignment between my Keystones and some 15" x 2" (Fulcrum DX1565) tops....crossed over at 100hz on Jupiter 8 running FIR...so some latency added there.

If I do the old play a 100hz tone and flip polarity and listen for null - I get about 1.5 to 2ms as best.

Using REW I find around 7ms gives a nice smooth transition and sounds even better.

Does that seem reasonable?

Both seem reasonable, but the tops probably should be delayed by 7ms so they are time aligned, at 2ms the path length of the horn puts it around one wavelength behind the front loaded DX1565, unless the latency of the FIR filters are correcting down to the bottom end of the DX1565, in which case, as zettairyouiki wrote, that time could be correct.
For the "flip polarity and measure the null" procedure to work best, you must first balance the SPL output of the top and sub, with both placed on the ground equidistant to the measurement mic.

If you were to cross at a lower frequency, the polarity inversion of the DX1565 port output will require a different alignment time.

Delaying the tops by an additional wavelength will make the LF sound more "present" due to the Haas effect, we perceive sound arriving first as louder, even if it isn't.

Art
 
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Delaying the tops by an additional wavelength will make the LF sound more "present" due to the Haas effect, we perceive sound arriving first as louder, even if it isn't.

FWIW, I believe the Haas ("Precedence") Effect is something that happens with identical or nearly identical sounds that are coming from different sources. See this link for more information - https://en.wikipedia.org/wiki/Precedence_effect

If that's correct, it's not the Hass Effect that's making the difference here. Even if it is, the text suggests that you'd have to have delays up to 40ms for the effect to be noticeable.

I suspect that if there's a difference that's noticeable, and desirable, by delaying the tops that way, it might have something more to do with how the combined wavefront is being shaped.

Looks like I have something else to test this weekend :).
 
FWIW,
1) I believe the Haas ("Precedence") Effect is something that happens with identical or nearly identical sounds that are coming from different sources.
If that's correct, it's not the Hass Effect that's making the difference here. Even if it is, the text suggests that you'd have to have delays up to 40ms for the effect to be noticeable.
2)Looks like I have something else to test this weekend :).
Brian,

1) Although fusion of two sounds may occur with a lag between legato low frequency wave fronts as long as 40 ms (only 1 to 5 ms for high frequency clicks) the Haas effect will insure that you will hear the earlier arrival as louder. The nearly identical sound from the low end of the top cabinet driver and the top end of the low driver will sound louder from whichever arrives first. If the sub wave front arrives before the top, it will sound louder, "bigger bottom", if the top cabinet sound arrives first, it will sound more "present", or as those PRAT (Pace, Rhythm And Timing) guys say, "forward".
2) As an "ear opener", take a second cabinet about 10 meters from the first, delay it to match the arrival time of the first, then delay it a little bit more. You will be able to turn the delayed cabinet up as much as 10 dB louder than the first cabinet, yet all the sound will "appear" to come from the lower volume first cabinet.

Psychoacoustics, the Final Frontier!

Art
 
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