Keystone Sub Using 18, 15, & 12 Inch Speakers

Ishom,

The NX4-6000 is an updated version of the NU4-6000.
I have powered a pair of Keystones with a single NU4-6000, channel pairs bridged mono to each 4 ohm sub.

That said, with a three way system, normally I used one channel pair of the NU4-6000 bridged into the sub, and the other two channels for mid/high, the two amplifiers on either side of the stage to reduce cable length.
If one amplifier failed, the system could still be run mono, with one sub per channel, ~3dB less power than in bridged mono mode.

Art
 
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Would someone mind double checking my math? I'm considering a CVR DSP-654 to run one Keystone (two bridged channels) and one Syntripp.

The DSP-654 can put out 3740W @ 4Ω bridged and 72.1V RMS. The 18SW115-4 in the Keystone takes 3400W max and 1700W RMS, and I see Art recommends limiting RMS to 1/2 of the nominal RMS rating, so 850W.

850W at the speaker's DCR of 5.3Ω gives me 67V which is within the amp's RMS output of 72.1V. Is this sufficient, or should I oversize to something like the DSP-1004 with 2 x 5780W or the DSP-1504 with 2 x 7140W? I'm playing low-crest-factor EDM.
 
The DSP-654 can put out 3740W @ 4Ω bridged and 72.1V RMS. The 18SW115-4 in the Keystone takes 3400W max and 1700W RMS, and I see Art recommends limiting RMS to 1/2 of the nominal RMS rating, so 850W.
The nominal 4Ω 18SW115-4 has a DCR of 3.3Ω, near the minimum impedance of it loaded in the Keystone Sub ~ Fb.
In post #1, I recommended peak limiting of ~3400watts, and long term "RMS" limiting with a time constant of longer than 500 ms (milliseconds) no more than half the 18SW115-4 AES rating of 1700 watts (850 watts), but if you tend to get "heavy handed" on the volume fader playing compressed music over long time periods, just 425 watts.

850W at the speaker's DCR of 5.3Ω gives me 67V which is within the amp's RMS output of 72.1V. Is this sufficient, or should I oversize to something like the DSP-1004 with 2 x 5780W or the DSP-1504 with 2 x 7140W? I'm playing low-crest-factor EDM.
You are asking about a 18SW115-8, a nominal 8Ω speaker with a DCR of 5.3Ω.
72.1V into the impedance minima is around 981 watts.
~47.5 volts should be safe for low-crest-factor (similar to sine waves..) EDM.
If you want to get the peak performance ~3400 watts, ~134volts peak would be required, compared to ~106v for the 4Ω driver.
 
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Whoops, looking at the wrong specs. I'm using the 18SW115-4. Ok, so for maximum peak performance (most of my music has strong bass hits but not sub-bass sine waves) I should aim for something that puts out at least ~106V, but limit the long-term RMS rating to 425-850W. Does that sound correct?
 
ACX could work OK, without working with a particular plywood brand hard to say.
"A" and "C" refer only to the front and back plys, "X" denotes the use of an exterior grade adhesive to join the panel’s veneers together.
The knots and other imperfections in "C" grade could be a problem on some pieces like the baffle.
The amount (more is better) and what is in the inner plys is important, avoid plywood where gaps, loose knots and "waves" are visible on the sides.
 
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Ended up with four sheets of marine grade, though I'll likely use acx for future builds (my wallet is on fire)

It's void free, but lacks as many plys as birch. The birch was just a little more pricy and only comes in 5x5; which makes the layout more inefficient with more waste.
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Ishom,

The NX4-6000 is an updated version of the NU4-6000.
I have powered a pair of Keystones with a single NU4-6000, channel pairs bridged mono to each 4 ohm sub.

That said, with a three way system, normally I used one channel pair of the NU4-6000 bridged into the sub, and the other two channels for mid/high, the two amplifiers on either side of the stage to reduce cable length.
If one amplifier failed, the system could still be run mono, with one sub per channel, ~3dB less power than in bridged mono mode.

Art
For reference, I was originally using a behringer nx6000, 1 sub per channel into b&c thw100 8ohm drivers for a fair while. The sound in general was excellent but I ended up upgrading to an admark ad42 for 2 of our cabinets while the other 2 run on a matrix xt7000. The difference in warmth and depth of the bass is quite frankly obscene. These cabinets can move some serious air when driven properly!
 
During the last few months I've been building a pair of Keystones to match the SynTripPs I built last year. Have been running them at three parties so far and maaaaan do they kick! I've lost count of the numbers of compliments the subs have recieved. Like others has stated, the output and overall "tightness" is out of this world.

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  • 18TBW100-4 powered by a NX6000
  • 30hz BW24 and crossed to the SynTripP at 100hz with a BW24
  • Limiter at 50v

Some build photos: https://photos.app.goo.gl/ZFY16m1YwE1VHc7u5

The only downside is that I've come to the realization that sub-bass gets a lot of neglect in music production haha. After playing around with the subharmonic synth on the PA2 and adding a tiny bit of SX3040-processing I could really feel the sub-bass come alive on most tracks! I like it when the air feels like liquid :) Highly recommend!

Built horns as well! 35cm deep with 45 deg sides. Now in retrospect I'm not really sure why since I was already more than happy with the power output... Anyways, got to try them out today and took some quick measurements with and without the horn extension:

keystone_with_and_without_horn_extension.png


Taken at 2m distance ~5cm from the ground, 1/12 smoothing. If you look close you'll see some minor fluctuation, but it's most likely due to my dying computer having some grounding issues. The measurement with the horn attached had the microphone moved back 35cm to account for the added depth. Here's the separate measurements with phase:

keystone_2m.png
keystone_horn_2m.png


Overall a 2-4dB increase in the whole frequency range! While I could have hoped for an additional dB or two in the 30-50hz region I'm still extremely happy with the results! Art, as I said last year in the SynTripP thread, thank you!
 
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