Warehouse party, 6 T30's, 2 OT12's

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CoronaOperator
Posts: 1648
Joined: Wed Mar 25, 2009 7:07 pm
Location: Medicine Hat, Alberta, Canada

Re: Warehouse party, 6 T30's, 2 OT12's

#31 Post by CoronaOperator »

Bill Fitzmaurice wrote: You don't want a big mass that holds heat around the voice coil, you want something that sloughs heat away from the voice coil. That's what the finned aluminum heat sink on the 3015LF does.
This isn't rocket science, if you're blowing drivers you don't have enough of them for what you're doing. Either add more cabs or upgrade to a better driver, like the 18Sound NLW 9300.
Thermodynamics is rocket science. Heat doesn't melt voice coils, temperature does. If I hold a torch for 30 seconds to a needle or for 2 hours to a bathtub full of water, which one gets hotter? Which one absorbed more heat? The lower thermal mass will increase in temperature faster. The fins increase the surface area which is a good thing but for a given input of power (like a 2 second bass note) the smaller thermal mass will get hotter until that heat can get dissapated. However none of that matters if that heat can't leave the cabinet at the same rate that it is applied.

On a side note with the Lab subs. PK Sound used to use labsubs and they are a provider for the Shambhala EDM music festival where daytime temps can get 34*C - 38*C. They blew every lab12 driver in the rig (over 50 I believe) more than once. To be fair Function 1 blew all theirs too that year. The following year they brought 2 independent rigs so that they could cycle them on and off every 2 hours. They eventually gave up on that idea due to logistics (more trucks, more labour, etc) and sold them for firesale prices (and got in a bunch of IP rights trouble with Tom for that) and went to their own ported direct radiator version.
Built:
17" width 10" driver Autotuba
2 x 29" width dual Lab12 Tuba60
6 x DR250 2510/asd1001
In progress:
2 x DR250 2510/asd1001
For best results, point the loud end of the array towards the audience

commander_dan
Posts: 461
Joined: Sun Feb 16, 2014 7:19 pm
Location: Perth, Western Australia

Re: Warehouse party, 6 T30's, 2 OT12's

#32 Post by commander_dan »

After pondering all of your replies, my plan of attack is to more efficiently deploy the T30's at the next gig, and as soon as the amps get turned off at the end of the night, pull one of the access covers and get a temperature reading of the magnet/back of the driver to see where it's actually at. And go from there.

Thanks guys for the info and help.
Built:
6 T30 (24", 3012LF)
2 OT12 (MA, 3012HO)
2 T24 (18", 3010LF)

Running:
DCX2496
XTi 2002
XTi 4002
TRAKTOR Z2
TECHNICS 1210 Mk5's

Rich4349
Posts: 855
Joined: Wed Jul 30, 2008 10:18 am
Location: Kankakee, IL

Re: Warehouse party, 6 T30's, 2 OT12's

#33 Post by Rich4349 »

You could also run them at home, with less voltage, for a short bit, maybe 15 minutes, and also record THAT temp, to see how much difference there is. For science! For duty and humanity!
2 DR250s, 2 27" Lab15 T-60s, 2 30" Neo Titan 39s, 1 Autotuba...and looking for more!

commander_dan
Posts: 461
Joined: Sun Feb 16, 2014 7:19 pm
Location: Perth, Western Australia

Re: Warehouse party, 6 T30's, 2 OT12's

#34 Post by commander_dan »

I like that idea, and I'll keep a record of the results. Thanks!
Built:
6 T30 (24", 3012LF)
2 OT12 (MA, 3012HO)
2 T24 (18", 3010LF)

Running:
DCX2496
XTi 2002
XTi 4002
TRAKTOR Z2
TECHNICS 1210 Mk5's

commander_dan
Posts: 461
Joined: Sun Feb 16, 2014 7:19 pm
Location: Perth, Western Australia

Re: Warehouse party, 6 T30's, 2 OT12's

#35 Post by commander_dan »

First step: temp monitoring.

http://www.aliexpress.com/item/Remote-W ... 5ff897f47b

No wires to seal up coming out of the access cover. Next gig will install and monitor during the span of the evening and see what we get.
Built:
6 T30 (24", 3012LF)
2 OT12 (MA, 3012HO)
2 T24 (18", 3010LF)

Running:
DCX2496
XTi 2002
XTi 4002
TRAKTOR Z2
TECHNICS 1210 Mk5's

Boyd
Posts: 248
Joined: Thu Sep 27, 2012 11:20 pm
Location: New Zealand

Re: Warehouse party, 6 T30's, 2 OT12's

#36 Post by Boyd »

One of the key things with limiting (with respect to thermal protection) that few seem to ever mention, is limiter release time. A fast release time is fine for peak limiting to protect against over excursion, but can actually exacerbate the thermal issues by acting as a crude compressor, and increasing the average signal density if the system is pushed into limiting for any extended period of time.

If you have the facility to do so, I highly recommend using a very long limiter release time on subs, say 4-5 seconds (4 seconds in my case, as this is the maximum available on the dcx2496). This practically eliminates any additional compression, and affords some degree of improvement in thermal protection.

I still wouldn't recommend consistently pushing into the limiters, but it sure helps when you have to leave a DJ to it for a while.
Built:

2x Titan 48 18" wide 3012LF loaded
2x Otop 12 J-Array 3012HO Melded

Building:

2x Titan 48 36" 3015LF

Grant Bunter
Posts: 6915
Joined: Mon Nov 28, 2011 11:12 am
Location: Ilfracombe Queensland Australia
Contact:

Re: Warehouse party, 6 T30's, 2 OT12's

#37 Post by Grant Bunter »

Boyd wrote:One of the key things with limiting (with respect to thermal protection) that few seem to ever mention, is limiter release time. A fast release time is fine for peak limiting to protect against over excursion, but can actually exacerbate the thermal issues by acting as a crude compressor, and increasing the average signal density if the system is pushed into limiting for any extended period of time.

If you have the facility to do so, I highly recommend using a very long limiter release time on subs, say 4-5 seconds (4 seconds in my case, as this is the maximum available on the dcx2496). This practically eliminates any additional compression, and affords some degree of improvement in thermal protection.

I still wouldn't recommend consistently pushing into the limiters, but it sure helps when you have to leave a DJ to it for a while.
Boyd,
Interesting.
Please read the responses regarding release times in DCX's, in my "how to set up a DCX" thread some time back. Those responses are somewhat polar to yours:
http://billfitzmaurice.info/forum/viewt ... 3&start=15

Feel free to comment on same, and I'll grab the popcorn...
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel.
Bunter's Audio and Lighting "like"s would be most appreciated...

Boyd
Posts: 248
Joined: Thu Sep 27, 2012 11:20 pm
Location: New Zealand

Re: Warehouse party, 6 T30's, 2 OT12's

#38 Post by Boyd »

Grant Bunter wrote:Boyd,
Interesting.
Please read the responses regarding release times in DCX's, in my "how to set up a DCX" thread some time back. Those responses are somewhat polar to yours:
http://billfitzmaurice.info/forum/viewt ... 3&start=15

Feel free to comment on same, and I'll grab the popcorn...
It depends on what you are trying to achieve, and the content (read crest factor) of your material . A shorter release time may result in slightly higher perceived volume, as only the peaks are being reduced (and therefore your crest factor is reduced / average signal density increased). This is basically an aggressive form of compression. It will still protect against over excursion, and may even be somewhat beneficial on highly transient material with a high crest factor, but will do little if anything to protect against thermal failure. Usually excessive dynamic range is better dealt with upstream by channel or bus compression.

Most recorded music these days is already compressed within an inch of tolerability (10dB crest factor, or less) and EDM even more so (often 6dB crest factor, or less) so the average signal density (and therefore heat) is already pretty high when the peaks start to engage the limiters. Now lets say that the DJ playing that 6db crest factor EDM is now pushing into the limiters by 3dB's. With that fast release, only the peaks are squashed, and now your crest factor is closer to 3dB's (the same as a sine wave) and your driver (being only around 1% mechanically efficient) is now trying to dissipate nearly twice the amount of energy as heat, into a sealed compartment.

With a long release time, the entire bass band is pulled down, and held down, more like physically pulling down the master fader, and the crest factor is maintained without increasing the average signal density into the driver. It may seem 'slightly' quieter, but no more so than when you were just tickling the limiter occasionally.
Built:

2x Titan 48 18" wide 3012LF loaded
2x Otop 12 J-Array 3012HO Melded

Building:

2x Titan 48 36" 3015LF

commander_dan
Posts: 461
Joined: Sun Feb 16, 2014 7:19 pm
Location: Perth, Western Australia

Re: Warehouse party, 6 T30's, 2 OT12's

#39 Post by commander_dan »

Interesting reading. Thanks for the responses and info Boyd and Grant. For the record, we were never hard into the limiters. I saw limit lights twice over the duration of the night. Perhaps more interestingly, on one of those occasions, we heard clipping in the subs (it was a particularly low frequency track, low 30 hz), and notched down the sub gain on the dcx immediately. That made me question my confidence in the limiter setup, and I noted that away, I've started another thread relating to that issue.

I think I'll leave the DCX limiter release setting on the stock 407ms for now, until I understand it more. For now, we're going to try to stay clear of hitting the limiters by turning down when necessary.
Built:
6 T30 (24", 3012LF)
2 OT12 (MA, 3012HO)
2 T24 (18", 3010LF)

Running:
DCX2496
XTi 2002
XTi 4002
TRAKTOR Z2
TECHNICS 1210 Mk5's

sine143
Posts: 3066
Joined: Sat Feb 06, 2010 3:27 pm
Location: Raleigh NC

Re: Warehouse party, 6 T30's, 2 OT12's

#40 Post by sine143 »

Just wondering why you don't limit on board the xti 4002?
Built:
2x Tuba 30s delta12lf loaded (gone)
4x Otop12 d2512 loaded
8x t48s (18, 18, 24, 24, 30, 30) 3015lf loaded
2x AT (1 mcm, 1 gto 804)
2x SLA Pro (dayton pa6, 6 goldwood piezo loaded)
1x bastard XF208

2x OT212 (delta pro 450a loaded, eminence psd)

commander_dan
Posts: 461
Joined: Sun Feb 16, 2014 7:19 pm
Location: Perth, Western Australia

Re: Warehouse party, 6 T30's, 2 OT12's

#41 Post by commander_dan »

sine143 wrote:Just wondering why you don't limit on board the xti 4002?
That's just what I was doing, I failed to specify that in this thread. It's the xti2 limiter that I was questioning, as seen in this thread:

http://billfitzmaurice.info/forum/viewt ... =4&t=23561
Built:
6 T30 (24", 3012LF)
2 OT12 (MA, 3012HO)
2 T24 (18", 3010LF)

Running:
DCX2496
XTi 2002
XTi 4002
TRAKTOR Z2
TECHNICS 1210 Mk5's

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