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

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

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

#1 Post by commander_dan »

So we did the sound for the Perth Artifactory's opening drum and bass night with the above deployment. I didn't think I would need to bother wall or corner loading, or v-plating the stack for that matter, with 6 subs against 2 tops. I made sure the mouths were more than 8 feet from any wall (they measured 8'6" from both walls, centered in front of the stage as shown in the pics). All up sounded great, there was plenty of sound for the entire 6 hour evening.

A couple of notes, we did experience room modes, interestingly a dip at 43hz (and another at 86hz) toward the centre of the room (to be expected indoors, but we were pondering how that would change next time if we moved the sub stack further away from the walls).

Also, for the last couple of hours we found the limits of the T30's (and turned down accordingly, not wanting to stress the system), so next time was thinking of v-plating the stack and moving it further out, maybe a foot or so. At the end when we were packing up, I noticed that the access cover panels on the sides of all subs were warm to the touch, and it rang alarm bells as I remembered sine143's post on his similar experiences with his T48's, here: http://billfitzmaurice.info/forum/viewt ... t&start=15

I don't particularly wish for thermal failures and am considering our options. A question, is there a way of integrating a liquid cooling system to assist cooling the drivers? Has it been done?

All up, a successful night, and great sound! A very versatile system with effortless SPL. Thanks Bill!
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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

Ryan A
Posts: 867
Joined: Thu Mar 01, 2012 11:19 am
Location: Minneapolis, Minnesota

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

#2 Post by Ryan A »

commander_dan wrote:
I don't particularly wish for thermal failures and am considering our options. A question, is there a way of integrating a liquid cooling system to assist cooling the drivers? Has it been done?
If your running close to max voltage you need more cabs or deploy them more efficiently.

Once you near max voltage a lot of the power is transferred to heat anyway decreasing efficiency and distortion increases too, so it becomes a lost cause to try to cool an overworked driver just so you can shove more power into it.

Nice stack you got there...

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Tom Smit
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Joined: Sat Jan 05, 2008 1:24 pm
Location: Sarnia, Ont. Canada

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

#3 Post by Tom Smit »

Wall (+6db), or corner load(+12db), if possible, plus a v-plate (+3db).
That is quite the stack, especially when compared to just two tops. :chainsaw:
TomS

Grant Bunter
Posts: 6915
Joined: Mon Nov 28, 2011 11:12 am
Location: Ilfracombe Queensland Australia
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Re: Warehouse party, 6 T30's, 2 OT12's

#4 Post by Grant Bunter »

My question, re going towards thermal is, were you running all the cabs off one amp?

Sure, we measure volts, but as output impedance goes down due to adding cabs, output amperage rises. That increases heat not just in the amp, but also in the drivers...
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...

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

#5 Post by commander_dan »

Thanks for the compliments guys :)

Grant Bunter wrote:My question, re going towards thermal is, were you running all the cabs off one amp?

Sure, we measure volts, but as output impedance goes down due to adding cabs, output amperage rises. That increases heat not just in the amp, but also in the drivers...

Interesting. We ran 2 T30's off the XTi2002 and 4 T30's off the XTi4002, so those 4 were receiving more heat in that respect. I was never going to run all 6 off one amp though, for the sake of the amp (having heard from many that XTi's don't play well with 2 ohm loads), but I never considered that extra amps also = extra heat in the drivers. Good to know.

Roger that re more efficiently deploying the stack. That was our general thought at the end of the night too, although I initially believed the T30's would outrun the Otops, which is why I lazily deployed them. Next time we'll v-plate the stack at the very least.
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

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

#6 Post by CoronaOperator »

Grant Bunter wrote:That increases heat not just in the amp, but also in the drivers...
That is just silly. The amperage is evenly divided between the cabs. Nothing changes inside the cabinet. That's like saying a 100w light bulb glows hotter if you plug more than one of them in.
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

Grant Bunter
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Joined: Mon Nov 28, 2011 11:12 am
Location: Ilfracombe Queensland Australia
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Re: Warehouse party, 6 T30's, 2 OT12's

#7 Post by Grant Bunter »

CoronaOperator wrote:
Grant Bunter wrote:That increases heat not just in the amp, but also in the drivers...
That is just silly. The amperage is evenly divided between the cabs. Nothing changes inside the cabinet. That's like saying a 100w light bulb glows hotter if you plug more than one of them in.
You're right, my bad.
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...

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

#8 Post by Grant Bunter »

Grant Bunter wrote:
CoronaOperator wrote:
Grant Bunter wrote:That increases heat not just in the amp, but also in the drivers...
That is just silly. The amperage is evenly divided between the cabs. Nothing changes inside the cabinet. That's like saying a 100w light bulb glows hotter if you plug more than one of them in.
You're right, my bad.
Sheesh CO,
You've really got me thinking now, and I'm not sure saying it is "silly" is quite fair.

Here's why, and tell me where I go wrong with this line of thinking.

If I plug in more than 1 x 100W globe, in terms of current to it, you're quite right. It gets the same current.
But you now have two of them.

Energy can neither be created nor destroyed, only converted into other forms of energy. Said, or at least paraphrased, by someone much smarter than me.

If you have two of them, then, in the case of a light bulb, despite having evenly divided amperage, you will not only have more light, but you will also produce more heat, because you now have 2 radiating surfaces, ie filaments.
That is because light globes are not 100% efficient, so they do not convert all the power applied to them into light. The other form of energy that arises from light bulbs due to that inefficiency is heat.

That is not dissimilar in many ways to speakers or speaker cabs, which are also not 100% efficient in converting power into sound.
Again, any power delivered to an individual cab that is not converted into sound (due to inefficiency), is converted into heat.
Double the cab count, double the "heaters".
All things being equal, doubling the heaters in a given room, will aid in raising the temperature of everything within that room. Including each cab.
Within itself, that may or may not be statistically significant.

We can add some other factors.
What do we do when we stack (horn) cabs? We put them side by side, either by stacking them horizontally, or vertically, or both, in groups.
The net effect of doing that in terms of ability for any given cab to dissipate an individual cabs heat is now dependant on it's position within a stack, because, as an individual cab, it's radiating plane, in terms of ability for heat dissipation, has been diminished/reduced. That means net effect is a higher average cab temperature.

Also, decreasing the impedance load increases amperage output in the amp. That isn't disputed, but it displays itself in increased heat output from the amp, which contributes to ambient temperature, and thus cab temperature.

Then let's add an audience...
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...

Ryan A
Posts: 867
Joined: Thu Mar 01, 2012 11:19 am
Location: Minneapolis, Minnesota

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

#9 Post by Ryan A »

Grant Bunter wrote:My question, re going towards thermal is, were you running all the cabs off one amp?

Sure, we measure volts, but as output impedance goes down due to adding cabs, output amperage rises. That increases heat not just in the amp, but also in the drivers...
Each individual driver generates the same thermal no matter how many drivers are electrically connected to it.

There's a slight increase in system operating temperature due to environmental factors and other cabs in close proximity, but its negligible.

Also, there shouldn't be a time when you have to consider the heat generated by a system, because that means you're running the gear too hard.

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

#10 Post by CoronaOperator »

All the watts you put into the driver eventually has to be dissapated into the environment. So 400 watts in means that 400 watts has to flow through that wood into the air. (Maybe 390w as some of that energy got turned into sound).


The faster that energy flows into the environment, the lower the temp inside the cabinet.

The rate of heat flow=R
The thermal conductivity of the material (wood) =K
The surface area that the heat has to flow through=A
The temperature difference between the inside of the cabinet and the outside of the cabinet=deltaT
Thickness of the material = x

R=K*A*deltaT÷x
(Units in watts, meters squared, and kelvin)

So to get the heat out faster we need to either increase K or A or deltaT or decrease x.

Mother nature increased deltaT in the OP's gig. By increasing the internal temperature of the cabinet, mother nature increased the difference between the inside of the cabinet and the outside air which increased deltaT which increased the heat flow R. It had to to get the watts out of there. In other words, the hotter the inside of the cabinet got, the faster it dissapated heat to the environment.

Since don't want the inside to get that hot we could deal with the other parameters of that equation. We could make the area bigger by buildimg the widest cab possible (another reason to build wide as you can). We could make the material thinner (I think it is already as thin as is prudent), we could only gig where the outside air is colder (not always possible) or the last thing left is to use a material that has a higher thermal conductivity than wood.

K of plywood = 0.13
K of aluminum = 205

Which means aluminum moves heat 1,600 times faster than plywood. You could build aluminum access covers and that will help out tremendously. The cabs stuck in the middle of the stack would need a small inch or 2 airgap between cabs for those access covers to effectively transfer heat to the environment.

However, I'm not sure I would go through the trouble. Next gig throw a thermometer with a wired probe inside one of the cabinets(wire through access cover). Just because it is warm might not mean it is excessively hot Inside. It can't dissipate the heat unless there is some temperature difference.
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

Bruce Weldy
Posts: 8301
Joined: Fri Nov 27, 2009 11:37 am
Location: New Braunfels, TX

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

#11 Post by Bruce Weldy »

I'm pretty sure that the subs weren't hot because of the temperature - they were hot under the collar having to endure 6 straight hours of that kind of music. :cussing:


I'd be hot too.

6 - T39 3012LF
4 - OT12 2512
1 - T24
1 - SLA Pro
2 - XF210


"A system with a few knobs set up by someone who knows what they are doing is always better than one with a lot of knobs set up by someone who doesn't."

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JonoSkip
Posts: 77
Joined: Thu Nov 17, 2011 2:09 am
Location: Hamilton, NZ

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

#12 Post by JonoSkip »

Bruce Weldy wrote:I'm pretty sure that the subs weren't hot because of the temperature - they were hot under the collar having to endure 6 straight hours of that kind of music. :cussing:

I'd be hot too.
:loler: :loler:
Built: 2x Jack 112.
Bass: Cort Action A.
Amp: GenzBenz Streamliner 600.

NukePooch
Posts: 371
Joined: Mon Jun 30, 2014 8:07 pm
Location: Berea, Kentucky

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

#13 Post by NukePooch »

Bruce Weldy wrote:I'm pretty sure that the subs weren't hot because of the temperature - they were hot under the collar having to endure 6 straight hours of that kind of music. :cussing:


I'd be hot too.
Image
Built:
4 Jack 112L- 3012HO, melded array
17.5 wide AutoTuba with Infinity 860w
6 Wedgehorn W6 w/ Panel Mount Piezos
2 T48 Slims (15" wide) with 3012LF
4 T48 Fattys (32" wide) with 3015LF

Bruce Weldy
Posts: 8301
Joined: Fri Nov 27, 2009 11:37 am
Location: New Braunfels, TX

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

#14 Post by Bruce Weldy »

NukePooch wrote:
Bruce Weldy wrote:I'm pretty sure that the subs weren't hot because of the temperature - they were hot under the collar having to endure 6 straight hours of that kind of music. :cussing:


I'd be hot too.
Image
Excellent play!

6 - T39 3012LF
4 - OT12 2512
1 - T24
1 - SLA Pro
2 - XF210


"A system with a few knobs set up by someone who knows what they are doing is always better than one with a lot of knobs set up by someone who doesn't."

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

#15 Post by commander_dan »

CoronaOperator wrote:Which means aluminum moves heat 1,600 times faster than plywood. You could build aluminum access covers and that will help out tremendously. The cabs stuck in the middle of the stack would need a small inch or 2 airgap between cabs for those access covers to effectively transfer heat to the environment.

However, I'm not sure I would go through the trouble. Next gig throw a thermometer with a wired probe inside one of the cabinets(wire through access cover). Just because it is warm might not mean it is excessively hot Inside. It can't dissipate the heat unless there is some temperature difference.
CO, this is just what I was thinking in my earlier post. Except more along the lines of this, except custom built to suit a 3012LF magnet:

http://www.ebay.com.au/itm/Corsair-Hydr ... SwnGJWTMD-

Mount cooling block to driver magnet, drill holes for pipes in access covers and lower down the cab to inside the horn mouth on side panel, route pipes and seal with PL, re-finish, and mount radiator/power solution inside horn mouth, out of the way.

Ryan A, I know that I'm running the gear too hard if I'm considering things like this but as you can see I'm also out of pack space, so building more cabs isn't an option right now. In computers and general electronics, cooling parts means you can push more power more efficiently through them, which is why I was thinking along the lines of cooling for the drivers.

CO I'm going to take your advice and temp monitor one of the cabs during the next gig to see if there is actually something to be worried about (right now it's just a similarity to sine143's experiences in the past), any pointers as to what would be a temperature to be worried about? I'm guessing > 75 degrees celcius?
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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