Help wanted

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soundxtreme
Posts: 20
Joined: Sat May 02, 2009 10:07 pm

Help wanted

#1 Post by soundxtreme » Mon Sep 17, 2018 8:24 am

I recently sold my setup which I have had for 9 years. Didn’t have much use. That was my reason for selling. Two t39’s powered by cerwin Vega 2800 ran thru driverack px. Both cabinets are wired in parallel. What caused this power, bad signal or distortion? I ran them for years with no issues. Any thoughts are appreciated
Burned coil
Burned coil

Bruce Weldy
Posts: 7196
Joined: Fri Nov 27, 2009 11:37 am
Location: New Braunfels, TX

Re: Help wanted

#2 Post by Bruce Weldy » Mon Sep 17, 2018 8:59 am

soundxtreme wrote:
Mon Sep 17, 2018 8:24 am
I recently sold my setup which I have had for 9 years. Didn’t have much use. That was my reason for selling. Two t39’s powered by cerwin Vega 2800 ran thru driverack px. Both cabinets are wired in parallel. What caused this power, bad signal or distortion? I ran them for years with no issues. Any thoughts are appreciated

08F21F04-7712-4EE0-ADBE-150D1A6DE3C0.jpeg
Power. Distortion doesn't cause speaker failure, signal is signal. It just got too much juice. Limiter must not have been set properly or got turned off. How long was it running before the smoke started?

6 - T39 4-25" 2-22" 3012LF
4 - OT12 2512 Melded/NSD2005
1 - T24
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."

soundxtreme
Posts: 20
Joined: Sat May 02, 2009 10:07 pm

Re: Help wanted

#3 Post by soundxtreme » Mon Sep 17, 2018 9:14 am

I dont know how long it was running. He’s had it for 7 months and have had many functions at his venue. Gonna have to check settings on driverack.

ACUA
Posts: 354
Joined: Sun Sep 25, 2016 6:21 pm

Re: Help wanted

#4 Post by ACUA » Mon Sep 17, 2018 12:55 pm

all of the driver units that I have ever cooked like that I did in bass reflex cabinets, I always could smell burning coil winding rosin long before I melted it down. when I did melt one down I did it knowingly therefore, I have yet to damage any of my horn loaded gear. I have also done will to protect my gear(I perceive), the way Bill wants it protected. I still wish I better understood the limits of the gear and want to push the limits but for now those self assuring experiments will wait and I will trust the guy who designed them for financial sake. I have over driven drivers hard enough to create nonlinear excursion and have had coils short to the magnet and have blown drivers and amplifiers that way.

that picture looks to me like heat over some time and not an acute failure exactly. It has to have been over driven/powered, so to much voltage supplied in whatever signal form for longer than it could thermally handle. I hate the situation you are sitting in. The person who bought the gear from you wants to blame you for the failure and it looks like the failure was all their fault for over powering/driving the equipment. they likely don't understand that and cant exactly, so having to blame someone, you are the fall guy! well good luck, and I am sorry. I hope you can determine that someone tampered with the limiter on the driverack unit, that would make it easier. the other thing I would put weight on is details comparing how you ran the system and how they were running the system, did you in fact have it limited properly. Could you have had it under limited but never really pushed the equipment that hard, and the new owner road the limiter hard for several hours and the heat just slowly creep up until a thermal even occurred. I suppose limiters could fail, I'm way to new to the game to have seen that,

I don't believe that a limiter clips the signal like typical amplifier clipping does, I could use some schooling in this category actually thinking about it harder. I do know that comparing an unclipped sinewave at max amplifier gain vs a severely clipped wave through same amplifier, the clipped signal will generate much higher rms voltage which is physically unusable energy that can only manifest ultimately as heat. A ton of heat is generated by a clipped or squared wave to a coil transducer speaker. i see a common practice to set up limiters in equipment and then when a band comes in or dj he pushes the rig into hard limiting and the indicators will stay lit all night. that is not in my opinion a correct method of operation in any form. I see the limiter as protection from a runaway signal so to speak, i never hover in that realm but just below it rather. I have my limiters set to the best of my knowledge correctly and then I only ever let the limiter lights
illuminate a few time an event, only when I am digging for max output and once I get an indication I pull the level down just below the limiting function.
Advanced concepts underground audio

Bruce Weldy
Posts: 7196
Joined: Fri Nov 27, 2009 11:37 am
Location: New Braunfels, TX

Re: Help wanted

#5 Post by Bruce Weldy » Mon Sep 17, 2018 1:53 pm

Even if they had the limiter engaged, they could have just cooked it with hours of non-stop bass. So, content, EQ, and how much time between songs for cooling could be an issue also.

7 months is way more than anyone would expect a used system to be warrantied.

6 - T39 4-25" 2-22" 3012LF
4 - OT12 2512 Melded/NSD2005
1 - T24
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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Bill Fitzmaurice
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Joined: Tue May 02, 2006 5:59 pm

Re: Help wanted

#6 Post by Bill Fitzmaurice » Mon Sep 17, 2018 2:02 pm

Those were abused. Abuse is not a warranty item.

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