blown driver issues

Anything not covered elsewhere.
Message
Author
djtrumptight
Posts: 793
Joined: Tue Dec 15, 2009 6:08 pm
Location: Detroit,Michigan

blown driver issues

#1 Post by djtrumptight » Wed Sep 04, 2019 1:16 pm

first i hope this is the right board for this post and secondly DAMNED !!! i had typed a book and went to add the pics and had to log back in and the book is gone lol.

So,i had been having a problem with my sub amp clipping on hard bass notes and the lows would disappear temporarily.Even when i have used stacks of 4 v plated T-48s i kept my hi pass at 40hz and my voltage at 56 so there is no way i should be getting clipping in my amps so i assumed the amp was bad and sent it back to QSC for warranty repair.Meanwhile i had 4 gigs lined up this past weekend so i ordered a new QSC GX7 which would pay for itself and i would need it anyway if i have to run 8 T-48's.Went to do a gig with the new amp and had the same clipping issue.I did another gig later that day that only called for 2 T48's and everything went fine.I have did rentals where the power in the whole neighborhood went out and u could hear the transformers buzz.I also did a rental for an outside event where there was only one power source for us,the cameraman and all the outside lights.The cameramans back drop was right in front of the power outlet,twice our cord got knocked out of the socket until i duct taped it.I also had a DJ that didnt follow the "turn amps on last and turn them off first" rule and by the time i got back to the event he was all packed up but my whole rack was still on.So i spent Monday with my system outside trying to narrow this down.i set up 4 subs and 2 tops,connected 2 subs and the tops,turned it up,no problem.I daisy chained a sub on one side and turned it up,no problem.Daisy chained a sub on the other side,turned it up and got clipping.I turned the volume down and went and listened to the subs and one was noticeably lower than the rest and low and behold i seen a piece of cone material in the horn mouth.Both of the drivers in the pics still play,just alot lower.My question is,is there some kind of battery backup available that i could plug my sub amp into ? These are the T-48 drivers
busted drivers.jpg
Also here is the gain structure of my rack with nothing exceeding unity gain,channels 1 and 3 on the DCX2496 are sub channels:
https://www.youtube.com/watch?v=QizLaX4VqwA

Any suggestions on how to avoid these problems ?
Built:
2 Autotuba's MCM 55 2421
8 T48's 24"wide 3015 LF
2 DR 250's melded Deltalite II 2510
2 DR 250's flat Deltalite II 2510
2 SLA HT systems
1 Table Tuba Dayton DCS 255-4
2 T 39's 20" wide 3012 LF
1 T-18 13" wide MCM 55 2421
2 SLA Pro's

User avatar
Bill Fitzmaurice
Site Admin
Posts: 26804
Joined: Tue May 02, 2006 5:59 pm

Re: blown driver issues

#2 Post by Bill Fitzmaurice » Wed Sep 04, 2019 2:26 pm

That damage can only occur via abuse. It probably happened during a previous gig. With the cone shredded the impedance of the cab will drop way down, so that 56v isn't 425 watts, it might be twice that or more, explaining the clipping.

jimbo7
Posts: 594
Joined: Fri Dec 28, 2012 10:45 am
Location: St. Louis

Re: blown driver issues

#3 Post by jimbo7 » Wed Sep 04, 2019 6:13 pm

So you noticed this after renting out your equipment?......
BFM builds:
XF212
T24 BP102 24"
2x SLA's 6-5" mids, 9- gt-302's
2x AT 14" MCM 55-2421
TrT 5" MCM 55-2421
AT 18" JBL GTO804
2x OT12 flat array
2x SLA Pro 2-Alpha 6's 2-Goldwoods
2x T39 24" 3012lf

SethRocksYou
Posts: 342
Joined: Thu Sep 10, 2009 8:06 pm
Location: Sacramento, California, USA
Contact:

Re: blown driver issues

#4 Post by SethRocksYou » Wed Sep 04, 2019 6:46 pm

Sorry to hear of the damage.
djtrumptight wrote:
Wed Sep 04, 2019 1:16 pm
Also here is the gain structure of my rack with nothing exceeding unity gain,channels 1 and 3 on the DCX2496 are sub channels:
https://www.youtube.com/watch?v=QizLaX4VqwA
The sub channels on the DCX2496... the green segments seem to be mid level, about the same as the input indicators on the left of the unit, so I assume that's the limiter indicator that's blinking red. Correct?

Have you double checked the amplifier output to verify that it's actually limiting at the voltage you think it's at? Double checked the high pass slope is still at 48dB and 40Hz? Tripple checked?

CoronaOperator
Posts: 1603
Joined: Wed Mar 25, 2009 7:07 pm
Location: Medicine Hat, Alberta, Canada

Re: blown driver issues

#5 Post by CoronaOperator » Wed Sep 04, 2019 9:30 pm

Like was mentioned, double check your limiters with a dmm. Also, double check for leaks around the drivers, are all the screws tight and the gasket airtight? That is something that should be done after the first few days, then yearly after that.

I really don't like your gain structure at all. The sub clip indicators on the dcx2496 are coming on when your main mixer isn't even close to yellow/red lights (unity) on the main output vu meter display. It is way too easy for a helper to not notice the dcx2496's lights but by looking at the main mixer vu meters, it would seem the system has plenty of headroom and just unknowingly turn up the main mixer - burying the system into hard solid red limiting.

You really want everything in the system showing red at the same time. To do that (disconnect speakers) play a 60hz tone through your main mixer and bring the level up (most likely channel gain as your faders look like they are at unity) until you hit unity/first yellow/first red on your main mixer vu meter outputs. Then adjust your input gains on the DCX2496 until you have the same on the input vu meters. Adjust the output levels until the red limiting lights just barely start to flicker. If you do not have enough travel to turn down the output gains then you can always turn down the input gains as well if need be. Now play with the fader up and down on your main mixer, both the mixers yellow/red lights on the vu meter and the dcx2496's limiting lights should come on at the same time. Adjust until they do. You will have to turn down the input gains on the tops as well on the dcx2496 to level match the system. Now this way, when you see red on the mixer, your dcx is hitting its limiters at the same time giving you another visual clue.
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

djtrumptight
Posts: 793
Joined: Tue Dec 15, 2009 6:08 pm
Location: Detroit,Michigan

Re: blown driver issues

#6 Post by djtrumptight » Wed Sep 04, 2019 11:23 pm

Bill by abuse do you mean User abuse or possibly the loss of power while the system was playing ?

Jimbo7 yes,nowadays i do 3 times as many rentals as i do DJ gigs,i prefer to do rentals now as the party scene is so boring for a DJ nowadays,people dont dance anymore unless its a mature party,other than that they stand around with their phones on Instagram and Facebook,nobody cares about how good a DJ is anymore,they think you are good if you play all the songs that are played 50 times a day on commercial radio,to me thats being a human jukebox,people want to hire cheap DJ's,not good DJ's and its alot of guys with a cheap controller or just a computer,Virtual DJ and some weak cheap powered speakers that will DJ a Cabaret of 1,000 people for $150 just to say they DJ'd a big event whereas i would be charging $1,000 or more for that event.

Sethrocksyou,yes,that is the limiter kicking in,i did go back through my system and double checked the limiters step by step (according to the setting limiters post on this forum) with a 60hz sine wave,even slamming the channel fader and master volume fader up real fast,limiter responded properly,i have the Radio Shack DMM,with the limiter off i measured up to 82.3 volts.I will double check but im pretty sure im using a 48db LR filter,im 1,000 percent sure about the 40 hz hi-pass,how am i sure ? I toasted some drivers by lowering the highpass to 35hz because i was using 4 subs BUT,i didnt stack them... :owned: Since then i havent lowered my hi pass again.

Coronaoperator,u may be on to something,what i have been doing after i recone a driver (i reconed 4 blown drivers after i built 4 more T-48's) is to install the driver,check for leaks,come back 24 hours later after the gasket compresses,tighten screws more if i can then install the driver cover,check for leaks,let it compress for 24 hours,tighten screws more if i can then consider that cab good for use,this is the first time i have ever heard of checking the screws days later but that may be a good idea because one of the blown cabs has machine screws and a couple of recex screws and the machine screws werent as tight as they should be,the driver with the recex screws was still tight.
I dont like my gain structure either,it seems like the sub channels arent getting much signal before the limiter kicks in but thats how it balanced out when i set the limiter.The tops also seem to be getting a weak signal,it will limit after the 3rd light whereas the subs limit after 2 lines,i should be getting about 5 lines just to reach unity gain,tops have been set with a 1000hz sine wave.I have lowered the input into the DCX by 9 DB in an effort to balance the system.
Also 1 change i made to my system is i took the DEQ2496 out as it was malfunctioning sometimes to where i would have to turn everything off and reboot it or turn the amp gains down and slam the mixer fader up to get the signal to kick in on the right side.
Im gonna go to storage in the morning and grab my rack and go through the system according to your suggestions and see what happens,i will make a video.
Thanks fellas,i really need to get this together
Built:
2 Autotuba's MCM 55 2421
8 T48's 24"wide 3015 LF
2 DR 250's melded Deltalite II 2510
2 DR 250's flat Deltalite II 2510
2 SLA HT systems
1 Table Tuba Dayton DCS 255-4
2 T 39's 20" wide 3012 LF
1 T-18 13" wide MCM 55 2421
2 SLA Pro's

CoronaOperator
Posts: 1603
Joined: Wed Mar 25, 2009 7:07 pm
Location: Medicine Hat, Alberta, Canada

Re: blown driver issues

#7 Post by CoronaOperator » Wed Sep 04, 2019 11:53 pm

djtrumptight wrote:
Wed Sep 04, 2019 11:23 pm

I dont like my gain structure either,it seems like the sub channels arent getting much signal before the limiter kicks in but thats how it balanced out when i set the limiter. The tops also seem to be getting a weak signal,it will limit after the 3rd light whereas the subs limit after 2 lines,i should be getting about 5 lines just to reach unity gain,tops have been set with a 1000hz sine wave.I have lowered the input into the DCX by 9 DB in an effort to balance the system.
Having a weak output signal from the processor to the amp is just a consequence of having your gains on your amps turned all the way up (which you want to avoid tampering with the limiter settings). Unless you are experiencing excessive background noise in the system I wouldn't worry about it.

I would be more worried about your system clipping when your mixer shows everything is fine, ESPECIALLY for rentals. That mixer should show red on its VU meters at the same time your DCX's limiting kicks in. Most DJ's run their gear just flickering the reds, your driverack should clip at the same time, not before.

For rentals I would make another program in the DCX2496 with the limiters set 10 volts below what normal safe levels are. You would lose about 2.5 dB's but gain a lot of piece of mind.

Another trick for rentals could be to set a dynamic EQ that rolls off the bass once a certain threshold is reached. This way if they go too loud on the levels, they will notice the loss of bass, tell them that the way to get it back is to bring the levels down.
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

djtrumptight
Posts: 793
Joined: Tue Dec 15, 2009 6:08 pm
Location: Detroit,Michigan

Re: blown driver issues

#8 Post by djtrumptight » Thu Sep 05, 2019 4:04 am

Another trick for rentals could be to set a dynamic EQ that rolls off the bass once a certain threshold is reached. This way if they go too loud on the levels, they will notice the loss of bass, tell them that the way to get it back is to bring the levels down.

I love that idea and never thought about using the dynamic EQ,thanks.
Built:
2 Autotuba's MCM 55 2421
8 T48's 24"wide 3015 LF
2 DR 250's melded Deltalite II 2510
2 DR 250's flat Deltalite II 2510
2 SLA HT systems
1 Table Tuba Dayton DCS 255-4
2 T 39's 20" wide 3012 LF
1 T-18 13" wide MCM 55 2421
2 SLA Pro's

User avatar
Bill Fitzmaurice
Site Admin
Posts: 26804
Joined: Tue May 02, 2006 5:59 pm

Re: blown driver issues

#9 Post by Bill Fitzmaurice » Thu Sep 05, 2019 6:39 am

The most critical aspect with a rental is that the electronics are inaccessible. They can run the mixer, but that's it. If they're able to mess with the processing and amps they will.

ketoet
Posts: 335
Joined: Thu Jul 08, 2010 3:19 pm
Location: kortrijk , Belgium

Re: blown driver issues

#10 Post by ketoet » Thu Sep 05, 2019 3:08 pm

My experience is that they always find a way to break your stuff. I just make sure they have to pay if they break something. Also not everyone can rent my bfm system, teenagers get the active behringer stuff. It's more than good enough for their needs.
building BFM speakers isn't a hobby , it's an addiction

1 x THT
1 x autotuba
2 x dr250 melded

2 x wedgehorn 10
2 x tlah

SethRocksYou
Posts: 342
Joined: Thu Sep 10, 2009 8:06 pm
Location: Sacramento, California, USA
Contact:

Re: blown driver issues

#11 Post by SethRocksYou » Sat Sep 07, 2019 2:32 pm

I noticed the Behringer DEQ2496 EQ has password password protection option. I didn't see the option in the DCX2496 crossover, but I wasn't looking for it either. Maybe it's got one???

I have yet to fiddle with the dynamic EQ, but I really like them when they're applied tastefully, giving a seamless boost to the bottom end at low volume. I hadn't considered the option of using it the way mentioned by CO. Creative. I like it!

All in all, it seems to me, protecting the gear is in everyone's best interest. Especially the guy that's renting them. Gotta protect him from himself so the gear makes him look good. A driver is a driver, easy replacement. But the effect blown drivers could have on the event could possibly be more damaging the just a material driver. Reputations and referrals and ego's and pride are at stake.

djtrumptight
Posts: 793
Joined: Tue Dec 15, 2009 6:08 pm
Location: Detroit,Michigan

Re: blown driver issues

#12 Post by djtrumptight » Wed Sep 11, 2019 2:42 pm

My processor is locked,no one can tamper with that and I have a piece of tape at unity gain on my channel faders and master fader on my mixer.The problem with DJ’s is not turning up the main mixer,amps are wide open so nothing to tamper with there but they will turn their DJ mixer up too far without even going in front of the speakers to hear them.
Built:
2 Autotuba's MCM 55 2421
8 T48's 24"wide 3015 LF
2 DR 250's melded Deltalite II 2510
2 DR 250's flat Deltalite II 2510
2 SLA HT systems
1 Table Tuba Dayton DCS 255-4
2 T 39's 20" wide 3012 LF
1 T-18 13" wide MCM 55 2421
2 SLA Pro's

Bruce Weldy
Posts: 6709
Joined: Fri Nov 27, 2009 11:37 am
Location: New Braunfels, TX

Re: blown driver issues

#13 Post by Bruce Weldy » Wed Sep 11, 2019 3:13 pm

djtrumptight wrote:
Wed Sep 11, 2019 2:42 pm
My processor is locked,no one can tamper with that and I have a piece of tape at unity gain on my channel faders and master fader on my mixer.
What's to stop them from just turning up the gain on the channel strip? That's assuming that your board has Gain and a fader. I really don't know what kind of boards DJs use. I'm guessing the DJ has his own mixer and you just bring L and R into two channels of your board? What do you use for a mixer?

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."

SethRocksYou
Posts: 342
Joined: Thu Sep 10, 2009 8:06 pm
Location: Sacramento, California, USA
Contact:

Re: blown driver issues

#14 Post by SethRocksYou » Wed Sep 11, 2019 4:07 pm

djtrumptight wrote:
Wed Sep 11, 2019 2:42 pm
My processor is locked,no one can tamper with that and I have a piece of tape at unity gain on my channel faders and master fader on my mixer.The problem with DJ’s is not turning up the main mixer,amps are wide open so nothing to tamper with there but they will turn their DJ mixer up too far without even going in front of the speakers to hear them.
If your DCX2496 is the last processor in line before your amps, it should catch and limit anything that exceeds the set limiter value. Too hot a signal from any source, input gains too hot, pops and clicks from improper shut down, etc. Which is why I think it's a real good idea to double check that the amp output isn't exceeding your intended limit and output voltage. Something isn't right in the settings for your drivers to look like they do. You mentioned an issue with the DCX... maybe the driver failure is related?

Granted the tops may sound like sh!t if they're run into distortion like you mention. Maybe put a limiter on those too, so they never get into distortion no matter what an un-tech-savy DJ might do... short of clipping the input on the mixer. But your gear should still be safe.

CoronaOperator
Posts: 1603
Joined: Wed Mar 25, 2009 7:07 pm
Location: Medicine Hat, Alberta, Canada

Re: blown driver issues

#15 Post by CoronaOperator » Wed Sep 11, 2019 4:14 pm

djtrumptight wrote:
Wed Sep 11, 2019 2:42 pm
... but they will turn their DJ mixer up too far without even going in front of the speakers to hear them.
That's why you need to align your input gains so that their mixer shows red when your mixer/limiter shows red - both at the same time! That will give them a visual clue. Some dj mixers don't show red until +12 dbu's! (cough cough pioneer). Adjust your input gains accordingly, use pads if you have to.
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

Post Reply