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[Chris Hindle]

In the perfect world, positive DC bias on a driver would produce a gentle and constant cool breeze out of the front of the speaker...

ahhhh. No.
Positive DC bias would move, and hold the driver xxx thousands of an inch off rest position. No breeze, no cooling.
Chris.

[Lyle Williams]

ahhhh. No.
Positive DC bias would move, and hold the driver xxx thousands of an inch off rest position. No breeze, no cooling.
Chris.

...it was a joke.   :-)

If you put a lot of positive DC bias on then you could plug a vacuum cleaner hose into one of the speaker ports and clean up after the gig.  :-)

[Jonathan Johnson]

If you put a lot of positive DC bias on ...

Hey, no politics!

Oh, you weren't talking about the bias in that DC?

[Steve M Smith]

If you put a lot of positive DC bias on then you could plug a vacuum cleaner hose into one of the speaker ports and clean up after the gig.

You would need an AC signal and a one way valve!


Steve.

[Mike Monte]

I know you're being tongue-in-cheek, but yes, there are professional DJs. The GOOD ones know about levels and clipping and what-have-you, as they care more about making it sound good then just being freaking loud. I've worked with quite a few, both on the local (smaller corporate/etc event) level as well as the larger festival circuit. (Of course, I've also seen my share of 'amatuer' DJs, about whom this topic is being discussed in the first place!)

-Ray

"Professional" means being paid for a service IMO.  I provide the rig for one of the most successful DJ's in my area's NYE gig.  He is a nice guy but does like to make things loud.  I also subcontract him to provide tunes for a local "Relay for Life" event in the Summer.....He does a good job...but he likes it loud.

This past June he could not make the Relay gig and I had another DJ fill in for him.  My rig filled the whole football field with music as I told the sub-DJ to keep his mixer's output in the green (a non-clipped signal) which allowed me to boost his signal in the mix.  It was night and day having a "non-clipped signal" to work with as I usually have to severely limit a clipped signal.

I told the original DJ about the recent Relay gig and I could tell that he didn't believe me...  Oh well, if I do the upcoming NYE gig with him I will (as usual - lol) bring my compressors.

A note:  Last year's NYE (by the end of the night) I had the gain on the DJ's channel turned totally down.  His signal still clipped the channel on my mixer but I had him severely limited using the (top) limiter on my DBX2231.  (The LED's on the DBX's limiter were lit up like a xmass tree.).  BTW I had the top limiter's output fed directly to the bottom limiter just in case I needed more.

I have been working with this DJ for the past several years....  Things will never change as he "knows better"....'cause he's a successful DJ (I guess).   

He does, however, pay me well.

Mike M 

[Lionel Croom]

This is a fascinating debate.

I've replaced my share of baskets and horn drivers in the past.  Mostly due to not compressing the Kick or not being able to stop the lead vocalist before walking 1 foot in front of a horn.   I know a little about the mechanics of speakers as I started out studying electrical engineering before switching my degree to software engineering some 26 years ago.

In every case while inspecting the coil it was a burn mark that put the coil to rest.  A simple test is a VOM set to continuity on the speaker connectors.   I guess from an electrical point of view I agree that it's heat that finally cooks the copper in the coil winding.  However, a wave or continuous frequency for a very long time which exceeds a certain voltage will achieve the same "oh crap" moment. 

If we get into the physics of it copper. Copper absorbs heat very well while aluminum does not.   Its the glue holding the copper in place that can melt and cause the coil to rub against the magnetic driver.  Usually you start hearing that in a sub woofer when the kick drum is actuating the coil.  The ole tell tale sign that you are about to spend money.

I'm starting to ramble, but I can sympathize with both arguments.  No speaker will like a constant frequency for a long time at the upper 10 percent of its voltage limit.  In my opinion the cause is too much of something which creates enough heat to change the physical state of the coil.  Good sound engineers avoid this because they are good at separating EQ frequencies between vocals, bass, guitar, and drums.  If your mix is pounding the crap out of the same frequencies for all instruments and vocals your probably heating up your speakers aside from damaging peoples hearing.  Bad sound, more heat, no sound. 

-Lionel 

[Guy Morris]

"Professional" means being paid for a service IMO.  I provide the rig for one of the most successful DJ's in my area's NYE gig.  He is a nice guy but does like to make things loud.  I also subcontract him to provide tunes for a local "Relay for Life" event in the Summer.....He does a good job...but he likes it loud.

This past June he could not make the Relay gig and I had another DJ fill in for him.  My rig filled the whole football field with music as I told the sub-DJ to keep his mixer's output in the green (a non-clipped signal) which allowed me to boost his signal in the mix.  It was night and day having a "non-clipped signal" to work with as I usually have to severely limit a clipped signal.



I told the original DJ about the recent Relay gig and I could tell that he didn't believe me...  Oh well, if I do the upcoming NYE gig with him I will (as usual - lol) bring my compressors.

A note:  Last year's NYE (by the end of the night) I had the gain on the DJ's channel turned totally down.  His signal still clipped the channel on my mixer but I had him severely limited using the (top) limiter on my DBX2231.  (The LED's on the DBX's limiter were lit up like a xmass tree.).  BTW I had the top limiter's output fed directly to the bottom limiter just in case I needed more.

I have been working with this DJ for the past several years....  Things will never change as he "knows better"....'cause he's a successful DJ (I guess).   

He does, however, pay me well.

Mike M

Leaving the technical brick wall solutions to one side there are a couple of other things that can be tried.  Unfortunately sound companies/techs have an inbuilt loathing of DJ's automatically assuming they will redline everything (and sadly that can be the case) BUT it is worth giving the DJ the opportunity to prove his technical ability to produce good levels and if not then out comes the brickwall protection and dirty looks!

Firstly: Provide the DJ with good monitoring we all do it for musicians and other performers and he is no different just another type. A 12" or even 15" on a pole or floor position does not really cut it, he needs to feel bass and get an impression of what the crowd is hearing, in all the times I have provided a loud (if they want to turn it up) stereo booth mix with solid LF the DJ level has been good as they do not feel the need to try and compensate for what they cannot hear out front (think vocalist trying to use FOH to hear because the monitor is not loud enough  they may pitch wrong and try to sing louder (mic up closer). This does not mean a huge set up (although the Funktion one DJ monitors are awsome) I either use an HK Nano 600 two small pole mount tops at ear level and a 10" sub  if it is nearfield or a Martin W2/W2S  set up (bigger events) rarely do any of the DJ's turn it up to max as they either use it to fill the gap between them and the mains and mix on headphones or as a mix reference to the headphone cue and the positive comments coming back from them proves the point.

Secondly: Sound guys before even meeting the DJ have locked down the channel with over the top compression and often route the DJ booth through the desk to control that with even more compression on the mix out! This is akin to placing heavy compression on an IEM mix, vocalists hate it because rather than smoothing the vocal they simply cannot judge their voice properly and for a DJ trying to mix where the dynamic range has been squashed it is the same
effect.(if the beat does not 'kick in' on a mix what will they do ..turn up the bass)

I would say if your PA is loud and the monitors likewise the DJ is more likely to get the vibe and just mix his set rather than trying to overcome what has been put in his way. So many sound guys become elitist in their attitudes and just assume the worst from the outset,if that does happen then of course manage it but do not instigate it from the start.

There are many reasons why certain DJ's ruin it for others and I have seen it, Too much red wine,Ego,Ignorance,Misunderstanding... yes blame that on manufactures who always show their products with lights all in the red even Yamaha digital desks brochures have it! No wonder you get told by DJ's red is where it is supposed to be!

I usually deal with DJ's just like I would with guitarists who will always turn it up to a level that is not acceptable once set up, a polite attitude to what is better usually sorts it and that result is gained by giving the guitarist more of him in his monitor and less from his backline
once he likes the balance the problem is gone.

Of course if non of that advice works, turn him down or take him around the back....for a chat :-)

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