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How Far Can I Turn it Up? |
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jacethebase 
Old Croc 
Joined: 23 September 2009 Location: Somerset Status: Offline Points: 5699 |
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 Posted: 28 December 2009 at 4:19pm |
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You got it chap ;)
You never want your amp hitting clip levels!!!!!! Maybe free party boys work this way but if you go to a event being run by a pro audio company you will find amps sitting around -6db ish.
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Steevo
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Joined: 21 December 2009 Location: Glos. Status: Offline Points: 58 |
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Posted: 28 December 2009 at 4:25pm |
Is it standard practice to have that much headroom on an amp that has clip limiters enabled?
Was considering running some 4ohm 500w RMS Peavey subs using a Numark Dimension 4 amp which puts out "660W RMS @ 4 Ohms, 1KHz, 1% THD per channel (stereo)" - is this a stupid thing to do? |
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jacethebase
Old Croc
Joined: 23 September 2009 Location: Somerset Status: Offline Points: 5699 |
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Posted: 28 December 2009 at 4:31pm |
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Yeh for instance if i phoned up one of the companys i get a gear from and asked for 20k of funktion on site i would get 20k of stacks and around 30k of racks turn up.
No thats not stupid its the right thing to do! A cool amp is a happy amp! Also always bare in mind when your quoting what k your system is, your system is only as powerfull as the amps pushing the power in to the speaker units.
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Steevo
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Joined: 21 December 2009 Location: Glos. Status: Offline Points: 58 |
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Posted: 28 December 2009 at 4:50pm |
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Now I feel even more confused.....
Earlier you were saying you would only run max 600w from an amp that had a 1000w capacity. (i.e. only using 60% of amps power.
My example of my Peavey subs, uses 75% of the amp's power - should I be aiming to use an amp with even more headroom? i.e. 850w amp (which would thus put me at 58% utilisation). As for quoting the power of the setup - I always work it out based on the RMS total of my speakers, and ignore what the amps are putting out. I've always been taught to have a bigger amp than speakers so counting my speakers RMS gives me the max I could put out. Only trouble (hence my interest in this thread) is that I'm unsure how far up I can turn the amp. I've never pushed it too far for fear of doing damage, thus I don't know what "too much" sounds like if that makes sense.
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jacethebase
Old Croc
Joined: 23 September 2009 Location: Somerset Status: Offline Points: 5699 |
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Posted: 28 December 2009 at 5:10pm |
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You will chap trust your ears!
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Jasonstry
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Joined: 11 September 2007 Location: Cannock. J11 M6 Status: Offline Points: 1367 |
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Posted: 29 December 2009 at 10:34am |
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Steveo, most drivers or speaker cabs will have 3 power ratings. RMS, constant and peak. In general, the RMS value is the power the driver will take as a continuous sine wave in the middle of its range. Drivers hate sine waves but normal music is not a sine wave so the driver can handle more watts on average when asked to reproduce music. This is the constant rating of the driver or box. Even then, the driver can handle even higher power levels provided it is not asked to for any great length of time, think the initial impact of a kick drum. A typical arrangement would be for a driver to have an RMS handling capacity of 'x' Watts, a constant handling capaicty of 2x watts and a peak handling capacity of 4x Watts. So if you have a cab with a handling capacity of say 500W RMS, it will have a constant handling capacity of 1000W and a peak handling capacity of 2000W.
So it is quite in order to have a 1000W RMS amplifier driving a 500W RMS cab although you really need to check the specs on your cabs before you try it.
There are things that can affect the handling capacity of the speakers. Modern music tends to be quite compressed to start with and this tends to increase the average level asking more of the speakers, especially if it includes distorted sounds or electronic music which often consists of sine waves. Clipping anywhere in the system adds distortion making the system sound nasty but also increases the average level again, making the drivers work still harder, as well as adding high frequency subharmonics that can blow tweeters. However the biggest offence is driving your amplifier into clipping as, if you do, it will effectively deliver a square wave signal at about twice its rated output, which can kill drivers very quickly.
You have 3 priorities then. Your amplifiers must not be allowed to deliver more power than your drivers can handle, your amplifiers should NEVER be allowed to clip more than the very occasional flicker of the warning led and you should not allow clipping anywhere in your system. There are some links earlier in this thread about setting up a proper gain structure and other posts about setting limiters. One thing to remember is that the "gain" control on your amplifier does not control how many Watts it delivers, it controls how powerful the input signal has to be in order for the amplifer to deliver its maximum output.
Hope that helps.
Andy
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Dislexic
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Joined: 21 November 2007 Location: United Kingdom Status: Offline Points: 815 |
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Posted: 29 December 2009 at 1:45pm |
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I only run with aproximatly anywhere typically 50% headroom on my amps....
Say for example I have a 1k box, I will run with min of 1200w amp, shove pink through the box and wait for the amp to clip, then set a compressor or the DSP limiter to cick in just before the amp say 1.5-3bd lower so the amp never clips... then I'm happy to run all night long. I know I will be driving the system with more than the speakers rated power, however (didnt read all the posts ;)) Headroom is their to absorb the peaks without compromising the clarity of your system and most any decent driver will happily absorb thumps n pop's and loud DJ's randomly throughout the evening. 1000W continuose RMS of pumping bass is not going to kill an 800w speaker as it will never see 1000w unless you clip all night long and basically throw flat lines at it(typicaly from an under powered amp or distorted program material). I always think back to the AC/DC heating effect of resistors when looking at components like speakers, it takes a lot less voltage cliped to blow a driver than some people realise, hence why an oversized amp is 99% of the time better :) you always have to take the program material into consideration. a voice coil will heat up when overworked, no doubt their, however what you have to remember is that those big "none compressed or limited" spikes normaly wont do any damage, the heating effect on the driver is tiny since its only over a brief moment in time this off course is untill you have this happening continually over an excesive period of time. The main factor is not allowing the driver to heat up so much that it distorts outof shape or expands past its airgap.
Right gear right job = no problems (except when somthing breaks lol)
Most of my work is live bands, and I will happy do anything from a 4-10 hour show with amps twice the size of my cabs with no limiters or distortion.... ohh and I have only had 1 driver fail on me in 17 years and that was not blow just fatigue of the suspension due to age :)
I think what we really have to remember with volume is the continuouse and peak SPL, start measuring that and you will know how far you can turn it up, thats after you have the right kit for the job ;-)
My 2p today off to get my hard hat....
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Jasonstry
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Joined: 11 September 2007 Location: Cannock. J11 M6 Status: Offline Points: 1367 |
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Posted: 29 December 2009 at 4:40pm |
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Dislexic, you and I seem to do similar things (live bands) and I agree with almost everything you say. The difference is that I ALWAYS use a brickwall limiter at -1 dB on all outputs from the (digital) desk I use. Like you, I have only lost one driver but in my case it was because a "helper" dropped a live mic during set up..... So, after that, the limiter has always been on-line.
For me, once the desk is sorted, it is a matter of correcting the gain structure to take account of eq changes for the venue and then setting the amplifiers so that either 1) I have the desired SPLs in the desired areas or 2) one or more is clipping. As soon as I have an amplifier even remotely clipping then that is the maximum SPL of the system established. If that is not enough then I haven't brought enough rig for the gig.
Andy
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Dislexic
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Joined: 21 November 2007 Location: United Kingdom Status: Offline Points: 815 |
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Posted: 30 December 2009 at 10:07am |
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Great minds ehh ;) and I will do the or foools bit b4 anyone else does ;P I use LS9 & TT24, still got a couple of older SC's but they gathering dust now >;) I never liked bricks because if they are set below the amps clip then some muppet will no doubt turn the rig up till it redlines all the time sounds crap & loud because of it and then pop pop pop by the end of the night or scratch scratch when your out next, but thats just my pref :) I do agree with other coments that you CAN hear when your rig is maxing out as the sound does change, the trick is to recognise it but being honest I never normaly get that far these days... I must be getting old :(Dont think anyone mentioned the "midband" most limiters actualy use either hence why I'm never overly worried if me or those I trust are out with the gear. Also to put a cat into the woods.... what about volume vs clarity.... if your rig sounds sweet next to another rig thats identical but sounds crap.... in 9 of of 10 cases which rig will sound loudest.....
One of my grudgest against (no offence to anyone intended ok!) people who have badly setup rigs. their rig sounds louder because its distorted in variouse places making it less tolerent to listen to and theirfor perseved to be louder, when infact it just sounds crap lol
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jacethebase wrote: