Members flip333 Posted March 28, 2005 Members Share Posted March 28, 2005 Hi: I just read the post where Audioeast recommended a limiter. Limiters are new to me.... I did not want to hijack the other thread. I have been running my speakers at program power because that is what I have been taught. I would like to protect them... Would a limiter be recommended to protect my speakers in this configuration: PV 2600 running two Yamaha clubs (each speaker gets 540W)and a PLX 3402 running four Peavey 115X subs (each sub gets 550W. The Yamaha club IV's are rated of course at 500W program and the subs are rated at 600W program Thanks, flip Link to comment Share on other sites More sharing options...
Members agedhorse Posted March 28, 2005 Members Share Posted March 28, 2005 Yes a limiter can help, but beware that driving hard into limit will also increase the average thermal power the speaker sees beyond the program power rating. It's just not quite as mechanically abrubt at clipping, and better control is maintained on the driver mechanically. Just as important is to be sure the 50Hz high pass filter is engaged on the 3402 for your subs. You are running in stereo and not bridged mode right... Link to comment Share on other sites More sharing options...
Members Harmonycat Posted March 29, 2005 Members Share Posted March 29, 2005 If what you say regarding ratings of those speakers consider the following. If the Yamaha Clubs are rated 500 watts program and therefore 1000 watts peak, then the -6db rating equivalent to the actual RS-426A rating is 250 rms continuous. If you check any thread here regarding recommended amplifier power you will commonly see 1.5 times the rms continuous rating as the given. (250 rms X 1.5 = 375 rms). The amplifier power you are discussing is in excess of twice the rms continous rating. ( 250 rms x 2 = 500 rms). You will also note in other threads that running at twice the actual rms rating which only leaves 3 db of room for transient peaks is a risky business that should only be undertaken by those with a great deal of experience. Bear in mind that allowance for 6 db peaks does not consider extreme dynamics often associated with certain source material, and even at only 250 watts input, you may be clipping or limiting. The use of a limiter will buy you some protection, but it ain't the be all and end all......except maybe to shorten the life of your speakers through careless reliance on such a device. Thermal stress is thermal stress no matter whether clippng occurs or not. I just would not run your Yammie Clubs at more than 375 watts rms even with a limiter/compressor. At 540....Buddy....you are pushing them. If you need more volume.....add speakers. BTW: this really applies to your subs too.... Link to comment Share on other sites More sharing options...
Members flip333 Posted March 29, 2005 Author Members Share Posted March 29, 2005 Thanks for your input guys. I am not running the subs in bridged mode. The 50hz filter in engaged. They are doing "pretty" nice in stereo (more on that in a new thread). Last year I ran the subs on the PV2600 for many gigs thinking the 40hz filter was on.... DUH! It was not on! When I did put it on .... the performance improved. The speaker no longer had to flap around trying to reproduce frequencies it could not do. I once read a post elsewhere in which someone said they could dial in a value on a limiter and calculate a power rating delivered to the speakers.... hmmm.... Thanks, flip (learning all the time) Link to comment Share on other sites More sharing options...
Members dboomer Posted March 29, 2005 Members Share Posted March 29, 2005 Originally posted by flip333 I once read a post elsewhere in which someone said they could dial in a value on a limiter and calculate a power rating delivered to the speakers.... hmmm.... It's easy enough to do in theory. You need to know the input impedance of your amp and the sensitivity of your amp. You dial up the limiter to come on and limit the drive voltage to whatever is needed to drive your amp to so many watts of output. The problem with predictive limiting comes when everything changes. If your speaker load impedance changes (an 8 ohm speaker is really only 8 ohms at a few frequencies and is constantly changing with frequency) and the power from the wall changes Link to comment Share on other sites More sharing options...
Members boseengineer Posted March 29, 2005 Members Share Posted March 29, 2005 Actually its very hard to calculate, even in theory unless you play only sine waves. A limiter is really handy (if properly dialed in) because all real world material is not that handy-dandy test signal that many engineers (including yours truly) like to use on the bench. Most amplifiers and speakers are mostly amplitude (and not power) limited. Since the maximum voltage for amp/speaker are fixed, the amount of actual power you are getting depends on the "peakyness" of the input signal. The mathematical term for this is "Crest factor" and is defined as the ratio of peak value to rms value. Sine waves have a crest fractor of 1.414 (3dB). Pink noise has a crest factor of about 4 (12 dB) and most music material is considereably higher still. In practice you'll rarely get more than a 3rd of the rated power even if everything is optimally tuned and you compress the living daylights out fo your signal. A limiter detetects when the peaks in the signal are too high and reduces those more or less gracefully. So it reduces the crest factor and allows for more power at a slight loss of sound quality. It also protects your whole setup as it avoids hard clipping. The catch is, that you need to tune it very carefully to the clip levels of the amp, the speaker and the voltage gain of the amp. Link to comment Share on other sites More sharing options...
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