What limits volume and causes clipping?

[4-2-7]

have had the Crowns maxed out volume wise with no problem..I just feel safer keeping it backed off a bit for my speakers sake. I have one Crown running my 250's and one for my 240's. On the 240 amp I have it set at 5/8 of max...my reasoning being the 240's are rated at 300 watts and the 250's are 400 watts. The Crowns are 500 watts each.

Generally the lights on amps like this Crown and McIntosh are showing you they are detecting distortion at a predetermine setting like 0.01%, they are not indicating clipping. The Crown most likely has a circuit like the macs Power Guard. When the input signal to the power amp reaches a distortion setting the lights flash and the power amp does not go past that level, even when you turn the volume up, the power amps dial back the output to hold and not go past that distortion setting.

I know your 250 will handle more than that crown will give them and maybe the 240s as well. McIntosh is known to under rate their amps, heres two pairs of JBLs L250 and 250ti driven with two MC501 mono blocks 500wpc, and a MC402 400wpc. You'll also will see my power amp lights flashing witch means the power guard is activated, nothing is clipping though.

 

[jazzmans]

That! That is along the lines of what I read awhile back and why I dont have the gain controls maxed out...it may have even been in one of your post.

@jazzmans ...This is the only protection the Crowns have listed...it doesnt say if it does anything to correct for clipping..like throttle back.
From the manual...
Protection against short circuits, no-load, on/off muting,
RF interference. Stable into reactive or mismatched loads.
Voltage Gain for it is 33dB

@bowtie427ss ..Thanks..yep I'm working on that.

I dont understand this chart for it either. I get the Line current amps column...but what is the Power in and out columns? So at 1/8 Power @8Ω it has 325 watts going IN to the amp and is putting OUT 62 watts? It is rated at 500 watts per channel @8Ω.
View attachment 1828568


I will have time tomorrow to do some more experimenting so I will get back to you guys on what it actually does with what settings.

What, precisely model of crown amp(s) are you using?

Your posted info on the crown shows no peak limiting protection.

Give us the model number (s) and i'll get back to you

 

[whoaru99]

It really doesn't matter what you call the blinking lights.

If you light'em up it means you're asking the amp to do something it really doesn't want to do (hence why it is alerting you with a flashing indicator). If you light'em up on a regular basis it generally means you don't have enough rig for the gig.

 

[LHorn]

What that chart is telling you is with an 8 ohm, typical music playing, with the volume turned up so the clipping indicators occasionally flicker, the average power output is roughly 62 watts per channel, and the amp is drawing an average of 325W from the wall.

Under that condition the amp is putting out peaks of its rated power or even a bit more and drawing higher peak power from the wall.

Your amp cannot put out 500 watts continuous power with music (that is unless you like a horrific amount of distortion/clipping) because it must have power to cover the peaks that occur in music. This peak to average is typically figured around 1/8 to 1/10 duty cycle, so to speak. Meaning, if you wanted an amp that could actually produce 500W continuous average power playing music, you'd need an amp that is rated 4000-5000 watts per channel.

I see...got it thanks. This is how Crown says they are rated...

How does Crown measure power?
Output power is measured using the "Maximum Average Power" method. The Maximum Average Power test is designed to be an easy way to more closely approximate output power with real world musical sources. The test is simple: the amplifier is set up with the level controls turned to the maximum setting, and then a connected sine wave source is increased until the specified total harmonic distortion is reached.

 

[whoaru99]

Yeah, sine wave continuous average power is a good way to determine the general output of an amp. But, when it comes to reproducing music, the possible continuous/average power is typically much lower due to the need to have unused power on hand to cleanly reproduce peak demands.

The 1/8 to 1/10 ratio is just a good overall factor to use. Some music has even higher peak to average ratio meaning the average level is even less relative to the peak level and some highly compressed music the average level is much closer to the peak level.

 

[LHorn]

Generally the lights on amps like this Crown and McIntosh are showing you they are detecting distortion at a predetermine setting like 0.01%, they are not indicating clipping. The Crown most likely has a circuit like the macs Power Guard. When the input signal to the power amp reaches a distortion setting the lights flash and the power amp does not go past that level, even when you turn the volume up, the power amps dial back the output to hold and not go past that distortion setting.

I know your 250 will handle more than that crown will give them and maybe the 240s as well. McIntosh is known to under rate their amps, heres two pairs of JBLs L250 and 250ti driven with two MC501 mono blocks 500wpc, and a MC402 400wpc. You'll also will see my power amp lights flashing witch means the power guard is activated, nothing is clipping though.

Crown states this about clipping but they dont list the Xli model like I have..so I'm not sure if they have the same function or not.

I have watched those videos before..I would love to hear that in person. Yep...I dont need more power in the sense that they sound great as is....but man one day I would like to be able to see what they can really do.

@jazzmans ..correct..they dont state a peak limiting protection. I have the Xli 2500's.

 

[LHorn]

Yeah, sine wave continuous average power is a good way to determine the general output of an amp. But, when it comes to reproducing music, the possible continuous/average power is typically much lower due to the need to have unused power on hand to cleanly reproduce peak demands.

The 1/8 to 1/10 ratio is just a good overall factor to use. Some music has even higher peak to average ratio meaning the average level is even less relative to the peak level and some highly compressed music the average level is much closer to the peak level.

So a recording with a lot of dynamic range would really come into play here right?

 

[whoaru99]

So a recording with a lot of dynamic range would really come into play here right?

Sure.

The higher the dynamic range of the recording (dynamic range in this case meaning higher peak to average ratio) the lower average power the amp can achieve without clipping.

But, it's easy to get sideways and analytical about all that.

In the end it is exceeding simple. If the clipping indicators or whatever are flashing it means the amp has reached the point of what it is generally intended to do. If they flash more than occasionally it is a general order to turn it down a bit from an amplification standpoint (edit: or get a more powerful amp).

 

[LHorn]

If you crank the preamp to the point it is distorting, it is most likely distortion resulting from clipping.


Here is what you do....

Turn the level controls on the Crown amp (presuming there are level controls, down far enough that you're not blowing out the windows or your ears when you crank up the pre amp volume.

Now play your loudest source and start turning up the preamp volume until you hear distortion or doesn't sound right. Turn down the levels on the Crown amp if you need to. You're not trying to see how loud it gets, you're trying to find the maximum "clean" point of the preamp volume.

Once you find that max clean point, back off a little so you have some cushion.

Once you have that point set, now turn up the level controls on the Crown to make it the about as loud, or a bit more, than you'd normally ever go.

Once there...

Do the amp clipping lights never flash and it's not loud enough...but levels on the amp turned high as they go? If so, probably want to go to the 0.775 setting on the amp and repeat all the above from scratch.

Do the amp clipping lights flash occasionally? No big deal.

Do the amp clipping lights flash regularly? If so, you need a bigger amp or more sensitive speakers or to settle for a little lower volume.

Once you have that all dialed then then just go back to running the volume as you normally did...except now you know that you don't necessarily have to stop at 10-11. You understand now the max clean point of the preamp and you have scaled net gain of the power amp to accommodate that volume control range.

OK...so on the 1.4v setting I turned the gain on the amp back to 1/4 of its range...slowly cranked up the R-117 until it was almost at 3 position...no clipping and sounded fine but I didnt want to take it any further than that. I backed the 117 off to 12 and started raising the gain on the amp and no clip lights all the way to max gain. Cranked up the 117 to almost to 2 or so before the clip lights started flickering slightly only on heavy bass. So I know I'm good to 2 with the 250's. I did the same thing with the 240's amp and pretty much the same thing..but I did back the amp off a couple notches because I run both pairs together at times. At least now I'm not sweating it if I am cranking around the 12 position on the 117...the preamp stress was my main concern...but normally between 10-11 is all I need anyway. Its also more in line of the way it was when using the 117's amp itself. The speakers never broke a sweat either...so one day maybe I can afford to feed them what they want.

Thanks again for your help and advice.