Over powering a bass cab?

[SwamiRob]

http://en.wikipedia.org/wiki/Audio_power

Heh, so much of that it's written in such a sarcastic, snide manner. Pretty funny to read when you know why it's being done, but it's not really up to Wikipedia's "standards"

 

[Way Off Bass]

Headroom is key. I have an AMped PR1832HE and I have run the system with both a Peavy Tmax Bass amp (500w@4) and a Crown XTI1000 (with the tmax preamp). Guess which one sounded like delicious bass and which one farts out at low spl?

 

[rbonner]

I don't think anybody can really control the volume knob. They should all be removed from amplifiers.

Like BILL SAYS, 8 tweleves and you should be safe.

 

[lem8r]

if you have 16 oz of water, are you going to put it in an 8 oz cup? no. so overpowering cabs is not a myth.

yeah, great example

All amps are limited by max output voltage. With the same amplitude(read max output voltage of your amp) of audio signal you never get as much RMS power as pure sine wave delivers. And cabs/amps are always rated for sine wave not audio signal!

 

[René_Julien]

Sorry René but this is incorrect. You can control the volume of the amp but not its output power. A 1000W amp @ 4Ω will always be able to provide 1000W@4Ω no matter where its level controls are. At almost minimum if the input signal is sufficiently high you'll still get that 1000W.

Paul

Really?

Well.. I knew the input signal matters (I put that in my post too.. I also know that it's possible to put even more wattage than the amp is rated, sometimes)...

But I did not know that the input signal can make a very huge different compared to the master control.

If the input signal is high enough (like you suggest), won't that possibly damage components in your amp?

At almost minimum if the input signal is sufficiently high you'll still get that 1000W.

I did not realize that this ^ can happen.
I know the master control is not solely responsiple for what actual wattage is being put out, but I thought input signals were smaller factors than what you tell me.

 

[billfitzmaurice]

But I did not know that the input signal can make a very huge different compared to the master control.

It does. If you cut the amp gain by 1/2 with the master while increasing the amp input by a factor of four the net result is double the output.

If the input signal is high enough (like you suggest), won't that possibly damage components in your amp?

It can, but the levels would have to be very high, like connecting the speaker output of one amp to the input of a second.

 

[JimmyM]

well in the real wold it works more like what you're saying, rene, but paul is right that volume knob position doesn't correlate to wattage. took me a while to wrap my head around that since it's rare that a bass will cause your amp to put out 1000w at lowest volumes, but...

 

[René_Julien]

It does. If you cut the amp gain by 1/2 with the master while increasing the amp input by a factor of four the net result is double the output.

It can, but the levels would have to be very high, like connecting the speaker output of one amp to the input of a second.

Okay.
Thanks for clarifying.

I got to look into the science of that.

well in the real wold it works more like what you're saying, rene, but paul is right that volume knob position doesn't correlate to wattage. took me a while to wrap my head around that since it's rare that a bass will cause your amp to put out 1000w at lowest volumes, but...

I've got to stop living in the real world then.


Yeah.. I see what I did...
It was a foolish statement, Paul is correct calling me out on the wattage/volume issue.

I should have known that. (Since this has been brought to my attention only a few months ago.)



We are talking about extreme theoretical cases? Right?
Or are there other examples where this is a big issue?

 

[lem8r]

...but paul is right that volume knob position doesn't correlate to wattage...

yeah, treble control on my amp didn't really affect high freq too, especially when I cut my highs on bass preamp)

 

[Mark Reccord]

Turning the volume controls on a power amp down effectively reduces the input sensitivity of the amplifier, so that you need more input signal to achieve full power than you would if they were fully up.

And I think what a lot of people miss in this debate is that there's a difference between powering a cab with an amp capable of producing far more than the cab's rated power and actually putting that amount of power into the cabinet on a long term basis.

Believe me, if you have an honest 500W rated cabinet and you actually put 1000W average power into it, you will blow the drivers.