Can you guys help me figure this out?
I have an old reliable QSC RMX 1450 AMP that I use to use for DJing parties . It use to crank these 2 two-way 15" woofer and a horn tweeter cabs.
The other day I adopted these 2 high-end 6" bookshelf speakers. I hooked up the QSC amp and I could easily push them to 9/10 volume levels with no problem. I was scratching my head. This amp puts out 250W@ 8 ohms STEREO and 450W@ 4 ohms STEREO. I use to drive those 15"s at 7/10 or maybe 8/10. So I figured ok..ok.. those high end monitors must have a weird large impedance x-over or some weird high current amp necessity thing.
So today I get a pair of brand new POLK Audio db521 coaxial car speakers. They are 5.25 inches and are rated 45W RMS 100W MAX 4 OHMS and 93 db. I hook them up to the QSC amp and they are asking for some at 8/10 volume. What ?!?! @ 450 WATTS !!!
What is up? Is my amp messed up? It sounds fine, looks fine, I know how to hook up this stuff. I am confused.
Thanks,
JV
I have an old reliable QSC RMX 1450 AMP that I use to use for DJing parties . It use to crank these 2 two-way 15" woofer and a horn tweeter cabs.
The other day I adopted these 2 high-end 6" bookshelf speakers. I hooked up the QSC amp and I could easily push them to 9/10 volume levels with no problem. I was scratching my head. This amp puts out 250W@ 8 ohms STEREO and 450W@ 4 ohms STEREO. I use to drive those 15"s at 7/10 or maybe 8/10. So I figured ok..ok.. those high end monitors must have a weird large impedance x-over or some weird high current amp necessity thing.
So today I get a pair of brand new POLK Audio db521 coaxial car speakers. They are 5.25 inches and are rated 45W RMS 100W MAX 4 OHMS and 93 db. I hook them up to the QSC amp and they are asking for some at 8/10 volume. What ?!?! @ 450 WATTS !!!
What is up? Is my amp messed up? It sounds fine, looks fine, I know how to hook up this stuff. I am confused.
Thanks,
JV
Ran it for a whole song with the car speakers. Amp never even got hot. Plus the amp use to get hot with the big DJ speakers. Now with the bookshelfs for hours or the car audio it is blowing cold air.
Is there an easy way for me to test the output watts?
I read some FAQ online and tried it. It only went up to 8 volts. Iused a test tone sweep of Youtube. I know.. i know. high tech stuff.
Is there an easy way for me to test the output watts?
I read some FAQ online and tried it. It only went up to 8 volts. Iused a test tone sweep of Youtube. I know.. i know. high tech stuff.
JV,
You might want to start with your source. Amps require certain input voltage to attain full power. For example, if your amp requires 1V input for full power output and your source only provides 200mV, then your amp is only doing 1/5 power.
A quick check with your manuals maybe helpful on this case without getting any tools.
Ps: if you are getting only 8V @ 8ohms, then your speaker is only dissipating at 8W.
You might want to start with your source. Amps require certain input voltage to attain full power. For example, if your amp requires 1V input for full power output and your source only provides 200mV, then your amp is only doing 1/5 power.
A quick check with your manuals maybe helpful on this case without getting any tools.
Ps: if you are getting only 8V @ 8ohms, then your speaker is only dissipating at 8W.
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Nope. Not even close. 1/5 the Voltage reduces the power to 1/25. Remember power is E²/R.
G²
Unless your clip lights are flashing wildly, the amp will be putting out less than 10% rated power on average. An amp rated at "400 watts RMS" is really only good for 400 watts peak, unless you want every cycle of a constantly-changing waveform to be clipped. If you did push that amp to full power continuously, it would get blazing hot within a few minutes, the speakers would be toast, and before that, the distortion would be so bad you can't tell what song is playing. And you'll probably trip your 20 amp mains breaker.
I think this has been covered but to recap don't pay any attention to where the input control is set. If its set a say a 9 it doesn't necessarily mean the amplifier is putting out almost full power. It all depends on the signal being fed into the amplifier. More signal = more power at the same number setting.
Fixed an amplifier for a guy once and his comment to me was I only had it set a 5 on the input control. Well a source like the 1812 overture with cannon blasts being fed into a preamp that was turned up 3/4 or more output was enough to do the deed. Like I said I fixed the amp checked it out let it run on a load and pronounced it good. The guy took it home and did the same thing.
I repaired it again explained the situation to him once more and the amp still lives yet today.
A small speaker will and usually survives when being fed by a large amplifier as long as the person doesn't do something stupid like asking the speaker to put out extra low end or drive to very loud levels. I am of the opinion that most speaker specifications are 100% bs. I look for spec that rates the speaker with pink noise at a specific wattage. Example is a pair of Altec model 9 speakers rated at 60 watts pink noise. The same speaker are rated for amplifiers I believe in the 30-250 watt range. Took out a low freq and a midrange in my younger years by driving the speakers with a 60 watt amplifier. They have had 400 watts per channel on them since without problems.
Fixed an amplifier for a guy once and his comment to me was I only had it set a 5 on the input control. Well a source like the 1812 overture with cannon blasts being fed into a preamp that was turned up 3/4 or more output was enough to do the deed. Like I said I fixed the amp checked it out let it run on a load and pronounced it good. The guy took it home and did the same thing.
I repaired it again explained the situation to him once more and the amp still lives yet today.
A small speaker will and usually survives when being fed by a large amplifier as long as the person doesn't do something stupid like asking the speaker to put out extra low end or drive to very loud levels. I am of the opinion that most speaker specifications are 100% bs. I look for spec that rates the speaker with pink noise at a specific wattage. Example is a pair of Altec model 9 speakers rated at 60 watts pink noise. The same speaker are rated for amplifiers I believe in the 30-250 watt range. Took out a low freq and a midrange in my younger years by driving the speakers with a 60 watt amplifier. They have had 400 watts per channel on them since without problems.
I'm going to suggest an alternative approach to determining if amplifiers and speakers are compatible.
This comes from the realisation that music has a high peak to average voltage level in the signals we normally listen to.
Depending on the type of music and the type of source equipment then the Peak to Average ratio (dBpk/av) varies significantly.
Some music has a low 10dB ratio, more dynamic music can approach 20db ratio and in extreme conditions (probably recording Live Music) get up to around 30dB ratio. These are peak to average ratios, not peak to minimum signal ratios.
Using these figures for peak to average ratios, with a 400W amplifier and trying to listen without clipping any of the signal.
The 400W amp using 10dBpk/av music putting out 40W will never clip.
A 45W speaker with 40W average level will not remain undamaged for very long.
If the music is more dynamic (or not) but the operator sets the system gains such that the average music level fed to the speakers is 20dB below maximum then the average level will be 4W and no clipped signal will ever be sent to the 45W speakers. The speakers are likely to live for a long time and the music, depending on sensitivity of the speakers and the listening environment could be termed "quite loud".
If one were to adopt the extreme case of trying to reproduce music with 30dBpk/av without ever clipping any signal then the average level from the 400W amplifier is 400mW.
A 45W speaker will last a lifetime without damage due to overdriving.
In summary, it relies on the operator being sensible. Parties never have 100% sensible operators!!!!
This comes from the realisation that music has a high peak to average voltage level in the signals we normally listen to.
Depending on the type of music and the type of source equipment then the Peak to Average ratio (dBpk/av) varies significantly.
Some music has a low 10dB ratio, more dynamic music can approach 20db ratio and in extreme conditions (probably recording Live Music) get up to around 30dB ratio. These are peak to average ratios, not peak to minimum signal ratios.
Using these figures for peak to average ratios, with a 400W amplifier and trying to listen without clipping any of the signal.
The 400W amp using 10dBpk/av music putting out 40W will never clip.
A 45W speaker with 40W average level will not remain undamaged for very long.
If the music is more dynamic (or not) but the operator sets the system gains such that the average music level fed to the speakers is 20dB below maximum then the average level will be 4W and no clipped signal will ever be sent to the 45W speakers. The speakers are likely to live for a long time and the music, depending on sensitivity of the speakers and the listening environment could be termed "quite loud".
If one were to adopt the extreme case of trying to reproduce music with 30dBpk/av without ever clipping any signal then the average level from the 400W amplifier is 400mW.
A 45W speaker will last a lifetime without damage due to overdriving.
In summary, it relies on the operator being sensible. Parties never have 100% sensible operators!!!!
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