or Connect
AVS › AVS Forum › Audio › Speakers › Less Power Mr Scott?!
New Posts  All Forums:Forum Nav:

Less Power Mr Scott?!

post #1 of 17
Thread Starter 
Am I being a fool trying to pair up Monitor 9 series 7 with a. McIntosh mc2300 amp 300/300W, McIntosh C32 preamp? Are my 9s going to blow the minute I switch on the McIntosh system?!!
post #2 of 17
Only if you turn the volume up to ear-bleeding levels. The amp will only put out what you tell it to. Whether it is rated at 10 watts or 1000 watts, the preamp controls the amount of power going to the speakers.
post #3 of 17
Quote:
Originally Posted by chrgri217 View Post

Am I being a fool trying to pair up Monitor 9 series 7 with a. McIntosh mc2300 amp 300/300W, McIntosh C32 preamp? Are my 9s going to blow the minute I switch on the McIntosh system?!!
Are you instantly going to go 140MPH the moment you turn the key if your car has a 500HP motor? Not if you don't put the pedal to the metal. cool.gif
post #4 of 17
Quote:
Originally Posted by Bill Fitzmaurice View Post

Are you instantly going to go 140MPH the moment you turn the key if your car has a 500HP motor? Not if you don't put the pedal to the metal. cool.gif

Well where's the fun in that???
post #5 of 17
Thread Starter 
Quote:
Originally Posted by Bill Fitzmaurice View Post

Are you instantly going to go 140MPH the moment you turn the key if your car has a 500HP motor? Not if you don't put the pedal to the metal. cool.gif
j

Thanks for the reply. That's kind of what I figured, it's all in the gain controls. But with a new $1200 investment in these Monitor 9s I wanted to be sure. I wonder if I'll be able to hear the difference between driving them with my Onkyo 809 vs. the McIntosh amp. Not sure if I have a golden ear. LOL.
post #6 of 17
Thread Starter 
Quote:
Originally Posted by Bill Fitzmaurice View Post

Are you instantly going to go 140MPH the moment you turn the key if your car has a 500HP motor? Not if you don't put the pedal to the metal. cool.gif

Well actually my car does have a 500 HP motor and it'll do 140 easy LOL!! But you're right it's not instant, obviously I need a pulley swap yet and some nitrous. Thanks for your reply.
post #7 of 17
Quote:
Originally Posted by chrgri217 View Post

I wonder if I'll be able to hear the difference between driving them with my Onkyo 809 vs. the McIntosh amp.
Maybe, maybe not. The advantage to having plenty of power on tap is that the amp never strains. AVRs will, mainly because they're almost never able to actually deliver their rated output power. If you want to know how much power you can realistically get, look at the spec sheet for the power draw, multiply that by 1/2. If you see an AVR rated for 100wpc x 5 but the draw is only 400 watts the smell of rat should be pervasive. cool.gif
post #8 of 17
Quote:
Originally Posted by Bill Fitzmaurice View Post

If you see an AVR rated for 100wpc x 5 but the draw is only 400 watts the smell of rat should be pervasive. cool.gif
That's just wrong. Power ratings on the back of amplifiers are not an all channels driven at max, but an average at 1/8 power because that is the most likely draw from the supply in use.
post #9 of 17
The mentioned Onkyo NR809 claims 160wpc x 7, for a total of 1120w. It's current draw is 7.5a at 120v, which is 900w. I guess it has 125% efficiency? eek.gif
With 70% efficiency, and that's being generous as it burns 95w at idle, it can only put out 630w. Yes, each channel can put out 160w individually, but not all simultaneously. If you look closely at the manual you'll find it can only deliver 160wpc with two channels driven.
post #10 of 17
Quote:
Originally Posted by Bill Fitzmaurice View Post

The mentioned Onkyo NR809 claims 160wpc x 7, for a total of 1120w. It's current draw is 7.5a at 120v, which is 900w. I guess it has 125% efficiency? eek.gif
With 70% efficiency, and that's being generous as it burns 95w at idle, it can only put out 630w. Yes, each channel can put out 160w individually, but not all simultaneously. If you look closely at the manual you'll find it can only deliver 160wpc with two channels driven.

ummm.....135 W/Ch, 8 ohms, 20 Hz20 kHz, 0.08, 2 channels driven, FTC

source
post #11 of 17
Quote:
Originally Posted by Bill Fitzmaurice View Post

The mentioned Onkyo NR809 claims 160wpc x 7, for a total of 1120w. It's current draw is 7.5a at 120v, which is 900w. I guess it has 125% efficiency? eek.gif
With 70% efficiency, and that's being generous as it burns 95w at idle, it can only put out 630w. Yes, each channel can put out 160w individually, but not all simultaneously. If you look closely at the manual you'll find it can only deliver 160wpc with two channels driven.

Quote:
Originally Posted by 67jason View Post

ummm.....135 W/Ch, 8 ohms, 20 Hz20 kHz, 0.08, 2 channels driven, FTC

source

Yeah, 160w for a 6ohm load, 135w/8ohm as Jason shows, butchyou know, 300w for a 3ohm load with 1ch driven biggrin.gif
post #12 of 17
Quote:
Originally Posted by Geoff4RFC View Post

Quote:
Originally Posted by Bill Fitzmaurice View Post

The mentioned Onkyo NR809 claims 160wpc x 7, for a total of 1120w. It's current draw is 7.5a at 120v, which is 900w. I guess it has 125% efficiency? eek.gif
With 70% efficiency, and that's being generous as it burns 95w at idle, it can only put out 630w. Yes, each channel can put out 160w individually, but not all simultaneously. If you look closely at the manual you'll find it can only deliver 160wpc with two channels driven.

Quote:
Originally Posted by 67jason View Post

ummm.....135 W/Ch, 8 ohms, 20 Hz20 kHz, 0.08, 2 channels driven, FTC

source

Yeah, 160w for a 6ohm load, 135w/8ohm as Jason shows, butchyou know, 300w for a 3ohm load with 1ch driven biggrin.gif

i didn't catch that...i rarely ever look at anything but 8 ohm ratings.
post #13 of 17
Quote:
Originally Posted by Bill Fitzmaurice View Post

The mentioned Onkyo NR809 claims 160wpc x 7, for a total of 1120w. It's current draw is 7.5a at 120v, which is 900w. I guess it has 125% efficiency? eek.gif
With 70% efficiency, and that's being generous as it burns 95w at idle, it can only put out 630w. Yes, each channel can put out 160w individually, but not all simultaneously. If you look closely at the manual you'll find it can only deliver 160wpc with two channels driven.

A device like an AVR does not draw a constant load like other appliances, eg a heater, so it is tested at 1/8 power to all channels as this more closely represents the sort of load it will draw from the mains when in actual use, eg playing music or watching a movie which may have a peak to average ratio of 20dB (100:1) or more. This is useful to determine the maximum demand for a line, as well as the average heat put out by the device so that you can calculate cooling requirements. Both are useful to system designers and installers.

Refer to the two attached documents from Yamaha for the P-S series pro amps. Compare the rated power outputs to the rated line current draw (near the bottom labelled Power Consumption). You'll see the value for line draw is at 1/8 power into 8R for each of the amplifiers (see link).
http://www.yamahaproaudio.com/global/en/products/poweramps/ps_series/specifications.jsp

P-S_datasheet.pdf 2131k .pdf file
p_heatspec_en.pdf 139k .pdf file

Yamaha's site makes it awkward to link directly, but you can get the attachments through the link I included above.
post #14 of 17
The Yamaha spec state idle and 1/8th power, most manuals don't and I expect they don't rate at 1/8th power. Otherwise the Onkyo above would be tested to draw 900 W while outputting only 1/8th full power, 118W. That would be very inneficient and won't never allow it to scale to full power (drawing 7200W ?)
post #15 of 17
Good grief.

The Yamahas are almost pure power amps with only a tiny bit of processing so the figure represent more closely a power amp only.

The Onkyo NR809 is not and has a ton of other features that consume power.

Now viewing the NR809 manual it states a 'no sound' draw of 95W (US), this figure then accounts for all the DSPs, codecs, video processing, AM/FM radios, switching, display, controller etc plus any supply losses at that level, ie everything but the power amps beyond their quiescent currents. How much this equipment varies in draw between idle and full utilisation, I can only guess, but it would be a fair bit for the DSPs and video processing

So, 7 channels of class AB amplifier producing 135W. Each will be about 55% efficient, so each will consume 245W for rated power. At 1/8 we have 7 x 30.6 = 214W plus additional losses through the power supply because of the higher load. If Onkyo chose, or are forced by newer regulation to use 1/3 power then the power amp contribution becomes 572W. Add that to the 95W idle, plus extras from the processing and higher supply losses and you aren't far from the 825W (7.5A x 110V) Onkyo claim. It works out even closer for the 240V models so it might be due to different measurement processes as required by law.

Best still, why don't you email them and see if they'll give a technical answer as to how they come to their figures?

I use 1/8th rated as it represents hard, but reasonable use with program material (see second pdf I linked earlier). It was also the basis for an FTC regulation back in the power wars era, but I can't be stuffed searching my paper files to find it.
post #16 of 17
Quote:
Originally Posted by A9X-308 View Post

The Yamahas are almost pure power amps with only a tiny bit of processing so the figure represent more closely a power amp only.
They are also class H amps.
Quote:
Now viewing the NR809 manual it states a 'no sound' draw of 95W (US), this figure then accounts for all the DSPs, codecs, video processing, AM/FM radios, switching, display, controller etc plus any supply losses at that level, ie everything but the power amps beyond their quiescent currents. How much this equipment varies in draw between idle and full utilisation, I can only guess, but it would be a fair bit for the DSPs and video processing
Given the power draw of an iPad: I doubt it. Much more likely is the class A component on the AB amp in the Onkyo is drawing the bulk of that.

For example: Here's a 2-channel Onkyo amp which draws 45W with "no sound" http://www.onkyousa.com/Products/model.php?m=M-5010&class=Amplifier&source=prodClass
Sadly: their 9-channel amp doesn't list idle power consumption, but The Emotiva XPA-5 draws 75W with no sound : http://emotivalounge.proboards.com/thread/5691
post #17 of 17
Quote:
Originally Posted by psgcdn View Post

The Yamaha spec state idle and 1/8th power, most manuals don't and I expect they don't rate at 1/8th power. Otherwise the Onkyo above would be tested to draw 900 W while outputting only 1/8th full power, 118W. That would be very inneficient and won't never allow it to scale to full power (drawing 7200W ?)

Quote:
Originally Posted by A9X-308 View Post

Good grief.

[cut]
At 1/8 we have 7 x 30.6 = 214W plus additional losses through the power supply because of the higher load.
So nowhere close to 900W
Quote:
Originally Posted by psgcdn View Post

If Onkyo chose, or are forced by newer regulation to use 1/3 power then the power amp contribution becomes 572W. Add that to the 95W idle, plus extras from the processing and higher supply losses and you aren't far from the 825W (7.5A x 110V) Onkyo claim.
So... you agree with me after all that they probably don't spec at 1/8th power.
New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: Speakers
AVS › AVS Forum › Audio › Speakers › Less Power Mr Scott?!