Careful. That 1500 watts quoted is actual toaster watts. In more customary consumer watts (watt is claimed by manufacturers of overhyped consumer audio products in big box stores that magically output more power than they consume) that would be 15,000 watts!
Actually I am in the process of gathering bits on my lab bench to make a 1500 watt amp that will do this into 8 ohms with just two output devices, but they run at about 3400 VDC, and being tubes, may not warm the hearts of folks in this forum who prefer their amps to radiate solely in the long wavelength, completely invisible infra red.
Actually I am in the process of gathering bits on my lab bench to make a 1500 watt amp that will do this into 8 ohms with just two output devices, but they run at about 3400 VDC, and being tubes, may not warm the hearts of folks in this forum who prefer their amps to radiate solely in the long wavelength, completely invisible infra red.
over 3KW all you need is a decent sub station
There are much clever ways to do it, namely class G and class H:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=68415
http://www.diyaudio.com/forums/showthread.php?s=&threadid=77586
There is also class D, but I'll leave it apart because it's seen as pure vodoo by conventional "linear" minds (who think amplifiers only in terms of big toroids and bulky storage capacitors).
http://www.diyaudio.com/forums/showthread.php?s=&threadid=68415
http://www.diyaudio.com/forums/showthread.php?s=&threadid=77586
There is also class D, but I'll leave it apart because it's seen as pure vodoo by conventional "linear" minds (who think amplifiers only in terms of big toroids and bulky storage capacitors).
Eva said:
You still have "big toroids and bulky storage capacitors" in class D as well, although not quite as big as class AB or B amplifiers. It's converting the PSU to switch-mode that gets rid of the "big toroids and bulky storage capacitors", and you can do that on a linear amp if you like?.
I mean that class D power consumption is ridiculous. For example, some days ago I measured a bare 5W to 15W of input power being used while putting +/-28V peak of music (loud disco/house) into a 8 ohm two-way speaker with slight clipping, and the gate drive circuit was already using 3W of that.
Class G and class H are also remarkable improvements, as power consumption and dissipation with music can be easily halved in comparison with plain class B.
It's a bit pointless to give more or less merits to amplifiers depending on how much iron, copper and electrolytics they have inside.
Class G and class H are also remarkable improvements, as power consumption and dissipation with music can be easily halved in comparison with plain class B.
It's a bit pointless to give more or less merits to amplifiers depending on how much iron, copper and electrolytics they have inside.
Remember that music signals don't ask the amplifier to output maximum voltage amplitude to the load all the time. Average power content of music signals is usually between 1/5 and 1/20 of what it would be with a pure sine wave of similar amplitude (we would become deaf otherwise!). Note also that class B circuits start to become a bit efficient (p_out > p_loss) when output voltage is above 50% of rail voltage, but with music signals that happens during a small portion of playback time. In practice, this means that power efficiency of plain class B amplifiers fed with music is around 15% (I wrote a program to analyse wav files in order to obtain that figure, and it didn't simulate a reactive load, just a plain resistor).
Also, remember that loudspeaker loads are reactive. This means that a fraction of the energy delivered by the amplifier to the speaker (sometimes over 25%) is returned back to the amplifier (nothing strange there, just plain capacitance and inductance). That energy is completely dissipated in the output devices for plain class B systems, but class G and class H systems manage to dissipate only a fraction of it, and class D systems return all that energy back to the power supply
(indeed that concept may be a bit shocking for people used to amplifiers that can only draw current from the PSU).
That's why I say that class D stuff is seen as vodoo by most people. You can't understand it well before previously understanding a lot of general amplifier concepts (that most people seems to ignore, since they are too busy dreaming of big toroids and supply capacitors).
Also, remember that loudspeaker loads are reactive. This means that a fraction of the energy delivered by the amplifier to the speaker (sometimes over 25%) is returned back to the amplifier (nothing strange there, just plain capacitance and inductance). That energy is completely dissipated in the output devices for plain class B systems, but class G and class H systems manage to dissipate only a fraction of it, and class D systems return all that energy back to the power supply
(indeed that concept may be a bit shocking for people used to amplifiers that can only draw current from the PSU).That's why I say that class D stuff is seen as vodoo by most people. You can't understand it well before previously understanding a lot of general amplifier concepts (that most people seems to ignore, since they are too busy dreaming of big toroids and supply capacitors).
Pass Labs X1000
Description: Solid-state monoblock power amplifier. Maximum output power (1% THD, 1kHz): 1000W into 8 ohms. Maximum output voltage: ±45V. Maximum output current: ±30A. Frequency response: -0dB at DC, -3dB at 60kHz. Input impedance: 20k ohms balanced. Damping factor: 60 ref. 8 ohms nominal. Voltage gain: 30dB. Slew rate: >40V/µs. Output noise: 500µV unweighted, 20Hz-20kHz. Random noise floor: approximately 2µV. Dynamic range: 155dB (random noise floor to peak output). Balanced Common-Mode Rejection Ratio: 85dB 1kHz. DC offset: <100mV. Power consumption: 600W idle, 2400W maximum.
Dimensions: 19" W by 10.5" H by 28" D. Shipping weight: 250 lbs each.
Serial numbers of units reviewed: 08892/08893.
Price: $24,000/pair. Approximate number of dealers: 35. Warranty: 3 years parts & labor, transferable without notice.
Description: Solid-state monoblock power amplifier. Maximum output power (1% THD, 1kHz): 1000W into 8 ohms. Maximum output voltage: ±45V. Maximum output current: ±30A. Frequency response: -0dB at DC, -3dB at 60kHz. Input impedance: 20k ohms balanced. Damping factor: 60 ref. 8 ohms nominal. Voltage gain: 30dB. Slew rate: >40V/µs. Output noise: 500µV unweighted, 20Hz-20kHz. Random noise floor: approximately 2µV. Dynamic range: 155dB (random noise floor to peak output). Balanced Common-Mode Rejection Ratio: 85dB 1kHz. DC offset: <100mV. Power consumption: 600W idle, 2400W maximum.
Dimensions: 19" W by 10.5" H by 28" D. Shipping weight: 250 lbs each.
Serial numbers of units reviewed: 08892/08893.
Price: $24,000/pair. Approximate number of dealers: 35. Warranty: 3 years parts & labor, transferable without notice.
LightwaveDude said:
Amplifers 'should' be specified as RMS watts, continuously driven by a sinewave, at a specific distortion level, and across a specific range of frequencies. This is an HONEST spec, that you can use to compare between different units. Generally PA amplifiers still use this method, as do quality HiFi units.
It was the Americans who started using rubbish figures to try and makes the amps sound better than they were, an amplifier sold in the UK as 10W per channel would be sold in the USA as a '200W amplifier'.
This comes about by a number of dubious methods:
Firstly, you add the two channels together, so your 10W per channel becomes 20W (still at low distortion, and still RMS).
Next you only drive ONE channel, this increases the power as the supply doesn't drop as much.
Then you OVERDRIVE that channel, so it's highly distorted, this increases the power greatly, but isn't listenable.
You then find the one specific frequency where it will output it's maximum power, and use that.
You only measure the power for a very tiny period of time (milliseconds), so the supply voltage doesn't have time to drop.
You don't quote RMS, you quote peak power, which is much more.
By these dishonest (advertising people) methods, you can give the impression (to the electronically ignorant majority) that an amplifier is MUCH better than it actually is.
Car amplifiers and speakers are particularly bad, honest ratings are commonly only 1/10 to 1/5 of the advertising claims. If you fed an honest 200W RMS to your 1000W car speaker you will probably have to jump back to avoid the pieces!
Good eplanation Nigel! I want to add that there is a goofy power output rating called PMPO that I have seen used on computer speakers which seems to be rediculously overblown. I have coined my own definition of this acronym which is probably in the real ballpark. PMPO = Peak Milliwatts Power Output. By this definition a 1/2 watt RMS amplifier (about 1 watt peak) can be rated as a "1000 watt amp PMPO" .
I wonder how a Pass X1000 produces the claimed 1000W at 8 ohms with just +/-45V output.
In my world, amplifiers with +/-45V output produce only up to 125W at 8 ohms, and +-127V are required to produce 1000W on that load.
It may be the 'PMPO' stuff hitting again... It has a lot of 'P' from 'Pass' in it
A similar thing happens with computer speakers claiming 1000W and powered from a 12V single supply...
In my world, amplifiers with +/-45V output produce only up to 125W at 8 ohms, and +-127V are required to produce 1000W on that load.
It may be the 'PMPO' stuff hitting again... It has a lot of 'P' from 'Pass' in it
A similar thing happens with computer speakers claiming 1000W and powered from a 12V single supply...
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