If I understand your test, then it sounds about right to me. A sine as an RMS voltage that is 70% of its peak, right? So the 60% test should be right in there, with a little extra headroom.
With so many different amp topologies available generalizations are not so useful.If I understand your test, then it sounds about right to me. A sine as an RMS voltage that is 70% of its peak, right? So the 60% test should be right in there, with a little extra headroom.
Some amps are not capable of any more peak output than RMS, others can put out much higher very short duration peak voltage.
What most people need for home stereo is a 1 watt amp that can put out 100 watt peaks...
is this telling us that the test tone is recorded at -9dB ref maximum output signal?
Increase the test tone by 9dB and any higher, then the test tone will clip?
LOL. That's a new one on me, don't know that topology. Or is that just a 50 WPC amp with a wimpy power supply?
I use 20dB of overhead from average to maximum output, if I can get it.
If I use much less than 20dB of overhead, I can hear the speaker output degenerating as the average comes up past that -20dB value.
An example of the above is that a 28.3Vac amplifier can sound quite nice at a particular average signal level. Swap in a good 20Vac amplifier and the music has just started to sound like it is loud, even though the average signal to the speaker is the same as before and is now say only 17dB below the clipping level of the 20Vac amplifier.
If I was to swap in an amplifier that had 11dB less overhead, i.e. a 5.8Vac amplifier and try to play that same average signal level, the sound would be so grossly distorted I would want to run out of the room.
When you quoted -12dB, I had reservations, but since it was only 4dB less overhead than -16dB, I thought "maybe it's acceptable" if one only uses that one type of music source that can never exceed 4times the average voltage level of the test music and test signal.
I cannot accept your -9dB ref maximum output, as a valid method of determining the maximum signal voltage that your speaker needs.
If I use much less than 20dB of overhead, I can hear the speaker output degenerating as the average comes up past that -20dB value.
An example of the above is that a 28.3Vac amplifier can sound quite nice at a particular average signal level. Swap in a good 20Vac amplifier and the music has just started to sound like it is loud, even though the average signal to the speaker is the same as before and is now say only 17dB below the clipping level of the 20Vac amplifier.
If I was to swap in an amplifier that had 11dB less overhead, i.e. a 5.8Vac amplifier and try to play that same average signal level, the sound would be so grossly distorted I would want to run out of the room.
When you quoted -12dB, I had reservations, but since it was only 4dB less overhead than -16dB, I thought "maybe it's acceptable" if one only uses that one type of music source that can never exceed 4times the average voltage level of the test music and test signal.
I cannot accept your -9dB ref maximum output, as a valid method of determining the maximum signal voltage that your speaker needs.
I cannot agree your method.
Your method relies on the -9dB ref maximum signal as being representative of the loudest average music signal that Members are being asked to set their systems to.
It is completely nonsensical to suggest that a 3.1times voltage overhead (+9dB ref the test tone) is sufficient to indicate the maximum power requirement of the amplifier/speaker combination.
Your method relies on the -9dB ref maximum signal as being representative of the loudest average music signal that Members are being asked to set their systems to.
It is completely nonsensical to suggest that a 3.1times voltage overhead (+9dB ref the test tone) is sufficient to indicate the maximum power requirement of the amplifier/speaker combination.
A cool and free way to examine the dynamic content of music files etc.
ORBAN Loudness Meter
"VU" (Volume Unit) is an average that sounds pretty much like how your ears hear loudness but with flat response while other views of the actual signal tell more about what is present such as the peak values.
Check your music files!.
To see if you have *inaudible instantaneous clipping anywhere in the signal chain, use an oscilloscope to examine the peaks on your amplifier output.
*it's too short to hear as traditional "clipping" but becomes detectable when compared to 'not clipped" version as it is less dynamic sounding.
Best,
Tom Danley
ORBAN Loudness Meter
"VU" (Volume Unit) is an average that sounds pretty much like how your ears hear loudness but with flat response while other views of the actual signal tell more about what is present such as the peak values.
Check your music files!.
To see if you have *inaudible instantaneous clipping anywhere in the signal chain, use an oscilloscope to examine the peaks on your amplifier output.
*it's too short to hear as traditional "clipping" but becomes detectable when compared to 'not clipped" version as it is less dynamic sounding.
Best,
Tom Danley
No, it does not. You are looking at the wrong thing. Forget the average music level, it's leading you astray. Just look at the -12dB signal vs max power. I know you can figure it out.
Pano, I ran tests with two speakers. B&W683s gave me a 5.2V for the 120V signal. And 6.5" Tannoy dual concentrics in a Voight pipe gave me 4.0V. That would mean a peak of 16V is required. By your equation, that means a 250W amp for clean peaks. Hmmm... kinda high.
My horn/woofer system is currently down for improvements. With a few more db of efficiency, maybe the reading will go down to 2V. We shall see.
I have new FirstWatt p-p amp (no, not the F5) that delivers about 25W into 8 ohms. Sounds more than enough to me
This is a wonderful test. Thanks! Oh, can you elaborate on why we don't divide by 8 when calculating power from the peak volts?
My horn/woofer system is currently down for improvements. With a few more db of efficiency, maybe the reading will go down to 2V. We shall see.
I have new FirstWatt p-p amp (no, not the F5) that delivers about 25W into 8 ohms. Sounds more than enough to me
This is a wonderful test. Thanks! Oh, can you elaborate on why we don't divide by 8 when calculating power from the peak volts?
LOL. That's a new one on me, don't know that topology. Or is that just a 50 WPC amp with a wimpy power supply?
That's a Quad 405 on a good day into around (when the mains is up anyway) \x£&^ ohms, hmmm.... or maybe not
This test is a lot more subtle than appears...
You play the tone, measure the RMS voltage, square it and thats your max power needed.
Huh......... what about my 8 ohms, or was it 4 or does it matter. And it varies too.
So you measure 4 volts RMS. Square it and get 16 and go and buy a 16 watt rms amp because that can put out all you need. How does that work then...
Lets say your speaker really was 8ohm. 4 squared/8 is 2. You are drawing two watts for Panos test. The clever bit is in the -12db level chosen and knowing how digital works. How so !
16 watts rms into 8 ohm (that this test says you need) is 11.3 volts rms. db's and stuff. Ohmages and impedancies !!
No, 11.31 volts RMS... now there's a coincidence
Maybe ! What's the impedance of a foobar ? Come to that, what's a foobar ? But we are working in volts today (much nicer) and so we use the magic db =20logv1/v2 do-dah. That tells us that the db thingy for 11.3 volts and 4 volts is 9db or -9db depending which hemishere you are in. Does 9db mean anything. Someone mentioned it somewhere
This test all comes down to the "cast in stone" maximimum output of a digital system.To rearrange and clarify some statements... the test in this example says a 16 watt amp is sufficient. Well actually it doesn't. It says that the amp has to put out 11.3 volts RMS. It's not the same thing. To quote power means you know impedance... we don't always. If your speaker impedance dips then it's up to you to make sure amp can sustain that voltage. And the power taken by the speaker varies as the impedance varies. Because we are working in volts that doesn't matter (as long as the amp doesn't clip or output fall).
The watts into 8 ohm is an old standard measurement that most folk at least have some idea what it means. I know some on here favour specifying an RMS output voltage into a minimum load impedance as a more revealing and "honest" method of stating amplifier power. A lot to commend it for sure.
And just to wander a bit (or 16)...
CD (or a digital system) has a 16 bit (for CD) dynamic range. 2 times 2 times 2 and so .... 16 times. Answer 65536. What does that mean ? It means if a CD player designer says "this player will output 3.25 volts at 0db" we have a player capable of 65536 individual voltage steps from 0 to 3.25volts. Is that peak or RMS ? Doesn't matter as long as we are consistent in our units. Each step is 3.25/65536 which is 0.00004959 volts. What it is really saying though is that the max voltage level can never be exceeded and that is why we can say we will never need an amp of more power (or more correctly voltage) than this test shows. It's because no peak, transient etc can ever go over that level.
Moving on to vinyl and a scratched record and stylus velocity... nah
I propose a new test.
What is the minimum value of fuse you can get away with in series with your speakers ?
i did the test.
with 87db/2.83volt speakers the room
is 40 square meters and listening seat
3.5 meters from speakers.
at 120hz 7volt and this is the maximum
the speakers can take.
trying to figure out the the maximum i
hit the speakers protection.
there is something wrong at calculating
the amps power need since this
would translate at 49watts according
to you but it`s not even close.
mooly`s calculation is more realistic.
with 87db/2.83volt speakers the room
is 40 square meters and listening seat
3.5 meters from speakers.
at 120hz 7volt and this is the maximum
the speakers can take.
trying to figure out the the maximum i
hit the speakers protection.
there is something wrong at calculating
the amps power need since this
would translate at 49watts according
to you but it`s not even close.
mooly`s calculation is more realistic.