Hi,
I am now listening to an 8" SEAS fullranger with a sensitivity of 94dB per watt. The volume control of my tube amp is about a notch above the minimum volume.
Did a bit of reading up, it seems that 85dB or so if prolonged exposure could result in hearing loss, and vacuum cleaners are 70dB or so. At which point I am wondering how much power am I sticking into them?
By these definition, at 0.1W, I should be risking hearing loss... which is possible, looking at how low the volume control is turned down.
Makes me wonder, if one were to design an amp for such a speaker, would 1 watt have been enough?
Oon
I am now listening to an 8" SEAS fullranger with a sensitivity of 94dB per watt. The volume control of my tube amp is about a notch above the minimum volume.
Did a bit of reading up, it seems that 85dB or so if prolonged exposure could result in hearing loss, and vacuum cleaners are 70dB or so. At which point I am wondering how much power am I sticking into them?
By these definition, at 0.1W, I should be risking hearing loss... which is possible, looking at how low the volume control is turned down.
Makes me wonder, if one were to design an amp for such a speaker, would 1 watt have been enough?
Oon
Unless you're using it for headphones I shouldn't worry, intensity drops off fairly quickly over distance. The inverse distance law 1/r for the sound pressure - no square - acoustic audio sound reduction free field particle amplitude volume loudness level distance laws dB decibel calculator distance dropratio- sengpielaudio Sengpiel Berlin
One watt may be giving you reasonable listening levels, but you always want as big an amp as possible-the ideal amp would have limitless power: Dynamic range is what makes music feel real. The wider the dynamic range the louder the loud bits are and quieter the quiet bits are, making the experience more visceral.
One watt may be giving you reasonable listening levels, but you always want as big an amp as possible-the ideal amp would have limitless power: Dynamic range is what makes music feel real. The wider the dynamic range the louder the loud bits are and quieter the quiet bits are, making the experience more visceral.
Oon,
have you measured the signal voltage at your speakers?
Use that to estimate the power the speakers are receiving.
Allow at least 100times your normal listening power to allow short term transients to pass through unclipped. That's the upper half of the dynamic range referred to in post2.
BTW, using 1W and 94dB/W @ 1m ends up with a maximum SPL at a 2.5m listening position of just 89dB from a pair of 1W amplifiers/speakers.
For good reproduction of dynamics one would normally expect transient peaks of 105dB at your listening position. 110dB would be excellent and some builders/listeners demand even more.
have you measured the signal voltage at your speakers?
Use that to estimate the power the speakers are receiving.
Allow at least 100times your normal listening power to allow short term transients to pass through unclipped. That's the upper half of the dynamic range referred to in post2.
BTW, using 1W and 94dB/W @ 1m ends up with a maximum SPL at a 2.5m listening position of just 89dB from a pair of 1W amplifiers/speakers.
For good reproduction of dynamics one would normally expect transient peaks of 105dB at your listening position. 110dB would be excellent and some builders/listeners demand even more.
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With the right amp, I'd say 2W or so would be enough depending on the type of music you like. I don't buy the 'you need a gazillian watts for the transients' stuff myself, but maybe I just don't listen to the kind of music where this is important. The advantage of flea powered amps is usually that they enjoy different design tradeoffs that can make them very enjoyable to listen to - i.e. DHTs.
Hi,
Thanks for all the replys....
Dear AndrewT,
While it is true that sound level falls off at inverse square, this won't be true in a room (non anechoic chamber) since there is reflection from the walls. I think it really depends on the size of the room and how much carpeting I have....
I suppose, my interest in this is I want to try out class A. Since efficiency is something like 10W DC in, 1 W power out, I would want to keep it as small as possible...
Maybe just build a class A of 1 or 2 W only...
Oon
Thanks for all the replys....
Dear AndrewT,
While it is true that sound level falls off at inverse square, this won't be true in a room (non anechoic chamber) since there is reflection from the walls. I think it really depends on the size of the room and how much carpeting I have....
I suppose, my interest in this is I want to try out class A. Since efficiency is something like 10W DC in, 1 W power out, I would want to keep it as small as possible...
Maybe just build a class A of 1 or 2 W only...
Oon
If you can measure low AC voltages, that would be a great guide as Andrew suggests.
For example: With my system (not single driver) I get 85dB at the listening seat when both speakers are fed 1V RMS. That's 1/8th Watt. I need very little power to hit 110dB peaks. And 85dB average is pretty loud.
If you have a way to measure the voltage at your speakers, you can figure out how much power you need. I'll bet 5W RMS will be plenty.
For example: With my system (not single driver) I get 85dB at the listening seat when both speakers are fed 1V RMS. That's 1/8th Watt. I need very little power to hit 110dB peaks. And 85dB average is pretty loud.
If you have a way to measure the voltage at your speakers, you can figure out how much power you need. I'll bet 5W RMS will be plenty.
Hi Pano,
I figure I will also be using about that. I can always measure with a multimeter, just don't have a sine wave generator. But i suspect 1V is going to be plenty for me, and 1/10W is closer to what I need....
BTW, just out of curiosity, how are efficient are your speakers? 90+dB/watt
Oon
I figure I will also be using about that. I can always measure with a multimeter, just don't have a sine wave generator. But i suspect 1V is going to be plenty for me, and 1/10W is closer to what I need....
BTW, just out of curiosity, how are efficient are your speakers? 90+dB/watt
Oon
I would go for at least 40 watts ....
1v, That must be 85db narrow band .......
Your 94 Db for the SEAS driver is just touching the lower band of the truly high efficient arena.......Ever wonder why garage bands seem so very loud?........and they are using 30 Watt or so guitar heads, times..three? Guitar drivers are around the 100 Db range......PA style Large format Horns are running around 108Db.
I recall long ago as a teenager, running a cassette (Walkman, early) thru a set of old tube era loudspeakers...of high efficiency(102 Db+)?? A casual listener who happened by was stymied by the lack of tuner, receiver......or SOMETHING that was the source for the loudspeakers....only when I picked up the cassette player off the top of the cabinet & flicked it off, did they know.
150 mW worth of power was enough for those drivers.
_________________________________________________________Rick.....
I recall long ago as a teenager, running a cassette (Walkman, early) thru a set of old tube era loudspeakers...of high efficiency(102 Db+)?? A casual listener who happened by was stymied by the lack of tuner, receiver......or SOMETHING that was the source for the loudspeakers....only when I picked up the cassette player off the top of the cabinet & flicked it off, did they know.
150 mW worth of power was enough for those drivers.
_________________________________________________________Rick.....
you don't need a signal generator.
Measure the music signal at the speakers.
You may find that your preferred listening level with your speakers in your room is 1mW to 10mW.
Once you know your preferred listening level you are armed with the information to decide on compatible amplifier power.
Prior to that you are guessing. We are guessing. Use the tools available to you. Make informed decisions.
Oon, I can supply you with some test ones that you can play from the computer or burn to CD. I'll post them here.
I don't know exactly. Maybe 95-96dB/W The 85dB I get at 1V is with BOTH speakers playing, as they normally would be with music.
Narrow (sine) or wide (pink), no matter. As long as it's 1V RMS going to each speaker.
OK, attached you will find 2 test signals in a zip file. Both have an RMS value of -16dB (below full scale). This is a typical CD mastering level for most pop and rock, unless it's one of the recent "compressed to death" CDs.
Find a few recordings that you feel have a good (but not wild) dynamic range. Play them back at a good, healthy level. About as loud as you would normally listen to them. Note where your volume knob is and take an average. Set it there for the next tests, don't change it.
Now play the brown sound (similar to pink) and listen if it is similar in level to your music tracks. If it is, good. If it's way off, let me know.
Next play the 120Hz tone and measure it with your AC voltmeter. Note the voltage. Be sure your meter has a low AC volt range for accurate results. All meters I have checked have had accurate response at 120Hz.
You will now know the voltage needed for your typical loud listening. You will need about 16dB peak above that to avoid clipping on a typical CD. That's your headroom.
For example, let's say you measured 1V RMS on the 120Hz tone. 16dB above that is 6.3V. That's the peak you need not to clip. 6.3V into 8 ohms is 5 watts. An amp that can do 5W RMS into 8 ohms without clipping will do almost 10W (9V) peak. You have the headroom you need. Once you find out your average voltage, you can use Ohm's law to figure out how much power you need.
That's about all there is to it. Of course if you play music that is recorded with a higher average to peak ratio, say 20-22dB like classical, you'll need a more powerful amp to play at the same average level and avoid clipping. Maybe a 20W amp.
Find a few recordings that you feel have a good (but not wild) dynamic range. Play them back at a good, healthy level. About as loud as you would normally listen to them. Note where your volume knob is and take an average. Set it there for the next tests, don't change it.
Now play the brown sound (similar to pink) and listen if it is similar in level to your music tracks. If it is, good. If it's way off, let me know.
Next play the 120Hz tone and measure it with your AC voltmeter. Note the voltage. Be sure your meter has a low AC volt range for accurate results. All meters I have checked have had accurate response at 120Hz.
You will now know the voltage needed for your typical loud listening. You will need about 16dB peak above that to avoid clipping on a typical CD. That's your headroom.
For example, let's say you measured 1V RMS on the 120Hz tone. 16dB above that is 6.3V. That's the peak you need not to clip. 6.3V into 8 ohms is 5 watts. An amp that can do 5W RMS into 8 ohms without clipping will do almost 10W (9V) peak. You have the headroom you need. Once you find out your average voltage, you can use Ohm's law to figure out how much power you need.
That's about all there is to it. Of course if you play music that is recorded with a higher average to peak ratio, say 20-22dB like classical, you'll need a more powerful amp to play at the same average level and avoid clipping. Maybe a 20W amp.
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I don't know if I'm alone on this, but when I attend live concerts of classical music, I sometimes find them too loud - I wonder if the musicians playing in the orchestra are getting hearing damage.
Hi,
Thanks for all the reply. There is a reason why I didn't want to test with multimeters and music. The signal will go up and down for typical music (soft and loud passages) and the readings of the digital multimeter will go all over the place because of how slow it responds. Ultimately, you don't know what it is measuring. Analogue multimeters are a bit better in that sense.
Thanks for the files Pano. You have been of great help.
Oon
Thanks for all the reply. There is a reason why I didn't want to test with multimeters and music. The signal will go up and down for typical music (soft and loud passages) and the readings of the digital multimeter will go all over the place because of how slow it responds. Ultimately, you don't know what it is measuring. Analogue multimeters are a bit better in that sense.
Thanks for the files Pano. You have been of great help.
Oon
For those of us who are too old, too loud is TOO LOUD.
You whippersnappers can go ahead and wait for nanobots to repair your tinnitus. Some of us are out of time for excess spl, which a full orchestra is fully capable of.
This power requirement jawbone has been going on a long time. I have a signal generator and it tells me than ordinary drivers need about one watt to reach their linear excursion limit. Then things get exponential and distorted.
I'm old. I have to respect my limits. I treat my aged gear with respect. Including my ears of course.
Most of the time
You whippersnappers can go ahead and wait for nanobots to repair your tinnitus. Some of us are out of time for excess spl, which a full orchestra is fully capable of.
This power requirement jawbone has been going on a long time. I have a signal generator and it tells me than ordinary drivers need about one watt to reach their linear excursion limit. Then things get exponential and distorted.
I'm old. I have to respect my limits. I treat my aged gear with respect. Including my ears of course.
Most of the time
All of the classical concerts (70 piece orchestra)I have attended recently are unamplified and the levels can get quite high.. I have a friend who plays bass trombone and I measured the spl a meter out from the mouth of the horn and it was over 120dB! He warned me he was loud.. Imagine sitting in front of that...
I'm currently running 20W GM70 SE amps with >100dB speaker system, not hard to imagine how loud it could get..
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