OK!
No dangers, the voltages are small. You can put the probes at the amp terminals or at the speaker terminals. Look for a voltmeter that has a 20 volt AC range (or similar). Most inexpensive ones don't have a range lower than 200V AC. That will work, but the measurements at the low end of the 200V scale may be hard to read or not very accurate. You'll will likely be measuring less than 10 volts.
Other than that you just need a way to play back the test tones I posted. Computer or CD player, whatever you normally use. That's it, simple. Please let us know what you find.
No dangers, the voltages are small. You can put the probes at the amp terminals or at the speaker terminals. Look for a voltmeter that has a 20 volt AC range (or similar). Most inexpensive ones don't have a range lower than 200V AC. That will work, but the measurements at the low end of the 200V scale may be hard to read or not very accurate. You'll will likely be measuring less than 10 volts.
Other than that you just need a way to play back the test tones I posted. Computer or CD player, whatever you normally use. That's it, simple. Please let us know what you find.
I know I'm late to this, but with my 98dB @ 1W speakers, and 1 watt per channel class A amplifier, it is loud enough not to hear the shouts of "turn it down". It easily fills a 9m long room, and at a recent meet, got a sensible volume level in a 20m x 10m room without clipping. I don't get rock concert levels, but I don't want that. It follows that 2W per channel should be enough for 95dB @ 1W speakers and so on doubling power for every 3dB loss in sensitivity.
The good thing is that it is relatively easy to build class A at that power - mine only runs with a 0.5A constant current source for the output stage.
Brian.
The good thing is that it is relatively easy to build class A at that power - mine only runs with a 0.5A constant current source for the output stage.
Brian.
If you can,
Use a true RMS multimeter with a peak hold function then play the most dynamic music in your collection at levels at the high end of things. It won't give you a completely accurate reading, the impedance varies with frequency but it will get you in the ball park.
I do find it annoying that most amplifiers or receivers add a bunch of useless junk but delete the power level meters--heck, a clip light should be the minimum. My kids grew up learning to never play the stereo output lights past -20dB peaks (2.5 watts) with mom around...Soundcraftsmen, you left us too soon.
The Pioneer SX-3700 with the power meters still works out in the garage, if a real car has a tach...why are they missing from "audiophile" amplifiers?
Use a true RMS multimeter with a peak hold function then play the most dynamic music in your collection at levels at the high end of things. It won't give you a completely accurate reading, the impedance varies with frequency but it will get you in the ball park.
I do find it annoying that most amplifiers or receivers add a bunch of useless junk but delete the power level meters--heck, a clip light should be the minimum. My kids grew up learning to never play the stereo output lights past -20dB peaks (2.5 watts) with mom around...Soundcraftsmen, you left us too soon.
The Pioneer SX-3700 with the power meters still works out in the garage, if a real car has a tach...why are they missing from "audiophile" amplifiers?
The integration time on a true RMS voltmeter is unfortunately far too slow to register anything remotely near the peak voltage in music.
I could use the peak hold function on my scope,
Years ago they had power meters on receivers, amps and even on speakers (remember those?) Now, I guess they are considered ugly or something... To counter that I use pro amps for subs and set the limiter on them so the -10dB light is 6dB below the limiter function.
For speakers, they are generally 92dB or higher at one watt so conventional receivers work well in my small living room. My HT receiver is getting old and it is hard to find something that has the minimal clip light on it. Sure, I can surf the internet with the new ones...Angry Birds is coming for 2012
Peak hold on a Fluke might not be the most accurate way to measure, but it sure beats watching the digits rapidly changing. Sure miss those 20+ LED output displays on Soundcraftsmen amps...green, yellow and red...
Years ago they had power meters on receivers, amps and even on speakers (remember those?) Now, I guess they are considered ugly or something... To counter that I use pro amps for subs and set the limiter on them so the -10dB light is 6dB below the limiter function.
For speakers, they are generally 92dB or higher at one watt so conventional receivers work well in my small living room. My HT receiver is getting old and it is hard to find something that has the minimal clip light on it. Sure, I can surf the internet with the new ones...Angry Birds is coming for 2012
Peak hold on a Fluke might not be the most accurate way to measure, but it sure beats watching the digits rapidly changing. Sure miss those 20+ LED output displays on Soundcraftsmen amps...green, yellow and red...
FWIW, I was inspired by Pano's instruction in this thread and decided to get out the volt meter just now. I didn't bother to get too scientific about it; I put on "Money" by Pink Floyd and turned it up as loud as I thought reasonable on my dual-EL70 microTowers (EL70 is not even a high sensitivity driver at 86dB 1w/1m). Let's just say it was quite a lot louder than I ever play it when the family is around, and my dog left the room). I enabled the "B" speaker outputs and connected my volt meter. I was hitting 3.3v to 3.4v peaks, with an approximate average around 2.2v. I was running my SPL meter at the same time and getting peaks up to around 89dB, perhaps 85dB average. So I was using what, about 2 watts max? (2.83v = 1w, right?)
Also FWIW, I define "reasonable SPL" as <85db.
Also FWIW, I define "reasonable SPL" as <85db.
System is currently pulled down , so i'm not able to measure as per your suggestions currently , i have done so in the past, less just say 10 amp speaker fuses are keep in abundance around here.......
that is quite typical of louder music at home.
2.2Vac average into 8ohms speaker is ~0.6W.
Applying the +16dB and the +20dB allowances for overhead to pass peak transients without clipping, results in amplifier power of 24W to 60 W for that level of average SPL.
60W+ 60W into a pair of 86dB/W @ 1m speakers results in ~99dB (102dBpk) @ 2.5m listening distance.
Some would like another +6dB for their "loud" listening and some others would like +11dB for their very loud listening.
Adding those extra loud requirements to our amplifier specification for 86dB/W speakers gives us a range of 24W to 500W.
It seems any amplifier will do. Just adjust it so that it doesn't clip. If at the threshold of clipping it is not loud enough then you buy an amplifier that has 4 times the power for an extra 6dB of SPL. If that's not enough, divorce the spouse and quadruple again.
Now back to high efficiency speakers.
If we swap 96dB/W @ 1m for the example 86dB then we can divide all the power values by ten to give
normal to loud from 2.4W to 6W, very loud from 24W, & excruciating from 100W.
If we are wealthy enough to have good 99dB/W speakers then halve those power values again.
We are now in the range for "wife at home & listening together" using a 1W to 3W amplifier.
Wife away shopping and some "serious" listening 12W.
Kids at home holding an unauthorised party 50W.
Look at the specifications of full rangers in the 95dB/W to 100dB/W sensitivity range. Many have maximum power in the 20W to 50W range
Last edited:
try 5 watts .....
Tried a 10W Tripath. Obviously they could go louder, but I don't need it so went back to the class A.
I will put the scope on them later (probably tomorrow) to see how much power I am using, but I reckon the maximum will be around 0.1W (94dB for the pair) for normal listening. At the meet, it wasn't clipping, so the peaks must have been less than 1W.
I've got fairly inefficient B&W DM683s. Just as a matter of interest I measured what power I was pumping into them when they were LOUD.
Surprisingly it was only 5.8W.
In order to allow for transients, a 50W amp would suffice.
I've got a 100W Aleph 4 and it is more than enough - I never use it at any more than 60% on the volume control.
Surprisingly it was only 5.8W.
In order to allow for transients, a 50W amp would suffice.
I've got a 100W Aleph 4 and it is more than enough - I never use it at any more than 60% on the volume control.
60% on the volume control may be only 8dB to 10dB of attenuation. Depending on the source signal 60% could be giving regular clipping of that 5.8W speaker signal.
+16dB on 5.8W is ~230W
+20dB on 58W is 580W
I would suggest that 50W is for quiet listening only.
Regardless. I measured just under 6 Watts by averaging the Pk-Pk voltage at the output on a scope.
I stated the 60% bit, as that is where I stop when it's incredibly loud.
The Aleph 4 is only 100W. Its a Class A amp with +/- 48V rails so wont go much higher without serious clipping.
using the scope Vpp and estimating an average probably results in a Power Value that is way over average power to the speaker.
The fact that you were monitoring Vpp, you are clear of clipping.
I suspect your 5.8W was 6dB to 10dB above average power.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.