Measuring power output of a speaker amp to the speaker?

[Blumlein 88]

For that send a max test signal from your source with volume set to provide 14 volts at the speaker. That will be in the ballpark for an 8 ohm speaker. Obviously have volume well turned down and raise it to 14 volts. I'd use 440hz for the tone.

The reason this is fine is an amp rated as 25 watts will have been tested into an 8 ohm resistance as a load.

 

[NoxMorbis]

For that send a max test signal from your source with volume set to provide 14 volts at the speaker. That will be in the ballpark for an 8 ohm speaker. Obviously have volume well turned down and raise it to 14 volts. I'd use 440hz for the tone.

The reason this is fine is an amp rated as 25 watts will have been tested into an 8 ohm resistance as a load.

The one I am using is a lot more than 25 watts per channel, though. Does that matter? Also, I could still do it with an 8 Ohm resistor, as Doodski said,
then just unplug the DMM and resistor and keep the volume where it was while testing = apprx. 25 watt?

Also, why did you choose 440hz? Is that because it is midrange (as in a sortr of average tome that would be played musically)?

 

[Blumlein 88]

The one I am using is a lot more than 25 watts per channel, though. Does that matter? Also, I could still do it with an 8 Ohm resistor, as Doodski said,
then just unplug the DMM and resistor and keep the volume where it was while testing = apprx. 25 watt?

Also, why did you choose 440hz? Is that because it is midrange (as in a sortr of average tome that would be played musically)?

Yes to all of that. One way it will differ using a higher power amp throttled is it will be a "very strong " 25 watts. By that I mean it will act like a 25 watt amp with very high current capacity. The 440hz is partly what you said plus 25 watts at 440 is far less piercing than 1 khz. I suggest hearing protection when you do this test with speakers. If you use a resistor that won't matter. You'll need a resistor rated for that or more.

 

[Doodski]

I'm not trying to see what it puts out maximum, though. I just want to see what relatively 25 watts-ish a channel sounds like going through my speakers playing a song. I'm not comparing it to anything else, just my ears. I'd have to somehow calculate how many amps = (app) 25 watts to the speakers so like yuo state about estimating amps, but not before clipping, but around 25 watts? 25 watts-ish is my target.

Use the calculator that I linked you to. You only need two variables to use the calculate function. Enter the load resistance of say 8 Ohms for example into the (Z)impedance text field and then 25 watts into the (P) power text field and click calculate and voila it will calculate the current and voltage. Very nice calculator; saves lotsa time and effort and no mistakes to correct.

Ohm's Law | AE Techron

www.aetechron.com

 

[Doodski]

The one I am using is a lot more than 25 watts per channel, though. Does that matter? Also, I could still do it with an 8 Ohm resistor, as @Doodski said,
then just unplug the DMM and resistor and keep the volume where it was while testing = apprx. 25 watt?

Yes, that's how it is done. As @Blumlein 88 advised things will get loud at 25Watts.

 

[NoxMorbis]

Use the calculator that I linked you to. You only need two variables to use the calculate function. Enter the load resistance of say 8 Ohms for example into the (Z)impedance text field and then 25 watts into the (P) power text field and click calculate and voila it will calculate the current and voltage. Very nice calculator; saves lotsa time and effort and no mistakes to correct.

Ohm's Law | AE Techron

www.aetechron.com

I've used this a lot of times: https://www.rapidtables.com/calc/electric/ohms-law-calculator.html

 

[NoxMorbis]

Yes, that's how it is done. As @Blumlein 88 advised things will get loud at 25Watts.

Something must be wrong. I set up a 440kH sine and measured from the speaker outs on the amp, but it was only 2.9mV. I had to use the 200mV setting on the DMM to get anything. What measurement did I screw up?

 

[fpitas]

Something must be wrong. I set up a 440kH sine and measured from the speaker outs on the amp, but it was only 2.9mV. I had to use the 200mV setting on the DMM to get anything. What measurement did I screw up?

Wait...440kHz? Or Hz?

 

[Blumlein 88]

Something must be wrong. I set up a 440kH sine and measured from the speaker outs on the amp, but it was only 2.9mV. I had to use the 200mV setting on the DMM to get anything. What measurement did I screw up?

Don't know, unless you really used 440 khz. Was this reading all you could get even with volume up pretty good? Did you set the DMM for AC volts? Your number looks like a DC leakage number. Was the 440 hz tone plenty loud?

 

[Doodski]

Hmmz... As @Blumlein 88 stated the DMM might be on DC volts and not AC volts. 440 Hz should be in the bandwidth of the DMM but it is possible your meter does not have the capability to go to 440Hz. Are you sure the DMM probe wires are plugged into the voltage metering connection and not the current? What DMM are you using? I thought you where going to measure the speaker/load connection output current and then use that to set the wattage output.

 

[Doodski]

I've used this a lot of times: https://www.rapidtables.com/calc/electric/ohms-law-calculator.html

This is a nice calc. Thanks for linking that.

 

[sejarzo]

I'm not trying to see what it puts out maximum, though. I just want to see what relatively 25 watts-ish a channel sounds like going through my speakers playing a song. I'm not comparing it to anything else, just my ears. I'd have to somehow calculate how many amps = (app) 25 watts to the speakers so like yuo state about estimating amps, but not before clipping, but around 25 watts? 25 watts-ish is my target.

I'm not sure you are going to find out the answer you are seeking so easily.

You can fairly simply find out what the SPL is for a single tone at roughly 25 watts, but that's not at all like listening to music with dynamic peaks at 25 watts, or like listening to music at an average of 25 watts input to your speakers.

Speakers rated at 8 ohms are tested for efficiency using a 2.83 Vrms input voltage, which is equal to 1 watt power across an ideal 8 ohm load.

Let's assume you are driving a bookshelf speaker with a sensitivity of 88 dB. If you increase the input voltage to 14.1 Vrms, the voltage increase in terms of dB is about 14 dB, so you should expect an SPL of roughly 102 dB from that speaker, assuming no room gain, etc.

 

[NoxMorbis]

Wait...440kHz? Or Hz?

L 440Hz!!

 

[NoxMorbis]

Don't know, unless you really used 440 khz. Was this reading all you could get even with volume up pretty good? Did you set the DMM for AC volts? Your number looks like a DC leakage number. Was the 440 hz tone plenty loud?

AH I did set it to DC damnit! I know speakers have to have AC to work!!!! Be right back with the true reading! Thanks! You guys are awesome.

 

[sejarzo]

What sort of DMM are you using? I have read that the less expensive ones might not provide a proper RMS reading at anything other than 50-60 Hz because they are calibrated for homeowners who only want to check their mains voltage. Before I read that, I took my relatively cheap ones into work and compared them to the high-end Fluke that the electricians used, and they were within a volt or two--but I only was able to check them on nominal 120 VAC/60Hz supply voltage on the bench.

 

[sejarzo]

Hmmz... As @Blumlein 88 stated the DMM might be on DC volts and not AC volts. 440 Hz should be in the bandwidth of the DMM but it is possible your meter does not have the capability to go to 440Hz.

My inexpensive DMMs both read varying voltages when set on the 20 VAC range when connected the speaker inputs and I play music. OTOH I have no idea if the readings on music are all that accurate based on my other post.

 

[NoxMorbis]

I'm not sure you are going to find out the answer you are seeking so easily.

You can fairly simply find out what the SPL is for a single tone at roughly 25 watts, but that's not at all like listening to music with dynamic peaks at 25 watts, or like listening to music at an average of 25 watts input to your speakers.

Speakers rated at 8 ohms are tested for efficiency using a 2.83 Vrms input voltage, which is equal to 1 watt power across an ideal 8 ohm load.

Let's assume you are driving some bookshelf speakers with a sensitivity of 88 dB. If you increase the input voltage to 14.1 Vrms, the voltage increase in terms of dB is about 14 dB, so you should expect an SPL of roughly 102 dB from those speakers.

Who knows exactly what the speakers are. They are Klipsh R512-M with a stated sensitivity of 93dB, but I'm just doing a listening test. I just want to know that 25 watts-ish per channel sounds like. I'm going to listen to the speakers and watch the voltage of the DMM, then just do a quick average in my head. Then see what the calculator spits out for general wattage.

It may help if I say the reason is that I just bought the Aiyima 08 Pro, and while I like it just fine, I'm on the fence as to whether I should keep it, or return it for the new Topping MX3s. According to Hatto here, "The test [08 Pro] covers all power levels available, but A08 only clears the -80dB threshold for the 1-10W interval, while MX3s clears the -90dB threshold for at least the 2-23W interval."

He is getting his soon, so I hope he will test it and give his information before the 30 return window for my 08 Pro closes. The 08 Pro, does 75 watts per channel at "less than 1% THD. If I never listen to anything over 20 watts, there is no reason for me to keep the 08 over the Topping MX3s (It does 30W x2 at 1%). I do like the looks of the Aiyima 08 Pro though. I love the VU meter. But then I love the sleek look of the Topping MX3 also. I do not like Topping trying to get 200 bucks out of it. It was recently on sale for 169.00.

 

[NoxMorbis]

I couldn't get over .5 volt from the speaker posts and it was getting LOUD. I'm sure that reading is wrong.

 

[sejarzo]

Who knows exactly what the speakers are. They are Klipsh R512-M with a stated sensitivity of 93dB, but I'm just doing a listening test. I just want to know that 25 watts-ish per channel sounds like. I'm going to listen to the speakers and watch the voltage of the DMM, then just do a quick average in my head. Then see what the calculator spits out for general wattage.

It may help if I say the reason is that I just bought the Aiyima 08 Pro, and while I like it just fine, I'm on the fence as to whether I should keep it, or return it for the new Topping MX3s. According to Hatto here, "The test [08 Pro] covers all power levels available, but A08 only clears the -80dB threshold for the 1-10W interval, while MX3s clears the -90dB threshold for at least the 2-23W interval."

He is getting his soon, so I hope he will test it and give his information before the 30 return window for my 08 Pro closes. The 08 Pro, does 75 watts per channel at "less than 1% THD. If I never listen to anything over 20 watts, there is no reason for me to keep the 08 over the Topping MX3s (It does 30W x2 at 1%). I do like the looks of the Aiyima 08 Pro though. I love the VU meter. But then I love the sleek look of the Topping MX3 also. I do not like Topping trying to get 200 bucks out of it. It was recently on sale for 169.00.

OK, but I am still confused by what you want to learn here. A constant tone at 25 watts RMS into just one of those Klipsch speakers would generate around 107 dB SPL at 1 meter, and that would be a typical peak for a lot of contemporary music but only if you listen at an average level of perhaps 88-90 dB...which is LOUD.

 

[sejarzo]

I couldn't get over .5 volt from the speaker posts and it was getting LOUD. I'm sure that reading is wrong.

Depends on how close you were sitting to the speaker. Do you have any way to measure SPL--even a phone app would get you at least in the ballpark.