Audio watt meter for speakers?

[Raxumit]

I would like to know how many specific watts I'm using on my various speaker setups, in real time, measured. I can't find any simple "audio watt meter". Would it be possible, for example, to hook up one of these with banana plugs, and run it inline while listening to music?

https://www.amazon.com/Precision-Analyzer-Consumption-Performance-Backlight/dp/B0B8VWNY9X/ref=sr_1_9

I sincerely apologize if this is too rudimentary a question. I've searched the internet on and off for a few days, and can't find anything that looks anything like a definitive answer, one way or another.

 

[AudiOhm]

If the music is at a level that you enjoy and you measure the wattage at your speakers and you found out that it was exceeding 1,000 watts what would you do?

1.) Stop playing your music?
or
2.) Enjoy your music?

Why worry...

Ohms

 

[GXAlan]

That looks like it only measures DC watts.

A simple multimeter can measure AC voltage and then you can do v^2/nominal impedance to get an estimate of wattage.

The other option is splurging on this

MPM4000 Big blue meters!

I got my MPM4000 Big Blue Meters in yesterday. Well, they are not exactly big, but they are blue, and definitely cool. They are the same size as a car radio. They are made for car audio, but they will work with any amplifier. You just need to provide 12 volts to it. I used a wall wart...

audiokarma.org

 

[Raxumit]

If the music is at a level that you enjoy and you measure the wattage at your speakers and you found out that it was exceeding 1,000 watts what would you do?

1.) Stop playing your music?
or
2.) Enjoy your music?

Why worry...

Ohms

To answer your question, I'd keep listening for sure.

In all the amp discussions on this forum there's a lot of discussion about where distortion starts, how many watts are usable, etc. I sincerely doubt I'm pushing any but my smallest of chip amps. Still, I'd like to know.

 

[Mr. Widget]

I would like to know how many specific watts I'm using on my various speaker setups, in real time, measured. I can't find any simple "audio watt meter". Would it be possible, for example, to hook up one of these with banana plugs, and run it inline while listening to music?

The problem is that speakers are not simple resistors. They present a complex AC impedance to the amplifier so any speaker level "watt meter" including those built into amplifiers are only approximations at best.

I have seen LED bar display kits that would give you a close approximation to the actual power being drawn once you calibrate it to much the load of your speakers.

 

[JSmith]

I can't find any simple "audio watt meter".

Go oldschool...

Vintage Radio Shack Realistic Audio Power Meter APM-100 -UNTESTED | eBay

Find many great new & used options and get the best deals for Vintage Radio Shack Realistic Audio Power Meter APM-100 -UNTESTED at the best online prices at eBay! Free shipping for many products!

www.ebay.com

JSmith

 

[Blumlein 88]

Amir gave it a no recommendation. It slightly worsened distortion. I don't know if it would be audible (I think not). However you could use it for a time to convince yourself of what power was needed by your amp and then take it out of the system. A bit much for that, but up to you.

Douk VU3 Review (VU Meters)

This is a review and detailed measurements of the Douk / Little Bear VU3 dual analog VU meter and 2-way amplifier/speaker switcher. It is kindly sent to me by testing by a special member. VU3 costs US $140 from Amazon including Prime shipping. The VU meter are the "paper back" ones which I...

www.audiosciencereview.com

BTW, you can use a multimeter measuring voltage with a peak hold function and find out the max voltage and get some approximation of power that way. A few tutorials on the internet about how to do that.

 

[AudiOhm]

If you are going to measure the voltage at the speakers, you can use an AC amp probe to measure the current, then a simple calculation...

Ohms

 

[HarmonicTHD]

To answer your question, I'd keep listening for sure.

In all the amp discussions on this forum there's a lot of discussion about where distortion starts, how many watts are usable, etc. I sincerely doubt I'm pushing any but my smallest of chip amps. Still, I'd like to know.

The suggested multimeter approach is the best to get some accurate numbers.

However, to give you an idea of a ballpark figure, which might already give you your desired answer, you could calculate backwards and approximately measure (eg with your phone) the SPL at your listening position and plugging this into one of these SPL calcs and solve for the power (just keep plugging in values until you are close).

Peak SPL Calculator

It will show you how little power you actually need (P RMS) to get it pretty loud eg to 80dB SPL on average. However if you consider peak power and a worst case of 20dB crest factor for music (pop rock has much less) the power requirements go up by factor 100.

Again. Multimeter especially with amp probe is the way to go if you want it accurate.

 

[Raxumit]

Thanks to all who responded. So, it took a bit, but I finally bought a clamp amp meter and did some measurements. I would appreciate a sanity check here - I might be mis-using my measuring tools.

For a 30 second section of a bassy electronic track, I'm coming up with the following numbers:

0.228 A (peak)
2.1 V (peak)

That works out to:

0.4788 watts at 9.21805 ohms.

This is getting me the following peak measured volume (phone app):

77 db @ 17 feet
83 db @ 8 feet

My speakers are pretty sensitive, but do I really only need half a watt to get to loud (80 db?).

If there's an error here, let me know where you think it might be.

 

[RayDunzl]

My speakers are pretty sensitive, but do I really only need half a watt to get to loud (80 db?).

Maybe, on average.

 

[Chrispy]

Thanks to all who responded. So, it took a bit, but I finally bought a clamp amp meter and did some measurements. I would appreciate a sanity check here - I might be mis-using my measuring tools.

For a 30 second section of a bassy electronic track, I'm coming up with the following numbers:

0.228 A (peak)
2.1 V (peak)

That works out to:

0.4788 watts at 9.21805 ohms.

This is getting me the following peak measured volume (phone app):

77 db @ 17 feet
83 db @ 8 feet

My speakers are pretty sensitive, but do I really only need half a watt to get to loud (80 db?).

If there's an error here, let me know where you think it might be.

What are the speakers?

 

[Sokel]

Get a new Ice power edge module,they have amp and voltage analog meters (scaled) right on the outputs,you only have to connect a proper display to them (even VU meter style! )

 

[Raxumit]

What are the speakers?

I linked to them above, DIY Zaph SR-71s I built.

Zaph|Audio - ZA-SR71

 

[Raxumit]

Maybe, on average.

Thanks Ray, that's a very helpful graph!

Is it just derived from two input values, Speaker Sensitivity and Ohms? Wouldn't mind a source if it's an online calculator somewhere.

 

[sergeauckland]

I think the issue here is that all the VU meter type power indicators show average power, whilst what you want, I presume, is an indication of peak power. You therefore need a True-Peak reading instrument, or at least a Type 1 PPM, which will indicate the peak voltage and that can be calibrated in Watts on 8 ohms, or whatever the nominal rating of your loudspeakers.

However, this will indicate what the amp is putting out in volts, not what the loudspeakers are dissipating, which will be different due to the loudspeakers' impedance characteristics.

S

 

[Blumlein 88]

Hey with 500 watts you can play your speakers at 110 db (maybe).

 

[RayDunzl]

Is it just derived from two input values, Speaker Sensitivity and Ohms? Wouldn't mind a source if it's an online calculator somewhere.

Ohms law applied to a spreadsheet.

The sensitivity is stated as 85dB at 1 watt for 8 ohms above

The other values are derived from that.

 

[DVDdoug]

Audio watt meters are not a common thing. They are also very rare on amplifiers. It would be fairly cheap for a manufacturer to add one but then they might sell fewer high-power amplifiers..

Someday I might build one for myself with an Arduino. (I made a "giant VU meter" but it's just an LED effect that goes up & down with the loudness and it doesn't measure anything useful.)

Normally we want to know the peak power because we want to know if we are clipping, or nearly clipping, the amplifier.

Usually you'd just measure the voltage and then calculate based on the nominal speaker impedance ("assuming" the actual current). There's nothing "hard" about that but most standard measurement equipment isn't designed to do it.

https://www.amazon.com/Precision-Analyzer-Consumption-Performance-Backlight/dp/B0B8VWNY9X/ref=sr_1_9

No. That's not going to work with audio to a speaker.

An old-style electro-mechanical multimeter will do a pretty good job of measuring average RMS voltage with the readings smoothed-out by the mechanical inertia. Digital multimeters are also designed for continuous-constant voltage (or current) and they are unpredictable with audio program signals.

An oscilloscope can measure the peak voltage but a "decent" scope costs a few hundred dollars (or more).

 

[Raxumit]

Hey with 500 watts you can play your speakers at 110 db (maybe).

Amir measures N252MP based amps at 105 good watts it looks like, so I guess I'm good to over 103 dB going by Ray's graph. I don't need more than 90 dB like, ever, so I think I'm fine.

Sokel: Get a new Ice power edge module,they have amp and voltage analog meters (scaled) right on the outputs,you only have to connect a proper display to them (even VU meter style! )

That sounds nifty. I'd love to see a demo.

It would be great if Hypex/Purifi/etc. all put some values readable on an IO pin that OEMs and DIY tinkers could use for display/logging. I can dream.