A Test. How much Voltage (power) do your speakers need?

I measured the test tone at:

  • 2 volts or less

    Votes: 334 40.6%
  • Between 2-5 volts

    Votes: 252 30.7%
  • Between 5-10 volts

    Votes: 106 12.9%
  • Between 10-20 volts

    Votes: 55 6.7%
  • Over 20 volts.

    Votes: 75 9.1%

  • Total voters
    822
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Yes, somewhere in the thread. :)

Basically you would do the same as the normal test except that you need tones that are well within the bandpass of each of the ways. I have posted a few, but they might not be exactly what you need. If you ask, I can make and post other tones.

If measuring an active crossover system, it's often wise to turn off any EQ or to pick test tones that fall into a range where you know what the boost is. That way you know better what is going on across the range of frequencies covered by that section or way. An important thing to consider is that music falls off pretty fast up top, so it's not likely that you would ever see the same voltage at 10 kHz that you would at 1200 Hz. Meaning that it would be best to measure a tweeter (or mid) at the lowest point you can, but also where the crossover is not effecting the measurement.

Woofers are easier, as the peak power is usually around 50Hz for most genres. Again, if you have any EQ boost, you need to take that into account. For example; if you have a 12dB boost at 70Hz, then 70Hz will need 4X the voltage used in the range with no EQ. Since passive crossover have their EQ built in, and you are measuring up stream of the crossover, there isn't much need to worry about the EQ in the crossover. But with active crossovers, you are measuring downstream of the EQ and filters. It's very important to take that into account.
 
Hi Pano,

thank you for the reply.

I am confused by your recommendation to disable all the EQ. My understanding was, that the purpose of the test was to measure the system as it is set up for listening. But, perhaps I am wrong and have to re-read the beginning of the thread.

The reason why I became interested was that I measured a wave-guide with a musical signal (Carmen Suite), and was shocked by the low RMS volage.

Kindest regards,

M
 
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Well yes, the EQ thing is tricky. Do you measure with it and pick the test tone frequencies appropriate to the EQ, or do you turn off the EQ and do the math to take into account the EQ? Either would work, but doing the calculation means that you don't have to be too picky with the test tone frequencies.

Like your waveguide measurements, I recently measured some Altec hones with BMS drivers that I use for a PA system. The RMS voltage was perplexingly low in an amphitheater that seats 2600. But we don't do rock and roll levels, more like TV and cinema SPLs. The sub woofers need a much higher voltage, of course.
 
Hi Pano,

Do you measure with it and pick the test tone frequencies appropriate to the EQ, or do you turn off the EQ and do the math to take into account the EQ?
Aha, here is, as Dr Faust quipped “So that was the poodle's core!”, or this is the crux of the matter.

The RMS voltage [of the Altec horns with BMS driver] was perplexingly low. . . . The sub woofers need a much higher voltage, of course.
It is this discrepancy that prompted my question.

Kindest regards,

M
 
Speaking of measuring multi-way active speakers, I did a measurement almost by accident at the other end of the system.
I’d better explain a bit! I’d brought my 3 way quad amped towers in to the house for some in room testing. I powered both speakers and the preamp from a remote controlled power plug so that I could switch them all on and off together since the preamp does not have a mute relay in yet. These plugs report power use every minute or so. I noted that the idle power use was 46 watts. There are 8 TDA7293 amps with 4 each side, 2 bass , 1 mid and 1 treble. The speakers are slim and only have 5.25 drive units so I use a Linkwitz Transform to bring the bass up.
I played a few tunes at normal/moderate volume and noted that the power consumption went up to around 57 watts from time to time, so roughly an extra 10 watts, or 5 watts per side. Since the LT is very power hungry, I’d estimate that around 4 to 4.5 watts was just bass and that the mid was around 1 watt.
So time for some fun! Let’s turn it up!
I played some Pink Floyd and The Who and manger to see peaks at around 120 watts. This was VERY loud! I then played a track by Maggie Rogers, “Different kind of world” which at first sounds like girl and guitar folk, but she lets rip later in track and brings in electric guitar and a powerful bass guitar line that is quite deep bass. The power reading shot up to 260 watts! It nearly shook the sofa to bits! I was delighted that everything held together well and there was no obvious distortion at that level. That level is ridiculously above what I would normally use and was a fun experiment!
However going back to the premise of this thread, it does seem reasonable that only a few watts are needed for normal domestic listening even with the hit from the Linkwitz Transform and active baffle step compensation.
 
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Thanks for that. I used to have one of those inline power meters and made good use of it. I measured just about all the AV gear at work and made a list of how many amps each device drew. With that is was easy to figure out how much power we needed on a show.

I have thought about doing what you did, measuring the mains power used by the amps and subtracting the idle current. It seems like a logical approach. The only tricky part (I think) is catching peaks. Since the refresh rate on the power meters isn’t very fast, some peaks might be missed. But you did seem to catch yours.
 
Thanks Pano.

It is one of these: https://www.hivehome.com/guides/hive-sensors-and-plugs .

There is no spec on exactly what it measures, I suspect it is a short term average that is reported every minute or so.

Without hooking up my scope to something, I'd find it easy enough to believe that the power was an average power. I run the speaker from a 28V transformer giving me around +/- 40V at idle. According to the 7293 spec sheet that should give me up to 80W RMS per amp if the power didn't sag. That looks like a very short term power output of 320W per speaker at peak volume, but of course the treble and midrange power will be a fraction of what the bass drivers get. The power transformer is only 250VA so it does sag rather a lot when pushed and I suspect I'd only get about 40W per amp all channels driven at full power before the transformer and heatsinks overheat!

Since going really loud wasn't and isn't a requirement (other than I wanted plenty of headroom for loud peaks and to provide aircover for the bass equalisation). In testing at normal to moderately loud levels neither the transformer or heatsinks get too hot and as these are built for my own use rather than for sale I am comfortable with what may be perceived as as rather underspecified power transformer. It also keeps the size down, these cabinets are only 15cm wide and the Monacor SPH-135C carbon fibre midbass units barely fit between the side walls!

I plan to build some rather larger cabinets based on the same ESP crossovers as here but using some Peerless 10" basss units and I have a few blameless amps/ P3A and MX50SE to play with for amplification. Given the higher efficiency of the 10" units and the lower requirement for EQ, it may be that they will actually need less power for the same or higher volume.

I think my experience can be treated as "anecdotal" rather than "scientific" data, but it did at least give me a feel for the power use under different conditions so I was very happy with that.
 
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Can you please help me with the calculation. I have always been confused coz sometimes I would get 1V, 2V, 5V as reading. Now I understand why that happens.

My AVR volume control starts at - 80db. Using external amplifier using preout.

1. Spotify mp3 music at - 6db on volume control, maximum measured voltage using tones - 3.2V

2. FLAC music, around -21db, maximum measured voltage using tones - 1.88V

How many watts single speaker is actually consuming.

Thank you
 
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Different sources and type of music need different volume levels.

At -21dB 0.5V max(test tone)
At -14dB 1.25V max(test tones)
At -6dB 2.8V max(test tones) and 3.4V max(with music).

Need to know how many watts am I consuming at each of these volume levels, please share formula.

As for sources

Spotify free playing through Nvidia shield HDMI > AV receiver > Preout > External Amplifier

FLAC through DUNE media player HDMI > AV receiver > Preout > External Amplifier

I am no expert, but I believe it's the music. No volume control on devices.
 
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If you never go above -6dB on your volume control, then you would need amp rated at 8 watts into 8 ohms. But you might be more comfortable with 15-25 watts.

Caveat: If you have turned down the volume in your digital player, then we don’t know your highest possible level. But if your current settings and -6dB is as loud as you ever play, then you should be OK.
 
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