A Test. How much Voltage (power) do your speakers need? - Page 37 - diyAudio
 A Test. How much Voltage (power) do your speakers need?
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 Multi-Way Conventional loudspeakers with crossovers

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 View Poll Results: I measured the test tone at: 2 volts or less 206 38.08% Between 2-5 volts 177 32.72% Between 5-10 volts 71 13.12% Between 10-20 volts 37 6.84% Over 20 volts. 50 9.24% Voters: 541. You may not vote on this poll

diyAudio Member

Join Date: Oct 2002
Location: England
Well as to the number of pages it depends on your forum settings, this one only reaches 8 pages for me

The original poster was Pano though, he created this thread and it's his test and it is valid^>^

Quote:
 Oh hang on.....I thought this thread about a simple test everyone with a VM could carry out.
You can though. What is it you think you can't do?
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Join Date: Oct 2004
Location: Gulf Coast
Blog Entries: 4
Quote:
 Originally Posted by GM What do you calculate doing it your way and what formula did you use to calculate the theoretical voltage level at 85 dB?
Hard to say GM, the test isn't designed that way. Please see 5th Element's post above.

Basically you are doing this.
2. Play a test tone and measure its voltage
3. Calculate from the tone your maximum voltage level
That's all there is to it. There is no SPL target, no measuring of average loudness. It's simply a way to measure the max voltage you ever use.

Now, if for some reason you want to set pink noise at 85dB, I could supply a signal - if you supply the SPL meter. But how do I know where to set the level of the pink noise? At -12dB? -24dB? Somewhere else? My guess would be about -14dB as this is a common mastering level for the loud parts of well recorded music. But it's not universal.

So why not set the level with music at the loudest point you are comfortable with - which you say is 85dB (similar to a lot of folks) - and then do the test. If you have really set the volume to as loud as you like it on a good choice of several dynamic tracks, you will probably be close to 85dB. It doesn't matter if you aren't exactly at 85dB because you are at the loudest setting you like, by ear. That's how you determined 85 dB anyway, right? You measured music that you found by ear to be as loud as you like.

diyAudio Member

Join Date: Dec 2003
Location: U.K.
Quote:
 Originally Posted by 5th element You can though. What is it you think you can't do?
Oh no, I can do the test and will shortly with 12LTA's and maybe some Minimus 7's and I have a pair of kef uni-q's about the place somewhere.

The test is easy and valid - 2 points apparently lost on some

BTW is it 4am where you are? Me? I'm 45hrs without sleep and counting... snow is pretty though
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Join Date: Oct 2004
Location: Gulf Coast
Blog Entries: 4
Quote:
 Originally Posted by JRKO Any earnest mind has to battle through 30 odd pages of turd for a just a handful of measurement posts.
Naaawww.... Just look at the poll results.

As I predicted, things went well when it was about voltage. When I brought power into it, things went pear shaped. There are so many preconceived ideas about audio power that it was bound to get messy. No big deal. All I really want is for people to get an idea of what voltages they are actually using, and how that might compare to others. I really don't give a damn how much power anyone uses.

Just as a note, this measurement grew out of my trying to figure out how much voltage I needed to run my Altec horns with an active crossover. Could I use a single tube gain stage - say an EL84 in SEP mode, and get enough voltage out to drive the horns? Answer - yes (just). Can I drive the woofers loud enough with it? Answer - No. Power was not my worry, I know that an EL84 has enough for the horns. I was just interested in getting enough voltage.

Once you know the voltage you need, then you can figure out other things if they are important to you, things like power and amperage.

 5th February 2012, 04:56 AM #365 diyAudio Member     Join Date: Dec 2003 Location: U.K. its just a shame - your test is so simple and instead of being some hypothetical/standardised/extrapolated numbers its relevant to MY speakers in MY room with MY equipment MY music and most importantly MY ears!!! Naysayers be damned - how much more relevant could it be? __________________ If I'm not making noise, I'm making something to make noise
diyAudio Member

Join Date: Oct 2002
Location: England
Quote:
 Originally Posted by JRKO Oh no, I can do the test and will shortly with 12LTA's and maybe some Minimus 7's and I have a pair of kef uni-q's about the place somewhere.
I look forwards to seeing the results

Quote:
 Originally Posted by JRKO BTW is it 4am where you are? Me? I'm 45hrs without sleep and counting... snow is pretty though
Well 5am now

Quote:
 Originally Posted by Pano Naaawww.... Just look at the poll results. Just as a note, this measurement grew out of my trying to figure out how much voltage I needed to run my Altec horns with an active crossover.
It's funny how we both started doing this for similar reasons with similar systems I guess this happens though when you've got the luxury of hand picking an amplifier for a given driver.

Quote:
 Originally Posted by JRKO its just a shame - your test is so simple and instead of being some hypothetical/standardised/extrapolated numbers its relevant to MY speakers in MY room with MY equipment MY music and most importantly MY ears!!! Naysayers be damned - how much more relevant could it be?
Yes exactly and this is why this thread interests me so much too. People often quote SPL figures that your system should be able to reproduce and then often quote the ridiculous amounts of power you will need to get there. Most people though it seems simply don't listen as loud as these figures claim, or at least don't listen to music that actually requires the system to hit 105dB peaks with an average listening level of around 85dB.
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What the hell are you screamin' for? Every five minutes there's a bomb or somethin'! I'm leavin! bzzzz! Now with website! www.5een.co.uk under construction.

diyAudio Member

Join Date: Mar 2004
Location: At the output stage
Quote:
 Originally Posted by GM I've said nothing of the sort! Please don't put words in my mouth!
with all due respect, it's you who doesn't understand that it's basically what you're saying only put another way.

Quote:
 Originally Posted by GM Regardless, it shouldn't be unrelated! That's the point!GM
yes it will be unrelated. Pano's way will give exactly this:
Vout(cd) * gain

where:
Vout(cd) = the maximum voltage your CD player outputs
gain = your amp's gain (including the division factor caused by the position of the volume pot that gave your required SPL)

if the signal peaks are at 0dBfs you'll get exactly 12.6V (20W into 8 ohms). if they are below you'll get a larger number. different numbers. this is basic arithmetics. you are introducing unknown independent variables in the equation.
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diyAudio Member

Join Date: Mar 2004
Location: At the output stage
Quote:
 Originally Posted by 5th element Yes exactly and this is why this thread interests me so much too.
I wonder why no-one thought about it before. this is very informative. my levels are well within the majority as of today.
the reason why I hang out so much here is that I did the exact same test a while back and TBH the result (20-30W) surprised me. but fortunately I know since then that I don't need a kilowatt amp.

Quote:
 Originally Posted by 5th element People often quote SPL figures that your system should be able to reproduce and then often quote the ridiculous amounts of power you will need to get there.
old wives tales and cockeyed theories as fact... where did I hear that before? oh and a lot of marketing I would add.

the only objection to Pano's way I have is that it doesn't account for one thing: recording headroom. if a recording has a large headroom (like many but NOT ALL audiophile recordings) the resultant power will be actually larger.
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Quote:
 Originally Posted by mr_push_pull the only objection to Pano's way I have is that it doesn't account for one thing: recording headroom. if a recording has a large headroom (like many but NOT ALL audiophile recordings) the resultant power will be actually larger.
Well it's supposed to take that into account, it's just a little hard to police. Since I don't have any good music demo tracks that I can legally upload here, we have to let the end users pick from their own music library. Hopefully folks will take the time to pick some dynamic tracks and figure out their highest volume setting.

For those of you who like to work to a set standard, SMPTE and the EBU these days agree on 85dB, C weighted, slow for Pink noise recorded at -18dBFS RMS. You could playback a -18dB pink noise, set your volume control so that you measure 85dB and call it good. If you want to know what the peak voltage is at that calibrated level, you could then play back a test tone (mine, or some other) and measure it. Same results as my test, but you have set your level to a SMPTE/EBU standard via an SPL meter instead of by ear.

The big problem with that is that there is no CD mastering standard. They don't follow SMPTE guidelines. And I can guarantee you that -18dB pink = 85dB at your chair is going to be LOUD on most CDs in domestic settings. Try it, if you don't believe me.

 5th February 2012, 06:27 AM #370 Sin Bin   Join Date: May 2008 Location: Front Row Center I did just before running the warble tone ......

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