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Who wants to measure how much power (voltage) is REALLY needed?

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I came across this really terrific thread about measuring just how much power is needed for a given listening level.  Looking at the results, and knowing that most of the participants are not using speakers nearly as efficient as ours, I thought it might be fun to try duplicating the experiment here. New forum member Albert Zinski has graciously offered to oversee the thread and help clarify/answer any questions which come up.  I publicly thank him in advance as I simply don't have time right now to be on the computer for more than a few minutes here and there:

 

http://www.diyaudio.com/forums/multi-way/204857-test-how-much-voltage-power-do-your-speakers-need.html

 

 

I suspect that it is going to come as a big surprise when folks discover that they don't need 500 wpc to their K-horns for even extremely loud levels!

 

 

Maynard

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I am using around 10 watts... and I can barely turn the line stage to 55%~65% of max.

 

Home theater is different.

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Nobody wants a car with a 600cc motor in it (OK some guys like skate boards). We want big block muscle cars. What we need is a different topic. 

 

 

P.S. I'm happy with my 25 watt tube amps. 

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Would it have been better to use a db point like 100 db or more, instead of really loud or before distortion ? Wouldn't it be a better starting point for comparison ?

 

It seems I must have missed something along the line

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Heard some Altec A7s outside that were using millivolts, and it was loud enough,,,,

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I have been using a 2 wpc amp for years on my khorns and it will run you right out of the house if let it. I barely ever use more than 1 watt and reach levels that are more than enough...

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8 hours ago, dtel said:

Would it have been better to use a db point like 100 db or more, instead of really loud or before distortion ? Wouldn't it be a better starting point for comparison ?

 

It seems I must have missed something along the line

The nice thing about the test is that the spl doesn't matter.  Simply use your ears to determine the absolute loudest level at which you will listen.  It can be 100 db, or 130 db.  We all know when we simply can't take any more!  After making that determination, don't touch the volume control.

 

The guy who devised the test is very clever as it makes use of the fact that a digital source will provide its maximum output voltage at zero db.  No matter what the recording contains, zero db is the limiting factor for how much voltage the source will provide.  And we don't have to worry about speaker impedance (more on that in the future).  

 

To make things easier, perhaps one of the "digital" guys can record a 120 Hz sine wave at -12 db and post it on here (15 seconds in length should be enough).  It should be possible with Audacity, or a free online download.  

 

Most importantly, the test must use the same source device for both the music and test tone.

 

Some clarification about what is going on can be seen in posts 151, 161, and 171 in the linked thread.

 

 

Maynard

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"loud enough" is only one of many criteria for a great listening experience.   Sure it can be loud enough but can be lacking in other ways.   Isn't this like describing an elephant by only saying how tall it measures?  To follow the HP analogy I'd say I about got killed trying to pull into traffic driving my Dad's 45hp diesel Volkswagon but hey, it got up to 55.  It would do over 70 down hill so it was more than enough right?

I'm sounding pretty critical but I actually am interested in these results... I just saw all the pages of replys... I guess I have some reading to do.

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Maynard has answered the only question I see so far. I have been traveling and haven't checked in lately so I do apologize.

 

The appeal of this speaker voltage test is in that anyone can do it without special equipment, most of us have a cheap multimeter laying around. For the curious person it just gives you a reference to know roughly what power is required for your listening taste.

 

You need to use the same digital source for the listening session and the measuring session.

 

 

'well what about headroom for transients?'

 

 All you SS fans know that clipping your transistor gear can not only sound horrible but can also damage your speakers. The first answer is if you listen to digital music especially from the same source it cannot go past 0db so no need to worry about headroom, what you calculate for voltage at 0db is the maximum your digital source can produce. If you have analog sources that you also like to listen to you may want to give some cusion for headroom. It all depends, if you listen loud a lot and have SS gear then it's probably best to have some headroom. If you don't listen to loud a lot then it's less of an issue.

 

Feel free to just do the listen test and the measuring test and post your voltage readings along with what speakers you are using, either Maynard or myself can do the rest. It's a fun excerise to take part in.

 

Enjoy.

 

 

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9 hours ago, wdecho said:

...but why buy a 600 hp engine and drive only 55 mph... 

Cause you can get up to 55mph, really quick.:)

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17 hours ago, russ69 said:

Nobody wants a car with a 600cc motor in it (OK some guys like skate boards). We want big block muscle cars. What we need is a different topic. 

 

 

P.S. I'm happy with my 25 watt tube amps. 

I don't like motorsports analogies because there is always more than one way to skin a cat. Stick 600cc's into a 300lb vehicle or motorscooter and you got a fun little ride. Even a 1000cc's in a smart car and you have something to blow almost any car off the road.

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I will do the test later today.  It's got my curiosity.

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I was testing my home made horns with a sine wave in a garage. 

Putting in 2.82 volts measured with a meter at the input terminals which is nominally 1 watt.  Disaster.  It was unbearable to stay in the room. About 103 dB

Putting in 0.89 volts, nominally 0.1 watt was painful.  About 93 dB.

Putting in 0.282 volts, nominally 0.01 watt was loud.   About 83 dB

 

One reason not to use monster amps is that the 1st watt is where we listen, at best.  I suspect that 100 watt amps may have distortion down there.

WMcD

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Hey Maynard, 

 

I have a HP 400 EL volt meter.  I'll admit I bought it on a lark and know very very little about it.

 

Could I use it to see how many volts are being supplied at a given time to a speaker?

 

If so, would I attach the leads to the BARE speaker wires (speaker not attached) or, would I attach it to where the speaker leads are attached to the crossover?

 

(what about the Jube's which are actively biamped....?)

 

I tried about a week ago to play around with it....tried to attach it to the inputs of my LaSCalas.  I noticed that when I put the negative ground on the speaker, there was a small (very small but perceptible) "arc".  I hate calling it a spark....but I guess it was.

 

Anyway, the sound level blipped up just a tad too....just enough to notice it got a bit more loud.  No distortion or ugly 60 Hz causing any issues (it wasn't dumping wall power into the speaker)

 

Once i noticed the arcing, I decided I didn't know enough about what this did and how to properly do it.....so I stopped and put it back into the garage.

 

What can I do with that thing? (as in what type of playing around, not how to dispose of)

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3 hours ago, WMcD said:

One reason not to use monster amps is that the 1st watt is where we listen, at best.  I suspect that 100 watt amps may have distortion down there.

WMcD

Just thinking about how amps are made, this seems odd.  I would suspect that most have their highest distortion nearing max power.  I think it would be hard to construct an amp to do well after the first several watts and get better higher up.  I am a novice in amp construction and would love to hear more discussion.  I am a believer that most of us don't need mega watts and the common talk about the speakers came to life after I added a 200-300 watt amp are related to other factors and not watts.

 

For a given room and listening level, I do think there is an optimal volume which takes X amount of power.  Now with tube amps, it comes down to reaching a certain saturation level to get the harmonics flowing.

 

I did the test and was less than 2 volts.:huh: at -20 MV on the avr.  Most of the power being used on my power console is just the operating power.  The power console had a net change of 0 or no volume to -20 and went up by for 4 watts.  Minuscule at best.

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8 hours ago, derrickdj1 said:

Just thinking about how amps are made, this seems odd.  I would suspect that most have their highest distortion nearing max power.  I think it would be hard to construct an amp to do well after the first several watts and get better higher up.  I am a novice in amp construction and would love to hear more discussion.  I am a believer that most of us don't need mega watts and the common talk about the speakers came to life after I added a 200-300 watt amp are related to other factors and not watts.

 

For a given room and listening level, I do think there is an optimal volume which takes X amount of power.  Now with tube amps, it comes down to reaching a certain saturation level to get the harmonics flowing.

 

I did the test and was less than 2 volts.:huh: at -20 MV on the avr.  Most of the power being used on my power console is just the operating power.  The power console had a net change of 0 or no volume to -20 and went up by for 4 watts.  Minuscule at best.

I believe most distortion measurements include noise.  The noise ratio gets higher as the power increases.  I believe that is why a lot of distortion measurements start higher, tail down lower as power increases and then go into high distortion when power supply and output devices have reached close to maximum.  If the noise is very low, it likely doesn't matter against the low output.

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I've read the First Watt concept and reviews.  I can't seem to lay my hands or thought on what they did to make the first watt better than many other amp.  Sure, noise floor and a few other things make a difference in the amp but, this is not like other amp makers don't take this into consideration. NP would want a single driver speaker for ideal operation but, at least in this forum, most of the people buying into the concept have 3 way speakers.  I am trying to be the devil's advocate to generate discussion.

 

The discussion as two very contrasting points, 1.) we don't need much power for near 100 db sensitivity speakers and 2.) what drives the claim that the high watt amp really opened up the speakers.  These two view are about as far apart as you can get concerning audio amplification.

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10 hours ago, John Albright said:

Here are the test tones. 

 

220Hz test tone.zip

120Hz test tone.zip

John, thanks very much for posting the tones.  I just burned a CD and will run the measurements myself over the weekend.

 

Guys, you really need to give this a try!  It will truly dispel the myth that most Klipsch speakers need huge power when played very loudly.  If you look at the tabulated data on the DIY thread, many of the guys who indicated needing 2V or less are using far less efficient speakers than what we enjoy here.  If we can get enough folks to actually try this, we can try to set up a similar tabulation, and I suspect that we are going to need categories for 0.5V or less, 0.5-1V, 1V-1.5V, and 1.5V to 2V. Let's see if my suspicion is correct.  

 

By working with voltage calculations (which are then converted to power), and the absolutes of the digital domain, we can get a reasonable sense of how much power is needed to satisfy our listening requirements.  And, remember, you can run the test at all different volume levels.  Try it at the absolute limits of your tolerance, and also try it at your typical listening levels (which I assume will be somewhat lower).

 

If the data proves out as I expect it will, it will open up many new amp options.  Just think, instead of spending a huge fortune for monster power amps, you can put that money into lower power amps which offer better sound quality.  This is something which even the SS guys can appreciate, I'm sure.

 

 

Maynard  

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On 5/11/2017 at 6:13 AM, derrickdj1 said:

I've read the First Watt concept and reviews.  I can't seem to lay my hands or thought on what they did to make the first watt better than many other amp.  Sure, noise floor and a few other things make a difference in the amp but, this is not like other amp makers don't take this into consideration. NP would want a single driver speaker for ideal operation but, at least in this forum, most of the people buying into the concept have 3 way speakers.  I am trying to be the devil's advocate to generate discussion.

 

The discussion as two very contrasting points, 1.) we don't need much power for near 100 db sensitivity speakers and 2.) what drives the claim that the high watt amp really opened up the speakers.  These two view are about as far apart as you can get concerning audio amplification.

Power demands for audio are not linear.  That's why we spend most time under one watt, why most dynamic range is realized in the first watt, and also why copious power may be required.  Think of the crest factor of music, since that's what we listen to, and the dynamic power required to reproduce it.  +3db requires doubling of the power, +10db requires ~10x the power, +20db requires ~100x the power, and for those classical and opera fans, +30db requires ~1000x the power.  If your average levels are 0.1 w or so because you use high sensitivity speakers, most amps will produce the 10 watt (+20db) peaks easily.  Start with less sensitive speakers, however, and you very quickly run into needing ridiculous amounts of dynamic power, even at moderate levels.

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