A Test. How much Voltage (power) do your speakers need? - Page 18 - diyAudio
Go Back   Home > Forums > Loudspeakers > Multi-Way

Multi-Way Conventional loudspeakers with crossovers

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
View Poll Results: I measured the test tone at:
2 volts or less 141 37.50%
Between 2-5 volts 129 34.31%
Between 5-10 volts 49 13.03%
Between 10-20 volts 21 5.59%
Over 20 volts. 36 9.57%
Voters: 376. You may not vote on this poll

Reply
 
Thread Tools Search this Thread
Old 30th January 2012, 01:50 AM   #171
diyAudio Member
 
5th element's Avatar
 
Join Date: Oct 2002
Location: England
Yes Tom, but the point here is that peak power and apparent loudness don't come into it. The sine wave replayed at 0dB is the absolute maximum, by definition, that the system will be called on to reproduce. If you set your volume control such that the amplifier isn't clipping when a 0dB sine wave is being played, then no matter what music, or type of signal you feed the system afterwards, the amplifier will then never clip due to voltage limitations.

One sets the volume control based off of what they consider to be loud with their chosen piece of music. They then play a 0dB tone through the system as this represents the absolute maximum that any transient played at that volume setting could reach. If the amplifier isn't clipping, or the measured output voltage falls within the output spec of the amplifier, then no matter what music they then play, providing they don't advance the volume knob, the amplifier wont clip.

The music only matters here where its important, when one sets the initial volume from the actual listening process. I think it's obvious that if you listen to compressed pop that your average to peak ratio will be lower and the apparent loudness greater. Hence someone who listens to pop will set the volume control lower then someone who listens solely to dynamic classical works. But then again that might not be true, there will be a few people who will listen to pop at very loud levels and then some people (like my mother) who'd listen to classical at a low volume and certainly not anywhere near loud enough to hear it as the composer intended. This is the point of the thread though, to get an idea for what the individuals power requirements actually are.

Yes, I could look at a VU meter, or analyse my music using audacity, where I'd notice that the average level for my classical stuff is 15dB lower then my pop stuff. I'd also notice that the pop stuff sits at 0dB a lot of the time and the classical only ever reaches -1dB a couple of times. Naturally I'd set the volume control ~15dB higher for the classical then the pop and I'd need 14dB more headroom for the classical transients vs the pop, but I can arrive at this figure too by listening to the music and seeing where I set the volume control. Then of course the level I want the system at will differ from the next person and we actually need to listen to find that out.
__________________
What the hell are you screamin' for? Every five minutes there's a bomb or somethin'! I'm leavin! bzzzz!
  Reply With Quote
Old 30th January 2012, 03:44 AM   #172
Pano is offline Pano  United States
diyAudio Moderator
 
Pano's Avatar
 
Join Date: Oct 2004
Location: Milliways
Blog Entries: 4
Hello from Miami Beach!
Nice to see the good discussions. Mooly, your findings are interesting, and certainly merit a close look. I'll do some tests of my own when I get the chance. I do wonder if it's a phase problem at the top of the band. Maybe LP filter on the file could tell us.

5th E. Thanks for the posts. It does seems that a lot of folks are not getting it. We've both tried, but it's not sinking in yet. Of course choosing the music is important, that's why I've suggested trying a variety of dynamic tracks. If you don't ever listen to dynamic recordings, then no worries.

I've looked at hundreds of music tracks and although there is a nice range of dynamics in many, the loud sections tend to average about -10dBFS. How loud that sounds can depend a lot on spectral content.

So if you want to do the test well, play a good variety of tracks and pick your typical highest volume setting.
  Reply With Quote
Old 30th January 2012, 03:52 AM   #173
Pano is offline Pano  United States
diyAudio Moderator
 
Pano's Avatar
 
Join Date: Oct 2004
Location: Milliways
Blog Entries: 4
Quote:
Originally Posted by rongon View Post
I need a 12 watt per channel amp? Hmmm...
To keep out of clipping at the volume level, yes. If you turn it down a bit, you might not clip. You could repeat the test at a more "pleasant" listening level to see if you are clipping there.

A good SET has fairly benign clipping behavior, so you may not hear it or may not mind it if you do. A sort of direct heated compressor, if you will.
  Reply With Quote
Old 30th January 2012, 07:22 AM   #174
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
Morning all

Quote:
Originally Posted by Pano View Post
Hello from Miami Beach!
Nice to see the good discussions. Mooly, your findings are interesting, and certainly merit a close look. I'll do some tests of my own when I get the chance. I do wonder if it's a phase problem at the top of the band. Maybe LP filter on the file could tell us.
I feel a bit like this is hijacking Pano's thread a little... if you think another thread on this appropriate

Quote:
Originally Posted by Tom Danley View Post
Hi Mooly

Transfer the file to a computer and open it with some thing like Cool edit that can analyze the data in the digital form or try the orban VU meter and see what it says.
Hi Tom... I'll see what today brings. I've never player around with any audio editing software... we'll see.

I am reading all your posts, however speaker design and measurement etc is something I have no experience off


Quote:
Originally Posted by David_Web View Post
As I alluded in my previous post I thought it was phase related.
I did some quick comparisons between unfiltered white noise and one with a steep -15dB PEQ cut at 20kHz with a bandwidth of 0.110 oct. simulating a brick wall filter.
The peaks does become a lot higher with the PEQ in place.

Same when using Hilbert transform.

White noise has such a lot narrow spikes and high energy at high frequency so a phase shift causes them to stack on top of each other providing a greater signal amplitude then an unfiltered signal.

Very simple to play around with in Audacity.
I looked up the Hilbert transform... the maths is way over my head though I wouldn't like to say one way or the other on this. Whether it is or not though...

-----------------------------------------------------------------------------------------------------------------------

My simple reaction to this was that white noise on CD is still a valid test signal.
(this is opening a whole new can of worms...) When you can start to see differences on a scope between two signals then surely something very audibly different between the two players must be occuring.

Just think about that in a different way. I could swap the opamps in any CD player for 741's and scope the output using say the 1khz squarewave test track and I bet you wouldn't pick out any observable difference between the 741 and whatever audiophile opamp was fitted. That's something I have tried in the past. Is there an audible difference though on music ? We all know the answer to that one.

So what about music with lots of high level hf ? We can't see that on a normal scope, not in such a way that differences could be observed because we can't isolate and view the same music sample over and over and compare easily. Whatever is happening here on the very "dynamic" (as in lots going on) white noise test is revealing massive differences in the way the data is decoded and outputed in analogue form.


------------------------------------------------------------------------------------------------------------------------

Quote:
Originally Posted by 5th element View Post
Mooly it is entirely possible that the extra you're seeing could be high frequency hash as produced by the DAC. Granted that's a lot of ultrasonic noise but it has to come from somewhere.



It is physically impossible (Mooly's odd test results notwithstanding) to send a signal greater then 0dB through the system. So if you never move the volume higher then the position you did the above test at, then it is physically impossible for the output of the amplifier to clip due to voltage limitations as you've already proven that a 0dB signal wont clip your amplifier.
That much HF would be a scary thought...

In practice the real world result shows signals considerably over 0db. If there were HF present then that surely has implications for all circuitry handling that signal. We talk of "inaudible" HF interacting with frequencies lower down the band.

Quote:
Originally Posted by 5th element View Post
Wait a second, what happens if you play a 20khz signal through them both? A 6>7.4 volt difference = less then 1dB. It's quite possible that one player has a slightly peaky top end.
That's easy to test at some point

How do you get less than 1 db ?
__________________
-------------------------------------------------------
A simulation free zone. Design it, build it, test it.
  Reply With Quote
Old 30th January 2012, 08:18 AM   #175
just another
diyAudio Moderator
 
wintermute's Avatar
 
Join Date: Aug 2003
Location: Sydney
Blog Entries: 22
Quote:
Originally Posted by Pano View Post
Of course choosing the music is important, that's why I've suggested trying a variety of dynamic tracks. If you don't ever listen to dynamic recordings, then no worries.

I've looked at hundreds of music tracks and although there is a nice range of dynamics in many, the loud sections tend to average about -10dBFS. How loud that sounds can depend a lot on spectral content.

So if you want to do the test well, play a good variety of tracks and pick your typical highest volume setting.
I didn't have time to listen to a variety so I chose one which I knew had quite high dynamic range. Interestingly If I had have gone with my first choice I would have had a higher voltage value. not because the dynamic range was higher, but because that track had lower overall peak (and average) levels.

I downloaded an interesting program called ocenadio (a music editor) which does an analysis of the track and shows peak values and averages. I'm not 100% sure I've interpreted it properly but it seems to give a good indication of the dynamic range of the track. I think it is worth checking tracks to see if they are close to 0db on the peaks, because if you set the absolute loudest level on a track that the peaks are -4db then I think it is going to give an unrealistic high value when the test tone is played

I loaded up a whitestripes track that I really find sounds terrible on my current system and discovered it only had about 4db average to peak difference, which makes me think that is part of the problem.

Tony.
__________________
Any intelligence I may appear to have is purely artificial!
Some of my photos
  Reply With Quote
Old 30th January 2012, 08:24 AM   #176
kvholio is offline kvholio  Netherlands
diyAudio Member
 
kvholio's Avatar
 
Join Date: Jul 2005
Location: leeuwarden
I've made two screenshots in Cooledit Pro of two different tracks with
quite a different dynamic range throughout the songs.
Track number one is 'Private Investigations' by the Dire Straits,
track number two is 'The Unforgiven' by Metallica.
Track number two was taken from a cd purchased in 1991 so i'm
pretty sure this was before Metallica REALLY started to compress the heck
out of their music

If you set your volume-control to 'very loud' during the first half of the first track and don't turn down the volumecontrol in time, you might be in for a nasty surprise going towards the end of the track, if your equipment doesn't have the dynamic capabilities to reproduce the large peaks going towards the end.
If you set your volume-control to 'very loud' after the first snare-drum hit on the second track, you're basically safe throughout the rest of the track.
Attached Images
File Type: jpg private_investigations.jpg (20.1 KB, 126 views)
File Type: jpg the_unforgiven.jpg (24.6 KB, 122 views)
  Reply With Quote
Old 30th January 2012, 08:33 AM   #177
just another
diyAudio Moderator
 
wintermute's Avatar
 
Join Date: Aug 2003
Location: Sydney
Blog Entries: 22
Private investigations was my first choice! But I changed to Telegraph Road, which I had to turn down a couple of times during the track to be comfortable. It was those turned down levels that I used as my final setting! what I noticed was that overall Private Investigations peak levels were not at 0db but Telegraph road's were.

I have to shut down this laptop and plug my main computer back in. the white stripes track has large sections that are just flat across the top

Tony.
__________________
Any intelligence I may appear to have is purely artificial!
Some of my photos
  Reply With Quote
Old 30th January 2012, 08:40 AM   #178
back is offline back  Greece
diyAudio Member
 
Join Date: Nov 2005
Location: crete
nobody seems to pay attention at the link i gave a few posts back.

do you really guys believe that you really need the some power to play

a sine at 120hz at a given volume and the same power to play a sine

at 120hz and at the same time a 1000hz sine at that given volume?
  Reply With Quote
Old 30th January 2012, 10:07 AM   #179
just another
diyAudio Moderator
 
wintermute's Avatar
 
Join Date: Aug 2003
Location: Sydney
Blog Entries: 22
Hi Back, I've read that Rod Elliot article before it is an interesting and informative one. But I don't think you are getting the concept of the 120Hz sine signal. 120Hz is a nominal value chosen because the average DMM is most accurate around that frequency, and the 12db is chosen for calculation simplicity.... it is not a test about music power, it is a test about what voltage level clipping will occur at.

We are talking about digital reproduction here. The whole concept is based around the fact that you can't have a level higher than 0db from the digital source. You are not going to be able to put a 2V 120Hz sine wave and a 2V 1Khz sine wave superimposed onto your digital medium and get 4V out The limit is still 2V, so regardless of the make up of the waveform it is still going to be max 2V out of the digital source. It is a hard limit

Tony.
__________________
Any intelligence I may appear to have is purely artificial!
Some of my photos
  Reply With Quote
Old 30th January 2012, 10:19 AM   #180
just another
diyAudio Moderator
 
wintermute's Avatar
 
Join Date: Aug 2003
Location: Sydney
Blog Entries: 22
Here is why I chose in the end to use telegraph road for my test, rather than Private Investigations. Note the minimum and maximum sample values and then compare to telegraph road. Fairly obviously private investigations can have the amp volume cranked more (which I usually do!!) than telegraph road because overall levels on the track are lower.

lastly I've upload the analysis and waveform from Black Math of my White Stripes Elephant CD. I'm now less inclined to work out what it is about my system that makes this sound bad. What does interest me is what it is about hearing it in the car on the radio that makes it not sound bad... perhaps I just got a crap CD....

Tony.
Attached Images
File Type: png private_investigations.png (15.4 KB, 119 views)
File Type: png telegraph_road.png (14.7 KB, 120 views)
File Type: png private_investigations_waveform.png (116.1 KB, 119 views)
File Type: png telegraph_road_waveform.png (155.1 KB, 24 views)
File Type: png black_math.png (14.4 KB, 25 views)
File Type: png black_math_waveform.png (108.3 KB, 24 views)
__________________
Any intelligence I may appear to have is purely artificial!
Some of my photos
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
LM3875 power up test.. and it crackles w/o speakers attached? Keyoke Chip Amps 9 2nd March 2012 01:39 AM
how to test chokes for current and voltage speakerfritz Tubes / Valves 10 20th October 2010 11:32 AM
Aleph 30 problem - half of power supply voltage on speakers output yoke Pass Labs 18 15th March 2009 05:18 PM
How to test speakers? zaydenam Multi-Way 2 27th August 2008 01:02 PM
Test speakers? Ryssen Multi-Way 3 2nd March 2004 10:54 PM


New To Site? Need Help?

All times are GMT. The time now is 04:22 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright Đ1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2