Watts. How many does one need?

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Volts stay relatively low. Ohms with the help of a zobel or 2 stay relatively low/flat. What you really need are amps.

Cheers,
James

Doesn't really work that way...as current being predominant, that is. You can have an amp capable of 100A of current, but if it can only swing 1V it ain't worth a damn for a stereo system unless your speaker impedance is like 10 milliohms.

First and foremost, an audio amplifier is a voltage amplifier. When you turn up the volume you are turning up the voltage. Current then follows according to the load and the voltage across the load. So, while current certainly is important part of the equation it is no more important than voltage as both must be present in the correct relationship to satisfy Ohms Law.

V=IR
 
With the difference being that you CAN mash 550 horses into the pavement, but try 550 watts on a speaker just once.
:idea:

It's not really that different. Being able to mash 550 to the pavement means you also need the remainder of the power train to handle it. Same with the stereo system, the rest needs to be capable too. As well, duty cycle matters.
Pretty much...

 
Doesn't really work that way...as current being predominant, that is. You can have an amp capable of 100A of current, but if it can only swing 1V it ain't worth a damn for a stereo system unless your speaker impedance is like 10 milliohms.

First and foremost, an audio amplifier is a voltage amplifier. When you turn up the volume you are turning up the voltage. Current then follows according to the load and the voltage across the load. So, while current certainly is important part of the equation it is no more important than voltage as both must be present in the correct relationship to satisfy Ohms Law.

V=IR

Of course you and damacman are correct. I made a far too simplistic late night post.

Of course the voltage is being varied and the impedance doesn't really stay that flat. My point was/is that in terms of what is doing the real work of controlling the linear motors in our speakers it's the ability of the amplifier to supply variable and instantaneous current that does the work. Varying the voltage is opening and closing the spigot.

Our amplifiers are really nothing more than high precision, externally programmable, variable speed low voltage hi current motor controllers.

Cheers,
James
 
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If his cellphone isn't distoring - how loud can it be? :)
You know that's what I thought would happen as this was the first vid I made at that kind of volume, at some point me bringing up the volume would push the recording into distortion. That's not the case though with the phone as it must have some kind of auto control over that. Good listening level in that room with one amp and JBL setup would be around -25. I find to make a good recording of the audio I should be at least -15 which is a level that will start bothering next door neighbors at night. Now that's with only one pair and with two going it's doubled the volume.

I then made another vid right after that and put on Money for Nothing. I then had to stop it because things where falling over and sliding off the countertop across the room because of the SPL. In fact you can see the vid here blur on the beat as I bring up the volume, BTW no sub in the system.



This weekend I bought a SPL App for my old iPhone so I can capture the reading in the vids,, but the damn thing will not open.
 
You know that's what I thought would happen as this was the first vid I made at that kind of volume, at some point me bringing up the volume would push the recording into distortion. That's not the case though with the phone as it must have some kind of auto control over that. Good listening level in that room with one amp and JBL setup would be around -25. I find to make a good recording of the audio I should be at least -15 which is a level that will start bothering next door neighbors at night. Now that's with only one pair and with two going it's doubled the volume.

I then made another vid right after that and put on Money for Nothing. I then had to stop it because things where falling over and sliding off the countertop across the room because of the SPL. In fact you can see the vid here blur on the beat as I bring up the volume, BTW no sub in the system.



This weekend I bought a SPL App for my old iPhone so I can capture the reading in the vids,, but the damn thing will not open.

With the information you are providing to us don't really needs a lot of power to reach very loud music :

About 25 watts to get 103db with one paire of speakers.(I assumed that your sweet spot was at 10 feets)

Two paires won't double the spl output but will gives you 3db more.

So at 25 watts you'll get around 106db.

I don't suggest anyone to listen music at this level, like you said a +12db peak will gives you 115db(370w) to 118db (370w) depending on your configuration, the équivalent of running a chainsaw in your livingroom without ears protection.
 
Since impedance is varying with frequency I'm interested to see how watts varies.

1w = 2,83v @8ohm. Can I just run a sweep test and check the volts reading on a fluke?

Is there a way to get the impedance curve of a speaker (not driver or tweeter only)?
 
Since impedance is varying with frequency I'm interested to see how watts varies.

1w = 2,83v @8ohm. Can I just run a sweep test and check the volts reading on a fluke?

Is there a way to get the impedance curve of a speaker (not driver or tweeter only)?

Sure, you can measure the impedance of a speaker. I forget the exact details but basically it involves using a signal generator to step through a range of frequencies (say 10Hz increments). Feed that signal to the amp, then using a resistor to create a voltage divider with the speaker, measuring the ac voltage at each frequency increment. That voltage translates to ohms based on the voltage divider, then graph the result.
 
With the information you are providing to us don't really needs a lot of power to reach very loud music :

About 25 watts to get 103db with one paire of speakers.(I assumed that your sweet spot was at 10 feets)
I had a SPL meter on my phone before with a amp/speaker setup almost as loud, specifically.
Two MC275 Mk VI mono blocked with an estimated wattage of 180 wpc, Sansui SP-5000 90 watt and 102db. These speakers really handled all that the amps gave them and the only setup I was able to turn the C100 preamp all the way up to +15. The SPL reading I was getting at the time were in the area of 98 db in the same room and at 8-9 feet.

We don't live in anechoic chamber listening to test tones. It take a lot effort for the average enthusiast to get a home system in their home to go above the 100 db area at 8-12' feet. Then to do it very cleanly without distortion and clipping you need very good speakers. I'v used high efficient speakers but they also distort easy at high volume before 100db.

Anyway your math is off buy a long shot as to what's accruing in my room with my system, I also am using well over 2-3 watts at normal listening levels, at least with the mac SS and JBLs.
 
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Since impedance is varying with frequency I'm interested to see how watts varies.

1w = 2,83v @8ohm. Can I just run a sweep test and check the volts reading on a fluke?

Is there a way to get the impedance curve of a speaker (not driver or tweeter only)?
Doesn't really work that way...as current being predominant, that is. You can have an amp capable of 100A of current, but if it can only swing 1V it ain't worth a damn for a stereo system unless your speaker impedance is like 10 milliohms.

First and foremost, an audio amplifier is a voltage amplifier. When you turn up the volume you are turning up the voltage. Current then follows according to the load and the voltage across the load. So, while current certainly is important part of the equation it is no more important than voltage as both must be present in the correct relationship to satisfy Ohms Law.

V=IR


Could one build a volume control that converts voltage into current or the other way around depending on knob position? No resistors in the signal path - I could sell that to audiophiles! :)
 
If one wants to pay for a lot of power, then that's great! But needing and wanting are two different things. Having 200 watts for "headroom" is like saying one needs to be able to go 160 MPH "just in case".

I beg to disagree here, someone mentioned Bach's Toccata and Fugue in d Minor... just the single low notes will eat 40w's of power like tic tacs and if the amp is not quick enough to recover it is a pretty disappointing experience (unless you like listening at really low levels). Folks who like Baroque organ really appreciate watching the hairs on their arms moving just like if you were hearing it live w/ Virgil Fox or E Power Biggs at the registers. Like it or not, having a lot of power is a nice thing. It's ok to have an opinion, it's not ok to tell people what they should have for amp power. Do you realize that some notes on an album can require many times a little amps power rating. Whoaru can explain the need for power and how it pertains to crest factor far better then I can. When an amp runs out of gas, it's instant distortion, even if it's for a micro second
 
Sure, you can measure the impedance of a speaker. I forget the exact details but basically it involves using a signal generator to step through a range of frequencies (say 10Hz increments). Feed that signal to the amp, then using a resistor to create a voltage divider with the speaker, measuring the ac voltage at each frequency increment. That voltage translates to ohms based on the voltage divider, then graph the result.
http://sound.whsites.net/tsp.htm

tsp-f2.gif


EDIT: see also: https://www.stereophile.com/features/99/index.html

Here is a "typical" impedance curve of a modern (well... 1998 vintage; more or less randomly chosen) loudspeaker:

666Rt5fig1.jpg

source: https://www.stereophile.com/content/polk-audio-rt5-loudspeaker-measurements
This, I would say, is a nominal "4 ohm" speaker --- defined by that 'valley' centered at ca. 200 Hz. Polk spec'd it as "compatible with 8 ohm outputs": https://www.stereophile.com/content/polk-audio-rt5-loudspeaker-specifications

The impedance curve of a modern, 'intelligently' designed loudspeaker, to me, illustrates plainly why most of the "one number" specifications that hifi nuts used to obsess over (myself included) in the 1970s are -- frankly -- pretty darned meaningless.
 
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I beg to disagree here, someone mentioned Bach's Toccata and Fugue in d Minor... just the single low notes will eat 40w's of power like tic tacs and if the amp is not quick enough to recover it is a pretty disappointing experience (unless you like listening at really low levels). Folks who like Baroque organ really appreciate watching the hairs on their arms moving just like if you were hearing it live w/ Virgil Fox or E Power Biggs at the registers. Like it or not, having a lot of power is a nice thing. It's ok to have an opinion, it's not ok to tell people what they should have for amp power. Do you realize that some notes on an album can require many times a little amps power rating. Whoaru can explain the need for power and how it pertains to crest factor far better then I can. When an amp runs out of gas, it's instant distortion, even if it's for a micro second

If possible I would like to have the text or study that says a single note may needs 40w.

I'll begin measurement tests soon and it could ne helpful.
 
If possible I would like to have the text or study that says a single note may needs 40w.

I'll begin measurement tests soon and it could ne helpful.

I will make it easy for you, a cymbal crash and how it will affect meter levels instantly. You might be sitting at 2-3w's average and the meters will jump to 50w+ for a burst
 
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