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

[Paducah Home Theater]

Sine waves are a bit misleading, no?  Play pink noise through an amp and you're often already looking at power ratings that are four times less than what you think they're rated at.  

[alzinski]

Okay lets back track a bit sorry.

 

Derrick measured less thatn 2 volts. Was this the test tone? If so that's -12db and so we must multiply by 4. 

 

2*4=8.

 

So 8 volts would be the PEAK voltage  your speakers are seeing when you were listening to music. RMS would be that number x.707

 

Now on to power. I am going to assume 8 ohm speakers.

 

8*.707=5.656

 

5.656^2=31.99

 

31.99/8=3.99

 

 

 

You can get by with an 4 watt amplifier for your listening preference.

 

 

 

Some of you just input a sine wave and measured until it was unbearable, that's not the best way to do this hence why Pano came up with this method. It's best to listen to multiple music CD's or whatever digital files you have and make note of the max volume setting for how loud you will ever listen to music. The test tones provided should be -12db which makes it easier to tolerate when measuring and easy to calculte 0db (max power).

[alzinski]

1 hour ago, wdecho said:

I think he is making the case for Class A. The high power A/B amps are rated for distortion at close to peak and not below 1 watt. Many have higher distortion numbers below 1 watt than they do at close to peak. 

 

I don't believe this to be the case. When amps get closer to class B and one device goes in and out of conduction you will have more crossover distortion. Not to mention as the amplitude increases so does any nonlinearities.

 

I find the problem with some of the higher power amps is at lower levels of listening the distortion is quite low, BUT (and there is always a but) what distortion is present is all higher order harmonic distortion which is extremely unpleasent and dissonent. When you have a low power amplfier in Class A and even single ended the distortion that is present will be lower order harmonics (second and third) and usually mainly second harmonic which is benign and actually masks (if any) higher order harmonics. E.G. I find I prefer amplifiers which may have slightly higher THD numbers but it's all second and maybe a bit of third. Amps with very low distortion tend to have higher harmonics dominate which is a byproduct of distortion cancellation techniques.

[ClaudeJ1]

On 5/11/2017 at 9:22 AM, Ski Bum said:

 If your average levels are 0.1 w or so because you use high sensitivity speakers, most amps will produce the 10 watt (30db) peaks easily.  Start with less sensitive speakers, however, and you very quickly run into needing ridiculous amounts of dynamic power, even at moderate levels.

Paul Klipsch and I had that discussion about half my life ago in the summer of 1985. Keep in mind that ALL of his recordings were on Reel to Reel tape and done with only TWO spaced Omni microphones. Almost all of them were of Full Symphony Orchestras with the most dynamic range capability in unamplified music. He told me to use a figure of 17 DB for dynamic headroom over a nominal 1/4 watts RMS, or 0.25 watts. So, doing the math in accordance to PWK's words, this works out to 12.5 watts total.

 

That being said, if we use your 30 db crest factor example, which, I presume would mean .1 watts RMS  per channel, or 0.2 watts total, your example would require 100 WATTS of power PER CHANNEL, and not just 10 Watts..................unless, of course, all of my ASSUMPTIONS are incorrect.................

[ClaudeJ1]

On 5/10/2017 at 7:23 PM, WMcD said:

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

My measurements in the past all agree with YOURS. My K402 horns with K1133 drivers only needed about 10 milliwatts (0.010) of power for 85 db listening at my sweet spot. Plenty loud and satisfying for most blues/jazz recordings.

 

I liked to round off PWK's recommendation of 17 db peak headroom up to an even 20 db. So my 0.010 watts above translates to a negaive 20 dbWatts, so for full headroom a Plus 20 dbWatts equals Zero dbWatts, or 1 watt for the peaks on that horn/driver combo.

[ClaudeJ1]

4 hours ago, 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.

OK, Mr. Advocate. I'm currently listening to the best sounding amp I've ever owned, tubes or SS.

 

It's a First Watt Aleph J which is class A single ended, all FET transistors. It tops out a 40 Watts per channel at 8 ohms........maybe a bit more at 4 ohms. It never clips.

[ClaudeJ1]

4 hours ago, tube fanatic said:

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.

 

I already did just that.

[ClaudeJ1]

1 hour ago, wdecho said:

but as you said it is more 3rd which is obnoxious whereas 2nd is sometimes considered a plus. I like a touch of 2nd. 

I'm thinking this is true based on my Class A experience.

[mark1101]

On my 5 way MCM setup I use three 50 WPC s/s amps.......on the tweeter horn (510), midhorn (402), and midbass horn (305).........and 550 wpc s/s amp on the MWMs, and 900 wpc s/s amp on the subs.

 

The way I have it setup I bet most people with a pair of lascalas could play much louder than what I have.  The gains are turned up so little in an effort to keep it clean.  Only goes as loud as I would ever listen to it.

[mark1101]

If you go to the solid state forum and the "Crown" thread John Warren posted some distortion measurements of a new Crown s/s amp.  Gives an idea of the initial distortion, the "clean" range, then where it all comes apart on the high end.  WMcD is right.

 

I suspect Pass solved this with his first watt amps and they are probably sqweaky clean right out of the gate.  Would love to try one.

[PrestonTom]

3 hours ago, MetropolisLakeOutfitters said:

Sine waves are a bit misleading, no?  Play pink noise through an amp and you're often already looking at power ratings that are four times less than what you think they're rated at.  

Sine waves are not the issue in this demo. They are simply used to provide a steady state signal when you measure the set up with a volt meter. Have a look at what Pano assumed and did for this demo over at DIYaudio.

[PrestonTom]

1 hour ago, ClaudeJ1 said:

Paul Klipsch and I had that discussion about half my life ago in the summer of 1985. Keep in mind that ALL of his recordings were on Reel to Reel tape and done with only TWO spaced Omni microphones. Almost all of them were of Full Symphony Orchestras with the most dynamic range capability in unamplified music. He told me to use a figure of 17 DB for dynamic headroom over a nominal 1/4 watts RMS, or 0.25 watts. So, doing the math in accordance to PWK's words, this works out to 12.5 watts total.

 

That being said, if we use your 30 db crest factor example, which, I presume would mean .1 watts RMS  per channel, or 0.2 watts total, your example would require 100 WATTS of power PER CHANNEL, and not just 10 Watts..................unless, of course, all of my ASSUMPTIONS are incorrect.................

 

You need not worry about the dynamics or headroom. That is already taken care of when you do the initial test. First, have a look at what Pano did and assumed for this demo over at DIYaudio

[PrestonTom]

3 hours ago, alzinski said:

Okay lets back track a bit sorry.

 

Derrick measured less thatn 2 volts. Was this the test tone? If so that's -12db and so we must multiply by 4. 

 

2*4=8.

 

So 8 volts would be the max your speakers are seeing when you were listening to music.

 

Now on to power. I am going to assume 8 ohm speakers.

 

8^2=64  

 

64/8=8

 

You can get by with an 8 watt amplifier for your listening preference.

 

 

 

Some of you just input a sine wave and measured until it was unbearable, that's not the best way to do this hence why Pano came up with this method. It's best to listen to multiple music CD's or whatever digital files you have and make note of the max volume setting for how loud you will ever listen to music. The test tones provided should be -12db which makes it easier to tolerate when measuring and easy to calculte 0db (max power).

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

If this is the signal Pano used, then you are off by x2. Simply measure the test tone at the speaker input and square the value

 

[jwc]

What is the purpose of this thread....to see who is the biggest wimp?  

[mark1101]

Hey........I was trying to show that even with powerful equipment you can be wimpy.

[tube fanatic]

1 hour ago, jwc said:

What is the purpose of this thread....to see who is the biggest wimp?  

If by wimp you mean the guy who uses the least amount of power with Klipsch speakers, I'll claim the title right now!  No one on here uses as little power as I do (except for the guys who also use my amps ).

 

As I stated above, the purpose of the thread is to give a very clear demonstration of the power needed to satisfy each person's listening level.  For most, it will turn out to be far less than they ever imagined.  Someone with a specific budget can then spend less on the amp and put the rest of the money to other system upgrades like DACs, or whatever other equipment may provide a benefit.

 

Maynard

[jwc]

5 minutes ago, tube fanatic said:

the purpose of the thread is to give a very clear demonstration of the power needed to satisfy each person's listening level.  For most, it will turn out to be far less than they ever imagined.  Someone with a specific budget can then spend less on the amp and put the rest of the money to other system upgrades like DACs, or whatever other equipment may provide a benefit.

yes worthy...

 

I thought I would rub-it in for a sec as it started to sound like a contest.

 

FYI:  My McIntosh SS power meters pushing Cornscalas........... hit past 120 watt peaks after I've had a few drinks.

[mark1101]

This thread is going to make every on here even MORE cheap.  

[jimjimbo]

40 minutes ago, tube fanatic said:

 No one on here uses as little power as I do

Oh yea?

 

 

[tube fanatic]

21 hours ago, Coytee said:

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)

The 400 EL is an AC meter with a very high input impedance so it should be usable for this test.  However, you should not be seeing any kind of arc when you put it across the speaker terminals.  It's possible that the capacitor across the meter's input circuit is leaky.  For this test, just use any old multimeter which has a low AC range (10V should be plenty).  The speaker  must be connected to do the test and the meter probes can be placed across the speaker or amp terminals.  It doesn't matter.  

 

Maynard