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something to ponder...


acmaddox0825

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when amp is rated for wattage, say 500watts, does it push that when the eq is set at flat or when all the frequency knobs are at 10. or am i just thinking too hard. i mean, i DOES get louder when you set the frequencies to the max, dosent it. so wouldn't that equate to using more power to "push" the speaker?could that be why some bass amps that have the same power rating sound different (ie one sounds "louder" than the other) when set flat.assuming we are using the same speaker for both amps.

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EQ doesn't really relate to watts like that. With a 500w amp turned half way up, set flat, you're seeing an average of roughly 250w, with an additional 250w to cover dynamics and headroom.
If you crank the bass response, all of a sudden your power requirements go up big time. That's why you feel like you lose volume with the bass turned up, because it gobbles up power.
C7

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An amp produces its rated power when it receives a high enough input signal. In a bass head, the input signal comes from your bass, it is amplified by the gain stages of the preamp (including the EQ) and then the signal is passed to the power amp section.

The most likely difference between two amps with the same ratings is difference gain staging. While both amps may max out their usable power at 500 watts, one amp may do it with the gain/volume at 4 and the other at 9. The other likely difference is the voicing of the bass amp. A mid-heavy amp will sound louder than a more deeply voiced amp even if they are both operating at the same power level.

C7 - when a 500 watt amp is "halfway up" it typically puts out about 50 watts.

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C7 - when a 500 watt amp is "halfway up" it typically puts out about 50 watts.



I guess I'll have to take your word for that number, but I realize it's an algorithmic power increase; 250w was a "for example" number, I should have phrased it that way.

I can't imagine that my 480w amp is putting out less than 50w at the volume setting I use (about halfway) because it's maniacally loud, and my speakers aren't that efficient. Post some data, please; I'm not calling you a liar, I just don't believe you yet.:D
C7

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according to wikipedia (hah!):

 

The relationship between perceived volume and power output is not immediately obvious. A 5-watt amplifier is perceived to be half as loud as a 50-watt amplifier (a tenfold increase in power), and a half-watt amplifier is a quarter as loud as a 50-watt amp. Doubling the power of an amplifier results in a "just noticeable" increase in volume, so a 100-watt amplifier is held to be only just noticeably louder than a 50-watt amplifier. Such generalisations are also subject to the human ear's propensity to behave as a natural compressor at high volumes.

 

this is how it was explained to me. seemingly low wattages are loud

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I guess I'll have to take your word for that number, but I realize it's an algorithmic power increase; 250w was a "for example" number, I should have phrased it that way.


I can't imagine that my 480w amp is putting out less than 50w at the volume setting I use (about halfway) because it's maniacally loud, and my speakers aren't that efficient. Post some data, please; I'm not calling you a liar, I just don't believe you yet.
:D
C7



It's tough for me to "post data" but I understand your desire for more info.

The volume setting you are using could be at the full rated output of your amp. Unless I had it on the bench to test, I have no idea. I have seen lots of amps that put out their full rated power at close to half the volume knob.

My comment was directed to "halfway" being equal to half volume. Half volume of a 500 watt amp is 50 watts.

How about this. If you are playing a bass and you have the volume knob wide open and are pushing 100 watts and you turn the volume knob halfway down, you will be at 10 watts if the volume knob is a 10% audio taper and you will be at 30 watts if the volume knob is a 30% audio taper.

FYI - 50 watts is loud. You might be way over that, I have no idea, but I've freaked people out by plugging 6 watt amps into a 4x10 or 8x10 and showing them how loud that really is.

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It also seems to me that a tube 5 watt will be louder than a solid state 5 watt. I'm not sure why though.

 

 

There is more to this than I am going to write tonight. It boils down to harmonic distortion and psychoacoustic effect.

 

In general, even harmonics provide a doubling tone/effect making the output sound louder and fuller. Low order odd harmonics provide a muffled sound. High order odd harmonics produce a sharp edgy attacking quality.

 

When an amp reaches its clean power limit, it outputs a distorted signal with various harmonics emphasized. Tube amps tend to emphasize the second harmonic which compliments the fundamental tone making it sound louder and fuller. Solid state amps tend to emphasize the third harmonic which actually makes the output sound weaker and the higher order harmonics produced makes it sound sharper. That's why, in general, a tube amp sounds louder and fuller as it is cranked and a solid state amp ends up sounding weaker and dissonant.

 

That's the basics and enough from me for now.

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My comment was directed to "halfway" being equal to half volume. Half volume of a 500 watt amp is 50 watts.




OK, that's where we got crossed up. By" halfway" I meant 5/10 on the dial.:D

I understand your point, though. It's not a straight line from zero to full when dealing with volume : power.
C7

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An interesting thing to see is the Zvex iMPAMP 1-watt home stereo amp pushing a sub Link to videos. People sometimes forget how loud one watt can be. Of course, you could say in the case of a 1-watt amp pushing bass frequencies that distortion in the lower register is harder for the human ear to perceive and therefore, more of it is allowable while still hearing an "acceptable" output.

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An interesting thing to see is the Zvex iMPAMP 1-watt home stereo amp pushing a sub
People sometimes forget how loud one watt can be. Of course, you could say in the case of a 1-watt amp pushing bass frequencies that distortion in the lower register is harder for the human ear to perceive and therefore, more of it is allowable while still hearing an "acceptable" output.

 

 

very interesting, but, as i watched the video, i noticed that at lower frequencies the speakers "volume" decreased. which leads me to another question. in a bass amp, at what frequency is the wattage rated at,if they even do that, because im sure some manufacturer could say 1000 watts at 250hz and another would say 1000 at 50hz and i would guess the 50hz would sound louder because it would take more to push the lower frequencies.................. arg!!! somebody help me say what im trynna say!

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very interesting, but, as i watched the video, i noticed that at lower frequencies the speakers "volume" decreased. which leads me to another question. in a bass amp, at what frequency is the wattage rated at,if they even do that, because im sure some manufacturer could say 1000 watts at 250hz and another would say 1000 at 50hz and i would guess the 50hz would sound louder because it would take more to push the lower frequencies.................. arg!!! somebody help me say what im trynna say!

 

A few things at work here - human ears are best attuned to midrange frequencies. The end of the video had frequencies in the 10 Hz range - human hearing generally bottoms out at 20 Hz (and that's a really low frequency). So really, you shouldn't be able to hear it at the end. Heck, unless you have great home stereo speakers that are flat down to 20 Hz (which I really doubt), you should get very little volume at around 50 Hz or so, depending on your speaker's response.

 

Also, bass requires a lot of power to reproduce because of the length of the waves - they're very long and it requires power to reproduce them effectively.

 

As for ratings, hi-fi audio equipment is generally rated at a signal that is 20 Hz - 20 KHz (the range of human hearing, in audio terms "white noise"). This is full bandwidth, so it's sort of a "worst case" scenario. Lesser audio equipment is rated at one frequency (commonly 1 KHz in audio gear). However, you don't know unless the manufacturer quotes it. Even then, there's no real standard of rating and it's anyone's guess if the engineers and the marketing department are being truthful.

 

Also, remember watts is not directly correlated to sound pressure level (SPL). Watts is electrical power, converted into mechanical power by your speakers. More electrical power = more SPL. However, more mechanical efficiency (speakers) = more SPL.

 

That sort of answer your question?

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A few things at work here - human ears are best attuned to midrange frequencies. The end of the video had frequencies in the 10 Hz range - human hearing generally bottoms out at 20 Hz (and that's a
really
low frequency). So really, you shouldn't be able to hear it at the end. Heck, unless you have great home stereo speakers that are flat down to 20 Hz (which I
really
doubt), you should get very little volume at around 50 Hz or so, depending on your speaker's response.


Also, bass requires a lot of power to reproduce because of the length of the waves - they're very long and it requires power to reproduce them effectively.


As for ratings, hi-fi audio equipment is generally rated at a signal that is 20 Hz - 20 KHz (the range of human hearing, in audio terms "white noise"). This is full bandwidth, so it's sort of a "worst case" scenario. Lesser audio equipment is rated at one frequency (commonly 1 KHz in audio gear). However, you don't know unless the manufacturer quotes it. Even then, there's no real standard of rating and it's anyone's guess if the engineers and the marketing department are being truthful.


Also, remember watts is not directly correlated to sound pressure level (SPL). Watts is electrical power, converted into mechanical power by your speakers. More electrical power = more SPL. However, more mechanical efficiency (speakers) = more SPL.


That sort of answer your question?



im going to read it a couple of times to make sure, but i think i do.:D
thanks!! you les paul is in the mail!

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OK, that's where we got crossed up. By" halfway" I meant 5/10 on the dial.
:D

I understand your point, though. It's not a straight line from zero to full when dealing with volume : power.

C7



Your volume pot is logrithmic (audio taper) and at 5/10 on the dial it has 10% of its resistance on one side and 90% on the other (possibly 30/70). If full power was at 10, then you'd be at 10% power at 5. However, most amps are designed to be pushed to their full rated power well before you get to 10 on the knob. It's possible you are at full power at 5 depending on how strong your input signal is.

Regardless, I think we are on the same page.

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The ham radios guys can confirm that it gets even more interesting when you move into the rf frequencies. I love so see people's reaction when I tell them that I've made contacts into Brazil or Japan or Europe from the US using less power then their nightlight. That works out to about 1,000 miles per watt.

Yes - I'm a geek....but a damn cool geek. :cool:

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okay, i am kinda lost... explain the volume pot thingie again? ( the only dumb question is the one not asked!)
:D

 

A volume pot is a variable resistor. There are three leads connected to the pot; both ends of the resistor and a wiper. When you turn the pot, the wiper changes position along the length of the resistor. With the pot turned all the way one direction you have the full resistance of the pot in the circuit. With the wiper turned the other direction you have none of the resistor in the circuit (in most cases, you actually will have a very very small amount of the resistor in the circuit). If you measure the resistance from outer lead to outer lead, you always get the full resistance of the pot. If you measure from one of the outer leads to the wiper, you get the resistance between that end and the position of the wiper. In a LINEAR taper pot, when the wiper is in the middle of the resistor, you have equal resistance on both sides. In an AUDIO taper pot, when the wiper is in the middle, you have 10% of the resistance on one side and 90% on the other. You use AUDIO taper pots when you are dealing with volume because you hear things logrithmically. You use LINEAR pots with things like tremelo speed pots because twice as fast actually sounds like twice as fast.

 

And keep asking questions if you have them. The more you understand this stuff, the more likely you will be able to make your gear do what you want it to do.

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