That's exactly what I was thinking. This kind of conversation can become heated and opinionated very quickly.

But only when people take it seriously and overlook the inherent silliness of the whole subject.

 

Not wishing to stir the pot a bit, but from talking to friends who have some recording studio experience, one thing they say about monitors is most people's first experience of them is that they sound very cold. Which probably means they are closer to the source input than other systems.

To me, it would make sense for a good recording studio monitor to represent the original sound as accurately as possible. Even if you then knowingly altered that sound to make it "more enjoyable" for home equipment/typical LP player/mp3 compression/FM transmission down the line.

That way you know how much you are colouring the sound intentionally.

And whilst how pleasant a noise sounds is going to generally be a subjective experience, you can certainly throw sine waves through almost every section of an audio system and measure the output for accuracy.

Only ever going to be as accurate as your measuring equipment obviously.

 

Yeah but even if the amplifier does accurately reproduce pure sine-waves at all frequencies within the range that it's designed to work at (in this case 20-20khz) , does that guarantee that It will faithfully reproduce a very complex sound with high dynamic demands ?

 

Yeah but even if the amplifier does accurately reproduce pure sine-waves at all frequencies within the range that it's designed to work at (in this case 20-20khz) , does that guarantee that It will faithfully reproduce a very complex sound with high dynamic demands ?

Not necessarily. Things like IM (intermodulation) distortion or bad transient response can cause poor sound and those will not necessarily show up in a harmonic distortion analysis or frequency response test using single-frequency sine-waves.

 

Not necessarily. Things like IM (intermodulation) distortion or bad transient response can cause poor sound and those will not necessarily show up in a harmonic distortion analysis or frequency response test using single-frequency sine-waves.

Could you explain what you mean by 'Transient response ' ?
Does that mean the transition of one state (voltage perhaps) to another?

 

Could you explain what you mean by 'Transient response ' ?
Does that mean the transition of one state (voltage perhaps) to another?

TIM (transient intermodulation distortion) and transient response just mean that if a signal changes very quickly like the leading edge of a square wave, the output of the amp can't follow it precisely. The amp goes into a mode called slewing and there is a finite time lag until it "arrives" at the new level where the feedback loop starts controlling the amp again.

NOTE: a signal which changes that fast is certainly NOT audible (even if perfectly reproduced) but audiophiles claim that the amplifier's response to the signal can affect audible sounds which occur close in time after the "slew" is over.

As to how much of this effect is audible is highly disputed. Some relatively slow amps sound great and some fast ones sound terrible. There is a simple TIM test used on amps and the best ones have less than 0.1% distortion from slewing effects. It is easily measurable with the correct equipment. They inject a square wave which has a sine wave riding on the "porch" of the top and they null out the square wave and measure how much the sine wave was distorted.

For some years following the introduction of solid state amplifiers, their perceived sound did not have the excellent audio quality of the best valve amplifiers (see valve audio amplifier). This led audiophiles to believe that valve sound had an intrinsic quality due to the vacuum tube technology itself. In 1972, Matti Otala demonstrated the origin of a previously unobserved form of distortion: transient intermodulation distortion (TIM), also called slew rate distortion. TIM distortion was found to occur during very rapid increases in amplifier output voltage.http://en.wikipedia.org/wiki/Audio_power_amplifier#cite_note-3 TIM did not appear at steady state sine tone measurements, helping to hide it from design engineers prior to 1972. Problems with TIM distortion stem from reduced open loop frequency response of solid state amplifiers. Further works of Otala and other authors found the solution for TIM distortion, including increasing slew rate, decreasing preamp frequency bandwidth, and the insertion of a lag compensation circuit in the input stage of the amplifier.http://en.wikipedia.org/wiki/Audio_power_amplifier#cite_note-4http://en.wikipedia.org/wiki/Audio_power_amplifier#cite_note-5http://en.wikipedia.org/wiki/Audio_power_amplifier#cite_note-6 In high quality modern amplifiers the open loop response is at least 20 kHz, canceling TIM distortion. However, TIM distortion is still present in most low price home quality power amplifiers.http://en.wikipedia.org/wiki/Wikipedia:Citation_needed

 

Testing with a just a square-wave into a speaker load can tell a lot about the transient response of an amplifier. The signal into the speaker should have clean transitions with no sign of significant overshoot or ringing at the end of the transitions. Using a speaker load is preferred since it has inductance and non-linear load effects that are a better test of amplifier response then the resistive loads often used for amp testing.

 

Greetings!

I've recently unscrewed the back of my M-Audio BX5's to take a curious look on the insides and the amplifier circuit.
I've been playing around with electronics for about half a year now so i'm still a newbie... but upon examination of the main pcb I expected to see power BJT amps fueling the sound but instead what I found is some wierd many-legged IC attached to the main heatsink . After looking it the datasheets I discovered that It was an integrated audio amplifier which left me scratching my head.

Keep in mind that the monitors you're looking at are firmly in the 'budget' category. A company isn't likely to put significant engineering resources into a unique amplifier design at that price point. They're going to find a ready-made solution to do the job.

 

Interesting Review:
http://www.pcmag.com/article2/0,2817,2404801,00.asp

I thought the Bottom Line comment - these sound better than they should - was interesting. It points out something I think is very revealing. You don't need to spend a lot to get good performance.
I was impressed by the fact that at this price range these speakers were bi-amped.

Bi-amping can be a great benefit for a number of reasons. First of all, the need for inductors in series with the woofer can be eliminated. Second the bass-low mid frequencies which require the majority of the power can be separated from the mid-high frequencies to lessen inter-modulation issues.
Third the amp can be connected to the drivers with very short, lo-z connections.

 

Thanks alot bountyhunter and crutchshow for the answers.
They confirmed by theories of what I intuitively though 'transient response' was.

Another reason why I'm asking is because I want to make a 100watt car subwoofer amplifier for a friend of mind and I have no experience in power amplifiers but I'm guessing transient response will be important for sharp bass kicks

 

Keep in mind that the monitors you're looking at are firmly in the 'budget' category. A company isn't likely to put significant engineering resources into a unique amplifier design at that price point. They're going to find a ready-made solution to do the job.

Well yeah .. I know they are budget but still I expected it to have something more than an integrated amplifier , but yeah what you said make sense .

 

Interesting Review:
http://www.pcmag.com/article2/0,2817,2404801,00.asp

I thought the Bottom Line comment - these sound better than they should - was interesting. It points out something I think is very revealing. You don't need to spend a lot to get good performance.
I was impressed by the fact that at this price range these speakers were bi-amped.

Bi-amping can be a great benefit for a number of reasons. First of all, the need for inductors in series with the woofer can be eliminated. Second the bass-low mid frequencies which require the majority of the power can be separated from the mid-high frequencies to lessen inter-modulation issues.
Third the amp can be connected to the drivers with very short, lo-z connections.

Pretty much all 5'' monitors and bigger are bi-amped these days though ,
and specifically the Bx5 cost me 200Euros for the pair a few years ago so I went for them
I upgraded to My 8 ''behringer Truths1031a for more bass response

 

Well, I'm always learning new things here. Bi-amping has been common in commercial sound reinforcement and hi-spl monitors for a long while, but I didn't realize it had made it's way to smaller systems.

 

Thanks alot bountyhunter and crutchshow for the answers.
They confirmed by theories of what I intuitively though 'transient response' was.

Another reason why I'm asking is because I want to make a 100watt car subwoofer amplifier for a friend of mind and I have no experience in power amplifiers but I'm guessing transient response will be important for sharp bass kicks

You will also need to build some kind of switching power supply to boost up the car's 12V line to get that kind of power. Those are built into the amps you buy, along with the crossovers.

 

You will also need to build some kind of switching power supply to boost up the car's 12V line to get that kind of power. Those are built into the amps you buy, along with the crossovers.

What do you mean ? Boost the cars voltage up ?
Can't I just use power transistors in the end stage to give me about 10 amps ?

 

What do you mean ? Boost the cars voltage up ?
Can't I just use power transistors in the end stage to give me about 10 amps ?

P=E^2/R. To get 100 watts into a typical 4 ohm load requires about 20 volts RMS, which is about 56 volts Peak to Peak. You would need a few volts extra to account for circuit losses, so you might want about 60 volts available.
A split supply is normally used, so the output will idle at 0 volts. This allows the speaker to be directly coupled to the amp.

 

P=E^2/R. To get 100 watts into a typical 4 ohm load requires about 20 volts RMS, which is about 56 volts Peak to Peak. You would need a few volts extra to account for circuit losses, so you might want about 60 volts available.
A split supply is normally used, so the output will idle at 0 volts. This allows the speaker to be directly coupled to the amp.

Hmm and how would I get 60 volts from 12?
I'm guessing an inverter of some sort and step up the voltage with a transformer?

It's going to be an 8ohm speaker by the way

 

As bountyhunter mentioned, a switching power supply is the way to go.
Linear Technology and Texas Instruments have good info on this.
For 100 watts @ 8 ohm's you'll need ~ 80 volts P-P.

 

I thought switching supplies were an efficient way of regulating ( lowering) the voltage from a given power supply voltage ,
didn't know they could raise it aswell

but thanks alot for the info . I'll read about it

 

Second the bass-low mid frequencies which require the majority of the power can be separated from the mid-high frequencies to lessen inter-modulation issues.
Third the amp can be connected to the drivers with very short, lo-z connections.

That's one of the reasons active monitors became popular: the amps can be matched to the speakers, and biamping is easy, and both are benefits.

Another reason is probably that with decreasing chip sizes, quality amps were able to be designed in smaller sizes, and thus be more space-efficient...

Well yeah .. I know they are budget but still I expected it to have something more than an integrated amplifier , but yeah what you said make sense .

...To reiterate my last sentence, these days an integrated amplifier doesn't necessarily mean a low quality one. But more to my point about them being budget monitors is that, given a certain price point, a speaker manufacturer will choose how much engineering to put into the amp and how much to put into the enlosure. Quality integrated amps can be chosen without much difficulty, but quality acoustic design of the enclosure is more unique to the product at hand.