what if i want an amp that sounds good AND has low THD ? why won't any manufacturer oblige me ? don't they care what i want ? don't they want to sell their products ? am i the only person who wants an amp that sounds good AND measures well ?
Let me correct that: for a 50W amp you can achieve (with the needed dedication) true 100dB SNR - not to random noise floor (the usual marketing gimmick*), but in comparison to ripple and whatever else humm components there may be.
Have fun, Hannes
*in commercial amps the 50/100 Hz components are sometimes 20dB and more above noise floorThat's the reason if an on-paper perfectly quiet amp humms happily...
ok then i will correct my reply to your original post.
i want 120db to noise floor.
i don't care about 60 hz hum in a ribbon tweeter ...
This can not be under emphasized... Single number THD is a totally meaningless number. I start getting really worried when this number starts getting too low -- often a sign that an amplifier is going to sound bad. Why obsess over something that doesn't matter?
The spectra that it is collaped to get THD has some real use thou, but you really need to have a comprehensive set of them... measures from low frequency to high (say 50 -5000 hz) and from low power to more (say 1 mW to 10W at least). Then you need to look at how things change in both dimensions.
dave
50W amplifier + 100dB/W/m tweeter gives 117dB @ 1m.
For a pair of these operating in stereo with an in-phase input, we would have ~112dB @ 2.5m listening distance.
Add another 3dB to allow for peak SPL rather than rms SPL and you have a peak transient SPL from the tweeter of 115dB.
A very nice target to aim for in a stereo system for ALL drivers, not only the tweeter.
The normal maximum average SPL from a speaker driver set up like the above would be 20dB to 30dB below the peak, ie. maximum average SPL ~82dB to 92dB and use the volume control to take off ~ 10dB to 20dB for quieter listening.
For a pair of these operating in stereo with an in-phase input, we would have ~112dB @ 2.5m listening distance.
Add another 3dB to allow for peak SPL rather than rms SPL and you have a peak transient SPL from the tweeter of 115dB.
A very nice target to aim for in a stereo system for ALL drivers, not only the tweeter.
The normal maximum average SPL from a speaker driver set up like the above would be 20dB to 30dB below the peak, ie. maximum average SPL ~82dB to 92dB and use the volume control to take off ~ 10dB to 20dB for quieter listening.
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About numbers and performance..some thougths of me
In fact, almost everyone wants an amplifier that
has good sound and measure well ... why this is
considered important? For me indicates that the circuit
works well and is not generating more harmonics
compared to those already present in the music ... is a
kind of security that allows me to isolate, separate,
amplifiers from the system, where the speakers, the
house acoustics, the individual hearing differences the mixing quality while the CD/DVD is reproducing, also the player playback quality can influences sonics.
As a result of those variables we want something that sounds good and also measure good, in my imagination almost all of us wants that. We want to avoid the amplifiers as beeing a big problem to achieve the
faithful reproduction of music .... this is reasonable. In
However, as we build or heard several
units, consulting specifications,we realize that they are not always representing the reality, say, nice numbers not always represents the quality you are hearing ... certain methods using continuous test signals perform differently from music which is much more complex than tones, square waves,and so on. Even if mixed in any proportion, we sometimes use simulators to test.. and we use strange loads, alike resistances instead the complex load the speaker represents to the amplifier…usually the amplifier faces a very strange thing when connected to the speaker/crossover and cables… resistance has nothing to do with real speaker drivers that generates opposite signs,and does not behave linear,reinforcing and attenuating some parts of the audio spectrum…when you introduce electricity into a speaker coil this generates mechanical movement as a result..and this compresses and rarifies air producing the sound..moving your timpanic membrane inside your ears…but, when the coil moves as a result of electricity entering, it also generates electricity that goes back to the amplifier output…and this is mess!
..... to be continued.....
In fact, almost everyone wants an amplifier that
has good sound and measure well ... why this is
considered important? For me indicates that the circuit
works well and is not generating more harmonics
compared to those already present in the music ... is a
kind of security that allows me to isolate, separate,
amplifiers from the system, where the speakers, the
house acoustics, the individual hearing differences the mixing quality while the CD/DVD is reproducing, also the player playback quality can influences sonics.
As a result of those variables we want something that sounds good and also measure good, in my imagination almost all of us wants that. We want to avoid the amplifiers as beeing a big problem to achieve the
faithful reproduction of music .... this is reasonable. In
However, as we build or heard several
units, consulting specifications,we realize that they are not always representing the reality, say, nice numbers not always represents the quality you are hearing ... certain methods using continuous test signals perform differently from music which is much more complex than tones, square waves,and so on. Even if mixed in any proportion, we sometimes use simulators to test.. and we use strange loads, alike resistances instead the complex load the speaker represents to the amplifier…usually the amplifier faces a very strange thing when connected to the speaker/crossover and cables… resistance has nothing to do with real speaker drivers that generates opposite signs,and does not behave linear,reinforcing and attenuating some parts of the audio spectrum…when you introduce electricity into a speaker coil this generates mechanical movement as a result..and this compresses and rarifies air producing the sound..moving your timpanic membrane inside your ears…but, when the coil moves as a result of electricity entering, it also generates electricity that goes back to the amplifier output…and this is mess!
..... to be continued.....
.. continuing....
. A specification of 100 decibels of dynamic says very little because it is unreal when
Compared to CDs or DVDs..as they are compressed in dynamics, with a difference of volumes in low passages (pianissimo) and high passages (fortissimo) rarely reaches 60 decibels ... I mean .. how good is an amp that can do this? ... the sound source does not provide that, say, to home stereo, also the speakers cannot. We do not live in environments totally silent, our "noise floor" while listening disturbs signs of low levels ... and at low levels (volumes) we have deficiencies of audibility (human ear and loudness contour)... then .... all that stuff turns a little strange our concern about .. I think this concern is linked to our own insecurity. Some methods of measurements are not very good, they are alike to to measure automobile engine power and thereby try to preview/forecast, the vehicle speed performance ... some measurements are made with the engine not coupled to gear box that produces losses.. also differential satelite gears,
Also the long shaft that produces losses the Cardan axel, also alternator and sometimes cooling fan… the vehicle to achieve speeds faces air resistance ... the 7000 rpm reached disengaged is not achieved in fourth or fifth gear because of the resistance of the air ... the force developed against brake fails to set performance .. only serves to compare engines .. while the car is a mechanical system with many interdependent parts that will face friction, will face air resistance.. and all this stuff is different to face a break against
The engine movement..that means the car weigth to move, to acelerate.
Analog problems we face with amplifiers.. related some methods used to evaluate them.
regards,
Carlos
. A specification of 100 decibels of dynamic says very little because it is unreal when
Compared to CDs or DVDs..as they are compressed in dynamics, with a difference of volumes in low passages (pianissimo) and high passages (fortissimo) rarely reaches 60 decibels ... I mean .. how good is an amp that can do this? ... the sound source does not provide that, say, to home stereo, also the speakers cannot. We do not live in environments totally silent, our "noise floor" while listening disturbs signs of low levels ... and at low levels (volumes) we have deficiencies of audibility (human ear and loudness contour)... then .... all that stuff turns a little strange our concern about .. I think this concern is linked to our own insecurity. Some methods of measurements are not very good, they are alike to to measure automobile engine power and thereby try to preview/forecast, the vehicle speed performance ... some measurements are made with the engine not coupled to gear box that produces losses.. also differential satelite gears,
Also the long shaft that produces losses the Cardan axel, also alternator and sometimes cooling fan… the vehicle to achieve speeds faces air resistance ... the 7000 rpm reached disengaged is not achieved in fourth or fifth gear because of the resistance of the air ... the force developed against brake fails to set performance .. only serves to compare engines .. while the car is a mechanical system with many interdependent parts that will face friction, will face air resistance.. and all this stuff is different to face a break against
The engine movement..that means the car weigth to move, to acelerate.
Analog problems we face with amplifiers.. related some methods used to evaluate them.
regards,
Carlos
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because i can't listen to all of my music on every single amplifier using every possible source and speaker combination to determine which is the amplifier that i want based on sound alone
yes in a pefect world i would have a warehouse with all of the components and 20 lifetimes to mix and match them until i could be happy with my system
but in this world i would rather just go for an amp with 0.0001% thd and assume that some other amp with 1% thd that i never evaluated sounds worse. even though 1% of the time my assumption may prove to be wrong.
of course IF there was more measurement data available i would look at that, but often THD and SNR are the only data that is published.
wouldn't it be nice if every amp came with 20 pages of graphs testing its performance in every possible way ? well we don't have that most of the time.
don't try to make it seem as if this situation is my fault.
maybe if was selling amps i would simply post 24bit/96khz wav files of input and output signals ( for a variety of music at various power levels ) so that users could use whatever algorithm they wanted to process these files and extract any information they can out of them on amplifier performance.
or you could just listen to those files ...
From an engineering standpoint, this seems to me to be a no-brainer. The upper ranges require modest current levels but clean high frequency. The lower range often requires very high current levels - especially so with imperfectly designed passive crossover networks. Since the higher range is where our sensitivity to distortion is most acute, why not unburden it from the task of driving current hungry woofers? Different horses for different courses?
I suppose one could conjure up a way do do this, but why? I would think that it would create more problems than it would solve. And with feedback? Now that would be a real challenge. I don't even know why it would be needed. A fullrange driver isn't full range in the first place, unless you only listen to music with limited spectral range. No full range driver in any normal room system can fill out the bottom end. So you need a sub(s) for that anyway. Now you are biamped. And, since a fullrange driver is not expected to produce the lowest frequencies, nor is it likely to have an extreme dip in impedance, it's less likely to tax the current capabilities of the amp.
Sheldon
Much more needs to be known about the amps.. i suspect your assumption would be wrong half the time.
dave
Aren't you using that dual Trio8 woofer with your moon-kens? With a separte amp? That is bi-amping.
dave
Small THD numbers does not mean better quality than big THD numbers
Borat.
You will find units sounding nice with high THD numbers
You will find units sounding bad with low THD numbers
Also:
You will find units sounding bad with high THD numbers
You will find units sounding nice with low THD numbers
Good specifications does not guarantees audio quality.... sadly...but this is what you gonna find in the real world.
There's no simple solutions or clever short cuts in that stuff...many folks spent half century studying and are still searching for the best combination.... i know many guys already doing that...and all them started reading specifications too.
Even Ipod owners are searching for the best combination of earphones..the ones match their taste, their ears plus brain and also the ones are better mechanically, ergonomically matched with their ears.
I have asked several "white haired" folks what is the best amplifier...the best speaker...and the best player...the best room acoustics.... the ones that had the arrogance to answer, gave me different answers...no one matched ....no one agreed..... and the majority is still searching, they have several options, and they do not know the absolute best one...this does not exist!... may exist for yourself...best for you...you ears, your taste, your home, your music..and have to search a lot and for a very long time to find that one.
regards,
Carlos
Borat.
You will find units sounding nice with high THD numbers
You will find units sounding bad with low THD numbers
Also:
You will find units sounding bad with high THD numbers
You will find units sounding nice with low THD numbers
Good specifications does not guarantees audio quality.... sadly...but this is what you gonna find in the real world.
There's no simple solutions or clever short cuts in that stuff...many folks spent half century studying and are still searching for the best combination.... i know many guys already doing that...and all them started reading specifications too.
Even Ipod owners are searching for the best combination of earphones..the ones match their taste, their ears plus brain and also the ones are better mechanically, ergonomically matched with their ears.
I have asked several "white haired" folks what is the best amplifier...the best speaker...and the best player...the best room acoustics.... the ones that had the arrogance to answer, gave me different answers...no one matched ....no one agreed..... and the majority is still searching, they have several options, and they do not know the absolute best one...this does not exist!... may exist for yourself...best for you...you ears, your taste, your home, your music..and have to search a lot and for a very long time to find that one.
regards,
Carlos
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Yes ! - it was a very sound recommendation from you, but I didn't build the amp for that, it was a BASH Class D plate amp. I guess it is bi-amping isn't it.
the only way i would even consider using a single fullrange transducer is if it was an electrostatic panel with 30 square feet of area.
my system right now is 3-way active and it is most likely headed into 4-way active.
i already know what i would use for the lower 2 frequency bands. the question is what to use for stuff from about 500 hz and up.
lets say the crossover points are 60 hz, 400 hz, 3 khz then the lowest band will be class D, next one up class H. but from there on up its either AB or A still undecided.
my system right now is 3-way active and it is most likely headed into 4-way active.
i already know what i would use for the lower 2 frequency bands. the question is what to use for stuff from about 500 hz and up.
lets say the crossover points are 60 hz, 400 hz, 3 khz then the lowest band will be class D, next one up class H. but from there on up its either AB or A still undecided.
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Because they are crap designs marketed to audiophools with more money that brains - pretentious ***** that are as a rule as deaf as they are dumb.
Had been you trying for an year to understand why cars that show the better fuel economy are not military tanks?
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