I did not suggest the terms were interchangeable. Equally, there was no mention of 'output impedance'. In attempting to make sense of that post, I concluded that Michael Chua was describing the effect of paralleling the amplifier input with a potentiometer on a low setting.
My two statements say exactly the same thing. If you can't see this then, as I suspected, you don't understand speaker sensitivity. Low sensitivity means 'it needs lots of power to go loud enough'; it does not mean 'it needs lots of power in order to work correctly' - which is what you seem to believe.east electronics said:
It is unfortunate that the post required effort in order to make any sense of it. However, the effect of paralleling an amplifier input with a pot at low setting involves the output impedance of the pot - the input impedance of the amplifier remains unchanged whatever the pot is set to.currentflow said:
A speaker with 10db lower sensitivity will need 10x the power to yield the same pressure be it at very low level where it s more non linear.
So it need more power to be at same relative linearity given that this latter is dependent of the total motion irrespective of the actual power other than by mean of thermal compression.
The first part is interesting.
The second part is an gross mis-interpetration of my intentions which you yourself appear to agree with in post 21.
Sorry if I wasn't clear: I meant that 'east electronics' is trying to settle a technical argument by means of democracy.Charles Darwin said:
Learned something new today :
Before entering an argument with a forum member take a look at his posted threads You may learn a few things about his background.
Before entering an argument with a forum member take a look at his posted threads You may learn a few things about his background.
I am curious. What did you learn, about whom did you learn it, and what possible relevance could it have to a technical discussion?
Done Jacco !
Remember that your invitation is still valid ..... Nice beach cool beer some amplifiers and Greek food ....
Remember that your invitation is still valid ..... Nice beach cool beer some amplifiers and Greek food ....
There are so many things wrong with this there's no point in even trying to explain. And I doubt a real explanation will sink in anyway. Bye bye.
(don't get me started, I've also/always been more of a philos-o-file)
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Although I'm fairly new to this forum I still read through this thread and the discussion part in the other which started this. Mainly because my mid term goal is to DIY a complete chain formed by pre, volume control and main amp. Therefore it's quite interesting from my point of view if there is substantial truth to what the OP believes to hear.
I come to the conclusion that, as of yet, no conclusion was found and most of the verbally (written) thrown snowballs have their root in misunderstanding of the language, which isn't mothertongue for many of us, and therefore wrong assumptions and interpretations of "what has been said in what tone?". Best example is the quote of Nelson Pass a few posts back...(I'm siding with DF on this one btw - I read the last sentance basically as "they have to turn the volume up with a passive volume control compared to an active one so it's worse in their eyes" - But as I'm not native English, I might be wrong too).
With regards to the B&W loudspeakers and their stated "minimum wattage" : may this be because they have large coils / magnets and big speaker area which JUST NEEDS a certain amount of spinach to move?!
I come to the conclusion that, as of yet, no conclusion was found and most of the verbally (written) thrown snowballs have their root in misunderstanding of the language, which isn't mothertongue for many of us, and therefore wrong assumptions and interpretations of "what has been said in what tone?". Best example is the quote of Nelson Pass a few posts back...(I'm siding with DF on this one btw - I read the last sentance basically as "they have to turn the volume up with a passive volume control compared to an active one so it's worse in their eyes" - But as I'm not native English, I might be wrong too).
With regards to the B&W loudspeakers and their stated "minimum wattage" : may this be because they have large coils / magnets and big speaker area which JUST NEEDS a certain amount of spinach to move?!
@cddb
I placed my question
I placed my listening impression
I placed my opinion where the "fault" lays
Now ....
People that think that all 4U7 capacitors in the input of a given amplifier ,will play the same as long as the value is always 4U7
People that think that low sensitivity means that speakers will play softly
People that have Megnepans and think that is possible to operate them with 1W
People that are not familiar with B&W behavior in low listening power
Have not much to contribute in this thread .
It is impossible to have almost 30years of PA in your back if you are not familiar with terms like sensitivity and spl.
Anyone that thinks that a 10.000W PA system will operate correctly from a number of aspects if driven with a total of 200W will operate correctly has not much to contribute in this thread
In your/mine system happens the exact same thing with a PA system of 10.000W only numbers and behavior is different.
You have an opinion ? say it the rest is BS
I placed my question
I placed my listening impression
I placed my opinion where the "fault" lays
Now ....
People that think that all 4U7 capacitors in the input of a given amplifier ,will play the same as long as the value is always 4U7
People that think that low sensitivity means that speakers will play softly
People that have Megnepans and think that is possible to operate them with 1W
People that are not familiar with B&W behavior in low listening power
Have not much to contribute in this thread .
It is impossible to have almost 30years of PA in your back if you are not familiar with terms like sensitivity and spl.
Anyone that thinks that a 10.000W PA system will operate correctly from a number of aspects if driven with a total of 200W will operate correctly has not much to contribute in this thread
In your/mine system happens the exact same thing with a PA system of 10.000W only numbers and behavior is different.
You have an opinion ? say it the rest is BS
Lets give another turn to the discussion .....
For the past few hours i checked every available schematic of CD players i could find that feature a fixed and a variable output .
Some of the CD players belonged to the past of the CDP era from Sony others newer , also some from sony and a few other brands that i could find ....Checked also Advance Acoustics ,Xindak, CAyin and Teac that we do authorized service for and have access to schematics .
In the Cd players of the past variable output takes place with a classic hand turn pot while in the newest feature electronic pots digitally controlled ( few also used motorized pots )
Now please explain to me why all of them use the pot behind the gain stage ????
If the behavior/presence of the pot doesn't effect anywhere the next stage to be driven OBVIOUSLY there should be some of the manufactures should place his pot mechanical or electronic directly in the output of the CD player .
If there is any manufacturer that does so please let me know ...
Answer this then you solve my problem too
Under the same logic what will be the reason to have a configuration= CD player goes to a B 1 then goes to a pot , then goes to power amp ...
If you are buffering for the input of the pot this is totally useless since the CD player already has an active stage in its output ...Why repeat a gain stage or a buffer once more
Now if you are buffering between the pot and the amp we are getting somewhere ....
For the past few hours i checked every available schematic of CD players i could find that feature a fixed and a variable output .
Some of the CD players belonged to the past of the CDP era from Sony others newer , also some from sony and a few other brands that i could find ....Checked also Advance Acoustics ,Xindak, CAyin and Teac that we do authorized service for and have access to schematics .
In the Cd players of the past variable output takes place with a classic hand turn pot while in the newest feature electronic pots digitally controlled ( few also used motorized pots )
Now please explain to me why all of them use the pot behind the gain stage ????
If the behavior/presence of the pot doesn't effect anywhere the next stage to be driven OBVIOUSLY there should be some of the manufactures should place his pot mechanical or electronic directly in the output of the CD player .
If there is any manufacturer that does so please let me know ...
Answer this then you solve my problem too
Under the same logic what will be the reason to have a configuration= CD player goes to a B 1 then goes to a pot , then goes to power amp ...
If you are buffering for the input of the pot this is totally useless since the CD player already has an active stage in its output ...Why repeat a gain stage or a buffer once more
Now if you are buffering between the pot and the amp we are getting somewhere ....
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I'm still here (and will be until this thread is definitely dead) but what have 10.000W PA systems, audible differences in different caps in the signal path and different dynamics whether or not the pot is in front of or behind an active stage in common?
I'm serious: you said you have 30k worth of measuring equipment. Is a signal generator and a multichannel oscilloscope part of it? If yes: mind to log an input-response test? I think various frequencies, loud and quiet levels sequenced shortly together (mind: input not output). I'm really curious if the two build variants differ. This would be clearly visible when comparing the responses of those two.
I'm serious: you said you have 30k worth of measuring equipment. Is a signal generator and a multichannel oscilloscope part of it? If yes: mind to log an input-response test? I think various frequencies, loud and quiet levels sequenced shortly together (mind: input not output). I'm really curious if the two build variants differ. This would be clearly visible when comparing the responses of those two.
I expect that you understand that this is a rhetorical question and apply to DF96 's comments at the point where the power is to low to move the cones. Obviously here there is no question about pots .
Like a big PA system alike a home system that is a mechanical pump will require an amount of energy to be able to start moving the coil and overcome the mechanical resistance of suspension and spider ..
I expect that with energy lower than that the cone doesn't even operate so expect the result to be horrible not a good result but just low in power .
Kind regards
Sakis
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haha. if you realy believe you will hear a SPL level that low, you are realy dreaming. you would never know if the amp is on or not (as long as the amp itself has no audible noise).
I'm serious: you said you have 30k worth of measuring equipment. Is a signal generator and a multichannel oscilloscope part of it? If yes: mind to log an input-response test? I think various frequencies, loud and quiet levels sequenced shortly together (mind: input not output). I'm really curious if the two build variants differ. This would be clearly visible when comparing the responses of those two.
I can answer that i think
i think that measuring in the input of the amplifier the applied signal ( just in the input in front of the DC blocking capacitor ) a variety of configuration as extensively described ( would you like to do that with the amplifier on or off ) you will measure the exact same thing ...
In an active configuration you will probably measure signal plus any problems introduced in the signal from the active stage .....
But this my dear is a huge misconception of the real question !!!! The question is how the LTP stage of a P3A amplifier will work when its input is shunted to ground to as low as 100R or even less at low listening power ...
So i think that a more proper test will be to set up 2 ch of amplifier in a specific equal low power connected in a specific sensitive speaker and spectrum analyze the speaker making sure that they both accept the same amount of signal in the input While the one ch will receive signal from a passive pot while the other will receive the signal from an active stage ...
What do you think ?
I can answer that i think
i think that measuring in the input of the amplifier the applied signal ( just in the input in front of the DC blocking capacitor ) a variety of configuration as extensively described ( would you like to do that with the amplifier on or off ) you will measure the exact same thing ...
In an active configuration you will probably measure signal plus any problems introduced in the signal from the active stage .....
But this my dear is a huge misconception of the real question !!!! The question is how the LTP stage of a P3A amplifier will work when its input is shunted to ground to as low as 100R or even less at low listening power ...
So i think that a more proper test will be to set up 2 ch of amplifier in a specific equal low power connected in a specific sensitive speaker and spectrum analyze the speaker making sure that they both accept the same amount of signal in the input While the one ch will receive signal from a passive pot while the other will receive the signal from an active stage ...
What do you think ?
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Audiosan sorry my Eglish is not enough to understand the meaning of your post Could please explain in some other way ?
Thank you
Sakis
Thank you
Sakis
Hello Sakis,
I think that this phenomenon is closely related to input current distortion. By increasing the source impedance of the preamp, the distortion of the power amp increases considerably. This has been extensively studied by Douglas Self (Audio Power Amplifier Design Handbook - 5th edition, p. 97, Figure 4.18). Amplifiers with low beta ltp transistors are more sensitive to this phenomenon.
Greeting from Crete
Nick
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