2 Vrms - A funny old standard | EE Times
Besides that, some audiophile equipment outputs over 2.3Vrms, I guess because they know that most audiophiles don't properly level match and louder is perceived as different/better.
Besides that, some audiophile equipment outputs over 2.3Vrms, I guess because they know that most audiophiles don't properly level match and louder is perceived as different/better.
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I realise this going a bit off topic but what is there about a resistive potential divider which can produce "bad dynamics" (whatever that means) at low levels (i.e. higher attenuation)? This sounds like an 'audiophile' old wive's tale.east electronics said:
East, please show all here using the laws of electronics, how the dynamics are compromised in this system.
1: A CD player with 2v or more output and less than 200ohms Z out.
2: A 10kohm passive volume control.
3: A poweramp with 1v or even 2v input sensitivity and an input z of the standard 47kohm or higher.
Cheers George.
As it bears no relation whatsoever to the original topic, could you please make a new thread to discuss the supposed disadvantages of having the volume pot in a separate box (a.k.a. passive preamp)?
You beat me to it, Marcel.
Exactly my thought. -18dB FS is, or was, a pretty common master level for music that wasn't too dynamic. More dynamic recordings have an RMS level down around -24dB FS. That would put the average levels near to older sources.Guess they didn't foresee the Loudness Wars and CDs mastered at -10dB 🙄
It's ok to talk about potential divider here. Potential divider shouldn't affect the dynamics. Those 8.5 digits multi-meters still use resistor dividers for different input levels and maintain superior accuracy.
By the way ...to support my position farther more another similar issue in the forum also beaten to death is the chain between pre and main amplifier setups
Means that : there is configuration like source - potentiometer - buffer or preamp-main amplifier
Or : source - buffer or preamp -potentiometer- main amplifier
Both practice is acceptable but in a given circuit there is going to be noticeable difference in the area of dynamics depending on the listening level choice of pot and general impedance .
That on its own explains the problems of a passive preamp
Obviously there is applications that have buffers before and after the pot to eliminate any issue related to the configuration and if i remember well topology like that is given as an option in the B1 article by NP if i remember well ....
Means that : there is configuration like source - potentiometer - buffer or preamp-main amplifier
Or : source - buffer or preamp -potentiometer- main amplifier
Both practice is acceptable but in a given circuit there is going to be noticeable difference in the area of dynamics depending on the listening level choice of pot and general impedance .
That on its own explains the problems of a passive preamp
Obviously there is applications that have buffers before and after the pot to eliminate any issue related to the configuration and if i remember well topology like that is given as an option in the B1 article by NP if i remember well ....
I looked for an explanation in your post, but I could not find one. I found some statements; some true, some mere re-assertions of your view on "dynamics". Maybe when you say "dynamics" you don't mean what people usually should mean by it: ratio between softest and loudest sound, or sound level not properly varying as the program material varies in level.east electronics said:
The position of a buffer may affect frequency response and distortion, and have a small effect on noise. I can't think of a plausible mechanism by which it could affect "dynamics".
ok you are really making this harder ....
This is a part of the NP B1 article
Is impedance matching an issue? Passive volume controls do have to
make a trade-off between input impedance and output impedance. If the
input impedance is high, making the input to the volume control easy for
the source to drive, then the output impedance is also high, possibly
creating difficulty with the input impedance of the power amplifier. And vice
versa: If your amplifier prefers low source impedance, then your signal
source might have to look at low impedance in the volume control
About the configuration also from NP
If you put a buffer in front of a volume control, the control’s low impedance
looks like high impedance. If you put a buffer after a volume control, it
makes the output impedance much lower. You can put buffers before and
after a volume control if you want
Now NP is trying to describe the result and while its talking about the drive ability he doesn't say much on what happens in low listening level .... But looking at the configuration it doesn't seem to me that the system he describes is made for what we call casual listening 24/7 in low levels ...I think the speakers will run out of juice in low listening level let's say something like 1.5-4 W I don't think that the speakers will wake up at such a low power ....So i think he missed that point
Similar to that and as an example this phenomenon will be far more easier to describe in sensitive speakers ... My standard combination the latest 6 years is a P37 preamp and a P3A listening the hours i am at the lab (10.00-24.00 ) every weekday ... Obviously i have tried every possible combination for a pre (B1 included) and the result was always that something with a bit of gain was needed ....ended up with a P37 with an audiophile PSU and configuration on the PCB . all runing with 92db speakers
At the moment I’m driving a pair of Lowther DX55’s with some passive
baffle-step correction (6 dB loss there) and an F3 amp with only 12.5 dB
voltage gain. The preamp is fed by an Xono phono stage with a low output
cartridge (Grado Statement).
The sound is extremely neutral without being clinical - just about what you
were looking for when you were thinking about a passive preamp. A
teensy bit of second harmonic and no noise at all.
There’s just enough gain. If you were using any other power amp, you’d
get 8 to 18 dB more gain, and would be able to break your lease or the
speaker, or both.
Do I feel like the
pedal’s to the metal
and I’m only doing 55?
No - I’m listening as loud as I want and I sleep soundly at night, knowing
that I’m not throwing away signal with my volume control.
Some pointers from ESP pages
As many preamp modules as needed may be used. For example, you may use one module before the volume control, and another after it to provide some additional gain and present a low impedance to the outside world. In many cases, the module will provide the only gain stage, and may be bypassed for high level signals (such as CD players) that have enough signal to drive the power amp directly. This is a great advantage for those who want the minimum number of components in line with the signal.
That is more or less documentation i could find in two minutes though millions of consumer amplifiers prove me correct about this you may look at any you like ... I say again consumer cause additional cost in consumer amps is an issue
Regards
Sakis
This is a part of the NP B1 article
Is impedance matching an issue? Passive volume controls do have to
make a trade-off between input impedance and output impedance. If the
input impedance is high, making the input to the volume control easy for
the source to drive, then the output impedance is also high, possibly
creating difficulty with the input impedance of the power amplifier. And vice
versa: If your amplifier prefers low source impedance, then your signal
source might have to look at low impedance in the volume control
About the configuration also from NP
If you put a buffer in front of a volume control, the control’s low impedance
looks like high impedance. If you put a buffer after a volume control, it
makes the output impedance much lower. You can put buffers before and
after a volume control if you want
Now NP is trying to describe the result and while its talking about the drive ability he doesn't say much on what happens in low listening level .... But looking at the configuration it doesn't seem to me that the system he describes is made for what we call casual listening 24/7 in low levels ...I think the speakers will run out of juice in low listening level let's say something like 1.5-4 W I don't think that the speakers will wake up at such a low power ....So i think he missed that point
Similar to that and as an example this phenomenon will be far more easier to describe in sensitive speakers ... My standard combination the latest 6 years is a P37 preamp and a P3A listening the hours i am at the lab (10.00-24.00 ) every weekday ... Obviously i have tried every possible combination for a pre (B1 included) and the result was always that something with a bit of gain was needed ....ended up with a P37 with an audiophile PSU and configuration on the PCB . all runing with 92db speakers
At the moment I’m driving a pair of Lowther DX55’s with some passive
baffle-step correction (6 dB loss there) and an F3 amp with only 12.5 dB
voltage gain. The preamp is fed by an Xono phono stage with a low output
cartridge (Grado Statement).
The sound is extremely neutral without being clinical - just about what you
were looking for when you were thinking about a passive preamp. A
teensy bit of second harmonic and no noise at all.
There’s just enough gain. If you were using any other power amp, you’d
get 8 to 18 dB more gain, and would be able to break your lease or the
speaker, or both.
Do I feel like the
pedal’s to the metal
and I’m only doing 55?
No - I’m listening as loud as I want and I sleep soundly at night, knowing
that I’m not throwing away signal with my volume control.
Some pointers from ESP pages
As many preamp modules as needed may be used. For example, you may use one module before the volume control, and another after it to provide some additional gain and present a low impedance to the outside world. In many cases, the module will provide the only gain stage, and may be bypassed for high level signals (such as CD players) that have enough signal to drive the power amp directly. This is a great advantage for those who want the minimum number of components in line with the signal.
That is more or less documentation i could find in two minutes though millions of consumer amplifiers prove me correct about this you may look at any you like ... I say again consumer cause additional cost in consumer amps is an issue
Regards
Sakis
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The person making it harder is you. 🙂 The old saying goes.....if digging yourself into a hole, stop digging. 🙂
Subjective evaluation is not proof of your "dynamics" theory regarding passive preamps.
Plus, you're making incorrect conclusions from NP's statements.
Cheers,
Dave.
Subjective evaluation is not proof of your "dynamics" theory regarding passive preamps.
Plus, you're making incorrect conclusions from NP's statements.
Cheers,
Dave.
Dave could you please explain farther ???
What is the use of B1 ? Cause if it doesn't effect anything what is the point of having it ? one way or another it doesn't add any gain to the signal
What is the use of B1 ? Cause if it doesn't effect anything what is the point of having it ? one way or another it doesn't add any gain to the signal
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Yes (before) when output impedance of the source is stupid high like most tube outputs on cd players/dacs.
Yes (after) when there are stupid low input impedance on some poweramps, I've seen down to 5kohm on some Class D's.
Cheers george
yes that is fine with me but could you please explain what will happen when one stage is not able to drive the next one no matter if a pot is in the way ?
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The implementation of the B1 in Pass's schematic is putting the B1 after the volume pot to create a low output impedance.
From his intro section, to me it sounds like he doesn't think there is any use for one if the source already has a low output Z.
here is a question ...How many of you actually tested a configuration with the pot before an after to actually be able to tell the difference ?
To remind you the input Z of a P37 is a bit above 100k while the input of the P3A is a bit above 22K Anyone think that driving those two inputs from a given source will be the exact same thing ?
I expect not .... expect that the 100k input will be far more easier driven by the source and that will have some impact in the dynamics exactly as the KA5700 is made ( for example )
I wonder why i am still trying to convince you about that when the only thing i have to do is look at my schematics library 95% of consumer amplifiers have an active preamp configuration anybody wonder why ??? they could as well go passive and simply increase the gain of the amp a bit to compensate ...
Anybody knows what is exactly a loudness circuit > why and where its used ? having an active preamp in the system is a form of loudness while secrete lays in choices of impedance and gain of each stage ....
To remind you the input Z of a P37 is a bit above 100k while the input of the P3A is a bit above 22K Anyone think that driving those two inputs from a given source will be the exact same thing ?
I expect not .... expect that the 100k input will be far more easier driven by the source and that will have some impact in the dynamics exactly as the KA5700 is made ( for example )
I wonder why i am still trying to convince you about that when the only thing i have to do is look at my schematics library 95% of consumer amplifiers have an active preamp configuration anybody wonder why ??? they could as well go passive and simply increase the gain of the amp a bit to compensate ...
Anybody knows what is exactly a loudness circuit > why and where its used ? having an active preamp in the system is a form of loudness while secrete lays in choices of impedance and gain of each stage ....
If source is low , <200ohm (which most are) and passive pot is 10kohm, it has no trouble driving a poweramp that is over say 33kohm, (47kohm being the standard) and 100kohm for most tube amps.
Only if you have silly Class D's that I've seen with 5kohm or 10kohm will there be a question mark on it, maybe you have one of these and this is why you don't believe what's being said to you.
Cheers George
Only if you have silly Class D's that I've seen with 5kohm or 10kohm will there be a question mark on it, maybe you have one of these and this is why you don't believe what's being said to you.
Cheers George
A source impedance of around 200ohms will easily drive a 5k or 10k load impedance.
Using a 2.1Vac output the current around the connection circuit will be given by 2.1Vac /{200+5000} = 0.404mAac and for a sinewave = 0.57mApk
Absolutely no problem for any current capable source.
It's the cable & RF filter capacitance and other parasitics that strain the current capability of the Source.
The first part of the signal that shows this effect is the treble. It gets rolled off when the combination of R & C encroaches on the audio band.
That however is not a "dynamics" problem. That is rolled off treble.
This rolled off treble gets worse with high source impedance and with higher capacitance, from longer cables.
Using a 2.1Vac output the current around the connection circuit will be given by 2.1Vac /{200+5000} = 0.404mAac and for a sinewave = 0.57mApk
Absolutely no problem for any current capable source.
It's the cable & RF filter capacitance and other parasitics that strain the current capability of the Source.
The first part of the signal that shows this effect is the treble. It gets rolled off when the combination of R & C encroaches on the audio band.
That however is not a "dynamics" problem. That is rolled off treble.
This rolled off treble gets worse with high source impedance and with higher capacitance, from longer cables.
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