Is the way i write wrong ?
I never said anything about the ability to drive the amp I said that if very low listening level is the issue then a passive pot will have less dynamics nothing more nothing else ....
If input/output/input impedances are properly matched, then the signal into any stage should exactly match the signal into the following stage, after adjusting for gain. If that's the case, I don't see how dynamics can differ.
I think that part of the misunderstanding is that here on DIY we don't usually use tone controls. With a digital source, tone control is easier in the digital domain. Commercial integrated amps do almost always have tone controls. They typically have both digital inputs and provision for analog inputs. Tone control (e.g., Loudness) in the analog domain is done with active circuits. Maybe that explains the common use of active pre-amp stages in these amps?
Sheldon
I think that part of the misunderstanding is that here on DIY we don't usually use tone controls. With a digital source, tone control is easier in the digital domain. Commercial integrated amps do almost always have tone controls. They typically have both digital inputs and provision for analog inputs. Tone control (e.g., Loudness) in the analog domain is done with active circuits. Maybe that explains the common use of active pre-amp stages in these amps?
Sheldon
Sheldon ...No for consumer integrated amps having some gain stage before the amplifier input ( which i repeat is with in the reasonable impedance 10-100K ) is /was a standard practice ages ago regardless if for Sansui the pots was before the gain stage while for Denon was between the gain stage and the main amp ...( as an example )
So given what you say and impedance is within the reasonable area then a gain stage is not needed ...Fine with me then one has to explain why they put it inside ...
Tone controls is not involved in this since most of the time have their own gain stage or buffer . and/or some of them are nested inside the feedback chain of the main amp ( old technique) and also this is not involving digital systems at all ...
To make it even more easy to understand ( for me also if you like ) lets pick up any consumer amplifier that has this topology an analyze or comment on a given circuit .
So given what you say and impedance is within the reasonable area then a gain stage is not needed ...Fine with me then one has to explain why they put it inside ...
Tone controls is not involved in this since most of the time have their own gain stage or buffer . and/or some of them are nested inside the feedback chain of the main amp ( old technique) and also this is not involving digital systems at all ...
To make it even more easy to understand ( for me also if you like ) lets pick up any consumer amplifier that has this topology an analyze or comment on a given circuit .
marantz PM 350 as a very simple example
You may see the block diagram and the principal of operation copy from the service manual
Phono stage
selector switch
tape monitors
passive volume and balance control
18db ( !!! ) gain stage
tone control locally buffered
and main amplifier with impedance a bit above 33K
Ok i expect some losses from input termination probably filtering and some other losse from the passive volume and balance but could you please explain to me why the **** you need to have a 18db gain stage to drive a normal amplifier ?
Ok we have to take in mind that sources at the time was tuners and decks had 100-400mv output and obviously now days with 2 volt sources a 18db gain stage will be an obvious overkill But now days in amplifier that have CD inputs also gain stage exists but with not that much gain ....
You may see the block diagram and the principal of operation copy from the service manual
Phono stage
selector switch
tape monitors
passive volume and balance control
18db ( !!! ) gain stage
tone control locally buffered
and main amplifier with impedance a bit above 33K
Ok i expect some losses from input termination probably filtering and some other losse from the passive volume and balance but could you please explain to me why the **** you need to have a 18db gain stage to drive a normal amplifier ?
Ok we have to take in mind that sources at the time was tuners and decks had 100-400mv output and obviously now days with 2 volt sources a 18db gain stage will be an obvious overkill But now days in amplifier that have CD inputs also gain stage exists but with not that much gain ....
Attachments
That's a pretty common topology but just because they've done it that way for 40 or more years doesn't mean it's best or appropriate forever. It's not how I'd design a receiver today!
Conrad you are probably right ... no arguments about that ... still in many consumer amps the topology today is alike only numbers are changed ...regarding gain
The all argument we are having here is a tiny fragment of a complete sound system its a comment under specific situation very low listening power
there was never a question about drive ability
Still my opinion is that the topology as seen above and as done today by many manufacturers only with different gain in the stages is made like that to cover that need also
I need to place examples but i am not sure any more if my English is enough to describe correctly what i mean ...
Suppose you are listening in low power and the system is sleeping in a way and information that comes in your ear is not rich ..lets say bass is not enough
What do you do ?
Do you increase the all volume so the speakers wake up ?
or you may add in theoretically same volume position a couple of db bass from the tone control ???
Both approach will increase the total power to the speakers after all
while the second will alter also the tone of the system
Was this helpful ?
I ve been verifying a million times during the repairs and listening tests on the amplifiers i repair that the ones that have some gain stage mostly with the pot behind it play much rich and sweet sound in low listening level than others that have passive preamp for example ...
The procedure after a repair is to do all the needed test scopes gens loads res and cap bias offset and so on limiters if needed and after that all is done we let the amplifier play for at least 8 hours while looking for anything else that might go wrong
we use speakers according to the power of the amplifier from time to time we crunk the volume to full power but lets not fool eachother since for the rest of the day the amplifier plays with us at almost zero power ...telephone is ringing 24/7 in the lab so you cant have the music full power while talking at the phone .
So me and 3 more people working with me at the lab doing this for so many years noticed that there is a serious difference of how amplifiers play in very low power and all is pointing to this direction ..Amplifiers that have a pot and gain stage before the main amp produce far more rich and sweet sound better dynamics than others that have just a passive pot behind them when played at very low power
Does this help any better ?
The all argument we are having here is a tiny fragment of a complete sound system its a comment under specific situation very low listening power
there was never a question about drive ability
Still my opinion is that the topology as seen above and as done today by many manufacturers only with different gain in the stages is made like that to cover that need also
I need to place examples but i am not sure any more if my English is enough to describe correctly what i mean ...
Suppose you are listening in low power and the system is sleeping in a way and information that comes in your ear is not rich ..lets say bass is not enough
What do you do ?
Do you increase the all volume so the speakers wake up ?
or you may add in theoretically same volume position a couple of db bass from the tone control ???
Both approach will increase the total power to the speakers after all
while the second will alter also the tone of the system
Was this helpful ?
I ve been verifying a million times during the repairs and listening tests on the amplifiers i repair that the ones that have some gain stage mostly with the pot behind it play much rich and sweet sound in low listening level than others that have passive preamp for example ...
The procedure after a repair is to do all the needed test scopes gens loads res and cap bias offset and so on limiters if needed and after that all is done we let the amplifier play for at least 8 hours while looking for anything else that might go wrong
we use speakers according to the power of the amplifier from time to time we crunk the volume to full power but lets not fool eachother since for the rest of the day the amplifier plays with us at almost zero power ...telephone is ringing 24/7 in the lab so you cant have the music full power while talking at the phone .
So me and 3 more people working with me at the lab doing this for so many years noticed that there is a serious difference of how amplifiers play in very low power and all is pointing to this direction ..Amplifiers that have a pot and gain stage before the main amp produce far more rich and sweet sound better dynamics than others that have just a passive pot behind them when played at very low power
Does this help any better ?
When in the lab there is no amplifier under test and i want my personal music in front of me i have a couple of speakers 6.5" woofer 1'' silk tweeter that is 60 cm in front of me and in total in a spread of 1m80cm with an internal tilt and a front bass reflex
so it cant be more near field than that often i have to move my chair to enter the sweet spot of my system since its so near
amplifier is the P3A with some extra mods and behind it i have been trying anything from the ones you described above B1 included and all possible combinations regarding position of the pot or the buffer .
Target was to be able to get as much information possible from the system with as low power was possible in order to still be able to talk on the phone while music is playing , not to disturb other working close to me or talking at the phone ....
I needed bass middle and high from a zero power system .. co workers say about this system that its his personal headphone set ....
so tried passive
result was listening from a mobile phone or an under powered B&W speaker ( i trust that we all know how average B&W speaker plays if the amplifier has no serious guts to drive it)
Then tried a B1 first i dint like the edges ..seem to me that are a bit rounded sweeter in general added some in the specific application but not what i wanted ..I got some juice but not enough ...
Then tried a P37 as was in the site of rod in a vero board OOOOps everything comes exactly as i wanted it to be plenty of information at zero power
Trussed the vero board , design a sophisticated PCB dress it up with a very nice audiophile power supply use the best available parts closely match my components spent 3-4 years in occasionally mix match parts and choose difference transistor cook them hotter and decide about hfe and other characteristics while both measuring and listening was in order
I was done 2-3 years ago and after that i never had any other combo that can beat that system when played in the specific target of zero power ...
Obviously i have tried pot before and after and for the specific application pot goes before the gain stage big time !!!!
so it cant be more near field than that often i have to move my chair to enter the sweet spot of my system since its so near
amplifier is the P3A with some extra mods and behind it i have been trying anything from the ones you described above B1 included and all possible combinations regarding position of the pot or the buffer .
Target was to be able to get as much information possible from the system with as low power was possible in order to still be able to talk on the phone while music is playing , not to disturb other working close to me or talking at the phone ....
I needed bass middle and high from a zero power system .. co workers say about this system that its his personal headphone set ....
so tried passive
result was listening from a mobile phone or an under powered B&W speaker ( i trust that we all know how average B&W speaker plays if the amplifier has no serious guts to drive it)
Then tried a B1 first i dint like the edges ..seem to me that are a bit rounded sweeter in general added some in the specific application but not what i wanted ..I got some juice but not enough ...
Then tried a P37 as was in the site of rod in a vero board OOOOps everything comes exactly as i wanted it to be plenty of information at zero power
Trussed the vero board , design a sophisticated PCB dress it up with a very nice audiophile power supply use the best available parts closely match my components spent 3-4 years in occasionally mix match parts and choose difference transistor cook them hotter and decide about hfe and other characteristics while both measuring and listening was in order
I was done 2-3 years ago and after that i never had any other combo that can beat that system when played in the specific target of zero power ...
Obviously i have tried pot before and after and for the specific application pot goes before the gain stage big time !!!!
@Marcel
I truly apologize for messing up your thread ...while in the rush of argument we made a mess here ...I apologize for that but DF 96 refused to listen to what i say so i lost it some way ....
@ moderators
Please feel free to move in a new thread anything that is not related to the OP thread
My apologies to the mod team also .
Kind regards
Sakis
I truly apologize for messing up your thread ...while in the rush of argument we made a mess here ...I apologize for that but DF 96 refused to listen to what i say so i lost it some way ....
@ moderators
Please feel free to move in a new thread anything that is not related to the OP thread
My apologies to the mod team also .
Kind regards
Sakis
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I'll add my vote for this. In the decade before CD, the audio rags were all about "wait till we have digital audio and the dynamic range of comsumer recordings approach human hearing!" They had in mind things like the Telarc 1812, and to get the dynamic range, the "usual" playing level has to be well below what was considered the maximum level.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 🙄
The maximum level or "0 dB" for analog tape is defined when distortion hits something like 3 percent. When the level goes to about +10dB, distortion only goes to 10 percent or so, and as tape does "soft clipping," this doesn't sound nearly as bad as hard clipping at 10dB over the max input level).
So the idea was that the "usual level" in digital would be many dB (20 to 24) below the max, to make sure that even the biggest peaks wouldn't clip. This meant a CD player with a maximum RMS output of 2.1V would normally be putting out (when playing what was then thought to be a "correctly" recorded CD) signal in the 200mV range.
This is the part that most of are disputing.
We cannot see any reason for you arriving at that conclusion.
To us that conclusion just seems wrong.
Please Bonsai , Andrew T
place your comments in a new thread created for this
http://www.diyaudio.com/forums/solid-state/280463-lowest-listening-level-2.html#post4468562
place your comments in a new thread created for this
http://www.diyaudio.com/forums/solid-state/280463-lowest-listening-level-2.html#post4468562
Really now Andrew ...have you tested ever to see the difference if any Or your answer is coming from a theoretical approach or calculation ?
I have answered your questions. You may not like the answers, but there is nothing I can do about that.east electronics said:
You appear to have a misconception about the way that amplifiers and speakers are 'driven', especially by potential dividers set near their low end (i.e. high attenuation). In reality, a potential divider has the lowest source resistance (and hence best 'driving ability') at two ends of the range: lowest volume and highest volume. It is almost as good at low-middle volume. It is at its worst at -6dB: almost full volume. If a passive pot is going to damage the signal it will be at high volume - just short of maximum volume. Even then the main damage will be a slight HF loss. No effect whatsover on "dynamics".
The most likely effect of a gain stage before the volume pot is to introduce clipping on loud signals, and some distortion on other signals. Some mild clipping may be misheard as "rich" sound.east electronics said:
You can put gain before the pot as long as you consider the signal levels and design for it. In my latest preamp, I have c. 14dB before the volume pot. All 2V signals like CD etc are attenuated first. Legacy tuner, tape signals are not. They get amplified, and then feed a 5 k log pot (there's a tone control after the gain stage but before the pot that can be bypassed). After the volume control there is a buffer.
This arrangement means noise is attenuated with the signal. Since the max swing on the output is 24V Pk to Pk, and the nominal output 1V RMS, there is at least 26 dB headroom.
Ovation Symphony Line Preamplifier
This arrangement means noise is attenuated with the signal. Since the max swing on the output is 24V Pk to Pk, and the nominal output 1V RMS, there is at least 26 dB headroom.
Ovation Symphony Line Preamplifier
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Yes, so a well-designed gain stage before a volume pot is transparent - it does not contribute to "rich" sound.
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