The procedure after a repair is to do all the needed test scopes, gens, loads, res and cap,THD ,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 each other 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 one 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
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 each other 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 one 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
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 bit above 92db .
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 all available options like a pot in a box , a B1 buffer 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 didn't 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 rich sound and all the range of frequencies 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 different transistors, 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 all available options like a pot in a box , a B1 buffer 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 didn't 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 rich sound and all the range of frequencies 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 different transistors, 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 !!!!
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A summarized conclusion of the above, points to the configuration IE some active stage before the amp and the pot behind it ...
Common practice in the majority of vintage amplifiers ( only variations on the topology and the level of gain at the time of vintage )
Common practice also for many today's amplifiers
And common at least as a configuration for the most consumer preamplifiers existing as stand alone devices that i am aware of .
I described the above situation in a few lines in another thread saying that an active configuration like above will have better dynamics when played that low next to a pot in the box totally passive .
May the description is wrong but one way or another i got questioned about my knowledge in electronics by DF96, insulted by an other member Davey about my repair skills and so on .
Could you please join in and share your opinion ?
Kind regards
Sakis
( nothing in electronics comes for free obviously any active stage will introduce some problem in the signal like distortion , noise , phase issues ,linearity and probably many more next to a passive , This, together with impedance issues or drive ability of each configuration is NOT the discussion here ... )
Common practice in the majority of vintage amplifiers ( only variations on the topology and the level of gain at the time of vintage )
Common practice also for many today's amplifiers
And common at least as a configuration for the most consumer preamplifiers existing as stand alone devices that i am aware of .
I described the above situation in a few lines in another thread saying that an active configuration like above will have better dynamics when played that low next to a pot in the box totally passive .
May the description is wrong but one way or another i got questioned about my knowledge in electronics by DF96, insulted by an other member Davey about my repair skills and so on .
Could you please join in and share your opinion ?
Kind regards
Sakis
( nothing in electronics comes for free obviously any active stage will introduce some problem in the signal like distortion , noise , phase issues ,linearity and probably many more next to a passive , This, together with impedance issues or drive ability of each configuration is NOT the discussion here ... )
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Hi,
Many audiophile amplifiers have a passive line stage and active phono.
The power amplifier gain is higher than a "normal" power amplifier.
I doubt addition of a line stage would help low levels at all.
rgds, sreten.
Many audiophile amplifiers have a passive line stage and active phono.
The power amplifier gain is higher than a "normal" power amplifier.
I doubt addition of a line stage would help low levels at all.
rgds, sreten.
I feel like after my knowledge has been questioned , my repairing skills insulted so now my ears are also under investigation🙂🙂🙂
Guys have you actually been there ? or this is a theoretical approach based on general experiences ?
I am not trying to insult anyone but really any of you did this in real life to know ?
Guys have you actually been there ? or this is a theoretical approach based on general experiences ?
I am not trying to insult anyone but really any of you did this in real life to know ?
Looking at both answers coming with UK flag where most amplifiers are UK school i think it is my turn to question if you been there before to tell ...
if a passive pot is going to cause a problem it will be frequency related as the proceeding stage can't drive it and interconnects. It can't change dynamics. Edge case of very poorly chosen pot.
FWIW when I build the B1 I currently use I did plan to wire it with switches so buffered/passive could be tested then ran out of time and left it active as need to run 4m interconnects. I should finish that off sometime. I don't expect it to prove anything.
Edit: I have no uk built amplifiers in my hifi
FWIW when I build the B1 I currently use I did plan to wire it with switches so buffered/passive could be tested then ran out of time and left it active as need to run 4m interconnects. I should finish that off sometime. I don't expect it to prove anything.
Edit: I have no uk built amplifiers in my hifi
Hi Sakis,
I think it's just a matter of personal taste and I like the sound of P3A too! This is what 'works' best for me, no pot, no preamp:
PC(USB) -> Schiit Modi DAC -> P3A -> Cabasse MT31 speakers
Cheers,
Jacques
I think it's just a matter of personal taste and I like the sound of P3A too! This is what 'works' best for me, no pot, no preamp:
PC(USB) -> Schiit Modi DAC -> P3A -> Cabasse MT31 speakers
Cheers,
Jacques
Jacques your case doesn't match you have electronic volume control and nothing in between the source and the amp .
On the other you are an ideal subject to put a passive pot in between to see if this is going to effect the dynamics if played in very low level ...
Kind regards
Sakis
On the other you are an ideal subject to put a passive pot in between to see if this is going to effect the dynamics if played in very low level ...
Kind regards
Sakis
Never noticed a frequency issue given as fact a good pot and a proper value Could be interesting though if and ever you make the test to let us know
The experiment would be highly biased as the "low level" for my old ears is probably much louder than yours.
And objectively, ear frequency response also worsens with age.
This being said, how would the addition of a pot anywhere on the chain improve dynamics in my system?
In your specific case, some answer might be found in your sound source: low impedance analogic earphone output of a mobile phone.
When played a too low or too high volume, dynamics might be flattened. Did you ever try a better source?
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never said that the pot will improve dynamics ..The total opposite I said that the pot behind the amp will decrease dynamics in low listening level ....
Sources ???What are you talking about ?? I have available anything you like CD67 KIS , Teac VRDS 7 ( working ) Sony DVP NS900 and many many more ..... except the tone and character of each source the dynamics with a passive pot presented similar behavior if played in low listening level ....
Sources ???What are you talking about ?? I have available anything you like CD67 KIS , Teac VRDS 7 ( working ) Sony DVP NS900 and many many more ..... except the tone and character of each source the dynamics with a passive pot presented similar behavior if played in low listening level ....
Sakis what you say makes sense to me - I rather suspect its due to having a noisy ground in the passive case. At low signal levels the pot has higher 'gain' for the noise on the bottom end of its wiper. Same reason that most listeners say a trafo based volume control sounds better than a simple passive pot.
AFAIK we perceive dynamics mostly through transients.
Transients themselves are high frequency components of a given sound.
So if we lose HF we might well perceive this as sounding less dynamic.
For example if one were to remove HF from a kick drum the result will sound less dynamic.
So any perceived loss in dynamics may well be a secondary effect of treble loss.
PS: All amps in my hifi are UK designed and built. Not sure if they are 'UK school' though.
Treble loss from a passive pot is at its maximum (i.e. most HF loss) at a setting of -6dB - that is almost full volume, not low level. So if a passive pot damages 'dynamics' by losing HF then it would be at high level, not low level.
This appears to be an attempt to settle a simple technical argument by democratic means. Unfortunately, democracy is not the right method for finding technical truth.
This appears to be an attempt to settle a simple technical argument by democratic means. Unfortunately, democracy is not the right method for finding technical truth.
Interesting suggestion. No doubt, this means taking some serious comparative noise level numbers with some form of active or buffered volume control circuit.
In my own experience, there is always a volume level, below which the audio quality of a system diminishes to an undynamic sound. This is dependent on many factors like my threshold hearing limitations and the low level performance of the speakers. This is probably not what Sakis refers to but I'm sure it can also affect the dynamic quality we perceive.
Surely this has been examined in the past but unless there are some numbers here, we're just shooting the breeze.
This is probably largely a matter of how our ears work. In any case, it would not depend on how the volume was reduced, just that it was reduced.Ian Finch said:
Correct in a way but obviously when low level listening is the target we obviously talk about sensitive speakers
The behavior is alike when you don't have sensitive speakers
If you are able to describe in words how non sensitive speakers play if the power is too low to start them then you have the answer
Exactly this was the sound that i listen from my sensitive speakers when the amp was P3A pot was behind RK27/47k log and source was a CD 67 kis or a VRDS7 Or a Sony DVP NS900
(remember that we talk again .. for very low listening level )
The behavior is alike when you don't have sensitive speakers
If you are able to describe in words how non sensitive speakers play if the power is too low to start them then you have the answer
Exactly this was the sound that i listen from my sensitive speakers when the amp was P3A pot was behind RK27/47k log and source was a CD 67 kis or a VRDS7 Or a Sony DVP NS900
(remember that we talk again .. for very low listening level )
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