I do not know realy,
not listen to that card, even dont know from which model was...
*
a frieng gave me that card, because something was wrong, broken?
*
I just spoted that is too complicated design with DSP on digital side,
and complex, reconstuction circuit on analog end...
So I was not impressed with prominent brand,
and just pull out the DAC chips and some OP chips...
*
I remember that every dac was equiped with 2 trim pots
for adj.
that is all
not listen to that card, even dont know from which model was...
*
a frieng gave me that card, because something was wrong, broken?
*
I just spoted that is too complicated design with DSP on digital side,
and complex, reconstuction circuit on analog end...
So I was not impressed with prominent brand,
and just pull out the DAC chips and some OP chips...
*
I remember that every dac was equiped with 2 trim pots
for adj.
that is all
I copyed from the datas of pcm63 >
MSB ADJUSTMENT CIRCUITRY
Near optimum performance can be maintained at all signal
levels without using the optional MSB adjust circuitry of the
PCM63P shown in Figure 5. Adjustability is provided for
those cases where slightly better full-scale THD+N is
desired. Use of the MSB adjustments will only affect larger
dynamic signals (between 0dB and ñ6dB). This improvement
comes from bettering the gain match between the
upper and lower DACs at these signal levels. The change is
realized by small adjustments in the bit-2 weights of each
DAC. Great care should be taken, however, as improper
adjustment will easily result in degraded performance.
In theory, the adjustments would seem very simple to
perform, but in practice they are actually quite complex. The
first step in the theoretical procedure would involve making
each bit-2 weight ideal in relation to its code minus one
value (adjusting each potentiometer for zero differential
nonlinearity error at the bit-2 major carries). This would be
the starting point of each 100k potentiometer for the next
adjustment. Then, each potentiometer would be adjusted
equally, in opposite directions, to achieve the lowest fullscale
THD+N possible (reversing the direction of rotation
for both if no immediate improvement were noted). This
procedure would require the generation of the digital bit-2
major carry code to the input of the PCM63P and a DVM or
oscilloscope capable of reading the output voltage for a one
LSB step (5.72mV) in addition to a distortion analyzer.
A more practical approach would be to forego the minor
correction for the bit-2 major carry adjustment and only
adjust for upper and lower DAC gain matching. The problem
is that just by connecting the MSB circuitry to the
PCM63P, the odds are that the upper and lower bit-2 weights
would be greatly changed from their unadjusted states and
thereby adversely affect the desired gain adjustment. Just
centering the 100kW potentiometers would not necessarily
provide the correct starting point. To guarantee that each
100kW potentiometer would be set to the correct starting or
null point (no current into or out of the MSB adjust pins), the
voltage drop across each corresponding 330kW resistor would
have to measure 0V. A voltage drop of ±1.25mV across
either 330kW resistor would correspond to a ±1LSB change
in the null point from its unadjusted state (1LSB in current
or 3.81nA x 330kW = 1.26mV). Once these starting points
for each potentiometer had been set, each potentiometer
would then be adjusted equally, in opposite directions, to
achieve the lowest full-scale THD+N possible. If no immediate
improvement were noted, the direction of rotation for
both potentiometers would be reversed. One direction of
potentiometer counter-rotations would only make the gain
mismatch and resulting THD+N worse, while the opposite
would gradually improve and then worsen the THD+N after
passing through a no mismatch point. The determination of
the correct starting direction would be arbitrary. This procedure
still requires a good DVM in addition to a distortion
analyzer.
Each user will have to determine if a small improvement in
full-scale THD+N for their application is worth the expense
of performing a proper MSB adjustment.
*
*
MSB ADJUSTMENT CIRCUITRY
Near optimum performance can be maintained at all signal
levels without using the optional MSB adjust circuitry of the
PCM63P shown in Figure 5. Adjustability is provided for
those cases where slightly better full-scale THD+N is
desired. Use of the MSB adjustments will only affect larger
dynamic signals (between 0dB and ñ6dB). This improvement
comes from bettering the gain match between the
upper and lower DACs at these signal levels. The change is
realized by small adjustments in the bit-2 weights of each
DAC. Great care should be taken, however, as improper
adjustment will easily result in degraded performance.
In theory, the adjustments would seem very simple to
perform, but in practice they are actually quite complex. The
first step in the theoretical procedure would involve making
each bit-2 weight ideal in relation to its code minus one
value (adjusting each potentiometer for zero differential
nonlinearity error at the bit-2 major carries). This would be
the starting point of each 100k potentiometer for the next
adjustment. Then, each potentiometer would be adjusted
equally, in opposite directions, to achieve the lowest fullscale
THD+N possible (reversing the direction of rotation
for both if no immediate improvement were noted). This
procedure would require the generation of the digital bit-2
major carry code to the input of the PCM63P and a DVM or
oscilloscope capable of reading the output voltage for a one
LSB step (5.72mV) in addition to a distortion analyzer.
A more practical approach would be to forego the minor
correction for the bit-2 major carry adjustment and only
adjust for upper and lower DAC gain matching. The problem
is that just by connecting the MSB circuitry to the
PCM63P, the odds are that the upper and lower bit-2 weights
would be greatly changed from their unadjusted states and
thereby adversely affect the desired gain adjustment. Just
centering the 100kW potentiometers would not necessarily
provide the correct starting point. To guarantee that each
100kW potentiometer would be set to the correct starting or
null point (no current into or out of the MSB adjust pins), the
voltage drop across each corresponding 330kW resistor would
have to measure 0V. A voltage drop of ±1.25mV across
either 330kW resistor would correspond to a ±1LSB change
in the null point from its unadjusted state (1LSB in current
or 3.81nA x 330kW = 1.26mV). Once these starting points
for each potentiometer had been set, each potentiometer
would then be adjusted equally, in opposite directions, to
achieve the lowest full-scale THD+N possible. If no immediate
improvement were noted, the direction of rotation for
both potentiometers would be reversed. One direction of
potentiometer counter-rotations would only make the gain
mismatch and resulting THD+N worse, while the opposite
would gradually improve and then worsen the THD+N after
passing through a no mismatch point. The determination of
the correct starting direction would be arbitrary. This procedure
still requires a good DVM in addition to a distortion
analyzer.
Each user will have to determine if a small improvement in
full-scale THD+N for their application is worth the expense
of performing a proper MSB adjustment.
*
*
End of this thread???
This thread is dead more or less.
To end up:
Gentelmen, you cannot hear any difference between the PCM63P, PCM63P-K, PCM63P....K, J, Y and whatever has been printed on it, if all the signals entering it have been reclocked with a low jitter clock.
I have listened with Manfred's GOLDEN PAIR (thank you Manfred for trusting me by sending them to me); I have listened to many other PCM63s: NO DIFFERENCE!
BTW. The Golden Pair of Manfred did have far the most distortion of all PCM's I measured!!!
Obviously, without decent reclocking, one listens to a combination of factors which I cannot explain either.
I do not say that there are no audible differences without reclocking! You all are not mad.......
This thread is dead more or less.
To end up:
Gentelmen, you cannot hear any difference between the PCM63P, PCM63P-K, PCM63P....K, J, Y and whatever has been printed on it, if all the signals entering it have been reclocked with a low jitter clock.
I have listened with Manfred's GOLDEN PAIR (thank you Manfred for trusting me by sending them to me); I have listened to many other PCM63s: NO DIFFERENCE!
BTW. The Golden Pair of Manfred did have far the most distortion of all PCM's I measured!!!
Obviously, without decent reclocking, one listens to a combination of factors which I cannot explain either.
I do not say that there are no audible differences without reclocking! You all are not mad.......
surprises...
Herb,
Wait! we keep ongoing with this:
Manfred is trying to put his hand on a Tent DAC (with the re-clocking); my AVM will get a re-clocking circuit sometime soon (I will take under consideration all of your other important remarks - includes the needed clean PSUs, grounding, layers=compensation if possible, etc.).
I assume that in few month, we shell be able to meet all 3 of us together (possibly in Eindhoven) and do the listening-tests with all different PCMs.
What hardly solved yet is indeed the questions about sound and measurements. I would say that we think that we think we know, but what happens in reality?
An engineer working for one of the leading Hearing-Aids companies told me privately, that one can put an Hearing-Aid (HA) device in a Mess-Box, while programming it each time SLIGHTLY difference (slightly changes of the devices attack and decay time, compensation for compression, non-linearity amplification, etc.).
NOW PLEASE PAY ATTENTION TO THIS: He claims that he can regrettably make more the 100 very small changes in the programming of the sound domain & quality of the device: The client will notice them – but you will see NO DIFFERENCE in the Mass-box measurements (!)
BTW, they are using top Mess-Boxes and special dedicated test chamber, which can go wide range. They put a lot of energy and thought into this.
I was looking for something on the internet, to give us an idea:
http://www.interacoustics.dk/com_en/Pages/Product/HaAnalyzers/Hearinginstrumenttest.htm
Measurement and sound? Should have been an easy topic, but it is not so....
Greetings,
IJ.
Herb,
Wait! we keep ongoing with this:
Manfred is trying to put his hand on a Tent DAC (with the re-clocking); my AVM will get a re-clocking circuit sometime soon (I will take under consideration all of your other important remarks - includes the needed clean PSUs, grounding, layers=compensation if possible, etc.).
I assume that in few month, we shell be able to meet all 3 of us together (possibly in Eindhoven) and do the listening-tests with all different PCMs.
What hardly solved yet is indeed the questions about sound and measurements. I would say that we think that we think we know, but what happens in reality?
An engineer working for one of the leading Hearing-Aids companies told me privately, that one can put an Hearing-Aid (HA) device in a Mess-Box, while programming it each time SLIGHTLY difference (slightly changes of the devices attack and decay time, compensation for compression, non-linearity amplification, etc.).
NOW PLEASE PAY ATTENTION TO THIS: He claims that he can regrettably make more the 100 very small changes in the programming of the sound domain & quality of the device: The client will notice them – but you will see NO DIFFERENCE in the Mass-box measurements (!)
BTW, they are using top Mess-Boxes and special dedicated test chamber, which can go wide range. They put a lot of energy and thought into this.
I was looking for something on the internet, to give us an idea:
http://www.interacoustics.dk/com_en/Pages/Product/HaAnalyzers/Hearinginstrumenttest.htm
Measurement and sound? Should have been an easy topic, but it is not so....
Greetings,
IJ.
Re: surprises...
Are you not hijacking the thread? Find hoert mit!
You are absolutely right! Don't let me get started on that, but one of the nice things of our hobby is to try to find relationships between measurements and human audio perception.
To say it in other words: try to make audio a more scientific than a relegious affair, so that charlatans will get less chance to sell their dogma's for gold.
Sometimes we have success as I had with the EMC of loudspeaker cables and interlinks. Now we understand what is going on and come to an optimal solution (only in this aspect!).
The same counts for the phenominon 'jitter'. As soon as we knew that jitter is very audible, we can start measuring jitter on eg. oscillators in stead of listening to all kind of different oscillators.....
A new idea is rising that jitter in the low frequency regions does more harm than those in the higher.
I think, only the combination of measurements and listening could bring us further. Often we are walking as blind humans in the dark.
irgendjemand said:
Are you not hijacking the thread? Find hoert mit!
You are absolutely right! Don't let me get started on that, but one of the nice things of our hobby is to try to find relationships between measurements and human audio perception.
To say it in other words: try to make audio a more scientific than a relegious affair, so that charlatans will get less chance to sell their dogma's for gold.
Sometimes we have success as I had with the EMC of loudspeaker cables and interlinks. Now we understand what is going on and come to an optimal solution (only in this aspect!).
The same counts for the phenominon 'jitter'. As soon as we knew that jitter is very audible, we can start measuring jitter on eg. oscillators in stead of listening to all kind of different oscillators.....
A new idea is rising that jitter in the low frequency regions does more harm than those in the higher.
I think, only the combination of measurements and listening could bring us further. Often we are walking as blind humans in the dark.
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