I mean to have read somewhere that all you have to do to turn the PCM179X into a NOS Dac, is to shorten two pins.
When this is true, my question is: which two pins ?
Thx in advance.
Hans
When this is true, my question is: which two pins ?
Thx in advance.
Hans
PCM1792A:
setting the DFTH bit of control register 20 bypasses the internal digital interpolation filter
PCM1794A:
pin 1 low, pins 2, 11 and 12 high (page 22 datasheet https://www.ti.com/lit/ds/symlink/pcm1794a.pdf )
setting the DFTH bit of control register 20 bypasses the internal digital interpolation filter
PCM1794A:
pin 1 low, pins 2, 11 and 12 high (page 22 datasheet https://www.ti.com/lit/ds/symlink/pcm1794a.pdf )
I will! I will do 4 ABX tests with the files and try to select the best sounding ones.
(If I can tell the difference 🙂 )
You could test that hypothesis by putting a capacitor in parallel with the 25 ohm resistor you used in one of the other tests and see what happens. If that doesn't mess things up, also add a parallel inductor to mimic the input impedance of the MFB stage.
Ah! Now I see what the PGGB is about 🙂
I fail to see why the number of taps should be dependant on the file length.
But maybe we should discuss this in an other forum group 🙂
Marcel,
Could it be that the Dac is sensing it’s output to be used as an internal feedback signal ?
If so, I could understand why its behaviour depends on the external impedance.
Hans
Could it be that the Dac is sensing it’s output to be used as an internal feedback signal ?
If so, I could understand why its behaviour depends on the external impedance.
Hans
Last edited:
I have no idea what exactly is inside, I never designed a DAC for TI. I would guess either a bunch of PMOS current sources with switching PMOS differential pairs or NMOS switches below, or switching logic gates with series resistors.
They are probably doing something exotic to get really good matching, though. Maybe the resonant frequency of the RLC input impedance of the MFB circuit disturbs some sort of dynamic element matching algorithm?
Do you know of any patents related to the PCM17xx series?
Last edited:
So far things are going well with quite remarkable results.
Hopefully some more PM’s to be received.
A small give-away: one .wav file was digitized directly from LP, the other three came from a CD 😀 😀
Saturday I will disclose the outcome unless requests coming in for some extra time.
Hans
Hopefully some more PM’s to be received.
A small give-away: one .wav file was digitized directly from LP, the other three came from a CD 😀 😀
Saturday I will disclose the outcome unless requests coming in for some extra time.
Hans
Same as I found with ES9038Q2M. However as it turned out, it was possible to hack the I2C bus and take control of a register. Depends in part how the existing MCU (assuming there is one) reacts to loosing contact with the dac registers.
This sounds intriguing Hans. Without giving anything away what did you use to digitize the file? How was the RIAA done? This could also be studied later in a similar way with files generated by members of a common LP as shared with the group to find the best RIAA preamp and A/D device to digitize LP's.
Gerrit
Just looked at the <10Hz info on those files...
Lots of things happening there!
8Hz signals and one file even has DC in it...😕
Benz LP, VPI, head amp with current input, see
Designing a universal diff-in/diff-out Head Amp
Riaa with balanced preamp from LA nr 12.
A/D at 192/24 with AKM5386
20Khz brickwall filtered and downsampled with Audacity.
Hans
Thanks. I am experimenting with an old Linn/Ittok with a worn out Asak to a breadboarded moving coil phono. Haven't tried any A/D converters yet, so am interested in doing that.
Gerrit
Gerrit
Last reminder to perform the current DF experiment
A last reminder, to conduct the PGGB digital interpolation-filter listening experiment. Hans has conveniently prepared all the test files and placed them in a Dropbox (post #784) for easy download. Link below. All you have to do is listen and report what you hear.
https://www.diyaudio.com/forums/digital-line-level/371931-makes-nos-sound-79.html#post6703264
Hans plans to release the results by this Saturday, so please participate, and PM him your listening results no later than Friday evening. Thanks. 🙂
A last reminder, to conduct the PGGB digital interpolation-filter listening experiment. Hans has conveniently prepared all the test files and placed them in a Dropbox (post #784) for easy download. Link below. All you have to do is listen and report what you hear.
https://www.diyaudio.com/forums/digital-line-level/371931-makes-nos-sound-79.html#post6703264
Hans plans to release the results by this Saturday, so please participate, and PM him your listening results no later than Friday evening. Thanks. 🙂
Suspect Item B4 update
B4) The unsuppressed image-bands are, somehow, producing audible IM products directly within the ear. The notion here is that although the ear filters ultrasonic signals, is may be possible for the the structure of the inner ear to inter-modulate them down to being audible.
I have small an update on item B4 of our suspect list. I did some searching, but found very little information. I only a couple of sentences in a study report, as shown in the 3rd paragraph of the attached screen photo. The report claims that a researcher, Everest, found that ultrasonic frequencies can produce audible intermodulation products. I searched for the Everest 3rd edition book cited in the report, but only found the 4th edition, which doesn't appear to contain the cited claim. The writer of the report further says that his own listening experiment of this supposed IMD mechanism were negative.
Whether this an audible mechanism or not, IMD seems highly unlikely to produce the pleasant sound character associated with NOS. Just the opposite. In addition, analog filtered image-band DACs appear to retain the classic NOS character.
B4) The unsuppressed image-bands are, somehow, producing audible IM products directly within the ear. The notion here is that although the ear filters ultrasonic signals, is may be possible for the the structure of the inner ear to inter-modulate them down to being audible.
I have small an update on item B4 of our suspect list. I did some searching, but found very little information. I only a couple of sentences in a study report, as shown in the 3rd paragraph of the attached screen photo. The report claims that a researcher, Everest, found that ultrasonic frequencies can produce audible intermodulation products. I searched for the Everest 3rd edition book cited in the report, but only found the 4th edition, which doesn't appear to contain the cited claim. The writer of the report further says that his own listening experiment of this supposed IMD mechanism were negative.
Whether this an audible mechanism or not, IMD seems highly unlikely to produce the pleasant sound character associated with NOS. Just the opposite. In addition, analog filtered image-band DACs appear to retain the classic NOS character.
Attachments
Last edited:
Here are the results that came out of the PGGB test.
It was a great experience to have this support from Zaphod using his extremely interesting Remastro software for this test.
The outcome is rather strange on one item.
As already mentioned, there was a file that was recorded directly from LP, Day0 from Harry Belafonte.
This file was 100% correct for all of the 7 contenders.
I'm a bit puzzled how this was possible, so let's exclude this one.
Looking at the 3 other official 44.1/16 files, out of the 21 choices 47% where wrong, giving a result that is statistically insignificant.
My feeling therefore is that processing 44.1/16 as a reason why NOS sounds different cannot be seen as a major cause.
I have now included the link to the 88.2/24 file. It would be very interesting to hear from you whether this can be regarded as an improvement on the original 44.1/16 files.
Dropbox - NOS1_88.2 - Simplify your life
Hans
.
It was a great experience to have this support from Zaphod using his extremely interesting Remastro software for this test.
The outcome is rather strange on one item.
As already mentioned, there was a file that was recorded directly from LP, Day0 from Harry Belafonte.
This file was 100% correct for all of the 7 contenders.
I'm a bit puzzled how this was possible, so let's exclude this one.
Looking at the 3 other official 44.1/16 files, out of the 21 choices 47% where wrong, giving a result that is statistically insignificant.
My feeling therefore is that processing 44.1/16 as a reason why NOS sounds different cannot be seen as a major cause.
I have now included the link to the 88.2/24 file. It would be very interesting to hear from you whether this can be regarded as an improvement on the original 44.1/16 files.
Dropbox - NOS1_88.2 - Simplify your life
Hans
.
Attachments
Thanks Hans,
How do we interpret the table? I only told you what I liked best and now I see results like wrong and right? So does that mean, when I liked an unprocessed track it is green? and when I liked a processed track it is yellow?
and what about the others, did they claim what was best or did they try to guess what was processed? So when someone called a track as processed it was green but we do not know if they liked it or not?
no problem, but just want to make sure - arghh 😀 we should have agreed upfront on response options
Because there is no right or wrong for me. If this software does something with the track that makes it sound better, I would like to experiment more with this.
last time it was relatively easy and now it was all much more close
How do we interpret the table? I only told you what I liked best and now I see results like wrong and right? So does that mean, when I liked an unprocessed track it is green? and when I liked a processed track it is yellow?
and what about the others, did they claim what was best or did they try to guess what was processed? So when someone called a track as processed it was green but we do not know if they liked it or not?
no problem, but just want to make sure - arghh 😀 we should have agreed upfront on response options
Because there is no right or wrong for me. If this software does something with the track that makes it sound better, I would like to experiment more with this.
last time it was relatively easy and now it was all much more close