No. It's not placebo. The change in sound was very pronounced. I can insert the choke once again and the change would be the same. Also I noticed that when I put a ferrite clamp on the spdif cable the sound slows down.
It can't, but SPDIF is not optical but electrical. He has discovered that if you use badly engineered interfaces (e.g. mixing balanced and unbalanced digital connections, sending I2S through cables) and then modify them this can change the sound. Like many audiophiles before him, he seems to prefer this corrupted sound and so will come to the conclusion that badly engineered interfaces are best.HumbleDeer said:
You mean the CD plays more slowly? A Nobel prize may be on its way if you can explain that.momitko said:
It's not the music that slows down but the bass becomes sort of protracted and slow, the kind of bass that is unpleasant to listen to. How can I claim a Nobel prize? 🙂
Look. The soundcard has a balanced output. The converter has a transformer input and the other winding of transformer in the converter is connected to A+ and B- of SN75LBC176D. Judging by the datasheet A+ and B- are a balanced connection, aren't they? Please find attached schematics of the converter.
Attachments
The chip inputs may be balanced; that is irrelevant. The input transformer primary is grounded one side so is unbalanced. Therefore it should not be connected to a balanced output via a twisted pair cable.
If the sound slows down, but not the CD, then that's bango magic. If sound's transmitted slower, then there'd be a buildup of not-yet-sent sound.. Which doesn't make sense as there's not a buffer at the output to buffer any bits. Perhaps that wouldn't even be possible considering a CD has a high-bit output.
No. You are not correct. The primary winding of a transformer is not grounded. The sign of the ground means that it can actually be connected to the ground in SPDIF connection but in reality it is not connected to any ground but just to one end of a twisted pair.
I was wondering about this just like you. Perhaps you could make the same test in your equipment if you have any spdif connection. Just put a ferrite clamp on spdif cable and have a listen.
So the circuit you showed is incorrect? How can you make a point by showing a circuit which proves the opposite? Your comment about the chip input being balanced implies that you don't understand the circuit, as you would know that is irrelevant if you did understand the circuit.momitko said:
Did you remove the ground connection shown in the circuit? Did you change the termination from 75ohms to 110ohms? Did you make any other changes from the circuit you show?
The sign of the ground connection means that the lower end of the primary winding should be connected to the shield of spdif cable. In the past I did connect it to the shield but lately I removed spdif cable and connected both ends of the primary winding to a twisted pair without any ground. The shield of the twisted pair is connected only to the ground on the soundcard. The 75 Ohms resistor is still there. I did not remove it.
No. The ground connection symbol on the circuit diagram means that both the incoming coaxial cable outer and one side of the transformer primary is connected to signal ground. You now seem to say that this was not the case - so the circuit you showed was not the circuit you were using.momitko said:
So you partially converted an SPDIF input to an AES/EBU input by removing the ground connection - but did not tell us this in your opening post or later even when I queried the wisdom of connecting a balanced source to what you had led us to believe was an unbalanced input. The conversion from SPDIF was only partial because you did not change the termination resistor.
What was the characteristic impedance of the twisted pair cable? It probably was not 75 ohms so you had a mismatch which would have caused signal reflections. If the cable was not 110 ohms then you would get another reflection at the source end so multiple reflections which are likely to increase cable-induced jitter. Putting a ferrite around the cable will not affect this very much. Fortunately digital audio is quite robust so even the most foolish audiophile 'upgrade' does not do much damage to the signal.
SPDIF uses both Toslink aswell as RCA. You're using the RCA, I suppose?
SPDIF is Digital.
Now I understand what you mean. The ground of the primary winding is not connected to the ground of the secondary winding. This sign of ground in the far right side of the picture should not be there, I guess.
I have no idea what is the impedance of a twisted pair since I used just some kind of a double wire, not a specially designed AES/EBU cable. Do you want to say that I need to purchase a specially designed AES/EBU cable with 110 Ohm impedance to avoid reflections? Please note that 75 Ohms resistor is still at the secondary winding of the transformer. It would be too difficult for me to remove that resistor or substitute it with 110 Ohms resistor.
When people say SPDIF they usually mean the electrical version. TOSLINK uses the same protocol, but people usually say TOSLINK or fibre when they mean optical SPDIF.HumbleDeer said:
It should be there as the circuit was originally built. You should have modified the diagram when you modified the circuit.momitko said:
That is what I suspected.momitko said:
No. With your current circuit you actually need a 75ohm cable. Your setup is suboptimal, as you are mixing different impedances. Why on earth did you think that using the wrong connection would somehow be better than the perfection of using the right connection?
I don't believe there's a possibility for sound to sound different in an analogue way when the format is different.
I believe you're hearing what I call "A tube amp". Basically, tube amps distort the sound a way that you like it. If you put a choke around the electrical spdif cable, and it impacts the sound, then it's not the cable. It's your device that's getting messed up. If your device is getting messed up it's either cheap **** or malfunctioning. The signal itself can't be altered by inductance, the device making the signal can.
If you're getting distortion, obey Dem impedances, too. A choke can induce or reduce impedance. An amplifier will also delay the sound slightly, or deliver less output on 16 ohm speakers than 2Ohm ones.
I believe you're hearing what I call "A tube amp". Basically, tube amps distort the sound a way that you like it. If you put a choke around the electrical spdif cable, and it impacts the sound, then it's not the cable. It's your device that's getting messed up. If your device is getting messed up it's either cheap **** or malfunctioning. The signal itself can't be altered by inductance, the device making the signal can.
If you're getting distortion, obey Dem impedances, too. A choke can induce or reduce impedance. An amplifier will also delay the sound slightly, or deliver less output on 16 ohm speakers than 2Ohm ones.
No, no, no. This error in schematics was made by the designer. Ground at the primary winding is isolated from the ground at the secondary winding. Otherwise what's the use of SPDIF transformer?
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