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Datasheet: fOSC Oscillator frequency: AM2=1, AM1=0, AM0=0 1200kHz
Just cut AM2 from ground and connect to VDD. That's all.😎
Got some samples from Wurth to test.
Now we talking!
Quick test I have hard to tell Volt+ apart from Sanwu!
Have only made the 20db mod running it with 24v SMPS.
Very low noise, in same level as Volt+.
Adding a bad pic.
i like this testing scheme of simple substitution like you , drmod plus others yielding highly leveraged results.
im thinking next step possibly the subjective testing phase.
Putting pin1 high maybe has less thd penalty and might be preferred by all that ignore speakerload and complain about treble.
Interesting.
Why do you think the THD increased when the frequency went up?
Which harmonics went up - lower, upper or all in general?
Why do you think the THD increased when the frequency went up?
Which harmonics went up - lower, upper or all in general?
I didn't take accurate measurements after overclock with APTA.
But RMAA shown decrease of overall distortion ~ 0.08%.
Anyway overclocked sound seemed to me more natural, especially at highs, than stock 400KHz.
Maybe distortion @D3 is pleasant to ears? Like any tube preamp?
Got feedback from the lab regarding those cheap 3118 on the sanwu fake boards. Die is different compared to 3118 samples from TI.
So good to hear that the chip is confirmed to have authentic die and great work with measurements doctormord! 
I made some funny findings when comparing boards I have. Some time ago I ordered few boards from Ebay and all chips had serial number 4AAD6TTG4
Later I ordered 4 more from the same seller with same price and to my surprice this time all chips had unique S/N:
53AGQ7TG4
3CCC4YTG4
3CCC5CTG4
41AR7QTG4
Chip markings also vary regarding the position of TI-logo and the dot in the lower left corner. Comparing boards to previous ones, there is also differences in cap markings (fuzzy/sharp), silk screen colour (4AA... has darker) and ESD bag.
I'm not too worried about dies inside the new chips, just wondering if they are running out of 4AA... stock or new people playing with chip markings. 🙄
I made some funny findings when comparing boards I have. Some time ago I ordered few boards from Ebay and all chips had serial number 4AAD6TTG4
Later I ordered 4 more from the same seller with same price and to my surprice this time all chips had unique S/N:
53AGQ7TG4
3CCC4YTG4
3CCC5CTG4
41AR7QTG4
Chip markings also vary regarding the position of TI-logo and the dot in the lower left corner. Comparing boards to previous ones, there is also differences in cap markings (fuzzy/sharp), silk screen colour (4AA... has darker) and ESD bag.
I'm not too worried about dies inside the new chips, just wondering if they are running out of 4AA... stock or new people playing with chip markings. 🙄
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Lately there has been talk about cutting the "bottom trace" between input neg. and power ground. After mutilation of one board I can still measure short between these two points. What exactly should be cut and how to verify the cut with DMM? I would highly appreciate a picture from this operation. 😱
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Just the cut on left side. You will still measure short because analog groundpin tpachip is still connected to inputground, but it is a single connection then.
So good to hear that the chip is confirmed to have authentic die and great work with measurements doctormord!
I made some funny findings when comparing boards I have. Some time ago I ordered few boards from Ebay and all chips had serial number 4AAD6TTG4
...
Chip markings also vary regarding the position of TI-logo and the dot in the lower left corner. Comparing boards to previous ones, there is also differences in cap markings (fuzzy/sharp), silk screen colour (4AA... has darker) and ESD bag.
My contact at TI says:
Okey, that's reassuring info. 🙂
Having holiday and some time to play around. I noticed I get hum, if I use one SMPS for two boards. Both boards are set to 20 dB gain. Hum disappears when inputs are shorted individually, but reappears when input grounds are connected together. I'm using mini plug - stereo RCA cable as connection to source (PC has female plug connection).
I assume I'm creating a loop from the mini plug that goes through board, power supply and back. At the moment I'm testing with two power supplies, one for each board and everything looks good. I guess using input transformer would also solve the problem, but I haven't seen any cheap ones (or atleast with reasonable shipping fees).
So I'm asking more simple (cheaper 😉) solutions when using existing source. Would bringing source signal ground straight to PS negative DC out with one wire, skipping amp inputs, be a good idea? That would create star ground point when using only one PS and everything should be nice and dandy sound quality wise?
Having holiday and some time to play around. I noticed I get hum, if I use one SMPS for two boards. Both boards are set to 20 dB gain. Hum disappears when inputs are shorted individually, but reappears when input grounds are connected together. I'm using mini plug - stereo RCA cable as connection to source (PC has female plug connection).
I assume I'm creating a loop from the mini plug that goes through board, power supply and back. At the moment I'm testing with two power supplies, one for each board and everything looks good. I guess using input transformer would also solve the problem, but I haven't seen any cheap ones (or atleast with reasonable shipping fees).
So I'm asking more simple (cheaper 😉) solutions when using existing source. Would bringing source signal ground straight to PS negative DC out with one wire, skipping amp inputs, be a good idea? That would create star ground point when using only one PS and everything should be nice and dandy sound quality wise?