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Building the ultimate NOS DAC using TDA1541A
Building the ultimate NOS DAC using TDA1541A
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Old 17th July 2018, 11:26 AM   #6311
ryanj is offline ryanj  Australia
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Building the ultimate NOS DAC using TDA1541A
Quote:
Originally Posted by sumotan View Post
For all you know there could be an issue with your I2S set up Ryan

Cheers
Have you tried both input formats?

EC designs most recent post is absolutely spot on. His technical analysis corresponds exactly with my listening experiences. If you can't hear the difference between the two formats then im afraid you may have other areas in your system that needs attention. Just my 2 cents...
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Old 18th July 2018, 03:33 AM   #6312
Hanze Khronye is offline Hanze Khronye  Australia
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Quote:
Originally Posted by ecdesigns View Post
Hi Hanze Khronye,

Do you agree that when a I2S attenuator does not cause data corruption it won't have any effect on the data?

The only negative effect an I2S attenuator can have is on the signal that is used to determine the exact moment of output latching:

I2S -> BCK
Simultaneous -> LE

So if we use the wrong type of attenuator circuit here we can slow down transients causing trigger uncertainty and related jitter. In this case the successful manufacturer of TDA1541A-based DACs has point.

Hi John,

With the ever changing nature of these things I'm hesistant.

However, I could try the I2S attenuation.

Should I follow Ryanj's circuit and direction from #6305 pg631?.. diode circuit for LE and resistor circuit for BCK, DATA L, DATA R. Generic metal film resistors and 270R, or 1K series for the resistor attenuators?

Thanks.

Last edited by Hanze Khronye; 18th July 2018 at 03:37 AM.
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Old 18th July 2018, 11:15 AM   #6313
Alexandre is offline Alexandre
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Altough I haven´t implemented it for the TDA1541, I have no doubt that the simultaneous data format is better than I2S, if you use the "silence"

There´s a note about this (generally) on the PMD100 datasheet:
Quote:
“Silent Conversion” minimizes conversion jitter and ground bounce by allowing time for the DAC substrate noise to settle out prior to conversion.
Thanks,
Alex
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Old 18th July 2018, 12:03 PM   #6314
ryanj is offline ryanj  Australia
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Building the ultimate NOS DAC using TDA1541A
Quote:
Originally Posted by ecdesigns View Post

...The signal passes a pre amp based on a single NJET hybrid semiconductor I developed. (I amplified the voltage across a 75 Ohms passive I/V resistor).
Hi John,

Any chance you could elaborate on the single NJET hybrid semiconductor, and how you go about amplifying the small signal voltage after IV conversion?

Thanks.
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Old 19th July 2018, 06:21 AM   #6315
ecdesigns is offline ecdesigns  Netherlands
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Default I2S to SIMULTANEOUS CONVERTER

I attached a schematic diagram of an I2S to Simultaneous converter for the TDA1541A.

The circuit performs following functions:

- Identify and invert MSB within the serial data stream.
- Delay the left channel data in order to align it with the R channel data.
- Create a 16 bit window for clock and data output signals.

Timing diagram is added at the bottom.

The circuit can be built with logic building blocks like 74HC, 74 AHC, 74LV, 74LVC.

If U13 is a problem one can combine two 74HC86 XOR gates instead. One output goes to one input of the other XOR gate, we now have an XOR gate with 3 inputs and one output. The 74LVC1G386 is available in SOT32-6 housing:

http://www.ti.com/lit/ds/symlink/sn74lvc1g386.pdf



Depending on logic building block properties the circuit can work on voltages between 2V4 and 5V. I recommend to use 2V4 ... 3V3 supply voltage.


Connections:

I2S,

DI = D
WSI = WS
BCKI = BCK

Simultaneous,

OB/TWC (pin 27) connects to -5V to put the TDA1541A in simultaneous mode.

DOL connects to pin 3
DOR connects to pin 4
BCKO connects to pin 2
LE connects to pin 1


LE determines the exact moment of output latching, output latching occurs at the 0 -> 1 transition (TDA1541A set to simultaneous mode).
BCK clocks in the data on the 1 -> 0 transition (TDA1541A set to simultaneous mode).
Attached Images
File Type: jpg I2SIM.jpg (284.8 KB, 665 views)
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Old 21st July 2018, 07:20 PM   #6316
lcsaszar is offline lcsaszar  Hungary
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I decided to make the DEM mod in my Marantz CD94, i.e. change the oscillator capacitor to 1uF WIMA MKS-4, and replace the filter capacitors to 100uF/25V Nichicon Muse FG. Also added 2x 15k resistor from pin 16 and 17 to pin 15 (-13.5V).
During the first listening there was a disturbing static in the right channel. It went away after 10 minutes or so. What could be the reason?
BTW the sound seems to have cleaned up, but I need more listening to be more definitive.
I2S attenuator is not yet installed.
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Old 22nd July 2018, 07:04 PM   #6317
lcsaszar is offline lcsaszar  Hungary
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Default pictures

Heatsinks on top of TDA1541A, DEM filter capacitors around
Attached Images
File Type: jpg 20180721869.jpg (772.8 KB, 548 views)
File Type: jpg 20180721871.jpg (804.9 KB, 544 views)
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Old 23rd July 2018, 07:25 AM   #6318
SSerg is offline SSerg  Russian Federation
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Hi,
Quote:
Originally Posted by lcsaszar View Post
Heatsinks on top of TDA1541A
Do these heat sinks somehow affect the sound? Or do they only affect the thermal regime?
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Old 23rd July 2018, 08:15 AM   #6319
lcsaszar is offline lcsaszar  Hungary
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Quote:
Originally Posted by SSerg View Post
Hi,

Do these heat sinks somehow affect the sound? Or do they only affect the thermal regime?
It is difficult to do before/after listening tests, so I do not want to state something that might not be true. As for the thermal effect, the top of the chip was hot, which is not good, I think. Now it is just warm, and I have peace of mind (which has positive effect on sound, BTW ).
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Old 23rd July 2018, 10:39 AM   #6320
Alexandre is offline Alexandre
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Quote:
Originally Posted by lcsaszar View Post
During the first listening there was a disturbing static in the right channel. It went away after 10 minutes or so. What could be the reason?
I believe John warned about this. The large caps take several minutes to charge up to the working voltage (because of tiny DEM currents).
Thanks,
Alex
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