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Building the ultimate NOS DAC using TDA1541A
Building the ultimate NOS DAC using TDA1541A
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Old 7th August 2012, 09:23 AM   #4471
SSerg is offline SSerg  Russian Federation
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Quote:
Originally Posted by -ecdesigns- View Post
You are right
Hi , -ecdesigns-,

Glad that you did not take offence for critic.
Good luck!

Serg
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Old 30th August 2012, 09:52 AM   #4472
SSerg is offline SSerg  Russian Federation
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Hi, -ecdesigns-!

I have read begin this subject (thread interesting, but very big) and I faced the statement that your method Direct Interpolation allows to enlarge the resolution to 17 bits for twin DAC 1541 and to 18 bits for quad DAC 1541 (post #15).

You hitherto so think?

Respectfully yours


Serg
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Old 30th August 2012, 06:28 PM   #4473
ecdesigns is offline ecdesigns  Netherlands
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Hi SSerg,

Quote:
I have read begin this subject (thread interesting, but very big) and I faced the statement that your method Direct Interpolation allows to enlarge the resolution to 17 bits for twin DAC 1541 and to 18 bits for quad DAC 1541 (post #15).

You hitherto so think?
The input resolution remains 16 bits, the time resolution is increased (88.2 KHz sample rate with 2 chips, 176.4 KHz with 4 chips, 352.8 KHz with 8 chips). The extra samples are derived using linear interpolation (delay and add scheme).

Output bit resolution is theoretically increased to 17 bits (2 chips), 18 bits (4 chips) or 19 bits (8 chips). In practice the output resolution is limited by DAC chip bit errors and matching between DAC chips.

The result is a smoother output signal (oscillograms at the beginning of this thread) when using NOS. This in turn improves performance when using (pre) amplifiers and interlinks that were designed for use with analogue audio sources.

Linear interpolation causes trebles roll-off in combination with NOS. The wave form starts to resemble triangle wave shape at increasing frequency when fewer samples are available for reconstruction.

However it works fine when applied after digital filtering. This technique is applied in the Cambridge CD3 CD player in order to achieve 16 times oversampling using 4 x TDA1541A.
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Old 31st August 2012, 12:58 AM   #4474
jstang is offline jstang  United States
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I still love the 4x 1541 s1 direct interpolation NOS dac....treble role off does not matter to me. I don't know of a TT that will do a better job at the top end....

OS DACs produce artificial sine waves at high frequencies... You run out of samples in the source no matter.... Is it an 18k squarewave or sinewave? You will never know.

Jk

Last edited by jstang; 31st August 2012 at 01:04 AM.
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Old 31st August 2012, 02:39 PM   #4475
SSerg is offline SSerg  Russian Federation
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Quote:
Originally Posted by -ecdesigns- View Post
Output bit resolution is theoretically increased to 17 bits (2 chips), 18 bits (4 chips) or 19 bits (8 chips). In practice the output resolution is limited by DAC chip bit errors and matching between DAC chips.
Hi,-ecdesigns-
Thank you for fast reply.

Output analog signal can't have more information than had the input digital signal. Even theoretically.

The practical resolution 1541 not more than 15 bits. At the best you may obtain resolution 16 bits.

This as law of the conservation
of energy.

Respectfully yours



Serg

Last edited by SSerg; 31st August 2012 at 02:52 PM.
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Old 31st August 2012, 08:42 PM   #4476
ecdesigns is offline ecdesigns  Netherlands
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Hi SSerg,

Quote:
Output analog signal can't have more information than had the input digital signal. Even theoretically.
I mentioned this:

Quote:
The result is a smoother output signal
I didn't mention that we get more information out than we put in. I just mentioned that the output sample rate can be increased to 88.2, 176.4, or 352.8 KHz and that the output bit resolution can be theoretically increased to 17, 18, or 19 bits.

The gained output resolution is used for smoothing the NOS DAC output signal.

I attached some oscillograms. Upper traces show plain NOS DAC output signals, lower traces the same signal but now with 8 times linear interpolation (8 * TDA1541A). These show the desired smoothing effect.
Attached Images
File Type: jpg oscdac1.jpg (83.2 KB, 898 views)
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Old 31st August 2012, 10:14 PM   #4477
maxlorenz is offline maxlorenz  Chile
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Quote:
I still love the 4x 1541 s1 direct interpolation NOS dac
The DI4JM (scrambler/interpolator DAC) is not bad either. It also can be converted easily to DI2*4JM...

[IMG]http://https://picasaweb.google.com/...eat=directlink [/IMG]

[IMG]http://https://picasaweb.google.com/...eat=directlink [/IMG]

Cheers,
M.
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Old 1st September 2012, 08:16 AM   #4478
triode_al is offline triode_al  Netherlands
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Quote:
Originally Posted by maxlorenz View Post
The DI4JM (scrambler/interpolator DAC) is not bad either. It also can be converted easily to DI2*4JM...

[IMG]http://https://picasaweb.google.com/...eat=directlink [/IMG]

[IMG]http://https://picasaweb.google.com/...eat=directlink [/IMG]

Cheers,
M.
links did not post
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Old 1st September 2012, 01:08 PM   #4479
maxlorenz is offline maxlorenz  Chile
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Oops! I still don't get this image posting right, for example I still cannot post thumbnails...
Another try.




Last edited by maxlorenz; 1st September 2012 at 01:11 PM.
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Old 1st September 2012, 01:20 PM   #4480
s3tup is offline s3tup
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Click the image to open in full size.
Click the image to open in full size.

Right click on image - copy image url (in chrome). You need to get a link which ends with .gif or .jpg.
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