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Old 26th February 2012, 09:41 PM   #4211
roger57 is offline roger57  Canada
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Quote:
Originally Posted by studiostevus View Post
Gary, very elaborate reply.
You're right, the MODPWR2 is a pre-supply as far as I understand. John suggested earlier to combine it with the post regulators in post #4008. Have you tried any of this instead of the Salas shunts?
Depending on the complexity of his new regulators I may (or may not) try them. However, I'm unlikely to change at this point as I've pretty much bought into the Salas regulators (I have the parts already too!)

Quote:
Originally Posted by studiostevus View Post
Aside from size, the Salas shunts need significant heatsinking. I recall it is recommended to have at least 100mA additional on the CCS on each reg. I think John has tested Salas shunt as well, but never adopted them (not sure why)...
The power dissipation is a negative on the regulator; but in the end the positives outweigh that, and I've made way on the board to accommodate
the heatsinks as needed...

Gary
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Old 1st March 2012, 08:07 AM   #4212
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Hi studiostevus,

Quote:
Hi John, I am wondering whether there are any updates from your side…
Both my brother and I are now working on the new SD-player with built-in DAC and stepped shunt volume control.
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Old 1st March 2012, 08:08 AM   #4213
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Default The mystery of lost bits solved

Quote:
Originally Posted by Bernhard View Post
1) A simple test: 1 khz -60dB or - 80dB dithered sine wave displayed on a spectrum analyzer without averaging will show the noise floor. Comparison with other DACs will reveal the truth.
Bernard raises a 'killing concern' and dismisses the TDA1541 altogether. But he may be jumping to conclusions, his argument looks like the technical rebuffing of the TDA1540 (that concatenated the bits from 16 to 14).

So what do I think the real reason for the off-measurements are?
In an article in L'Audiophile no. 13 (nouvelle série), Déc. 1990 Jean Hiraga writes about low signals with as general conclusion that it is clear that multibits gives the best outcome, but analogue even is better. There are many steps affectionados have to take to make great implementations, he mentions, like power supplies and earthing.

Have a look:
TDA1541 lot bits.jpg
A revealing picture.

It shows the effect of stock ceramic capacitors on the signal, and how the performance of the chip can be with audiophile caps. Yes, stock is is bland and noisy, but with audiophile caps of 220 nF there is a clean signal. Very revealing.

It underscores the importance of good caps, and John has taken the utmost in finding good caps with a short signal path and low inductance.

For me the TDA1541 and TDA1543 are chips that sound lifelike and analogue, and 'tube-like' even if the latter is sometimes somewhat raw. They sound warm and I can pull up the volume.
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Old 1st March 2012, 09:39 AM   #4214
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Quote:
Originally Posted by -ecdesigns- View Post
Hi studiostevus,



Both my brother and I are now working on the new SD-player with built-in DAC and stepped shunt volume control.

Could you post some more info and schematics of the MK8 PSU?
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Old 1st March 2012, 09:42 AM   #4215
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Dear John,
You convinced me to build your outstanding TDA1543 DAC with some modifications:

use alkaline batteries as PSU 4X1.5v D cell in series direct supply to the +5V (it will be +6V but 1543 should survive)

Tap in the middle of the 4x1.5V series to obtain the 3V that goes to the I/V resistors. Or has it to be 3.2V exactly? maybe by changing the value of the I/V resistors (820R) it is possible to have 3.0V as the best bias reference?

Any advice on this?
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Old 1st March 2012, 02:25 PM   #4216
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Quote:
Originally Posted by roger57 View Post
Depending on the complexity of his new regulators I may (or may not) try them. However, I'm unlikely to change at this point as I've pretty much bought into the Salas regulators (I have the parts already too!)



The power dissipation is a negative on the regulator; but in the end the positives outweigh that, and I've made way on the board to accommodate
the heatsinks as needed...

Gary
Roger, did you need to put any heatsinks on the MODPWR2 ?

Last edited by studiostevus; 1st March 2012 at 02:25 PM. Reason: eeeh... Gary
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Old 1st March 2012, 09:15 PM   #4217
roger57 is offline roger57  Canada
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Quote:
Originally Posted by studiostevus View Post
Roger, did you need to put any heatsinks on the MODPWR2 ?
Hi,

I used the small clip-on heatsinks, they proved adequate for the power dissipation. This may not be case for you studiostevus if your transformer secondaries are different from what I am using.

Regards,
Gary
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Old 2nd March 2012, 01:14 AM   #4218
roger57 is offline roger57  Canada
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Quote:
Originally Posted by studiostevus View Post
Roger, did you need to put any heatsinks on the MODPWR2 ?
Here's a link to what I used:

Digi-Key - 345-1087-ND (Manufacturer - 274-2AB)

Gary
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Old 2nd March 2012, 10:45 AM   #4219
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Hi triode_al,

Quote:
Bernard raises a 'killing concern' and dismisses the TDA1541 altogether.
That's bernhard's personal opinion.

I rely on facts like Philips datasheet specs and publications that specify Edl of typical 0.5 LSB and MSB change glitch of 0.25 LSB for TDA1541A. These were carried out using a decent lab measurement setup. Poor TDA1541A application and / or measurement setup can lead to different measurement results and that's probably what happened here.

We talk about LSBs and 16 ... 24 bit resolution and how important it is to gete every last bit.

Imagine we visualize bit resolution by translating DAC full-scale output signal to say a distance of 10 kilometer or 1,000,000cm. Then a LSB change on a 16 bit system would represent 1,000,000 / 65,536 = 15cm on a distance of 10 kilometer.

For a 24 bit system a LSB change would represent 1,000,000 / 2^24 = 590 micrometer or 0.059cm on a total distance of 10 kilometer.

With these high to extreme resolutions, the limits of audio equipment will be the dominating factor, not DAC bit resolution.

Quote:
Have a look: TDA1541 lot bits.jpg A revealing picture.
Indeed, it shows two examples of ineffective active divider decoupling.
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Old 7th March 2012, 01:26 PM   #4220
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Gary, just wondering... how and if have you implemented the circuit on the primary side? Are you using thermistors?
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