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Old 1st September 2011, 10:49 AM   #3801
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Quote:
Originally Posted by studiostevus View Post
Similar to the bias voltage used in Pedja's output stage (using 2sk170) I presume.
i didnt read properly... You are talking dc coupling. Pedja uses a bias for the tda's output current.
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Old 1st September 2011, 06:38 PM   #3802
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Quote:
Originally Posted by -ecdesigns- View Post
Hi Tazz,



If these caps indeed have 3uA leakage current, it is almost 50 times higher compared to the 0.061uA LSB current.

Problem is that the leakage current on the 6 MSBs (active dividers) won't be exactly the same and that the 10 LSBs (passive dividers) don't have this leakage current at all.

The result could be significant loss of (dynamic) resolution (up to 5 bits).
Looking at the TDA1540 schematic all the lesser currents are made to be accurate divisors of the MSB current any leakage on the MSB pin should only give an error in absolute magnitude since all lesser current are "automagically" rescaled to fit in with the MSB current.

I would expect the TDA1541A to be much the same with exception for the passive dividers but they also only divide further a divided down current.

Note however this would only be true for the MSB current as any leakage further down would put the larger currents off.
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Old 2nd September 2011, 12:02 AM   #3803
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Could we hear a loss of 5 bits - or is it just measurable ?
If I could hear it - what would it sound like...

Do we need to worry about it ?
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Old 2nd September 2011, 10:21 AM   #3804
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Could we hear a loss of 5 bits - or is it just measurable ?

It would sound as a telephone, I guess...
Young people listen music through mobile phones like if this was satisfactory...

Cheers,
M.
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Old 3rd September 2011, 12:17 AM   #3805
regal is offline regal  United States
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Quote:
Originally Posted by maxlorenz View Post
Could we hear a loss of 5 bits - or is it just measurable ?

It would sound as a telephone, I guess...
Young people listen music through mobile phones like if this was satisfactory...

Cheers,
M.
16-5 bits=11 bits dynamic range= 66dB. This is more that most Lp's, more than almost any commercial music, more than a typical SET amp. No it wouldn't sound like a telephone
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Old 3rd September 2011, 02:02 AM   #3806
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I think it's absolutely fantastic what is being achieved with the good old TDA. The attention to detail and the obvious comprehensive understanding of the workings of this chip is at times quite breathtaking.

So, when I listen to my super clocked, valved, damped, independently powered and regulated, cap changed, diode upgraded, DEM re clocked TDA based machine....I just wonder how much better it can all get.
Then, having read the recent posts I now have to consider how much information I'm losing when you guys are worrying about 5 bits

Is anyone actually listening to these advances or are we just getting figures from scopes ?

This is in no way meant to sound rude. demeaning or ignorant.
I just wonder however what all this does to the sound of the TDA.

I'd like ecdesigns, galeb and maybe even studiostevus to tell us how wonderful it all sounds and then what happens to the sound when they make another big step in technical performance..
Am I being too simple here ?
I have not read the words ' bass, midrange or hf ' anywhere.

....and to Regal, what do we gain musically speaking by capturing 5 bits instead of losing them ?

Thanks
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Old 3rd September 2011, 03:35 AM   #3807
regal is offline regal  United States
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Quote:
Originally Posted by AndrewGM View Post
....and to Regal, what do we gain musically speaking by capturing 5 bits instead of losing them ?

Thanks
Dynamic range, I was mearly pointing out that losing 5 bits does not equate to telephone quality. If you have a good amp and well mastered recordings the difference should be very audible. If the 5 bits are really lost from dc leakage, I would think it would raise the noise floor, 11 bis would give a noise for of 66dB.

Guess what I am saying is caps leaking dc current does not equate to the 5 LSB, as those are AC currents, they have nothing to do with dc current leakage IMHO. The TDA1541 does have a 2ma DC offset and few microamps leakage thru the caps does not correlate to with the TDA1541's AC output (which is the music, the 16 bit resolution.).

Simply put the issue to bed, what is the noise floor of the design? I am guesing much better than -66dB.
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Old 3rd September 2011, 05:57 AM   #3808
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The whole point of the internal architecture of the 1540/1541 is to accurately divide down a reference current. If you somehow affect this reference current and introduce some error all the lower bits will get rescaled by the dynamical element matching as well.

The caveat is this only works in one direction error introduced lower down in the chain will not affect larger currents and hence you will loose linearity.
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Old 3rd September 2011, 12:25 PM   #3809
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Again then...what comes out of the speakers when all these elements are covered ?
Is it nice ?
If I do all these things correctly is there yet more musical enjoyment to come ?


If I won the Lotto, I would go to ecdesigns website without hesitation and buy it all by the way....
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Old 3rd September 2011, 03:21 PM   #3810
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Thanks ryanj, Tazzz and EC. I'm get it.
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