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Old 29th May 2007, 08:35 AM   #1501
tubee is offline tubee  Netherlands
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Quote:
Originally posted by maxlorenz
Believe me, i do know what you mean!

I have Ubuntu already but have only played around with it. I can't access internet throught it yet. When I 'll do I'll make it my main OS, no problem.
Do you have a network card on this pc?

Btw tried to get a pcm2706/7, ti wiped me from the list (samples)
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Old 29th May 2007, 08:46 AM   #1502
omainik is offline omainik  Austria
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Default BInary twos complement

Hello ECdesigns,

If I understood your posts, You use a differential output stage. The differential signal is build by two groups of DACs. One group is fed with inverted data.

A negative number for the DAC is represented in twos complement. This is the difference to the number system base -1. In case of the binary system the difference to base is the inversion. The term -1 is missed. So in the DAC group fed with the inverted data there is a error with the value of 1. In the combined result after the differential output stage the error is halved to the value of 0.5.

This error is extremely small, but speaking of the ultimate DAC perhaps is the subtraction worth the effort.

The second solution would be to left out the differential mode. Capacitor coupling handles new distortion, so the error of value of 0.5 is perhaps the better way. Instead of capacitor coupling, there could be used a transformer. I made a good experience this way. But it is the more costly solution. Good transformers are rare, but they bring for me a live quality to the music. Price should not be an issue in an ultimate device.

Ciao
Peter
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Old 29th May 2007, 09:20 AM   #1503
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Hi dddac,

Thanks for your reply [post #1492]


Quote:
I hope your comments on "huge" differences are based on comparing the two designs life and not based on trying to elevate your kits compared to my humble design based on paper study ?

My aim is "live" sound quality, not elevate kits. The differences I mention are based on both measurements and listening tests. I shared a lot of information and research results on this thread for almost a year now, that document the design / optimation process step by step. By carefully studying this information, it must become clear why certain improvements resulted in better performance and why.

Paper studies are fine, but sometimes it requires an entirely different approach in order to get real improvements.

I am not going to explain why I think USBDI2S has better performance, I just added oscillograms of BCK using the standard TI PCM2706 application (upper oscillogram), and the same BCK signal after the shiftregister reclocker (lower oscillogram). Then consider that I continued to optimize the USBDI2S interface, after these pictures were taken.


Quote:
I would like to call for some more prudence on cracking my designs on expected audible outcome. You would be adding yourself to a line of people who judge the dddac on paper and drawing conclusions on expected measurements they never did, not to mention, never listened to it. Which is strange, as I very much like your approach of combining pure technic with intense listening sessions.
It was not my intention cracking your designs, and if it appeared as such, I apoligize for this. You make great audio kits, and this is confirmed by the feedback of many people who built them. I have respect for people who design products like these.


Quote:
May be your comment on "huge" is just the way you express yourself.... I remember you talking about your earlier design sounded like a "transistor radio", which was hard to believe too But not everyone would understand it in this way.
I use the term "huge" in a relative sense. Small improvements can result in a very clearly improvement in sound quality, I might call this huge in order to express the significance of this improvement in comparison with other (previous) improvements. I sometimes get too enthusiastic, like with the transistor radio incident, it was just a way to express how I perceived the audible improvement at that time.


Quote:
If the USB module would be that bad and jittery as you suggest and as you conclude therefore must be effecting negatively the sound, it would not be so much better compared to the best SPDIF like implementations, I have heard my self (and many others)
Jitter consists of specific frequency components, and these frequency components together have a certain average amplitude. The more different frequencies present, the worse it gets, so it's not just the jitter amplitude degrading sound quality, it's also the contained frequency components.

Jitter is only one of the many factors that degrade sound quality, and the sum of all these factors determine how an audio set sounds. One factor could attenuate or increase another. You can't pick-out one single component, without tuning it to the rest of the audio set. Basically optimizing a DAC, includes optimizing the interface that drives it, and all that's connected to the DAC, interlinks, amplifiers, and speakers. This is why I suggested trying to use the USBDI2S module, as it forms a unity with the DI DACs.


Quote:
A solution to the buffer problem could be to use buffering at the input of the towers, as I do to enable larger quantities of towers to be used in parallel. In that case a 8 x 12 1543 implementation would be no problem for Max
That sounds like a good solution, thanks. I appreciate your expertise on paralleling TDA1543 chips


Quote:
keep up the good work, you do great stuff and I read your posts with more than average interest, but don't try to act as if your designs are worthy and others are absoluely not. That would do no justice and I consider this as unfair.
It's not for me to decide who's designs are worthy or not. I leave that up to the people who build, test, and compare these designs.
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Old 29th May 2007, 11:53 AM   #1504
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Hi horus,

Thanks for your reply

Quote:
-ecdesigns- , how much does a project like this cost?
Where would you place it in comparison with commercial DACs ?(sound comparison)

The kit product configurator on my website lets you generate a pdf file online, containing all information about the selected project.

About sound comparison with commercial DACs, perhaps there will be some valuable feedback after demonstrations at audio shows and High-End audio clubs, that are planned this year.
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Old 29th May 2007, 12:21 PM   #1505
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-ecdesigns-, thanks for answering to my questions.
But as a personal opinion where would you place your DAC among commercial ones?
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Old 29th May 2007, 02:15 PM   #1506
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Quote:
Originally posted by -ecdesigns-
... Then consider that I continued to optimize the USBDI2S interface, after these pictures were taken.


Do you plan to publish modifications to your USB/I2S interface that you made after this circuit was published in post #1024?
I built Doede's USB/I2S reciver and results are remarkable, and as I have some spare PCM2707's I would like to build your version too, to make a comparison. I see your implemetation of PCM2707 is quite different from many circuits that can be found, so it's wery intriguing to try that solution.
I use Pedja's AYA DAC, very good TDA1541 NOS DAC.

I must admit that your work is quite remarkable!

Regards,
Zoran
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Old 29th May 2007, 05:42 PM   #1507
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OT nș1:

Omainik: try your CDPRO with some mechanical (non-magnetic) clamp system for the CD, like a little wraped paper or else...

OT nș2:

Tubee:

Quote:
Do you have a network card on this pc?
I believe I don't, but today an expert will come by...

Quote:
Btw tried to get a pcm2706/7, ti wiped me from the list (samples)
Me too Digikey US$6.8
http://www.digikey.com/scripts/DkSea...102060&Site=US

DDDAC,

Quote:
A solution to the buffer problem could be to use buffering at the input of the towers, as I do to enable larger quantities of towers to be used in parallel. In that case a 8 x 12 1543 implementation would be no problem for Max
So, one extra buffer for each tower, wich could allow for n chips/tower
Wich device? 74VHC125?

Thanks,
M
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Old 29th May 2007, 05:54 PM   #1508
dddac is offline dddac  Germany
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Quote:
Originally posted by maxlorenz


DDDAC,

So, one extra buffer for each tower, wich could allow for n chips/tower
Wich device? 74VHC125?

Thanks,
M
Or 74HC125, as the VHC is obsolete and very hard to get ....

Each of those drives easily 12 1543's. probably more, but there are limits of course....

doede
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Old 29th May 2007, 10:57 PM   #1509
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"WoW I have just install ,the sound improve a lot!!!! thanks for good gear...... "


this is my comment !

doede, discount nex time
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Old 30th May 2007, 05:45 AM   #1510
tubee is offline tubee  Netherlands
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Quote:
Originally posted by maxlorenz
The general picture,

[IMG]Click the image to open in full size.[/IMG]

M
M: Nice special transformer you used (the black&white one) where did you get it from?
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