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Building the ultimate NOS DAC using TDA1541A
Building the ultimate NOS DAC using TDA1541A
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Old 28th May 2007, 05:44 AM   #1491
horus is offline horus
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-ecdesigns- , how much does a project like this cost?
Where would you place it in comparison with commercial DACs ?(when comparing the sound)
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Old 28th May 2007, 03:06 PM   #1492
ecdesigns is offline ecdesigns  Netherlands
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Hi maxlorenz,


Quote:
Here I got lost, sorry. It is not 50/50?
Playing with 64 DAC chips will not be possible (with this given buffer) then, unless we limit the max current to each chip, or add buffers to the buffers
I'm only guessing...
With 8 * 8 configuration, buffer 1 drives 8 x TDA1543, buffer 2 drives 56 x TDA1543
With 16 * 4 configuration, buffer 1 drives 4 x TDA1543, buffer 2 drives 60 x TDA1543

You could experiment using a second buffer parallel with buffer 2 or split-up BCK inputs in 2 groups, and adding an extra buffer.


Quote:
Last night I listened again to DI16: it is becoming my favorite DAC. Wonderful tone and analog textures. You are right at saying that it sounds as it extracts all there is on the source. No way to test if this is true.
I think I will make an audio dedicated PC with passive cooling.
When USB interface jitter is lowered, and the 8 x 3 TDA1543 configuration is used, things can even get much better. The DI DACs are designed to retrieve every last bit of detail from CD recordings.



Quote:
Please EC, tell me if I made a mistake...
(some components are on the bottom side)

It's quite an achievement that you have this DI 16 up and running. The PCB assembly looks fine too.

I have some suggestions for improvement:

It looks like you didn't insulate the RCA sockets from the chassis. Usually the RCA connectors are insulated from chassis. I used a small plastic plate that holds the RCA connectors, I made the holes in the housing just big enough to ensure reliable insulation.

There is a loose un-insulated green wire near the primary of the transformer at the bottom of the picture. I am not sure where it's connected to, but I would insulate it, just in case.

Consider adding a mains filter.

Did you place insulation washers underneath the two nuts at the bottom of the DI16C PCB? they seem to be very close to the traces.

I would mount the LM7806 heatsinks directly to the chassis (angled aluminum heatsinks), this way they use the entire chassis for cooling, and the heatsinks could be much smaller. There are TO220 insulation sets to isolate the LM7806 voltage regulators from chassis. The LM7806 heatsink is connected to GND.

The LM4562 chips probably need some small heatsinks too.


The USB receiver you used is not reclocked, I just looked up the schematics to make sure. The Tent clock is an optional 12 MHz clock (IC2) that only drives the PCM2707, it's used for USB timing, it won't have a big effect on the jitter performance of the PCM2707 PLL that generates BCK. BCK jitter would be somewhere around 500...1000ps.

So you are now only listening to a fraction of the DI 16 performance. If the jitter frequency components that degrade sound quality are lowered to 50...75 ps, it will make a huge difference.

The USB module I2S output signals are not buffered / single ended, so noise from the PC switched mode power supply, and ground loops could disrupt these I2S signals as well, adding jitter to the BCK timing signal.
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Old 28th May 2007, 03:15 PM   #1493
ecdesigns is offline ecdesigns  Netherlands
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Hi omalnlk

Thanks for your reply [post #1478],


Quote:
The description of this speaker sounds really impressive. Coul'd You explain more about the acoustic-magnetic corrective element?
The correction element separates two resonator chambers, each resonator chamber has a different tuning frequency.

The interaction between both resonator chambers and the corrective action of the acoustic magnetic correction element gives the sonic resonator it's unique properties.

The acoustic-magnetic corrective element has multiple functions, it performs corrections, acts as an acoustically driven subwoofer, and transfers acoustic energy between both resonator chambers.

The acoustic-magnetic corrective element has a local feedback loop system.


Quote:
Thank You for the info. Sooner or later I'll have to try one of Your DACs. Preferably on the CDPRO2
Since I started using the USBDI2S interface, I no longer see the necessity of using a CD transport. When a computer based music player is able to match or exceed direct I2S sound quality from a High-End transport, I rather use the very comfortable computer based music player. Using salling clicker remote control software on a cellphone enables one to control it with every suitable cellphone trough Bluetooth.

I added a picture of a cellphone remote control application, the CD covers are automatically transferred to the cellphone graphics screen.


Quote:
It should be easy to transform the idea to 48 BCK/WS IS Bus.
It needs a modified timing chain (different tap settings), since it still must be able to process 64 BCK/WS (USB), the timing chain needs to be dual format. Since it's not handy to keep switching between both formats manually, an auto detection circuit would be nice.

I already set up a schematic diagram for this, the auto detection circuit detects 48 BCK/WS and 64 BCK/WS without problems. I use multiplexers to toggle the tap settings.

But since I have no CDPRO2 at hand, I can't test if extra glue logic is necessary in addittion to the modified tap settings.
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Old 28th May 2007, 03:58 PM   #1494
dddac is offline dddac  Germany
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Building the ultimate NOS DAC using TDA1541A
Quote:
Originally posted by -ecdesigns-
Hi maxlorenz,

With 8 * 8 configuration, buffer 1 drives 8 x TDA1543, buffer 2 drives 56 x TDA1543
With 16 * 4 configuration, buffer 1 drives 4 x TDA1543, buffer 2 drives 60 x TDA1543

You could experiment using a second buffer parallel with buffer 2 or split-up BCK inputs in 2 groups, and adding an extra buffer.

When USB interface jitter is lowered, and the 8 x 3 TDA1543 configuration is used, things can even get much better. The DI DACs are designed to retrieve every last bit of detail from CD recordings.


The USB receiver you used is not reclocked, I just looked up the schematics to make sure. The Tent clock is an optional 12 MHz clock (IC2) that only drives the PCM2707, it's used for USB timing, it won't have a big effect on the jitter performance of the PCM2707 PLL that generates BCK. BCK jitter would be somewhere around 500...1000ps.

So you are now only listening to a fraction of the DI 16 performance. If the jitter frequency components that degrade sound quality are lowered to 50...75 ps, it will make a huge difference.

The USB module I2S output signals are not buffered / single ended, so noise from the PC switched mode power supply, and ground loops could disrupt these I2S signals as well, adding jitter to the BCK timing signal.
John,

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 ?

Interestingly enough, the PCM2707 does respond audio wiselike on using the Tent Clock, rather than using the Crystal solution. This has been confirmed many times by people who built this design. If it sounds better, the goal is achieved by at least changing that part.

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.

The ones who actually used my design are mostly very happy with the outcome. It can always be better, that is why I try to motivate people to tweak the design and get some more out of it, which lives up the hobby of course.

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.

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)

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

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.

Doede

PS: this is the last one I got from someone who "upgraded" the PCM2707 with a Tent Clock:

WoW I have just install ,the sound improve a lot!!!! thanks for good gear......

If it is only for USB timing, how can this happen? I really don't know, but it seems to work
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Old 28th May 2007, 04:56 PM   #1495
maxlorenz is offline maxlorenz  Chile
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ECdesigns,

Thanks for your reply and nice words. Esthetically though, there is no difference if I take two days or two months to build it!


Quote:
With 8 * 8 configuration, buffer 1 drives 8 x TDA1543, buffer 2 drives 56 x TDA1543.
You could experiment using a second buffer parallel with buffer 2 or split-up BCK inputs in 2 groups, and adding an extra buffer.
It is easy for you to say so. You know I would need help for this.
Lets begin with 8*4 chips first.

Quote:
It looks like you didn't insulate the RCA sockets from the chassis.
They are insulated. The original photos have better resolution but are bigger and could not be uploaded.

Quote:
There is a loose un-insulated green wire near the primary of the transformer at the bottom of the picture.
Good sight. This is R-Core Tx's shield wire, wich let me to the following question, about grounding. Your project has "floating" ground from chassis. Will it be an improvement in EMi immunity from attaching this shield wire to a ground chassis and using a 3 wire cable?

Quote:
Consider adding a mains filter.
I allways use a "technical balanced power" filter as commercial filters degrade sound, IME.

Quote:
I would mount the LM7806 heatsinks directly to the chassis (angled aluminum heatsinks), this way they use the entire chassis for cooling, and the heatsinks could be much smaller. There are TO220 insulation sets to isolate the LM7806 voltage regulators from chassis. The LM7806 heatsink is connected to GND.
The LM4562 chips probably need some small heatsinks too.
Thanks for the advices. I will see how I can manage to solve these aspects.

Dear DDDAC,
I can confirm that your USB kit sound better than SPDIF, wich is very dependent on transport quality. I will have to experiment with USB cables and PC's PSuplies to see if USB format is also influenced by these parameters.

Regards,
M
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Old 28th May 2007, 05:54 PM   #1496
tubee is offline tubee  Netherlands
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Quote:
Originally posted by maxlorenz
Now I'm planing my audio dedicated PC. It should be relatively inexpensive.

M
M: A suitable pc for that would be a laptop. I have an old Compaq Armada E500, a free give away, ideal for music server. Repaired the USB connector, made it dual boot with win2k and ubuntu. (i am sick of XP, those yellow balloons with annoying messages...) Want more ram for it, but it uses special ram like compaq often did
The advantage of linux Ubuntu is you don't have to buy a special machine for it (apple), it can simply be 386-based, and runs very reliable.
Have to build a USB-I2S converter in time.

Problably you know this one allready: http://www.diyaudio.com/forums/showt...0&pagenumber=1
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Old 28th May 2007, 07:43 PM   #1497
maxlorenz is offline maxlorenz  Chile
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Hi Tubee,
Thanks for your interest.
Know that I have thought about these problems quite a few times. Probably I will end with both, a laptop and a fanless PC but for now PC is cheapest as I don't trust second hand units around here.

Yes I know that thread and though I'm only a "user-level" guy I feel the beauty of Linux. My new informatic engeneer friend should help me here.

Regards,
M
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Old 28th May 2007, 08:53 PM   #1498
tubee is offline tubee  Netherlands
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Quote:
Originally posted by maxlorenz
Hi Tubee,
Thanks for your interest.
Know that I have thought about these problems quite a few times. Probably I will end with both, a laptop and a fanless PC but for now PC is cheapest as I don't trust second hand units around here.

Yes I know that thread and though I'm only a "user-level" guy I feel the beauty of Linux. My new informatic engeneer friend should help me here.

Regards,
M
It was about 1.5 year ago when i switched over from M$ stuff to Linux Ubuntu. Just wanted to give it a try, because my newly installed win system, with all bells and wistlests: (Word,zip,adobe,pdf,scanner,network,printer,antivi rus, adware,firewall)lasted only two weeks, problems simply started all over again. A new install cost me another day, why not spend this time into a new OS? Well it was the best decision i made for a long time: switch to Linux. Now i have still that old overclocked pentium 3, it flies over the net with epiphany browser. It costs some time to get into Linux, but the community is willing to help you with problems in forums.

Btw, now i know how powerful a 616Mhz PC can be: type in in terminal apt-get install... and it is working for you in a hurry, i haven't seen that ever with win. And that's the secret: the pc works for you again with Linux. (don't worry, further it all works graphical)

When you install a silent PS in the desktop, and add a big passive cooling on the processor you have a cheap and reliable music server, easy diy. Read in on the internet about different Linux distributions. When you want a little win-lookalike, Kubuntu could be the choice, but it needs a rather fast system imo.

Good luck
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Old 28th May 2007, 10:26 PM   #1499
maxlorenz is offline maxlorenz  Chile
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Dear Tubee,

Quote:
my newly installed win system, with all bells and wistlests: (Word,zip,adobe,pdf,scanner,network,printer,antivi rus, adware,firewall)lasted only two weeks, problems simply started all over again.
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.
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Old 29th May 2007, 07:11 AM   #1500
omainik is offline omainik  Austria
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Hello ECdesigns,

yesterday I compared for a long time my tda1541 design to the tda1543 version, so I can make a decision which of your boards DI-8 / DI-16 is the better solution for me to try direct interpolation. I have 8 x TDA1541a left and so 60 pieces of the tda1543. The 1541 was always better.

With a power consumption of 50-60 mA the small IC of the tda1543 gets pretty warm in spite of massive cooling. So I put the DACs under oil. With the better cooling the TDA1543 version was under 30C and achieved the same quality level as the tda1541. On most tracks the difference is inaudible. On some tracks it is a matter of taste but not a quality difference. tda1541 is more transparent and clear, tda1543 seems to have more powerful dynamics.

So I currently tend to the DI-16 version.

Quote:
Originally posted by -ecdesigns-

The correction element separates two resonator chambers, each resonator chamber has a different tuning frequency.
I would love to hear this speaker. My active design needs four channel amplification. In tube technology this is quite place consuming and produces a lot of heat - 700W. During the summer I have to switch to other amps and don't like the sound of them (Class D). So I want to try a passive design or experiment with horn loading. So one tube amp would be sufficient.


Quote:
Originally posted by -ecdesigns-

Since I started using the USBDI2S interface, I no longer see the necessity of using a CD transport. When a computer based music player is able to match or exceed direct I2S sound quality from a High-End transport, I rather use the very comfortable computer based music player. Using salling clicker remote control software on a cellphone enables one to control it with every suitable cellphone trough Bluetooth.
I already have a silent computer with no fan. The blue tooth keyboard from Logitech - search for dinovo edge - is a nice remote option too. I like the big PC screen for navigating through the music library. It will be a hard time to rip more than 700 CDs.

Quote:
Originally posted by -ecdesigns-

It needs a modified timing chain (different tap settings), since it still must be able to process 64 BCK/WS (USB), the timing chain needs to be dual format. Since it's not handy to keep switching between both formats manually, an auto detection circuit would be nice.

I already set up a schematic diagram for this, the auto detection circuit detects 48 BCK/WS and 64 BCK/WS without problems. I use multiplexers to toggle the tap settings.

But since I have no CDPRO2 at hand, I can't test if extra glue logic is necessary in addittion to the modified tap settings.
The CD-PRO II should receive the best technology too. If that's not the case I can't sleep well ;-) Its not difficult to modify the timing chain. thank YOu for all the tips.

In Your design the I/V conversion is always done with a opamp. The tube stage is connected after that first opa. I want to try this first I/V conversion stage with a tube transconductance amplifier.

Is it difficult to obtain a low jitter crystal for the USB receiver board? Do You have a source? Are there other difficult to get parts?

Sad that all people interested in designing and building audio equipment are spread around the world. It were nice to know someone near vienna to exchange ideas about music, speaker, amps, dacs and turntables

Ciao
Peter
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