Hello Lasso,
I had the same problem. As I couldn´t solve it quickly enough I gave up on this DAC. As far as I could gather it is, as was mentioned before in this thread, a load problem. Playing with variable resistors on Rload and Rref I could improve the sound but didn´t get it right in the end.
I even ripped a TDA1543 from a Philips CDP to compare to the ones I used, but same result.
Anyone interested in a stuffed DDDAC board with several TDA1543s?
In the end I think with patience I could have gotten it to work properly; unfortunately not my forté.
Cheers and good luck,
Johan
I had the same problem. As I couldn´t solve it quickly enough I gave up on this DAC. As far as I could gather it is, as was mentioned before in this thread, a load problem. Playing with variable resistors on Rload and Rref I could improve the sound but didn´t get it right in the end.
I even ripped a TDA1543 from a Philips CDP to compare to the ones I used, but same result.
Anyone interested in a stuffed DDDAC board with several TDA1543s?
In the end I think with patience I could have gotten it to work properly; unfortunately not my forté.
Cheers and good luck,
Johan
JohanH said:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=12841&highlight=
http://www.diyaudio.com/forums/showthread.php?postid=150438#post150438
You need to do a bit of maths.
see link below aswell for pot' issue.
http://www.diyaudio.com/forums/showthread.php?postid=717619#post717619
Thank you for your input, JohanH. Good to hear from someone else having problems as well, but of course a pity that your DAC didn't work either.
About the I/V stage: I investigated carefully how to calculate the I/V resistors and the bias current, and when I measured them, the currents seemed to be within specs, IIRC.
But if we for a moment would assume that the problem *is* that the DAC sees a strange load, what possible causes could it have?
* wrong resistance
* bad solder joints
are probably the obvious ones. I've checked, doublechecked and triplechecked these.
The resistor values are nothing magical, it's all in the datasheet (when you figure out how to read it
, and besides, there are many designs on the net to check for what's being used. My values don't deviate much from others', if at all.
My soldering: well, ugly as it may be, it usually gets the job done, and I seldom have cold joints. And as I've mentioned, I resoldered the whole DAC + I/V stage the other night. And doublechecked the new joints. And the result was exactly the same, sound-wise and measurements-wise.
So, what more potential issues could there be?
* wrong capacitor type? (wima metal film caps, nothing fancy)
* bad grounding? (DAC and I/V are all grounded directly to regulator)
* cable lengths, interference, parasitic/stray capacitances? (cables are not overly long, but had I made a PCB the paths would have been shorter)
* the CS8414 is on an adapter (with all soldering triplechecked on two different chips), but could the adapter with the extra leg lengths cause disturbances in itself?
* ... something else?
These are things I considered before starting, but I wanted to wire up the DAC point-to-point to be able to experiment, and I didn't really think any one of these issues would affect the basic function of the thing. And I still don't find it likely, I would tend to think about them to be more of "the last 5-10 %" things.
But what if one or several do matter? In that case, which one is the most likely troublemaker?
About the I/V stage: I investigated carefully how to calculate the I/V resistors and the bias current, and when I measured them, the currents seemed to be within specs, IIRC.
But if we for a moment would assume that the problem *is* that the DAC sees a strange load, what possible causes could it have?
* wrong resistance
* bad solder joints
are probably the obvious ones. I've checked, doublechecked and triplechecked these.
The resistor values are nothing magical, it's all in the datasheet (when you figure out how to read it
, and besides, there are many designs on the net to check for what's being used. My values don't deviate much from others', if at all.My soldering: well, ugly as it may be, it usually gets the job done, and I seldom have cold joints. And as I've mentioned, I resoldered the whole DAC + I/V stage the other night. And doublechecked the new joints. And the result was exactly the same, sound-wise and measurements-wise.
So, what more potential issues could there be?
* wrong capacitor type? (wima metal film caps, nothing fancy)
* bad grounding? (DAC and I/V are all grounded directly to regulator)
* cable lengths, interference, parasitic/stray capacitances? (cables are not overly long, but had I made a PCB the paths would have been shorter)
* the CS8414 is on an adapter (with all soldering triplechecked on two different chips), but could the adapter with the extra leg lengths cause disturbances in itself?
* ... something else?
These are things I considered before starting, but I wanted to wire up the DAC point-to-point to be able to experiment, and I didn't really think any one of these issues would affect the basic function of the thing. And I still don't find it likely, I would tend to think about them to be more of "the last 5-10 %" things.
But what if one or several do matter? In that case, which one is the most likely troublemaker?
scottnixon said:
Hello Lasso,
Check it out everyone else ties pin 13 to ground (do you have separate analogue, and digital grounds ?)
Pin 16:- well the ddac design has it high, and the other has it low ! Try it high try it low
Also you need to improve the grounding !
..and i'm not sure about the 2700pf coupling caps (I use 10uf)
http://my.opera.com/lasso/homes/albums/45429/schematics.jpg
http://jwg.student.utwente.nl/fedde/images/nonoz3.gif
http://www.dddac.de/files/dddac1543ver22.pdf
Hope this helps.
More investigation
Well, not quite everyone, but I grounded it during the start of my investigations and forgot to update the schematics. Sorry about that. (It didn't make a change.)
Well, not really. But when several chips share the same regulator, would that really matter? I can see how separate groundplanes can help with their relatively large amount of copper, but the short wires?
According to the datasheet, it only controls what information should be displayed on the info pins. But of course I tried your tip anyway. Unfortunately to no avail.
Any specific tips on what to do? Now, the circuit is pretty much star grounded, where each chip has its own ground cable going directly to the regulator (the CS8414 has two cables, one for digital and one for analogue).
Suggestions to improve that further?
Oops. Miscalculation. The caps surely formed a high-pass filter with whatever resistance their connected input would have, and most likely with a cutoff frequency in the kHz range. Gah *smacks self*. Switching the caps to higher values (0.33 μF were the largest I had at hand) completely changed things. Thank you for spotting this!
---
Now, even with this change, the distortion remains at approximately the same digital levels as before. However, the big change is that the saw tooth signal actually looks like a sawtoot signal. Well, not really, because it's inverted...
Another interesting thing that I just noticed is that the channels are actually switched as well. I have the right channel to pin 8 on the TDA1543 as specced in the datasheet, but a sound in the right channel turns up being played in the left channel. My Squeezebox does the right thing. I've attached a screenshot showing both of these things.
I think it's because I was so preoccupied with the distortion that I didn't notice this channel switch earlier.
One thought I had was that there might be some miswiring of the TORX173 optical receiver involved, so I exchanged it with a regular coaxial input instead. But the sound remains the same. And RXN and RXP are correct as per the datasheet, AFAICT.
So now I'm suspecting a protocol error, since in EIAJ, the word clock is inverted compared to I2S. I found this picture in this thread showing the signals side-by-side.
Wouldn't the high volume output + the switched left-right channels be consistent with the CS8414 outputting I2S, and the TDA1543 receiving EIAJ? (I don't think the other way around would give these results, but it's getting late here so I might be a slow thinker.)
Edit: I can't see how it can explain the inversion, though.
I'll hopefully be able to try out switching modes on the CS8414 tomorrow, after checking its current mode config for the umpteenth time of course.
In the meanwhile, any thoughts on this?
Well, not quite everyone, but I grounded it during the start of my investigations and forgot to update the schematics. Sorry about that. (It didn't make a change.)
Well, not really. But when several chips share the same regulator, would that really matter? I can see how separate groundplanes can help with their relatively large amount of copper, but the short wires?
According to the datasheet, it only controls what information should be displayed on the info pins. But of course I tried your tip anyway.
Unfortunately to no avail.Any specific tips on what to do? Now, the circuit is pretty much star grounded, where each chip has its own ground cable going directly to the regulator (the CS8414 has two cables, one for digital and one for analogue).
Suggestions to improve that further?
Oops. Miscalculation. The caps surely formed a high-pass filter with whatever resistance their connected input would have, and most likely with a cutoff frequency in the kHz range. Gah *smacks self*. Switching the caps to higher values (0.33 μF were the largest I had at hand) completely changed things. Thank you for spotting this!
---
Now, even with this change, the distortion remains at approximately the same digital levels as before. However, the big change is that the saw tooth signal actually looks like a sawtoot signal. Well, not really, because it's inverted...
Another interesting thing that I just noticed is that the channels are actually switched as well. I have the right channel to pin 8 on the TDA1543 as specced in the datasheet, but a sound in the right channel turns up being played in the left channel. My Squeezebox does the right thing. I've attached a screenshot showing both of these things.
I think it's because I was so preoccupied with the distortion that I didn't notice this channel switch earlier.
One thought I had was that there might be some miswiring of the TORX173 optical receiver involved, so I exchanged it with a regular coaxial input instead. But the sound remains the same. And RXN and RXP are correct as per the datasheet, AFAICT.
So now I'm suspecting a protocol error, since in EIAJ, the word clock is inverted compared to I2S. I found this picture in this thread showing the signals side-by-side.
Wouldn't the high volume output + the switched left-right channels be consistent with the CS8414 outputting I2S, and the TDA1543 receiving EIAJ? (I don't think the other way around would give these results, but it's getting late here so I might be a slow thinker.)
Edit: I can't see how it can explain the inversion, though.
I'll hopefully be able to try out switching modes on the CS8414 tomorrow, after checking its current mode config for the umpteenth time of course.
In the meanwhile, any thoughts on this?
Attachments
lasso said:
Even if they were TDA1543A's, consider the logic of the proposition and rate its plausibility accordingly.
The '8412 has a range of output formats. The '1543A has its particular input format. For the proposition to be remotely plausible, the '8412, in response to a request by the '1543A or through an ability to read chip labels, would somehow have to reformat its out to match a format not included in its range of master mode formats.
Simply put, if the format of the '8412 is set to a particular type, it will not change, irrespective of what the downstream device is.
rfbrw said:
Oh, perhaps I wasn't entirely clear last evening. What I meant was that the I2S data from the CS8414, when interpreted as EIAJ, could give at least some of the symptoms that my circuit exhibits (switched channels, low-value digital signals interpreted as larger values etc).
The communication between the CS8414 and the TDA1543 is strictly one-way, I didn't mean anything else than that.
Back to the schematic....
Lasso,
http://my.opera.com/lasso/homes/albums/45429/schematics.jpg
Others may see the errors straight away.
Lasso,
http://my.opera.com/lasso/homes/albums/45429/schematics.jpg
Others may see the errors straight away.
Compliance.
According to the schematic the i/v resistors are 887R each and the reference resistor is 1K
From the above Iref is (Vref/1K)xAIbias = (2.2/1000)x2=4.4mA
This is then added to the output current. The fullscale output current for each output is 2.65mA and added to Ibias yields a total of 7.05mA per output. Full scale output voltage is 7.05mA x 887R = 6.25V. This seems a little. It makes a mockery of the compliance limits of the chip and the V+ rail is only 5volts. Perhaps you should reconsider some of the resistor values.
According to the schematic the i/v resistors are 887R each and the reference resistor is 1K
From the above Iref is (Vref/1K)xAIbias = (2.2/1000)x2=4.4mA
This is then added to the output current. The fullscale output current for each output is 2.65mA and added to Ibias yields a total of 7.05mA per output. Full scale output voltage is 7.05mA x 887R = 6.25V. This seems a little. It makes a mockery of the compliance limits of the chip and the V+ rail is only 5volts. Perhaps you should reconsider some of the resistor values.
Dear Lasso:
I am the first to confess I don't know what I'm talking about but I have to agree with rfbrw: for me Rref worked when equal to 2/3 to 3/4 of Rload (but my V+ is 8.5V)
Doede recommend to set 3.85VDC for pins 6-8 for his 8*dac, and VDC at pin7 is around 2.25 if I recall well. I don't know if this helps.
Also consider chip's Tº as a problem.
Good luck
M
I am the first to confess I don't know what I'm talking about but I have to agree with rfbrw: for me Rref worked when equal to 2/3 to 3/4 of Rload (but my V+ is 8.5V
)Doede recommend to set 3.85VDC for pins 6-8 for his 8*dac, and VDC at pin7 is around 2.25 if I recall well. I don't know if this helps.
Also consider chip's Tº as a problem.
Good luck
M
Noise!!!
Hi,
How did you guys deal with the noise out of your tda1543 NOS dacs? (not scoped mine but connected to computer and NOS noise clearly visible)
I've retired mine for a while as I swear my tweeters cut out the other day!
Might be due to high IV values causing clipping I guess.
Seem to be working fine now though which is a relief.
Speakers:B&W DM570 (with metal dome tweeters)
Hi,
How did you guys deal with the noise out of your tda1543 NOS dacs? (not scoped mine but connected to computer and NOS noise clearly visible)
I've retired mine for a while as I swear my tweeters cut out the other day!
Might be due to high IV values causing clipping I guess.
Seem to be working fine now though which is a relief.
Speakers:B&W DM570 (with metal dome tweeters)
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