Hi, I received a 2 X tda1541a OS & NOS (with switch) DAC yesterday. It uses this board
DAC DIR9001+TDA1541A 2.0B parallel output OS/NOS - eBay (item 220594292877 end time May-02-10 14:23:55 PDT)
but with an added HDAM module instead of the opamp, and an USB connector.
Still trying it out, but it's quite apparent already that it is quite noisy when there are some quiet music. The noise is kind of a noisy shadow to the signal and "moves" with the music.
Is it likely it is coming from the analog output stage, or before the 1541? It happens both in OS and NOS mode. The output stage has 4-5 transistors before the HDAM.
I'm going to make a "lampizator" output stage later, but want tot look into this noise first. Any ideas?
DAC DIR9001+TDA1541A 2.0B parallel output OS/NOS - eBay (item 220594292877 end time May-02-10 14:23:55 PDT)
but with an added HDAM module instead of the opamp, and an USB connector.
Still trying it out, but it's quite apparent already that it is quite noisy when there are some quiet music. The noise is kind of a noisy shadow to the signal and "moves" with the music.
Is it likely it is coming from the analog output stage, or before the 1541? It happens both in OS and NOS mode. The output stage has 4-5 transistors before the HDAM.
I'm going to make a "lampizator" output stage later, but want tot look into this noise first. Any ideas?
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
any input on what kind of noise this is would be appreaciated. Is this from the analog outputstage ? The dac chip itself? I'm not very familiar with dac design (yet), so I'm pretty basic in where to begin.
Hi. Do you mean how the transformers and input signal is connected? The PCB was already made.
There is also a USB input module which has some connection cable to a switch on the front. Can that kind of cable make inteference to the digital input signal? Those cables are quite close to each other.
Thanks, I will try that when I back home next week.
You mean filtering of the ouput signal of the DAC? Is that necessary?
There was another page of schematic of powersupplypart that I didn't upload, maybe I missed something important.
Thanks all for input. As I had to leave for a trip, I cannot try anything until next week.
Hi,
I tried removing one. When only the left one is playing the noise is very loud. Only right one is better, but not noiseless. Tried putting the right one in left ones place, but no difference.
What does this tell me?
I want to try with an opamp in place of the HDAM module to see if that makes any difference, but I don't have one at hand here.
Hi Nick,
When you tried the right one in the left socket, was the noise lesser or worse than the original left chip?
If the noise was the same as with the original left, you may have some problems in your circuit, otherwise I think you've got some nasty fakes of these chips, and yes, they are around
Sometimes they remark totally different chips and sell them as DAC, not very kind of the Chinese people.
Can you post me a picture of the chips? It likely that it is noticable when a chip is fake... I hope I'm able to help you further then
Best regards
When you tried the right one in the left socket, was the noise lesser or worse than the original left chip?
If the noise was the same as with the original left, you may have some problems in your circuit, otherwise I think you've got some nasty fakes of these chips, and yes, they are around
Sometimes they remark totally different chips and sell them as DAC, not very kind of the Chinese people.Can you post me a picture of the chips? It likely that it is noticable when a chip is fake... I hope I'm able to help you further then
Best regards
Joris,
the noise didn't change with the right chip in the left one's place. I can post a pic later, but the chips looks used and old, so I would be very supriced if they were fake.
So it might be some problems with the circuit then. That sounds complicated ..
I was planning to try a tube outputstage. That would be interesting to see how if the noise changes. But it woulndt if the noise is made in the digital part.
Thanks!
the noise didn't change with the right chip in the left one's place. I can post a pic later, but the chips looks used and old, so I would be very supriced if they were fake.
So it might be some problems with the circuit then. That sounds complicated ..
I was planning to try a tube outputstage. That would be interesting to see how if the noise changes. But it woulndt if the noise is made in the digital part.
Thanks!
pictures
Here are some pictures:
one tda1541
the other 1541
Here are some pictures:
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
one tda1541
An externally hosted image should be here but it was not working when we last tested it.
the other 1541
An externally hosted image should be here but it was not working when we last tested it.
Hi Nick,
Thanks for the pictures! I wish my DAC looks like that, very neat pcb!
The fonts on the chip are OK, also the date corresponds with the production location (HSH for Holland, unless marked TAIWAN on the left side)
So the chips are OK.
As those chips seem very reliable to me (never seen one broken), it must have something to do with the receiver (DIR9001?)
I use CS8414 myself, but maybe we can find some problems that need to be solved.
I guess you already know what I'm going to ask now: Are all the supply voltages correct?
You can measure them with a simple digital multi purpose meter. But since you bought this in the first place, you've probably got one of those and know how to handle one. (If not, I'll help you)
Have you contacted the seller of the DAC already? Maybe he has got some valuable information about these types of problems...
Best regards
Thanks for the pictures! I wish my DAC looks like that, very neat pcb!
The fonts on the chip are OK, also the date corresponds with the production location (HSH for Holland, unless marked TAIWAN on the left side)
So the chips are OK.
As those chips seem very reliable to me (never seen one broken), it must have something to do with the receiver (DIR9001?)
I use CS8414 myself, but maybe we can find some problems that need to be solved.
I guess you already know what I'm going to ask now: Are all the supply voltages correct?
You can measure them with a simple digital multi purpose meter. But since you bought this in the first place, you've probably got one of those and know how to handle one. (If not, I'll help you
)Have you contacted the seller of the DAC already? Maybe he has got some valuable information about these types of problems...
Best regards
Hi Nick,
Just another idea:
What about the digital filter? (SAA7220)
Under it seem to be some DIP-switches to change from OverSampling (OS) and Non-OverSampling (NOS), try removing the chip and put the switches into NOS mode, this might solve your problem.
Best regards
Joris
Just another idea:
What about the digital filter? (SAA7220)
Under it seem to be some DIP-switches to change from OverSampling (OS) and Non-OverSampling (NOS), try removing the chip and put the switches into NOS mode, this might solve your problem.
Best regards
Joris
An externally hosted image should be here but it was not working when we last tested it.
I have tried the switches, no differences.
The noise is very easy to hear if I turn down the volume at the digital side. When halfway up volume control in itunes, the sound is very noisy, and at minimum volume in itunes the sound is very distored and increadibly noisy.
Compared to my 100usd "707 super usb dac" (cs4398) this dual tda1541 sounds warm, natural, but with much less resolution and much narrower soundstage.
I didn't buy it on ebay, I bought it locally in China, as I live here. The seller's english is very limited, as is my chinese. Maybe the best solution would be to send it back to him. But I would maybe expect him to say that it is working perfectly, as it is producing sound, and at loud levels the noisy is not overwhelming.
The noise is very easy to hear if I turn down the volume at the digital side. When halfway up volume control in itunes, the sound is very noisy, and at minimum volume in itunes the sound is very distored and increadibly noisy.
Compared to my 100usd "707 super usb dac" (cs4398) this dual tda1541 sounds warm, natural, but with much less resolution and much narrower soundstage.
I didn't buy it on ebay, I bought it locally in China, as I live here. The seller's english is very limited, as is my chinese. Maybe the best solution would be to send it back to him. But I would maybe expect him to say that it is working perfectly, as it is producing sound, and at loud levels the noisy is not overwhelming.
That is indeed so. The seller said it should be this way for optimal operation, even if the schematic showing it there.
Can that cap make this big of a difference? From the schematic it is between leg 16 and 17 of the tda1541. (C42 in schematic)
Of course I should try to insert one. Can I temporarily try with a bigger size cap if I have ?
Use the DEM circuit from the schematic, one oscillator cap on each TDA1541A. You can temporarily use different DEM cap value (330pF ... 1nF), value determines DEM oscillator frequency. The higher the cap value, the lower the DEM frequency. DEM clock typical frequency is around 200 KHz.
Make sure to remove wiring (if present) on the solder side between both chip DEM oscillator circuits (pins 16 / 17).
Attempts to "synchronize" two DEM oscillators this way is very likely to fail / produce unpredictable results.
Yes the DEM oscillator can make such a big difference as it directly affects 6 MSB bit errors of both channels.
Make sure to remove wiring (if present) on the solder side between both chip DEM oscillator circuits (pins 16 / 17).
Attempts to "synchronize" two DEM oscillators this way is very likely to fail / produce unpredictable results.
Yes the DEM oscillator can make such a big difference as it directly affects 6 MSB bit errors of both channels.
I tried inserting a 0.1uf cap, and the sound became more distored than ever. It's the same type of noise/distortion I had before, so it seems likely that it has something to do with this cap. I should get hold of another 470nf cap to try, or could I change both caps to 0.1uf for now? The 0.1uf caps I have is quite big with long leads, will that pick up lots of noise?
Thanks!
Thanks!
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First check if pin 16 and / or 17 of TDA1541A chip #1 and pin 16 and / or 17 of TDA1541A chip #2 are inter-connected through PCB traces, wires or capacitor (attempt to synchronize both chips). Remove these inter-connections first, so you end up with the circuit shown in the schematic.
0.1uF (100,000pF) cap value is too high (use 330pF ... 1nF like I suggested). Make sure to use small cap size and shortest possible connections to pins 16 and 17 (few millimeters). Long wiring easily picks-up interference that can degrade DEM oscillator performance.
0.1uF (100,000pF) cap value is too high (use 330pF ... 1nF like I suggested). Make sure to use small cap size and shortest possible connections to pins 16 and 17 (few millimeters). Long wiring easily picks-up interference that can degrade DEM oscillator performance.
Thanks!
The seller says that I should not install this 470p, as they two 16 leg of the tda1541 are connected together, would need to cut this connection. So basically what you are suggesting to do. I think I will try this, because the present solution is not good.
Why would he make it like this in the first place? Can it work as is?
The seller says that I should not install this 470p, as they two 16 leg of the tda1541 are connected together, would need to cut this connection. So basically what you are suggesting to do. I think I will try this, because the present solution is not good.
Why would he make it like this in the first place? Can it work as is?
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