Hi,
I finished the PCM 2707 based DAC. The DAC is based on the recommended topology by TI. It works, however it reproduces sound with some very weird distortion, where some of the frequencies got echo. The specific sounds are audible many times with continually decreasing magnitude (with 4-5 audible repetitions). Does anyone have a clue what might be an issue? The sound got the same signature as if I was using old WINDOWS XP sound echo chamber mode. Just to be more specific: I used different USB cables- it did not help, also checked sound settings and all enhancements are disabled. I was not able to find much information about this chip on forum. Some photo attached. Here is a link for the project:
https://hackermagnet.com/usb-dac-pcb-with-pcm2707/
I finished the PCM 2707 based DAC. The DAC is based on the recommended topology by TI. It works, however it reproduces sound with some very weird distortion, where some of the frequencies got echo. The specific sounds are audible many times with continually decreasing magnitude (with 4-5 audible repetitions). Does anyone have a clue what might be an issue? The sound got the same signature as if I was using old WINDOWS XP sound echo chamber mode. Just to be more specific: I used different USB cables- it did not help, also checked sound settings and all enhancements are disabled. I was not able to find much information about this chip on forum. Some photo attached. Here is a link for the project:
https://hackermagnet.com/usb-dac-pcb-with-pcm2707/
Attachments
What do you mean by saying some of the frequencies have echo? Which frequencies? 1kHz? 100Hz? Maybe it would be more helpful if you recorded the output and linked to a wav file so we hear what it sounds like?
BTW, tried see if I could zoom in on the schematic some:
BTW, tried see if I could zoom in on the schematic some:
Attachments
Last edited:
Thank you for your answer. However, I must admit I do not know which frequencies within the audible spectrum got echo. It is just the way how I was able to describe my perception of the reproduced sound. Thank you for the schematics, but they are available on Texas Instruments official page and also on the web page of the project. As you requested, attached are two audio files, one recording of the volume control level of the w10 and another is the recording from the Nutcracker. It was recorded with phone so quality is not good. Does anybody else might have clue what might be an issue?
Sounds more like choppy or stuttering sound to me.
What version of Windows are you running?
Of possible interest: https://www.techtarget.com/searchwi...B-audio-problems-like-sputtering-or-glitching
Another: https://moviemaker.minitool.com/moviemaker/audio-stuttering-windows-10.html
What version of Windows are you running?
Of possible interest: https://www.techtarget.com/searchwi...B-audio-problems-like-sputtering-or-glitching
Another: https://moviemaker.minitool.com/moviemaker/audio-stuttering-windows-10.html
I am running W10. Thanks for the links, I checked them. They are too old (15 years), basically dealing with W XP. However, I tried to do some things which were relevant even today- without any change. I tried different cables and also 4 different computers (three of them running W10 and one W XP) with no changes whatsoever.
The schematic you linked to looks a little different from the closest one I found in the datasheet. For one thing the schematic you linked to appears to show 2 crystals, both 12Mhz
From page 29 of the datasheet:
Does you BOM match the example from the datasheet?
Another thing to check would be how Windows is configured for the default sample rate. This dac only supports 32kHz, 44.1kHz, and 48kHz. Its also limited to 16-bits.
Therefore if you go into Windows control panel, sound settings, and open the properties for this device. There you must set the default sample rate as shown below to 16/44 or else 16/48 (CD Quality, or DVD Quality).
Another thing to consider is that PCM2707 is considered obsolete. If yours came from somewhere like Aliexpress it might be used, fake, broken, etc. Hard to say.
From page 29 of the datasheet:
Does you BOM match the example from the datasheet?
Another thing to check would be how Windows is configured for the default sample rate. This dac only supports 32kHz, 44.1kHz, and 48kHz. Its also limited to 16-bits.
Therefore if you go into Windows control panel, sound settings, and open the properties for this device. There you must set the default sample rate as shown below to 16/44 or else 16/48 (CD Quality, or DVD Quality).
Another thing to consider is that PCM2707 is considered obsolete. If yours came from somewhere like Aliexpress it might be used, fake, broken, etc. Hard to say.
Last edited:
Control panel in Windows let you decide what sampling frequency at what quantisations level you can use automatically based on your DAC. You cannot choose 32bit 768kHz on your computer (based on your print screen), you can choose only 24 bit, 192 kHz, because that is maximum what your sound card can provide (your DAC chip). When you plug PCM 2707 DAC, you can choose only maximum level as well. My bom matched the data-sheet to some exemptions. Two crystal oscillators are used, if only one of them is used, no change at all. On of the oscillators got also inner load capacitance. Apart from datasheet, one coil at USB input is additional, but that also has no effect. I completed another PCB with same BOM material except from the chip (this one was from ebay, not aliexpress). The sound is now hissing and crackling and got completely different signature from the previous one. I would say more corrupted. All the chips were from China (Ebay and Aliexpress). It seems that probably chips are not good. If the schematic was not good, with different chips the sound should be similar ....