Hi, I’m building the Up2Stream Mini into a small obsolete multi-room zone amp. All is going well, except I have interference when using the 5V supply I have built inside the amp (the existing 5V supply wasn’t up to delivering enough current) So I’ve derrived 5v with a DC-DC converter (switching regulator) from one of the 25v amp rails.
I’d taken steps to filter the output from the DC supply, but I get interference that sounds like it comes from the CPU clock/Wifi on the streamer board (it clicks and whistles in time with the flashing LED when joining my wifi)…only when using the DC supply I built. No noise at all when using an external USB supply.
I suspect I have a Ground isolation/loop problem. I saw that others have suggested removing the jumper to isolate AGND from GND, which I think would help…but my V3 board has no jumper header in that position. Is there a way to isolate AGND on mini V3 boards that don’t have this jumper?
AGND is the ground return plane for audio signals, for some isolation it is usually connected to the DGND via an inductor or a resistance, in the case of the Pro board via 1k resistors.
I’m not familiar with jumper removal, which board’s allegedly have these?
You say that you have taken steps to filter the output, what have you tried? I would suggest yo try a LC network.
I have played around with DC - DC converters quite a bit and from personal experience found that the cheaper ones can be very noisy,
I have been using LT1963 low noise linear modules on my projects with great results.
Hope this helps.
If I power the Mini from this but connect the output to another amp then it’s fine…if I use it in the amp I’m building but power the mini from another source, then it’s also fine. Which is why I think I have some ground isolation issue…ordered an LC module but not convinced it’s going to help here.
To get the feed to my DC-DC converter the only supply available to me is one side of the ±25v supply on the amp board…so my supply ground is the centre (0V) rail and I suspect this is what is causing my ground isolation problem.
I also measured between AGND and GND on the mini when it’s disconnected and it appears to be a dead short (or a very small coil) which is why I was interested in that jumper mentioned in the thread.
Hi both, this (still) is an interesting topic to me.
Concerning the jumper mentioned in my thread, you can see the jumper in the first picture. In this case it is on the Up2Stream Mini. As I also experienced interference, I have experimented with removing it. But in all cases, the interference of the audio signal became stronger when the jumper was removed.
By making sure that all cables I add to a system are shielded, I have gotten better control over minimizing the interference. Though there still is a small distortion in the audio signal, and it sounds as a rattling noise.
At some point I changed the Up2Stream Mini board into a S10 (Up2Stream Pro inside), and the rattling noise was gone. Everything else was still the same (system configuration, cableing, power supply were all unchanged). Even the cheap power supply to the Mini/S10 was the same.
So I think there is something with the Mini board that makes it more sensitive to distortion.
I have now ordered the Arylic DAC Extensio Board. It has a different and higher quality DAC. So I will check what the effect of the added DAC board means to the rattling interference. And then come back here.
I am also looking for small AC>DC converter: input 230AC, output 5v / 1A.
Do you guys have any recommendation for such power converter, but especially with low noise?
I tried various things re screnning, I replaced the cable to the A out header on the mini with double insulated (automotive grade) line cables going into the back panel audio in connector, moved PSU wires etc further away…it doesn’t appear to be airbourne at all (and as I say based on it working fine on the same PSU but the output on another amp or a different PSU on this amp it’s almost certainly some isolation or ground loop issue)
Rereading that old post there does appear that the mini board has greater sensitivity to noise, I have one mini board and must have been lucky as mine doesn’t appear to have the same issues.
last year I did do some tests with some switching power supplies I also found a suppression board on eBay that I tried and showed good results in noise reduction (search 0-50V 4A DC Power Supply Filter Board Class D Amplifier Car EMI Suppression)
Can you check the backside of your Up2Stream for the date?
Thanks for the low noise power supply advise. Can use that for one of my projects.
Also I am looking for a 230v AC > 5v DC converter for building into small spaces, size of something close to 5 x 4 x 2 cm. There’s a lot of them, and a lot with noise. If you have a suggestion for something with limited noise, please let me know.
For a long time I have had issues with the Up2Stream Mini. Tested with three different models of active speakers, there was a ‘ripple’ interference in the audio signal. I have been looking for a long time to find the cause, so far not successful.
Tried an LC filter I bought between the DC-DC converter I’m using and the streamer…no change
Tried adding some resitance to the AGND to amp path (following the ground loop theroy I thought this might make it less of a path for supply)…made the noise worse
Tried a big (2200uf) cap on the 5v supply…dulled the noise but didn’t remove it completely
Tried the same cap on the 25v supply to the converter…made no difference
Removing either supply GND or AGND doubles the interference, tried alternate GND paths, shorting the GND to chassis etc…no change
Tried using GND rather than AGND on the output…no difference but none expected as they measure as a dead short
For now I’ve resorted to an external 5V (usb wall wart) supply to get the study amp working, for the other rooms I’ll try either the external DAC I think or add one of the internal mains to 5V DC PSU’s you’ve been looking at.
I think fundamentally I am fighting the combination of using the Amp 0V rail as the 5V GND and a switching DC-Converter when on my board, AGND and GND are the same thing…not sure why they deleted that jumper as I am sure in my case it would help
Does it draw any more than that during boot @Steve1 I did have a crafty go on the 5v supply that already existed in my amp, but that comes from a LM317 across the 25V supply…and it got very very hot very quickly. That should be in spec, but I’d need to add a heatsink…my my maths it only needs to disipate 3W of heat, but it sure felt like more than that when I touched it after 20 secs of operation…