| Unexpected upgrade [message #97992] |
Sun, 08 September 2024 12:11  |
Barryso
Messages: 202
Registered: May 2009
|
Master |
|
|
There was a noticeable change in the sound of the system this week.
It runs a Raspberry Pi as a music server with a PI2AES hat allowing a quality connection to the DAC.
Swapped out the hdd spinner hard drive for an ssd solid state drive. The old drive was getting loud and doing strange things. It was time.
Didn't notice a change in sound going from the hdd to the ssd but I didn't really expect to.
But the hdd had been run through a powered USB hub because the Pi wouldn't provide enough juice to run the old drive properly. So after listening to the new drive for a bit playing through the hub it got plugged directly into the Pi USB. That made a noticeable difference in that it seemed to remove a bit of midrange grunge from the sound.
Further, unplugging the switcher from the power strip also removed more grunge. That wasn't unexpected ... I've noticed that sort of change before when removing switchers.
So there's a good deal less grunge in the sound and it's a fine improvement to the system. To use an audiophile term things got more palpable. It's pretty nice given it was unexpected.
Anyone else run into something that turned into an unexpected upgrade?
|
|
|
|
| Re: Unexpected upgrade [message #97993 is a reply to message #97992] |
Mon, 09 September 2024 10:44  |
 |
Wayne Parham
Messages: 18772
Registered: January 2001
|
Illuminati (33rd Degree) |
|
|
Dude, that's awesome!
As an aside, when I find digital source hardware that improves from something like this, I always suspect a ground loop is or was the cause. Where there is no DAC change or anything else that is substantive - just a power supply or cabinet change, something like that - I always suspect the ground connection did it.
I think we sometimes forget about that as we've moved into the digital realm. It was more obvious in the analog world - a ground loop almost always presented as noise at power supply frequencies. Either hum from the fundamental or spikes from diode switching at those frequencies, making a harsher form but still at 60Hz or 120Hz, depending on half-wave or full wave rectified. Ground loops in car setups usually present as alternator noise. In each of those cases, the symptoms were familiar.
In the digital realm, sometimes ground loops make a sort of grungy or hashy "background," just like you've described. I see this not only in audio but also in control systems, where you won't hear the noise but can see it with a scope. The symptoms there are usually intermittent failures, usually in sensing, communications or control and when I see those, I almost always find a ground loop that shows digital noise reflected into a sensor input or communication interface. Sometimes, I'll see it go the other way, with a high-current control signal reflected back into the digital circuits, resetting them or otherwise causing mayhem.
Having digital in our audio world has made life much more convenient and quality can be great. But the connection between digital and analog can sometimes be tricky. I tend to prefer isolation - like through opto-isolators - because those remove the problem. It's not unlike using an isolation transformer for the same reason, usually done in purely-analog circuits where long signal lines are required making ground loops more likely.
|
|
|
|
|
|
| Re: Unexpected upgrade [message #98015 is a reply to message #97995] |
Fri, 20 September 2024 21:41 |
 |
gofar99
Messages: 1944
Registered: May 2010
Location: Southern Arizona
|
Illuminati (5th Degree) |
|
|
Hi I'm with Wayne on this. Ground loops of any kind nearly always cause problems. As Wayne mentioned often the only time you can actually see them is on a scope. I recently did a study of USB power sources. Both plug in and ones that actually replaced the outlet. Amazing. All put out some sort of noise. Some really bad some more reasonable. The best showed wide band noise at about -80dbv and asssorted peaks at about -60dbv. The actual frequency of the peaks varied from brand to brand. Some at relatively low frequencies like 1-5KHZ and most in the 8-50KHZ range. One unit (plugtul) was horrible everywhere S/N (if you can call it that) was -55dbv across the board with a large peak at 4KHZ. Since many devices now use the USB as power (instead of the previous 6 and 12 VDC wall warts) this can be a major source of problems. For sensitive audio gear like phono preamps I really like to see numbers in the -90 to -100dbv range for the power side. Something that many folks seem to overlook is that in nearly all audio gear the power source is one half of the device and is the return path for the audio signal. If it is full of crud then there is no hope for having a good S/N in the output.
Good Listening
Bruce
|
|
|
|
Posting Rules
Members
Search
Help
Register
Login
Get a T-Shirt!
