Hi All,
Firstly if this question has been asked before, or if I am asking in the wrong place.
I am in the throws of putting together a Mac Mini music server including a linear power supply, and today I stumbled upon this :
The Ground Control from CAD.
Computer Audio Design CAD - GC1 Ground Control Reviews & News
Computer Audio Design Ground Control
The concept of absorbing all the noise created by the switched mode power suppy, not to mention all the fall out from internal data / address buses shifting stuff around at Gb/sec, sounds interesting. But at 1400 quid cheap it is not.
It seems it is a box of filters that absorb all the noise(s) leaving the music kit more free to do its stuff on the real signal.
Anyone got any experience of using such a device ?.
Is this real or load of bull IYHO ?.
Thanks
Firstly if this question has been asked before, or if I am asking in the wrong place.
I am in the throws of putting together a Mac Mini music server including a linear power supply, and today I stumbled upon this :
The Ground Control from CAD.
Computer Audio Design CAD - GC1 Ground Control Reviews & News
Computer Audio Design Ground Control
The concept of absorbing all the noise created by the switched mode power suppy, not to mention all the fall out from internal data / address buses shifting stuff around at Gb/sec, sounds interesting. But at 1400 quid cheap it is not.
It seems it is a box of filters that absorb all the noise(s) leaving the music kit more free to do its stuff on the real signal.
Anyone got any experience of using such a device ?.
Is this real or load of bull IYHO ?.
Thanks
Hi,
Just my common sence humble opinion;
Earth is the final stop of any electrical signal. No electrical noise down there, nothing to clean up. Circuit ground is the returning path for signal - and noise - current loops. Special precautions are taken to keep noise away from the signal ground, by means of proper conection of the signal ground to the power supply ground and then - most likely - to earth. If this hasn't been done at the design stage of the device, a possible cure should not be searched at the speakers spades.
Finally, if the computer stays only at the digital domain i.e. server and not in the digital to analoge conversion, it just needs isolation at the usb power supply rail and a RFI filter at the mains so that it doesn't inject noise to the usb conected device and also back through the mains to the rest of the audio system. I hope that helps!
Just my common sence humble opinion;
Earth is the final stop of any electrical signal. No electrical noise down there, nothing to clean up. Circuit ground is the returning path for signal - and noise - current loops. Special precautions are taken to keep noise away from the signal ground, by means of proper conection of the signal ground to the power supply ground and then - most likely - to earth. If this hasn't been done at the design stage of the device, a possible cure should not be searched at the speakers spades.
Finally, if the computer stays only at the digital domain i.e. server and not in the digital to analoge conversion, it just needs isolation at the usb power supply rail and a RFI filter at the mains so that it doesn't inject noise to the usb conected device and also back through the mains to the rest of the audio system. I hope that helps!
If you use opto to your DAC, power supply don't matter/is perfectly ok. Or are you using the built in analog audio out?
//
//
If you are talking about the safety earth in your house wiring it has lots of noise. It is a big antenna.
Many hifi / audio / computer appliances today are double insulated and do not have any safety earth connection at all. The mac mini is like this.
This device apparently has no other connection - other that what you connect it too - be it by USB, XLR, RCA, etc... (they supply a bunch of cables). It seems it has some filters that present a short circuit to the noise (between the signal +ve and signal -ve of the connected cable) - or something like that.
Earth wiring is a big antenna connected to earth. Other than ground loop hum issues, there is no noise or any kind of electrical signal circulating in earth wiring.
Double insulation of appliances is not for avoiding "poluted" earth.
As for the particular device, it is not clearly documented how it works. It is definately out of the psu, if it is connected to a spare RCA means it stays out of the signal circuit so the same is expected when connected to a usb port and I can't understand if it establishes any connection between signal -ve and earth. It is mentioned that the best result occurs when it is connected to mains earth. Does this mean it is only a wire connected to earth and the whole device just floatting not connected elsewhere? Absorbing what?
*sigh*. Another expensive device to cure "noise" that isn't there in the audio stream anyway. Build your system. Use the power supply it came with.
Any noise? Worry about it when you hear it, and save your money...
I've used desktop PCs with standard power supplies, laptops, and now an OrangePi. I've never heard any background noise that a fancy power supply would fix. Yes, I connect the DAC via USB...
Any noise? Worry about it when you hear it, and save your money...
I've used desktop PCs with standard power supplies, laptops, and now an OrangePi. I've never heard any background noise that a fancy power supply would fix. Yes, I connect the DAC via USB...
There are no filters, it is just a box filled with some "sand" and a few conducting bars - see similar device Entreq Tellus grounding - Page 162
People hear sound improvement out of this? 198 pages is too much reading for such a subject!
Everyone can hear anything if he/she wants to. I very much doubt affluent customers of such voodoo will ever submit themselves voluntarily to a blind listening test...
I' m not going to read all this. Just some posts here and there claiming improvement by plugging these anywhere possible and wait for some burn in. Does anyone report differences removing these appliances after this?
I also have dead silence between tracks. I don't expect to improve this. But I do want to improve the sound during tracks as much as I reasonably can.
With the Mac mini connected via USB to the Audiolab DAC; on its internal SMPS I can hear occasional crackles on some difficult tracks. With the SMPS removed and it powered on a (large) 12v battery there are no crackles and the sound is more dynamic. Also there are no crackles if I connect my iMac to the DAC, but it sounds better with the Mac Mini on battery. So this tells me a decent linear PSU would be a good idea.
My original post was curiosity as to whether this type of noise absorber really does anything to significantly improve sound. Or is it just a sandbox. I would never buy one of these expensive black boxes – but I might try to make one if the technology does do something useful…
Originally I was thinking “this is just a box of RC / CRC / LC filters”….. I never really thought it might be a box of “minerals. I wonder if cat litter and a few bits of copper piping might work ?. Worth a try maybe….
With the Mac mini connected via USB to the Audiolab DAC; on its internal SMPS I can hear occasional crackles on some difficult tracks. With the SMPS removed and it powered on a (large) 12v battery there are no crackles and the sound is more dynamic. Also there are no crackles if I connect my iMac to the DAC, but it sounds better with the Mac Mini on battery. So this tells me a decent linear PSU would be a good idea.
My original post was curiosity as to whether this type of noise absorber really does anything to significantly improve sound. Or is it just a sandbox. I would never buy one of these expensive black boxes – but I might try to make one if the technology does do something useful…
Originally I was thinking “this is just a box of RC / CRC / LC filters”….. I never really thought it might be a box of “minerals. I wonder if cat litter and a few bits of copper piping might work ?. Worth a try maybe….
It's a good thing to test options and decide with open mind! An improvement to soundstage is expected from better grounding. But I think it's all about breaking ground loops and connect all earth wires together at a mains "ground star". As regards for RFI, it may inserts into the audio components not via the earth but through mains live and neutral lines. Here you can use a RFI filter. Anyway, since you use isolated usb connection you shouldn't have noise from the computer and if had it should be audible between tracks. From distance I can only assume that your observation about the crackles associated with the SMPS perhaps mean that this psu is underspecified and doesn't provide enough power in comparisson with the large battery, or that it injects high frequency noise back from the mains to the rest of the system.
This seems investigating some more. Especially with your USB isolator in place, I'd expect no such issues. (Any effect if you take that one out? Also, any effect if you ground the machine?)
Make some test tracks to track down where the crackling comes from:
1. Including pretty much nothing but dithering noise, just enough to keep the DAC from muting. Unwanted analog noise should be quite obvious then.
2. Including bass sines near full scale (0.999-ish). 20-100 Hz or thereabouts. Short interruptions or similar tend to be quite audible with these.
Audacity is fine for this.
If neither shows any issues, investigate what's so special about your critical tracks.
Also make sure output format (sample rate / bit depth) is set up correctly everywhere, or alternatively that the player software has control over that.
Crackles may be an indication of "buffer underrun" problems or perhaps clipping. You might be marginal on computing power, or simply need larger buffer space. I strongly doubt that the power source is going to cause this.
If I take out the USB isolator there is very low-level background noise / hum. Basically all the time there is silence. So the isolator is doing what is it supposed to do. The ‘crackles’ are still there without the USB isolator.
The 'crackles', as I described it, could be better described as “slight distortion with occasional pops” are always in the same places on the same tracks. Like I said these are difficult pieces - like Adel's chasing pavements - the s in the word chasing in the chorus. These are always at high frequencies – at the top end of soprano.
This problem disappears if the mac mini runs on a DC battery or a USB hub (on its own linear psu) is inserted between the mac mini and the USB isolator. The USB is an interesting one – since it is buffering the packets.
The mac mini is doing nothing else except playing music using Audirvana+,. All 3rd party apps have been deleted, all non needed things like widgets / notifications / messaging are disabled etc… System monitor shows about 5% memory and 5% processor use while tracks are playing. I5 processor with 8GB of memory with OSX El Capitan. It’s the same if the music file is on the local drive (SSD) or NAS server.
The Audirvana+ player has control over the sampling frequency / bit depth and the DAC is receiving this correctly for all tracks.
I’m going to have a look with a scope at the 5V coming out of the USB ports and also the 12v coming out of the internal SMPS. I have also bought another mac mini SMPS off eBay for 30 euro to test with.
It is quite possible there is some noise getting through from the SMPS that only affects certain frequency combinations via the USB host device.
- Status
- Not open for further replies.