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Post by Boomzilla on Dec 17, 2022 16:09:36 GMT -5
Layout:
USB HDD to
ROON NUC to
Topping D10s DAC to
Tube buffer to
CD inputs of Emotiva PT1 preamp to
Emotiva PA1 power amps to
GoldenEar Triton Three+ speakers
What's Happening?
Immediately, when I turn my left power amplifier on, there is a hash noise (not super loud but moderately so) from the speaker with a beep-beep roughly every second.
Things I've tried so far:
1. Switched the preamplifier to a different input (no change)
2. Unplugged all inputs from the preamplifier (no change)
3. Changed the interconnect from the preamp to the power amp (no change)
4. Changed the speaker cable from the power amp to the speaker (no change)
Conclusions I draw from what I've done so far:
a) The source of the noise is not upstream of the preamplifier (otherwise, switching inputs should have killed it)
b) The source of the noise is not a bad Interconnect (otherwise, switching interconnects should have killed it)
c) The source of the noise is not flaky speaker wires (otherwise changing the wires should have killed it)
Stuff I will try next:
Swap power amps from right to left (if the noise persists, it's in the power amp itself.
Any ideas about where this odd noise is coming from and what I might do to kill it?
Thanks - Glenn
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Post by Jean Genie on Dec 17, 2022 17:26:36 GMT -5
Layout: USB HDD to ROON NUC to Topping D10s DAC to Tube buffer to CD inputs of Emotiva PT1 preamp to Emotiva PA1 power amps to GoldenEar Triton Three+ speakers What's Happening? Immediately, when I turn my left power amplifier on, there is a hash noise (not super loud but moderately so) from the speaker with a beep-beep roughly every second. Things I've tried so far: 1. Switched the preamplifier to a different input (no change) 2. Unplugged all inputs from the preamplifier (no change) 3. Changed the interconnect from the preamp to the power amp (no change) 4. Changed the speaker cable from the power amp to the speaker (no change) Conclusions I draw from what I've done so far: a) The source of the noise is not upstream of the preamplifier (otherwise, switching inputs should have killed it) b) The source of the noise is not a bad Interconnect (otherwise, switching interconnects should have killed it) c) The source of the noise is not flaky speaker wires (otherwise changing the wires should have killed it) Stuff I will try next: Swap power amps from right to left (if the noise persists, it's in the power amp itself. Any ideas about where this odd noise is coming from and what I might do to kill it? Thanks - Glenn Sorry you're having this problem, it sounds quite annoying. You might want to try a coyote and some Acme TNT💣🙉😉 |
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Post by Boomzilla on Dec 17, 2022 17:26:55 GMT -5
I have identified the source of the noise. I had located that left amplifier on my equipment rack in close proximity (3 or 4 inches) away from an APC-brand uninterruptible power supply (UPS). The UPS was generating the noise that was being picked up and amplified by the Class-D power amplifier. The amp wasn’t plugged into the UPS, so the noise wasn’t on the amp’s AC power line. Simple proximity was sufficient to create the noise on the amp’s output terminals. With the amplifier a foot or more away from the UPS, there is no longer any audible noise on the amplifier outputs (inverse square law in action!). Consider this a FYI… Glenn Postscriptum - I don’t know if this is an artifact of Class-D amplifier technology, of switching power supplies, or whether the same thing might have happened with a “conventional amplifier.” KeithL? |
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Post by Jean Genie on Dec 17, 2022 19:10:18 GMT -5
I have identified the source of the noise. I had located that left amplifier on my equipment rack in close proximity (3 or 4 inches) away from an APC-brand uninterruptible power supply (UPS). The UPS was generating the noise that was being picked up and amplified by the Class-D power amplifier. The amp wasn’t plugged into the UPS, so the noise wasn’t on the amp’s AC power line. Simple proximity was sufficient to create the noise on the amp’s output terminals. With the amplifier a foot or more away from the UPS, there is no longer any audible noise on the amplifier outputs (inverse square law in action!). Consider this a FYI… Glenn Postscriptum - I don’t know if this is an artifact of Class-D amplifier technology, of switching power supplies, or whether the same thing might have happened with a “conventional amplifier.” KeithL ? I knew you'd track it down👏👏👏😇 |
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Post by routlaw on Dec 17, 2022 20:45:39 GMT -5
When I first read this, initial thoughts were it had nothing to do with the gear per se but rather something else within the house, and now you have found it. Doubt it’s because of the SMPS either but what you have discovered is the classic RMI/EMI issues and the need for shielding in some if not most situations. Well thats my 2¢ worth not being an EE. Good you figured it out in short order.
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Post by 405x5 on Dec 17, 2022 22:40:39 GMT -5
Layout: USB HDD to ROON NUC to Topping D10s DAC to Tube buffer to CD inputs of Emotiva PT1 preamp to Emotiva PA1 power amps to GoldenEar Triton Three+ speakers What's Happening? Immediately, when I turn my left power amplifier on, there is a hash noise (not super loud but moderately so) from the speaker with a beep-beep roughly every second. Things I've tried so far: 1. Switched the preamplifier to a different input (no change) 2. Unplugged all inputs from the preamplifier (no change) 3. Changed the interconnect from the preamp to the power amp (no change) 4. Changed the speaker cable from the power amp to the speaker (no change) Conclusions I draw from what I've done so far: a) The source of the noise is not upstream of the preamplifier (otherwise, switching inputs should have killed it) b) The source of the noise is not a bad Interconnect (otherwise, switching interconnects should have killed it) c) The source of the noise is not flaky speaker wires (otherwise changing the wires should have killed it) Stuff I will try next: Swap power amps from right to left (if the noise persists, it's in the power amp itself. Any ideas about where this odd noise is coming from and what I might do to kill it? Thanks - Glenn Sorry you're having this problem, it sounds quite annoying. You might want to try a coyote and some Acme TNT💣🙉😉 Had the same and tried your solution successful but not the first try….. youtu.be/e9aYzLA1nx8 |
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Post by Boomzilla on Dec 19, 2022 12:23:14 GMT -5
I was premature. Although moving the amp around relative to the UPS did diminish the noise volume (I think now, in retrospect because moving the amp inadvertently moved some other wires), the noise never completely went away. I concluded that the noise was gone then because the front end of the system (the computer server) wasn't on at the time. So what WAS the noise source?
WORST OF ALL POSSIBLE SOLUTIONS!
The noise is coming from the USB ports of my BRAND NEW NUC! Everything on = noise at speakers. Turn off the NUC - noise instantly stops.
The noise is not coming from the USB Library drive - I’ve taken the previous one out & substituted a completely new drive.
The noise is not coming from the UPS - I took it completely out of the system and now everything is plugged into the same power strip / surge suppressor.
The noise is not coming from the USB DAC - I took it completely out of the system and plugged the NUC directly into the digital USB input of my preamp.
The noise is not coming from the USB cables - I replaced every one (twice). I do notice, however, that I can wiggle the USB-A connector in its NUC socket and get static.
I had read that the USB sockets on NUCs were delicate, but this is RIDICULOUS! The NUC insn’t even a month old. I’d use TOSLINK optical instead but the %(*)^&_)^(%^ NUC doesn’t have a TOSLINK out.
The thing DOES have a socket in the rear with a lightning bolt on it, and one on the front that might be a USB-C? If I can find the right cords, maybe I can use one or the other of those? I’m just profoundly disgusted with the NUC. I’ve owned computers for decades and NEVER had another USB socket go bad.
And they ARE bad - now the NUC can’t even see the USB HDD plugged into its rear USB port (either of the USB-A ones). Are ALL NUCs so poorly made?
I’m inclined to just toss the NUC (and ROCK along with it) and go back to a Roon Core install on a Windoze laptop. At least the USB ports work on those…
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KeithL
Administrator 
Posts: 9,945
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Post by KeithL on Dec 19, 2022 14:37:10 GMT -5
The UPS undoubtedly has both switching power supply circuitry and some sort of processor in it (even when not "running" it's going to be monitoring the battery and keeping it charged). These can both generate significant amounts of high frequency noise. This noise could travel directly through the air or be radiated by any of the power cables entering or leaving the UPS (they will act like antennas at those sorts of frequencies). And, at that point, it could be picked up by the amp directly, or via its interconnects, speaker cables, or power line. (From the way you described the noise it sounds like it might have been a noise chirp from the UPS battery charging circuitry - as it periodically "checked" or "topped" the battery.) Class D amplifiers are notoriously sensitive to noise and fussy about grounding and shielding. And, since they normally internally operate at very high frequencies, they are sensitive to high frequency noise that a "regular" amplifier might ignore. It's also not improbable that an external high frequency noise source might interact with some internal source of high frequencies to produce an audible beat frequency. I would say that it might or might not happen with a conventional amplifier... but is certainly more likely with a Class D amp... (And I would be surprised if it didn't happen with something like a phono preamp or a turntable.) All in all, it's not surprising that something like this could happen, and not really suggestive that either piece of equipment was acting unusually. (And a good hint not to put digital circuitry within a foot of audio circuitry unless you really have to...) Good catch though...  BTW, since you like tube gear, I would also note that tube gear can be especially sensitive to this sort of noise as well. (Because tubes handle high frequencies well, tend to operate at very high impedances, and often aren't shielded properly against noise at all.) I have identified the source of the noise. I had located that left amplifier on my equipment rack in close proximity (3 or 4 inches) away from an APC-brand uninterruptible power supply (UPS). The UPS was generating the noise that was being picked up and amplified by the Class-D power amplifier. The amp wasn’t plugged into the UPS, so the noise wasn’t on the amp’s AC power line. Simple proximity was sufficient to create the noise on the amp’s output terminals. With the amplifier a foot or more away from the UPS, there is no longer any audible noise on the amplifier outputs (inverse square law in action!). Consider this a FYI… Glenn Postscriptum - I don’t know if this is an artifact of Class-D amplifier technology, of switching power supplies, or whether the same thing might have happened with a “conventional amplifier.” KeithL ? |
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Post by Boomzilla on Dec 19, 2022 15:06:53 GMT -5
No dice. Even with the USB DAC plugged into the FRONT USB-A port of the NUC, the noise is still present. Conclusion - The NUC's USB buss is toast (at least for outputs - the external USB HDD seems to work OK). Time for plan B:
Remove the NUC to the computer room & have it connect to the Apple TV3 in the living room via Ethernet.
Use the Apple TV's TOSLINK optical output to the DAC (or else plug it directly into the PT1 preamp's optical input).
Locate the tube buffer between the analog outputs of the PT1 and the power amplifiers.
Soup...
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Post by Boomzilla on Dec 19, 2022 23:15:42 GMT -5
Killed the noise FINALLY...
Put the NUC back in the computer room using its only remaining working USB port (the front) to connect the Music Library USB HDD. Ethernet streams from there to the living room & the Apple TV does streamer duty. Its TOSLINK optical goes to my PT1 preamp. Pre-out to the tube buffer and then to the power amps.
How does the tube buffer sound? Better than without.
But I really need a better streamer.
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novisnick
EmoPhile
CEO Secret Monoblock Society
Posts: 27,230 
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Post by novisnick on Dec 20, 2022 0:56:54 GMT -5
Killed the noise FINALLY... Put the NUC back in the computer room using its only remaining working USB port (the front) to connect the Music Library USB HDD. Ethernet streams from there to the living room & the Apple TV does streamer duty. Its TOSLINK optical goes to my PT1 preamp. Pre-out to the tube buffer and then to the power amps. How does the tube buffer sound? Better than without. But I really need a better streamer. A quality streamer is well worth the effort to find the one that fits you. Good luck. |
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Post by MusicHead on Dec 20, 2022 10:27:19 GMT -5
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KeithL
Administrator
Posts: 9,945
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Post by KeithL on Dec 20, 2022 10:57:56 GMT -5
Considering this new information I can tell you the most likely cause of the noise... which I've seen several times. Computer power supplies tend to be noisy... and that includes both the +5V output and the computer's system ground... which is also the ground used for the USB ports. This is not a problem for most DACs that are AC line powered... because they don't use that power ground as their circuit ground. But, for DACs that are powered by the computer's USB port, it can result in noise between "the DAC's ground and your audio system's ground". (And, unfortunately, simply connecting those grounds together via the interconnect cables will not totally eliminate this type of noise.) If this is the case, and the computer was a laptop, you would find that the noise was totally gone when running on batteries and the charger disconnected. The other alternative would be to galvanically isolate the DAC - and, unfortunately, there are a limited number of options for galvanically isolating a UBS-powered DAC. (Note that this is not the same as "the normal sort of ground loop noise you see with analog audio gear...+ - which typically results in line frequency hum.) Topping actually sells a USB galvanic isolator (I've never tried one.... but the specs look very good.) www.amazon.com/Topping-Isolator-Compatible-PCM32bit-withstands/dp/B09MF9VTQGshenzhenaudio.com/products/topping-hs01-usb-isolator-usb-2-0-high-speed-low-latency-eliminate-the-ground-loop-noise(And, of course, it probably wouldn't happen with a USB DAC that was AC line powered.) Killed the noise FINALLY... Put the NUC back in the computer room using its only remaining working USB port (the front) to connect the Music Library USB HDD. Ethernet streams from there to the living room & the Apple TV does streamer duty. Its TOSLINK optical goes to my PT1 preamp. Pre-out to the tube buffer and then to the power amps. How does the tube buffer sound? Better than without. But I really need a better streamer. |
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