Different DACs and amps, but I've been doing that since USB audio was suppoorted well enough, and used sound cards with external analog boxes before that. I still haven't heard a PC with a decent video card that doesn't make obvious noise on the onboard analog outs when the video card is not at idle, even some Asuses that have the separate traces and layers, shielded chips, and all that jazz. Often, the CPU cycling around power states will do the same thing. While you won't usually hear anything with included speakers, it really doesn't take much for it to start being apparent, and a lot of people don't hear it, even when it's obvious to me. With sensitive headphones, it's clear as day, though.So has someone tried something like a O2+ODAC from JDS and actually noticed a benefit when listening to music and/or playing games?
Yes, it is. Higher frequencies do not follow the path of least resistance. DC will. A fan should not be doing much in terms of AC, and everything it does should take the 'shortest' paths from power and ground. Meanwhile, your mouse is working at, IIRC, 60MHz.
You will in the opamp, which there will be at least two of, if not four (bipolar inputs). Not to mention some chance of antennae being connected.
Not if it contaminates the input.
Explain GSM noise, then, or picking up AM stations, with unshielded opamps (or insufficiently shielded, or unlucky cable lengths). Each follows a different path to just that end result. GSM noise is closer to most of what we can hear from inside our PCs.
Which is it? It's change is the fields that can causes noise, not their static state.
Different DACs and amps, but I've been doing that since USB audio was suppoorted well enough, and used sound cards with external analog boxes before that. I still haven't heard a PC with a decent video card that doesn't make obvious noise on the onboard analog outs when the video card is not at idle, even some Asuses that have the separate traces and layers, shielded chips, and all that jazz. Often, the CPU cycling around power states will do the same thing. While you won't usually hear anything with included speakers, it really doesn't take much for it to start being apparent, and a lot of people don't hear it, even when it's obvious to me. With sensitive headphones, it's clear as day, though.
So has someone tried something like a O2+ODAC from JDS and actually noticed a benefit when listening to music and/or playing games?
The motherboard has the analog audio. The video card makes the most easily heard interference, IME, on gaming PCs.What video cards have analog audio on them? Only ones I see throw digital audio out over HDMI, and leave it up to other hardware to do the DA conversion.
AC power is far away. The interference from a fan would be from it turning on and off, which would come from its normal operation (2+ times per cycle), controlling it by PWM on power (1+kHz), or the fan driving the motor using the 4-pin PWM signal (25kHz+harmonics).They do seek the path of least resistance. Specifically, what you're getting at is the path of least impedance...which will be inductance if you're talking about AC power (and on how the wiring is set up).
No. Generally, if you don't have a balanced output, your PC's audio is single-ended the whole way.Huh? Are you getting at how the opamp is more or less giving a single ended output from differential inputs (they don't have to be fully differential - you can do it with the signal and a reference of 0)?
That's not what I mean. I mean that as an effect.I maybe wasn't clear here - my point was that you're going to totally destroy the incoming signal. You don't put a rectifier on this.
217Hz is not supersonic, and is where the biggest spike will be seen with 3G and older GSM. 4G-only phones FTW! But, anyway, high energy spikes of high frequency signals can get turned into lower frequency signals, which, if contaminating your signal or ground, make noises as you do stuff, like with your mouse, or a PSU, or any number of other switching PSUs, and chips with quickly varying loads.I maintain that an audio amp isn't going to take something subsonic and make you suddenly hear it. Crappy amps have 60hz hum because the AC coming from the wall is 60hz (or it's 120hz for a full wave rectifier with no smoothing.)
The AD797 is known for being able pick up AM, with the "right" wiring. FM would take some pretty interesting accidental circuitry .What opamp do you have that picks up AM signals (let alone FM signals)?
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I never tried an ODAC because NwAvGuy is a [insert some unpleasant adjective in here] (perma-banned from Head-Fi last I knew), but I have built AMB's (Ti Kan's) gamma2 DAC with a good amount of success. I ended up with audio that sounded more than good enough for what I have in speakers and headphones. I plan to build his newer gamma1.5 which has a USB DAC that can go to 24/192 and a small-ish headphone amp in it (of course, this HP amp is powered by USB and it's PRETTY limited. He lists the Vpp it'll clip at.)
I thought that was the point of the O2+ODAC, that he went through the effort to debunk the BS of audio and get something on the scope that was as good as something like the Benchmark, but not with insane price markups and hype?
I'm just learning about it now, was his effort BS or did he actually accomplish what he set out to do? What I know is no one has heard from him it sounds like in a while (drop off face of earth online)...
Chuck
AC power is far away. The interference from a fan would be from it turning on and off, which would come from its normal operation (2+ times per cycle), controlling it by PWM on power (1+kHz), or the fan driving the motor using the 4-pin PWM signal (25kHz+harmonics).
In the case of USB devices themselves creating noise, it's going to be in the tens of MHz (about 60Hz for USB 1-2, IIRC), where inductance is most of what matters.
Very slowly changing stuff, like DC power draw, can be put on the same traces as audio power and 0V, so long as it has a better path to follow than through the audio devices. It would be easiest just to make them separate, but sharing a 0V somewhere else isn't going to hurt anything.
No. Generally, if you don't have a balanced output, your PC's audio is single-ended the whole way.
That's going to have nothing to do with other components making interference that may end up received, rectified, and amplified into audio range noise.
217Hz is not supersonic, and is where the biggest spike will be seen with 3G and older GSM. 4G-only phones FTW! But, anyway, high energy spikes of high frequency signals can get turned into lower frequency signals, which, if contaminating your signal or ground, make noises as you do stuff, like with your mouse, or a PSU, or any number of other switching PSUs, and chips with quickly varying loads.
The AD797 is known for being able pick up AM, with the "right" wiring. FM would take some pretty interesting accidental circuitry .
I thought that was the point of the O2+ODAC, that he went through the effort to debunk the BS of audio and get something on the scope that was as good as something like the Benchmark, but not with insane price markups and hype?
I'm just learning about it now, was his effort BS or did he actually accomplish what he set out to do? What I know is no one has heard from him it sounds like in a while (drop off face of earth online)...
Chuck
And that's too oversimplified. Low frequency AC may as well be DC. The faster it is, the closer it will follow the path of least inductance; the slower it is, the closer it will follow the path of least resistance. It's even easy to Google pretty pictures of it.That stuff is easily dealt with by adding a decoupling cap or similar. I don't know where you're going with this. I don't know how you're saying that high frequency doesn't follow the path of least resistance. Either it's DC and it's following path of least resistance, or it's AC and it's following the path of least inductance. I'm really over simplifying here, but that's the jist of it.
Page 3, top paragraph, is just what I was talking about. No matter what you have for a cap, if you route the ground so the easiest path is through the audio section, you'll get lots of noise, effectively like an AC signal, even if it's low frequency. Make it so it can go from the PSU, to the fan, to ground, without having to go through there, and it won't be a problem.Analog Devices has a doc on this issue, actually: http://www.powerampdesign.net/images/AN-24_Eliminating_Circuit_Noise_From_Cooling_Fans.pdf
The polling rate has nothing to do with anything, and generally maxes out at 1kHz, not some MHz. Decoupling is not going to be some simple thing for many-MHz signals.The noise from a USB device will be on the supply side (likely on ground?) An the DAC just isn't decoupled correctly. The polling rate of the sensor should have nothing to do with this.
There may be, or not, but that's generally trade secret stuff. And, again, it's not a specific component dedicated to the task, but an effect. I cited quite possibly the most well-known source, and you can go read several pages of the relevant section for free.Not necessarily. Either way, I only mention that because you seem to think there's a rectifier in a DAC?
I've no idea where he went; he ruffled A LOT of feathers (and proposed the idea that you cannot empirically measure the quality of audio equipment, that you can only use your ears). I know he compared his stuff to Ti Kan's stuff, notably his gamma2 DAC. I also seem to remember that to make his ODAC seem better, he intentionally built the gamma2 incorrectly. He also touted his ODAC as better because it could do higher bit depth & sample rates than the gamma2 could - which is true. His ODAC used a chip that you and I cannot buy in quantities less than 1000 at a time. The gamma2 uses one of the FEW ICs our there that can be purchased one at a time for USB audio (the TI 2707.) It's the same reason that the Twisted Pear Audio Buffalo DACs are all pre-made (it uses an ESS Sabre chip.) Ti Kan's latest uses a Atmel microcontroller, bypassing the need for a specialized chip.
Generally though, NWAvGuy was an exceptionally abrasive person and not one I could stand to sift through his writing for long periods of time. Will his stuff work? Sure. I've no clue how good it is...and I doubt I'll ever find out.
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I have no history with him, just was looking at what a good DAC+headphone amp would be, and came across a bunch of O2+ODAC references. Followed them to his blog, http://nwavguy.blogspot.com/2012/04/odac-released.html, but after 2012...he just disappeared.
To me it sounds like he built his DAC to compare to the Benchmark DAC1 which he used as a reference. Are you saying that this gamma2 is better? I'll have to go check it out...
Chuck
And that's too oversimplified. Low frequency AC may as well be DC. The faster it is, the closer it will follow the path of least inductance; the slower it is, the closer it will follow the path of least resistance. It's even easy to Google pretty pictures of it.
Page 3, top paragraph, is just what I was talking about. No matter what you have for a cap, if you route the ground so the easiest path is through the audio section, you'll get lots of noise, effectively like an AC signal, even if it's low frequency. Make it so it can go from the PSU, to the fan, to ground, without having to go through there, and it won't be a problem.
The polling rate has nothing to do with anything, and generally maxes out at 1kHz, not some MHz. Decoupling is not going to be some simple thing for many-MHz signals.
There may be, or not, but that's generally trade secret stuff. And, again, it's not a specific component dedicated to the task, but an effect. I cited quite possibly the most well-known source, and you can go read several pages of the relevant section for free.
The gamma2 is...different. The ODAC is meant for, I believe, USB only. The gamma2 has USB, but it isn't ideal. If DIY AND USB is what you want, look at the gamma1.5 for USB. If SPDIF is in your future (and not USB) the gamma2 (NOT the gamma1) is just fine.
The ODAC is probably a fine device too - I just don't buy into the crud that he was peddling.
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Oh I want something assembled already, I have zero time to be putting sh1t together.
You don't believe his measurements or just his viewpoints?
Well it looks like MSI finally got it by providing that board with a discrete power plug for the audio section. Actually they've copied asus in quite a few areas with it except they forgot a usb 3 motherboard header for the front panel connector. I wish they'd omit the m2 connector on the z97 boards for the shear fact that it forces you to disable pcie slots in order to make use of the m2 slot.