What is the cause of PCM glare? Bad recording or Bad DAC? Anything banish it?
- Thread starter caesar
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I would doubt it. The vast majority of digital anti-alias (recording) and anti-image (playback) filters used in audio are linear phase. The trouble in finding the casue of glare is that it is a subjective human perceptual effect, not an objective technical one. As we have all heard for decades, digial is essentially perfect, which it is - in theory. The digital devil, however, hides in the execution details. The current popular suspicion is that it is due to the pre-ringing exhibited of those digital filters, however, I have doubts about that.
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...which makes no sense. What we hear is distortion, in a specific FR range. We should be able to measure the FR output of the DAC and see it. And when we do, then we should be able to correlate it with what we hear. I don't hear it, or to put it more specifically, I hear it on some recordings and not on others. And I'm not using anything anyone here would call a SOTA DAC. So color me skeptical.
Tim
You seem to assume that we know exactly which objective parameter correlates with the subjective perceptual effect in question. I suggest that we do not know, else, there would not still be any question about the cause. Hopefully, you are not a strict objectivist, of the kind who declare that if traditional objective measures appear to reveal nothing of consequence then any contrary subjective perceptions are necessarily false. Don't misunderstand me, I don't believe in audio magic. I believe that if we consistently hear some difference, then the physical signal is also, somehow, different. That means that we would be able to measure the relevant physical signal difference once we know what the exact correlation is.
A problem I have with traditional audio measurements is that the test signals utilized are usually static, while music content is dynamic. Further, should we come to understand the relevant physical parameter causing some perceptual effect, we would also need to know the sensitivity of that parameter with respect to with the human pshycho-acoustic system in order to recognize it's significance. Glare may be the result of some complex distortion intermodulation spectra, or dynamic changes in harmonic distortion spectra profile, or low level quantization noise floor modulation, or jitter correlated distortion/noise modulation, or time-domain distortion due to insufficiently sharp band-limiting of the signal, or god knows what else.
I would suggest that you acoustically measure your listening rooms, all will be revealed.
Keith.
Keith.
My HD-800 will pierce my ears and shoot blood out my nose if I drive them with a crappy headphone amp. Yes I get glare with headphones.
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Keith.
M I believe the new 'domestic ' version has that peak toned down a little.Not as bad as most people think.
Keith.
Or put more plainly, digital reveals it. In the case you're talking about, the amp is the problem.
Tim
No, what I'm assuming is that if the perceptual result is harshness (distortion) in a specific range - upper midrange and treble - that it will show up as non-linear behavior in the frequency response. There may be even better ways to measure it, I'm not an engineer. I also assume that good DAC developers, especially on the pro side, are measuring and isolating distortions all the time, so they can find them and reduce or eliminate them. Hell, I'd further assume that they have tracked them down and know that these days, most "glare" comes from recordings, rooms and speakers.
I don't go quite that far, no. But in this case, what people are describing perceptually shouldn't be that hard to measure objectively. If we were talking about sound stage or PRAT, it would be a very different conversation.
I don't think that's as much of a problem as many people do. A lot of excellent equipment has been designed using such test signals, but I would prefer measuring the actual output of a system, in an anechoic chamber. Of course then we'd have to argue over the quality of the amplification, monitors and cables. That doesn't concern me much; unlike many audiophiles, I have great confidence that there are pro monitoring systems that would easily reveal any audible anomalies in the upper mids and treble, both in the ears and in the numbers.
I think I just had a little acid flashback...
Tim
if you play mostly vinyl, you may have optimised your system for vinyl playback, switching to digital which may have a little more HF extension, may well sound bright in comparison.
If you acoustically measure your room you will see exactly what the room and loudspeakers in combination are doing to the sound.
It is an obvious first step in optimising your system.
Keith.
If you acoustically measure your room you will see exactly what the room and loudspeakers in combination are doing to the sound.
It is an obvious first step in optimising your system.
Keith.
That makes sense to me. I'm not terribly concerned, personally. Glare, to my ears, is recording-related. I have reasons to update/change my system, but glare is not one of them.
Tim
Glare, some speakers have a 'smile' FR, upturned bass and treble, apparently it is to create an impression of resolution in the short term, but long term probably tiring.
Your room could have to much HF bouncing around , that's why you should measure to see exactly what is going on.
The recording, quality of recording trumps almost everything else.
Keith.
Your room could have to much HF bouncing around , that's why you should measure to see exactly what is going on.
The recording, quality of recording trumps almost everything else.
Keith.
Yes you are correct no one would use vinyl playback to design another component far too inconsistent , but in general terms, one probably chooses a cartridge, phono stage , loading tracking weight etc etc that one prefers.
Keith.
I do not subscribe to the notion. I merely alerted you to the inconsistency. Many use vinyl in their design process.
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