A very high damping factor=Overdamping headphones?

Discussion in 'Sound Science' started by gustavmahler, Jan 17, 2015.
  1. 71 dB
    Reading prochures and technical papers by companies selling audio products can be misleading. While not lying about physics and math, they tend to verbally exaggarate the problems and the significance of their solutions to those problems. Always think about the purpose. Are they sharing knowledge/understanding or are they selling something?
  2. castleofargh Contributor
    @SimonPac does it seem so unrealistic that you like the idea of analog more, and music coming from it more, simply because of emotional ties and nostalgia? could it be that what's wrong with digital is in part that it's not your beloved past, and mainly all the bad apples we've had from poor mastering and executive/artistic decisions to go heavy on CDs because we could?

    yes ringing on 44.1 is closer to the audible range, yes higher resolution can contain higher fidelity(having the recording for it and the playback gears to keep the level are different issues), yes dither is dither and quantization noise exists. but the desire to turn all those stuff into the reason why you prefer analog or highres, despite no clear evidence that any of those variables are actually audible cues in music for you, that's just advanced level confirmation bias.
    71 dB likes this.
  3. SimonPac
    Yes you could all be right and everyone's happy, so fine, I'm happy too. Thanks for talking.
  4. bigshot
    castleofargh likes this.
  5. 71 dB
  6. SimonPac
    And I thought there was a coffee molecule. I think this might be my last remark other than perhaps for politeness and completeness for the moment. Said that before. I have no desire whatever to make anyone dissatisfied with their audio gear or music format. That probably sounds patronizing. Digital including CD has got much better IMO and can be really good.

    Some early CD transfers, some of which are still available, are really not too good at all IMO. It's not mountains and molehills, the analogue simply worked much better IMO. Someone mentioned Neil Young, and the start of 'Don't Let it Bring you Down' sounds hard, muddled and flat on my CD, admittedly against aa distant memory. Of course no-one much expected this to happen at the time and I'm sure many will say it didn't and I'm talking rubbish. Fine, they have ears and an opinion and so do I. I found the following page as a result of looking at the Wikipedia entry for dither, then onto Bob Katz mastering engineer and his commercial page.


    My impressions, based on far less experience then his, are broadly in line with this. Yes, he may have a commercial axe to grind.
    1. Small but maybe not small enough so it can be heard. When you measure electric impedance you measure from the same side the signal is provided - not with a microphone so you can't judge what really is happening with the sound on the other side.
    2. I disassembled headphones and saw how much acoustic resistance there is to them. For instance HD439 have foam, cotton on the outside, synthetic grills on the inside and a small closed space. On the other hand SHL4500 have almost none. Also I have sources with different output impedance and it affects SHL4500 more than HD439. SHL4500 is prone to resonances at 900-1000Hz and I can tell how much output impedance there is by hearing how much it resonates. HD439 stays more stable throughout different sources yes distorting more at high volume.
    Last edited: Nov 4, 2017
    error... pressed quote instead of edit.
    Last edited: Nov 4, 2017
  9. gregorio
    Unless your impressions are misinterpretations/biases, how can they be inline with Bob Katz's experience/article?

    Firstly, Bob Katz was talking about ADCs not DACs. There's a significant difference because an ADC typically needs far more precision, far lower digital artefacts than a DAC. This is because what comes out of an ADC is typically processed. An individual ADC channel may end up being amplified by as much as 1,000 times and therefore any artefacts from the ADC process also amplified by up to 1,000 times. On top of that it may go through numerous processing stages, each of which will add noise/artefacts. Once that's all done, it's fed to a DAC, the output of which is amplified for your headphones/speakers. In other words, any issues/non-linearities/artefacts with an ADC are likely to end up being far more noticeable, well into the audible range, than any similar level of issues with a DAC.

    Secondly, you did notice that Bob was talking about MTRs and project studios? Digital MTRs (multi-track recorders) proliferated in the 1990s to early 2000s. They were enormously expensive in the 80s but a few companies started making some relatively cheap ones in the early 90's. By far the most famous was the Alesis Digital Audio Tape (ADAT) and it cost about $4k if I remember correctly, which sounds expensive but was about 1/20 the price of pro digital MTRs and 24trk 2" reel to reel machines of the time! It was 16/44 or 16/48 and was pretty good considering this vast difference in price point but it was effectively a pro-sumer device and compared to top of the line pro audio equipment the built-in ADCs and filters, jitter specs, etc., were dire. I tested one extensively for about a week when it first came out but it was a wasted week because I knew within a few minutes it was not even in the ball park of the sound quality I required/expected. Nevertheless, Alesis must have sold hundreds of thousands of ADAT machines by the late 90's and it was arguably the main driver of the explosion of project studios. Even some of the big studios ended up buying them, not to use as their primary recorder but simply because they started getting so many clients turning up and wanting their ADAT tapes mixed or mastered. This is what Bob Katz's article is about and in that context, at that time, I'd have heartily agreed with virtually everything he wrote but not today and not for quite a few years!

    Again, you are quoting irrelevancies: ADCs rather than DACs and ADCs which existed more than half the life-time of digital audio ago, for only a relatively few number of years and which was only used for certain types of underground indie music productions. Nothing whatsoever to do with the premise against which you're arguing, of modern, competently designed DACs!

  10. bigshot
    Back in the 90s, I used ADATs to archive split track bounce downs for TV. They were fine for that. I haven't seen an ADAT machine in many years now though.
  11. SimonPac
    I agree DACs are getting better, with the newer higher grade delta sigma and hybrids much better than older ones. They probably sound pretty similar especially with the same filter. Some are still only really good for 18 bit or so while others like the PCM1792 are good for 20 bits plus. DCS who I spoke with recently say they get a genuine 24 bit linearity performance using a custom d-s circuit with fast 5-bit decimation.

    I quoted the PCM63 (20 years old) because I have a player using them and it sounds good to me, better than an off-board converter I also have with a newer chip. The PCM63P-K spec looks easily good enough for CD and its linearity at -100 is possibly better than the cheaper new chips like the PCM5242. This has selectable filters and a 32-bit interface, but low level linearity is not great. The 32-bits is not very meaningful. The PCM63 and other top end r2r multibits were expensive to make.

    I quoted a paper based on results obtained at low level on a fast 11-bit DAC simply to highlight quantization noise correlation, in the context of a discussion on what dither will and won't do. Not because I would use it for audio. It's not intended for that. But the quantization noise issues would be paralleled with an audio DAC albeit at a lower dB level.

    I also agree that an ADC used multiple times is of course going to affect the final result more than a single-pass through a DAC. Bob Katz is drawing out that issue of multiple passes through digital processing and their outcome.

    I'm not sure when he wrote the second half of the article, it seemed to be an update of earlier opinions.
  12. SimonPac
    The issue of what we mean by dynamic range arises. Crest factor, or peak-to-rms ratio, over a certain time frame or for a song, is one way it's measured for a particular track in a particular medium, and relates to DR compression used during recording/mastering.

    DR for a DAC usually means something else. It is often defined as the percentage of distortion/noise at a low level, often -60dB, referenced to 0dB. It is intended to convey the range over which the DAC can meaningfully work to convey signals.

    You can have low crest factor but still benefit from DAC DR because you are resolving the detail of the high level signals better.
  13. castleofargh Contributor
    for DS DACs, DR is SNR.

    lol that sentence actually has meaning, I've impressed myself.
  14. SimonPac
    People define thd, snr and dr in various ways, with and without weighting curves, etc. I think the ability to reproduce a sine wave passably well in the time domain is a decent indicator of real dynamic range and resolution. If you look at the -110dB sine wave on P4 of the PCM63 data sheet and look at Fig 21 on the PCM1792A data sheet, you can end up doubting what real progress has been made. When you add in the fact that the PCM converter probably has less out of band noise and its ability to reconstruct arbitrary low-level waveforms is possibly higher, I'd probably choose the older chip.

Share This Page