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Post subject: 16-bit is old school...24-bit drivers needed for Mustsang I
Posted: Thu Jan 03, 2013 8:57 pm
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24-bit should be the minimum.


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Post subject: Re: 16-bit is old school...24-bit drivers needed for Mustsan
Posted: Fri Jan 04, 2013 3:09 am
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Huh? Not sure the reason for the question / statement; what do you want to achieve?

I'm always amused by the perception that more bits are needed for digital audio. 16 bits* at anything higher than about 40kHz** gives a signal to noise ratio of 96dB across the whole spectrum of human hearing, at least as far as the digital parts of the system are concerned.

This is far better than any of the analogue components in the system are likely to be, and also better than the background noise level in the average room. It's also better than anyone is going to be able to hear, unless in acoustically-perfect test settings.

Adding more bits* to the digital part of the signal, or sampling at higher frequencies**, isn't going to improve the sound quality. By contrast, improving the analogue components will improve the sound.

*Sadly, a lot of people listen to highly-compressed MP3s etc, which have been created from CD-quality originals. The poor quality they hear they thus think is a limitation of the original 16-bit sound. It's not of course, the quality loss is caused by the MP3 compression (even if a 16-bit signal is re-created from the MP3, it won't be the correct, original, 16-bit signal). When I rule the world, 'lossy' audio formats like MP3 will be banned...

**OK, a higher sampling frequency does make a difference if your 20kHz low-pass filter is poor quality and has a shallow cut-off; however, improving the analogue component (the filter) also solves this problem.


Last edited by scott-uk on Fri Jan 04, 2013 4:51 am, edited 3 times in total.

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Post subject: Re: 16-bit is old school...24-bit drivers needed for Mustsan
Posted: Fri Jan 04, 2013 4:44 am
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wow - you sound like you know a lot more than I do... thanks for the info. My 3 other interfaces I use @ 24-bit but it sounds like 16-bit is more than adequate for my home "wanking" and simple recordings 'eh. 8)

My ears aren't high end audiophile ears anyways, and it does sound great to me...

I'm 61 - still Rawkin' and lovin' all this new stuff. Back in my giggin' days (70's) we recorded on 2 akai Reel-to-Reels using an old Peavy 8 channel mixing board. We played our gigs back then without a p.a. or monitors, etc. cause we were dirt poor - just playing through our amps... the drummers were always mad cause they couldn't hear their drums when the Marshall stacks were Kranked Up! Once had a drummer walk off stage cause he was so mad ;)

Thanks again for the education Bro. You're a smart young man!


Last edited by Strangedogs on Fri Jan 04, 2013 4:57 am, edited 1 time in total.

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Post subject: Re: 16-bit is old school...24-bit drivers needed for Mustsan
Posted: Fri Jan 04, 2013 4:56 am
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24-bit I believe has value when a lot of re-recording is being done, eg overdubs, transfers to master tapes, etc, such as in a professional studio. Then, extra bits could be useful to preserve quality and prevent losses due to repeated digital/analogue/digital conversions. However, again, it's only any use if the analogue components are also of the same quality. I imagine top-end studio stuff, costing a LOT of money, probably is. Obviously though keeping it all in the digital domain is even better.


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Post subject: Re: 16-bit is old school...24-bit drivers needed for Mustsan
Posted: Sun Jan 06, 2013 12:53 am
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I could be wrong but that's not how I understand the advantage of a higher bit rate, scott-uk. As I understand it, the bit rate represents the signal's amplitude thus, 24 bit is a higher resolution representation of that amplitude. As far as I know, the advantage of 24 bit over 16 bit is in how the audio is reproduced as signal levels decrease such as in the decay of a sustaining instrument like an acoustic guitar or piano. In sixteen bit, most audio engineers spend a lot of time optimizing the signal level to keep it under digital zero but at averaging near or around 12 bits as the lower bits tend to be less smooth. Still they can't avoid what happens as the signal decays. At the 24 bit rate, that decay is represented with higher resolution and a smoother transition. Also, you can use far lower signal levels which increases the perceived dynamic range. While you still have to avoid exceeding digital zero, it is less finicky about signal level optimization. While most people's audio systems may not be able to allow you to hear the difference between the two, there is a smoothness in 24 bit recording that I can hear in the KRK VXT-8s in my project studio.

That said, I can't say that 24 bit capability is really all that necessary on any of the Mustang amps.

Peace.
O.


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Post subject: Re: 16-bit is old school...24-bit drivers needed for Mustsan
Posted: Sun Jan 06, 2013 1:34 am
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The best way to think about the bit depth is that it refers to the amount of different measurements which can be recorded about the amplitude of a waveform, so yes, 24 bit is a big improvement over 16 for a lot of things, as you gain a rather huge amount of extra sensitivity.

Not much to be gained when recording electric guitar, though, which tends to have a fairly restricted range at the best of times compared to acoustic instruments. As an example, fingerstyle acoustic guitar just explodes with life in 24 bit compared to 16!

Recording at 24 bit does have a lot of advantages even when the end result is going to be on 16 bit media (such as CD) though, as (amongst other things) it enables you to lower the noise floor to quite an impressive degree, as you're no longer using up as much of your precious resolution to accurately reproduce hiss and whine rather than the subtleties of your music. :lol:


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Post subject: Re: 16-bit is old school...24-bit drivers needed for Mustsan
Posted: Mon Jan 07, 2013 9:03 pm
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Thanks for posting a more eloquent explanation than mine, Vulpinity.
Cheers.

O.


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Post subject: Re: 16-bit is old school...24-bit drivers needed for Mustsan
Posted: Tue Jan 08, 2013 2:43 am
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Quote:
it enables you to lower the noise floor to quite an impressive degree

Indeed yes. I wasn't disputing the theoretical benefits of extra bits, for improving both SNR and sensitivity. My point is that this is only useful if all other components in the systems used for both recording and playback, plus the ambient environment, have an equally low noise floor and high sensitivity. Unfortunately that is unlikely to be true, particularly for the home recordist, hence the value of the extra bits is lost. That much is just fact, not an opinion.

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fingerstyle acoustic guitar just explodes with life in 24 bit compared to 16!

I am interested in this. Do you have comparative samples to demonstrate this you could send me or point me at please? Actually we need three samples: raw 24-bit, raw 16-bit, and a 24-bit recording re-encoded to 16-bit CD standard. I would love it to be the case that the extra bits can be used to make an audible difference; for the reasons I cite above I've never seen it convincingly demonstrated that this can actually be achieived in the real-world (rather than acoustically perfect test labs). If you'd like to send me the samples 'blind' (so that I don't know which is which - and honest I won't analyse them before listening), I'll happily genuinely report which one I think is best so you can prove me wrong.


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Post subject: Re: 16-bit is old school...24-bit drivers needed for Mustsan
Posted: Tue Jan 08, 2013 3:21 am
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scott-uk wrote:

Quote:
fingerstyle acoustic guitar just explodes with life in 24 bit compared to 16!

I am interested in this. Do you have comparative samples to demonstrate this you could send me or point me at please? Actually we need three samples: raw 24-bit, raw 16-bit, and a 24-bit recording re-encoded to 16-bit CD standard. I would love it to be the case that the extra bits can be used to make an audible difference; for the reasons I cite above I've never seen it convincingly demonstrated that this can actually be achieived in the real-world (rather than acoustically perfect test labs). If you'd like to send me the samples 'blind' (so that I don't know which is which - and honest I won't analyse them before listening), I'll happily genuinely report which one I think is best so you can prove me wrong.


I don't have anything to hand personally, as I'm at home slurping coffee - a very simplified explanation (I've not been awake long! :lol: ), assuming the end media is 16 bit, is below!

If you have 16 bits, perhaps as many as 4 of those are being used mostly for rendering the low level noise/jitter/etc, leaving essentially 12 for the dynamic range of the signal.

If you have 24, everything is still the same, but you now have 20 bits to handle the dynamic range of the stuff you want - when mastering, your signal can then take full advantage of the 16 bits the end media provides rather than 12 you would have if you recorded in 16-bit, as you can't add resolution which wasn't there on the master.

Basically, if you record in 16 bit, you can never actually have a real 16 bits of resolution - if you record in 24, you can, as you have a few to waste and can shove the noise right out of the equation.

In a perfect world with zero noise or other losses, nobody would need more than 16 bits if the end result is ending up as a CD, etc, but sadly I've yet to see this happen!

Of course, apply ridiculously heavy mastering compression like most do these days, and you probably essentially only need a few of those bits. To be fair, most of the time it's very hard to tell the difference in the end result, it mostly benefits sparse mixes with acoustic instruments or softer vocals. If you're recording a loud band, there's very little benefit other than saying "We recorded in 24 bits! That's 8 more than 16 innit!" :lol:

I still record at 16 bit at home unless it's for a job, it's perfectly adequate for most things, and saves a ton of disk space. :mrgreen:


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Post subject: Re: 16-bit is old school...24-bit drivers needed for Mustsan
Posted: Tue Jan 08, 2013 7:05 am
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Thanks, I know all the theory. I'm just interested to hear some comparative samples to demonstrate it all. Whenever I look I can't find any (or at least nothing to convinvingly support the arguments, on either side). This topic has re-piqued my curiosity, I'll go on another hunt...


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Post subject: Re: 16-bit is old school...24-bit drivers needed for Mustsan
Posted: Tue Jan 08, 2013 7:46 am
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very interesting topic.

I know nothing about AD conversion on musical equipment but I do know a bit about AD conversion for digital transmission of analog data in general.

Since the 60's somebody discovered that using bits to represent voltage changes linearly when doing AD conversion was a bad idea, that's when companding was invented. In a nutshell, lower signal levels get more granularity than higher signal levels when performing the AD conversion, mostly following a logarithmic scale (as the ear does naturally)

Following this same principle if we go from 16 bits to 24, most of the extra bits will go to add more resolution at the lower signal level part of the companding scale.

Unfortunately this same part of the companding scale is where the noise resides, so what I believe, please correct me if I'm wrong here) is that in a noisy environment, most of the extra bits will be wasted in having a more granular background noise encoding, kind of hi-fi noise :)

All this in an environment where most electric guitars are big antennas in disguise... mmmm not sure going from 16 to 24 to 32 or 64 bits will add anything particularly once most of the extra bits get filtered out as we reduce noise AFTER recording (when damage has already been done)

Again, this is my understanding coming from another field and do not know if it applies directly to AD conversion on guitar amplifiers. Any enlightenment will be greatly appreciated.


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Post subject: Re: 16-bit is old school...24-bit drivers needed for Mustsan
Posted: Thu Jan 10, 2013 10:55 am
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Ok, The increase in bit depth will improve DYNAMIC RANGE. With digital this ends up as "how low can you go"? Whilst helpful in a super discerning environment like a studio, it is probably not going to be useful with a guitar amp. The other thing to consider, which was alluded to before, is whether or not the analog hardware and the A to D/D to A conversion actually has that much dynamic range. 96db DR is quite sufficient as far as humans are concerned. The LPF construct will also have an effect on the quality as far as aliasing.

Anyhow, the extended dynamic range afforded with the extra bits is lost on a guitar amp. Go check the dynamic range specs (unweighted or otherwise) on your expensive tube amps. You may be surprised....

HOWEVER...


When it comes to the processing aspects like adding effects in the digital realm etc., the additional bit depth helps. See, people think that if it stays digital it doesn't degrade. But every process requires a complete rewrite of the digital "word". So each process would benefit from bit depth expansion and truncation and possibly dithering in an effort to maintain signal quality.

Unlike the analog world where what you get is "my original tone plus chorus" for instance, the digital process requires a rewrite, if you will, of each individual effect, eq choice, etc...truncation distortion ensues. Modulation of the least significant bit via dithering will help preserve the lower level signals and then you can knock the final output down to the desired bit depth on the way out while maintaining as much of the signal is possible.

pros and cons man, pros and cons....


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Post subject: Re: 16-bit is old school...24-bit drivers needed for Mustsan
Posted: Thu Jan 10, 2013 12:45 pm
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mmmm apparently this is the DSP used on the mustang series:

http://www.futureelectronics.com/en/technologies/semiconductors/microprocessors/digital-signal-processors/Pages/1872894-DSPB56725AF.aspx

if that is correct (i got the info from another forum post) the DSP inside the amp is already 24 bits so chances are the AD is also 24 bits already :) Who knew it would take a dual core processor to interpret my poor musicianship.

here is a short and concise article explaining the implications of 16 vs 24 bits.
http://www.homestudiocorner.com/24-bit-vs-16-bit/

honestly at this point the main source of distortion and noise in my case are my fingers so I do not care much. :)


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