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Old 29th October 2012, 05:13 PM   #601
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Actually if you read the last paragraph just above the conclusion the problem seems to be absent with 1 bit sigma delta type conversion.

It is just audible with non-oversampling convertors on reverb tails.
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Old 29th October 2012, 05:40 PM   #602
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Originally Posted by mondogenerator View Post
yes of course, i forget that when they say 16 bit, what they mean is 1 bit sigma delta DAC or something of the like.

Not true 16 bit, where there are 2^16 divisions.
a 1 bit sigma-delta DAC can be used (and IS used often) to play 16-bit samples; by using oversampling, the 1-bit DAC at 256x oversampling performs as a 16-bit dac at 1x sampling rate.
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Old 29th October 2012, 07:51 PM   #603
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Originally Posted by CopperTop View Post
Is this a job for compression, or simply setting the sliders to the right levels for each performer? One messes up the dynamics, while the other allows the dynamics to come through unmolested, with only the relative level being artificial. If I were recording a live performance I would try to get away with as little dynamic compression as I could. Of course if most people are listening with headphones on the bus or walking down the street then they might complain if the dynamic range is too great. Optional artificial compression in the playback device would be best, I think.
I was considering a hypothetical track, where everything is put onto the CD with no sliders adjusted.

Track starts with someone singing softly, and then, further on, there's a drum solo, using a full-size stage kit, with a very heavy-handed drummer.
The drums might then quieten down to a more soft-handed rhythm again for the track to continue.

I'd estimate at least 50dB of dynamic range would be needed here, in order to reproduce the full dynamic swing in volume that was there originally.

There's no option but to make the quiet bits louder and the louder bits quieter. The system I played a drum kit recording through (mentioned a couple of pages back) would manage the full dynamics of that track, but using almost all of the 600w available into a 98dB@1w speaker isn't an option for domestic listening - its bonkers loud, and would likely deafen the listener in due course.

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Old 29th October 2012, 08:41 PM   #604
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Originally Posted by flavio81 View Post
a 1 bit sigma-delta DAC can be used (and IS used often) to play 16-bit samples; by using oversampling, the 1-bit DAC at 256x oversampling performs as a 16-bit dac at 1x sampling rate.
Thanks Flavio for the explanation, im really a novice in the field of ADC and DAC. Most of my experience is with PIC micros and coding to use the ADC functions. DACs are something that ive rudimentary theory. Ill have to read up to learn how they achieve 65536 divisions using 1 bit and x256 over sampling. I could probably use a 10bit ADC on a cheap PIC that im familiar with. Others have better ADCs, but again, id have to look in a book or two.
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Last edited by mondogenerator; 29th October 2012 at 08:44 PM.
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Old 29th October 2012, 09:54 PM   #605
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Originally Posted by mondogenerator View Post
Thanks Flavio for the explanation, im really a novice in the field of ADC and DAC. Most of my experience is with PIC micros and coding to use the ADC functions. DACs are something that ive rudimentary theory. Ill have to read up to learn how they achieve 65536 divisions using 1 bit and x256 over sampling. I could probably use a 10bit ADC on a cheap PIC that im familiar with. Others have better ADCs, but again, id have to look in a book or two.
Oversampling is what you want... The main reason the CD player industry went to oversampling (first implemented as 4x the sampling rate on the first generation Philips CD players, which had a respectable 14-bit DAC chip) was that if the sampling frequency F s higher, then the images (artifacts produced by the DAC starting from frequency F/2 and higher) will be moved further away from the audible spectrum. This means that it will be easier to filter them out using analog filters.

When you go to the extreme (1-bit DAC and 256x oversampling), the problem is that any jitter on the sampling clock could potentially bring more trouble that the same jitter at 1x (no oversampling).

Or at least that's how i understood it.
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Old 30th October 2012, 02:11 AM   #606
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Increasing stiffness of the supension with increased travel will also bring in compression.
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if that really happens I guess you have exceeded driver limits and said goodbye to sound quality anyway
Yes, but you have saved the driver to play again another day. Very important in the biz and why it's designed that way. A progressive suspension can you keep you out of trouble when the fellow behind the console has had a few too many. And that's pretty often.
Of course you can still burn up the voice coil.
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Old 30th October 2012, 10:59 AM   #607
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Originally Posted by chris661 View Post
I was considering a hypothetical track, where everything is put onto the CD with no sliders adjusted.

Track starts with someone singing softly, and then, further on, there's a drum solo, using a full-size stage kit, with a very heavy-handed drummer.
The drums might then quieten down to a more soft-handed rhythm again for the track to continue.

I'd estimate at least 50dB of dynamic range would be needed here, in order to reproduce the full dynamic swing in volume that was there originally.

There's no option but to make the quiet bits louder and the louder bits quieter. The system I played a drum kit recording through (mentioned a couple of pages back) would manage the full dynamics of that track, but using almost all of the 600w available into a 98dB@1w speaker isn't an option for domestic listening - its bonkers loud, and would likely deafen the listener in due course.
I'll take your word on the figures, but I've still not grasped why the situation of listening at home is any different from listening to a live performance from a location that gives a similar SPL, e.g. in the audience in a classical concert. In the concert hall the listener is subjected to the full dynamic range yet can still hear the quiet bits and isn't deafened by the loud bits. There are differences of course, and maybe the listener in the concert hall has more information to work with which allows him to hear past his fellow coughing, shuffling audience members better, but at home he'll be listening in a quieter environment. His audio system can happily handle 90dB of dynamic range, say. Why is it imperative that the recording is compressed dynamically?

In the UK we have two large classical stations: Radio 3 and Classic FM. Classic FM is highly compressed and gives a superficially smooth presentation that, at first, sounds very sweet. But, after a little while it leaves you gasping for dynamics.
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Old 30th October 2012, 11:17 AM   #608
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This compression or extreme limiting is what i was referring to earlier. In my experience radio is over compressed and DAB is no better, id guesstimate that its worse. Even with CD the compression is lesser, probably vinyl is also better (once you take out the dynamic range lost to rumble and crackle).

To the best of my knowledge 40db is a reasonable goal for vinyl or cd dynamic range, and a well executed 2:1 compression from 80db to 40db isnt half as objectionable.

Frankly i find the bandwidth of DAB through DTV box to be severely lacking on all but the flagship BBC stations, let alone the compression, and i liken it to 64kbit mp3 quality (i.e. Not listenable)
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Last edited by mondogenerator; 30th October 2012 at 11:23 AM.
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Old 30th October 2012, 11:51 AM   #609
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80 to 40dB is 100:1 compression.
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Old 30th October 2012, 12:00 PM   #610
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Originally Posted by SY View Post
80 to 40dB is 100:1 compression.
Not for the common meaning of "compression ratio". From a dbx compressor user guide:

Quote:
The RATIO knob controls the amount of compression, which will happen once the input
signal crosses the Threshold level, described above. Ratio controls how much the input
signal will be reduced as a ratio of the input signal level. For example, if the compression
ratio is set for 6:1, the input signal will have to cross the threshold by 6 dB for the output
level to increase by 1 dB.
the maximum setting is typically labeled: 1 (infinity to 1),a nd is
also called Limiting.This means that the output signal won’t increase at all, no matter how
far above the threshold the input signal goes.
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