The thing is, I don't want to end up with CDR's that peak at -12dB or lower.By normalizing at 24-bit resolution, some info is effectively 'pulled' up into the usable dynamic range of CD-audio.
I guess that's the conundrum - add a pre-amp or add gain digitally. Probably you're right, and I should really get the analogue side optimized. The only problem is that simple, decent and affordable preamps are few and far between (no market for the little suckers, I guess)- I have thought of building a simple opamp based one myself.
I have thought of building a simple opamp based one myself.
Well something is pulled up into the dynamic range of the CD, but its not info. Probably just hiss, since the dynamic range of the CD is so much greater then the record (even including 10 or 20 dB of waste).
Quote from: Mike Giacomelli on 29 August, 2006, 10:18:24 PMWell something is pulled up into the dynamic range of the CD, but its not info. Probably just hiss, since the dynamic range of the CD is so much greater then the record (even including 10 or 20 dB of waste).Well, the whole point of dithering 16-bit PCM is that sounds like tape-hiss, for example, (say at -70 odd dB) can sound rather gritty and 'unnatural' without it. It's been argued that analogue noise (whether from tape or circuitry), which is essentially 'brownian', shouldn't be any more intrusive than other 'ambience noise'. I'd rather have that tape hiss quantized with as many bits as possible.
It's generally understood very low-level signals (such as ambience cues) aren't reproduced well by CD-audio near the bottom of it's dynamic range - simply not enough bits..
In the context of straight LP to CD transfers, I don't want to use more digital processing than absolutely necessary, and as you might have gathered I'm even a little suspicious of simply adding gain.
I don't think you're understanding this. The source media you have has maybe 60 or 70dB of dynamic range. If you're lucky. The CD you're going to has roughly 100dB, perhaps more with noiseshaping. Thats 30-40dB of headroom. Applying dither here isn't going to help you since the bottom 5-7 bit are already randomly distributed and thus contain no actual information.
Having done more than 400 LP transfers I submit that reasonable digital processing is no detriment to audio quality. Of course it depends on what you are looking for, but it is easy to produce a product through editing that is better than what came off the LP. Reading posts about DEA, it seems as though more than a few people are so concerned about the bits they end up with -- far beyond anything that might make an audible difference -- that one might believe they are building their eternal abode in paradise instead of a mobile music collection. Well, whatever you might think about that attitude, it is very silly to try to apply it to recordings you make from an LP. Record the same disk twice and the totally unavoidable differences between the two recordings will be far more significant than any "damage" you could possibly do by normalizing.Since peaks too near 0dB can produce waveforms as much as 8dB above 0dB (although that extreme is pretty unlikely in music), some DACs can clip on files that have no clipping. I recommend normalizing to about 97% instead of going to maximum.
Analogue sources have no '0dB' reference to allow direct comparison of 'dynamic range' or 'signal to noise' (which two terms are used, wrongly, interchangably).
However, since information can be stored, retrieved and heard *well* below that noise floor, the dynamic range is actually considerably greater.
Properly mastered, and played back on commensurately good equipment, LP actually has a dynamic range approaching 90dB, and all of this reproduced with distortion of no more than a few %, and this subjectively 'benign' distortion at that.
...While some people have speculated that greater signal depths can exist, actual measurable dynamic range [of an LP] is about 55 to 60 dB; in fact in many cases the recording is compressed to that neighborhood in the mastering process. With some fairly heavy duty noise reduction it might be extended to 70 dB in a transfer from LP. Where have you heard/read of anyone measuring anything approaching 90dB?
However if any DSP is going to be carried out, IMO 16 bits is really NOT adequate. This kinds of relates to my question about simple normalization.