John Curl's Blowtorch preamplifier part II

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The heck with audioquest. I am going to Meridian and try to hear the difference between ordinary CD and MQA with really good playback equipment, like I try to use in my own hi fi. We shall determine this tomorrow.

While you're at it John, do try to get hold of a NAD 565BEE CD player and do give it a whirl. That's a somewhat odd unit, it is based on a Wolfson DAC and in my view plays music better than most similarly priced units out there. And by all means, do experiment with its selectable (externally, from the remote) low pass filter settings. Unusually clean and well focused sound. A comparisom between it and a Meridian unit would be most interesting.
 
It will only work properly if the rebar is made from iron sourced local to the listening room.

No - meteor iron! Literally out of this world experience!

Jan

PS Just read an article that an iron dagger that was found in Tutanchamon's grave appears to be meteor iron (with a sprinkling of cobalt) and probably was considered much more valuable than the pair of gold precious stone studded daggers that were also found.

Lord Canaveron (sp?) already found it in what was it, 1954 or thereabouts, but it was not considered interesting, you know, just an iron dagger. Yeah sure.
 
Ed, while we're on a roll how about agreeing on this. Here's pink noise 20-20k scaled with ~2.5dB below full scale headroom (@ 16bits) in the time domain. The second plot is exactly the same but scaled -60dB. The waveform is preserved almost exactly demonstrating the important property of proper dither. At 16 bits on this scale nothing is lost until you reach ~-99dB at 24 bits even double 1/f roll off would be far above the noise floor. I know music on the long term average is worse than 1/f but looking at the spectrum of real music at moments when there is significant high frequency content it is not.
 

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No - meteor iron! Literally out of this world experience!

Jan

PS Just read an article that an iron dagger that was found in Tutanchamon's grave appears to be meteor iron (with a sprinkling of cobalt) and probably was considered much more valuable than the pair of gold precious stone studded daggers that were also found.

Lord Canaveron (sp?) already found it in what was it, 1954 or thereabouts, but it was not considered interesting, you know, just an iron dagger. Yeah sure.
Yes, that was a fascinating realization, iron in the bronze age.

Oddly enough I have an iron-nickel meteorite sitting on the floor under an MC stepup stage. However I don't have it there for any imagined sonic benefits, rather as a good hiding place (until now).
 
Ed, while we're on a roll how about agreeing on this. Here's pink noise 20-20k scaled with ~2.5dB below full scale headroom (@ 16bits) in the time domain. The second plot is exactly the same but scaled -60dB. The waveform is preserved almost exactly demonstrating the important property of proper dither. At 16 bits on this scale nothing is lost until you reach ~-99dB at 24 bits even double 1/f roll off would be far above the noise floor. I know music on the long term average is worse than 1/f but looking at the spectrum of real music at moments when there is significant high frequency content it is not.

We were never in disagreement on proper dither.

I was questioning the "test" source.

The other issues was mixing a full 16 bit recording with another attenuated by 60 dB does not allow scaling of the attenuated one for a result of 16 bits. So I don't see any difference between dividing by 1000 or shifting 10 bits.
 
The other issues was mixing a full 16 bit recording with another attenuated by 60 dB does not allow scaling of the attenuated one for a result of 16 bits. So I don't see any difference between dividing by 1000 or shifting 10 bits.

No problem, need another picture? All math done FP, as essentially all software does now, and dither to 16 bits as a last process. You don't see it does not mean that you are not mistaken. There is no scaling of the attenuated one to 16 bits the FP math essentially adds both as continuous analog waveforms (numerical noise <-200 to -300dB) the dither and resampling to 16 bits at the end losses the ~ 1 LSB not 10. This is trivial to demonstrate.
 
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No problem, need another picture? All math done FP, as essentially all software does now, and dither to 16 bits as a last process. You don't see it does not mean that you are not mistaken. There is no scaling of the attenuated one to 16 bits the FP math essentially adds both as continuous analog waveforms (numerical noise <-200 to -300dB) the dither and resampling to 16 bits at the end losses the ~ 1 LSB not 10. This is trivial to demonstrate.


?? Huh? Three negatives in three sentences!

When you drop a 16 bit sample by 60 db you certainly can keep all 16 bits of resolution in the internal registers. When you add those to something that hasn't been divided and then turn it back to 16 bits even with dither I only see how you get maximum 7 bits of the original.

IE 1111 1111 1111 1111 - 60dB = 0000 0000 0011 1111 1111 1111 1100 ....

0000 0000 0011 1111 1111 1111 1100 + 0111 1111 1111 1111 0000 ... = 1111 1111 1111 1111 1111 1111 1100 ....

Truncated to 16 bits = 1111 1111 1111 1111
 
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We went to an open house to see some of the competition in this market and the owner had a crazy collection of mineral specimens all over the place some were 100's of lb.
I have a 100 pound double-terminated smoky quartz in storage, and a 160 pound Magnesite that resembles a large skull. Both are more than I could manage to get up the steps here.

I looked for a picture of the meteorite but apparently I never took one. It is rather beautiful, somewhat reminiscent of a Henry Moore sculpture.

Brad Plunkett once told me that I must be very rich, as I had taken to spending money on rocks.
 
Comes down to whether you did the math by upscaling the 16 bit data to something much higher (even FP32 will give you 8-9 more to work with), then dither back down.

Then again, I haven't been carefully keeping track of what you, Scott, and Bill W. have been going on about. IIRC you're seeing a loss in HF signal? A loss of DR is expected (obviously) by scaling a signal -60 dB, but unless you downsample, Nyquist, et al., shouldn't be much bothered.
 
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