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John Curl's Blowtorch preamplifier part III
John Curl's Blowtorch preamplifier part III
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Old 13th March 2018, 06:24 PM   #1121
hhoyt is offline hhoyt  United States
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Quote:
Originally Posted by jan.didden View Post
The audio is cut at 15kHz with a very steep filter (100 dB/oct roll-off and 1000's of degree phase shifts) to avoid interference with the 19kHz pilot.
I once did DB listening tests on such a filter with a few guys; 3 out of 4 could reliably identify whether it was in the chain, and they preferred it with the filter in ...

Jan
The best stereo encoders like the Orban 8500 use a high-order 19 KHz notch coupled with a 20 KHz brickwall anti-aliasing filter, both implemented in the digital domain, not a LP filter. The result is 2 Hz to 15 KHz +/- 0.1 dB encode, 0.01% THD rising to 0.05% at 15 KHz, with 110 dB s/n, with 144 dB of processing dynamic range. There is significant encoding of 15-16 KHz signal. On my Kenwood 600T in full quieting I can measure >80 dB S/N from my station with the board potted down. Of course I hear little above 15 KHz at this point in life....

Either way, I consider the sound quality of WXYC-FM very high fidelity. All bets are off once a station adds HD subcarriers to it's signal which I have steadfastly refused to consider. These noise sidebands often raise the noise floor in many FM tuners, and the sound quality of the HD is often inferior to the main linear FM carrier, having been compressed, phase scrambled for symmetry and in a tragic final attack on quality, psychoacoustically data reduced.

The only reason for HD Radio is to allow station owners to have multiple channels and extract more revenue. Analog FM offers a gradual stereo-to-mono transition in weak signal areas, HD offers a full mute in these situations, so I guess it is quieter!

My $0.02 worth...
Howie
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Old 13th March 2018, 06:32 PM   #1122
Joe Rasmussen is offline Joe Rasmussen  Australia
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Originally Posted by scott wurcer View Post
That is why IMO folks that are used to casual sighted comparisons have strong reactions to suddenly going "blind".
Hi Scott, I hear you. I have mixed feelings about this and perhaps my unease has led to misconceptions as to where I stand. I also have a similar unease when we have audiophiles who turn into instant reviewers and can make major pronouncements in nanoseconds, that cause me to turn (so as they not see my face) and roll my eyes, where it is clear that often "brand bias" or some elitist name thinking has influenced them. So I see both sides of the coin.

Sometimes I just ignore them, mainly because I think that the 'defective' piece of equipment, where an instant flaw was detected, actually sounded like music to me. So go figure?

BTW, I did coin the "JLTi" acronym that the late Allen Wright also used, it stands for "Just Listen To it. This was definitely a shot at 'branding' mentality.
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Old 13th March 2018, 06:35 PM   #1123
gpauk is offline gpauk  Scotland
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Used to be three fourths of FA (old UK slang...) FM signal around here -- but now with DAB, for all it's faults, we have in house signal and on the road coverage all through the mountains here... They co-located a bunch of DAB repeaters with cell sites; which would not have worked with FM. Mostly I listen to Radio 4 - speech - or 6 (digital only anyway) so there's no real loss vs quality FM. Sometimes you win...
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Old 13th March 2018, 06:41 PM   #1124
jan.didden is offline jan.didden  Europe
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Quote:
Originally Posted by hhoyt View Post
The best stereo encoders like the Orban 8500 use a high-order 19 KHz notch coupled with a 20 KHz brickwall anti-aliasing filter, both implemented in the digital domain, not a LP filter. The result is 2 Hz to 15 KHz +/- 0.1 dB encode, 0.01% THD rising to 0.05% at 15 KHz, with 110 dB s/n, with 144 dB of processing dynamic range.
My experience was with traditional analog FM. I realize that more performance can and has been squeezed from the format. Your numbers are very good.

Jan
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Old 13th March 2018, 06:49 PM   #1125
morinix is offline morinix  United States
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Originally Posted by TNT View Post
More distortion to the people.
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Old 13th March 2018, 07:02 PM   #1126
scott wurcer is offline scott wurcer  United States
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Originally Posted by morinix View Post
TNT didn't say that as far as I can tell but of course "the people" seem to love their distortions how ever they appear.
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Old 13th March 2018, 08:06 PM   #1127
morinix is offline morinix  United States
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TNT didn't say that as far as I can tell but of course "the people" seem to love their distortions how ever they appear.
It is in his signature so I injected it in the quote field. I just caught me at the right time to hit my funny bone.
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Old 13th March 2018, 08:15 PM   #1128
DF96 is offline DF96  England
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Originally Posted by Tournesol
It is nice to get some background music, or in a car stereo, but, in a hifi system ?
Who cares about ceramic caps distortions in a FM tuner ?
There was a time when a decent FM tuner receiving BBC Radio 3 was an essential part of most British hi-fi systems. I cannot comment on Belgian radio, but I would be surprised if there was not an analogous station.

Quote:
On my system, FM radio is just awful (trebles). While it sound ok in little speakers.
You may have a bad tuner, or a bad antenna (causing multipath reception). Or maybe you just listen to a bad station - there are a lot of them these days.
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Old 13th March 2018, 08:35 PM   #1129
scott wurcer is offline scott wurcer  United States
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It is in his signature so I injected it in the quote field. I just caught me at the right time to hit my funny bone.
No biggie, it's becoming more and more obvious that the cold analytical hardcore accurate (by conventional standards) electronics are not what folks want, more and more people are admitting to their preferences for a little of this or a little of that.
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Old 13th March 2018, 08:46 PM   #1130
scottjoplin is offline scottjoplin  Wales
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I think this is the case, identifying what they are could be tricky. I wonder if it's more prevalent now due to the ability to do more speaker and room correction that may also have made the perceived sound too dry, for want of a better word
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