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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, 03:57 PM   #1111
billshurv is offline billshurv  United Kingdom
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John Curl's Blowtorch preamplifier part III
Quote:
Originally Posted by Tournesol View Post
Ah, Ok, in europa, we call this DAB+, not FM. And it is quite new: very little coverage.
But tell-me, John would listen to a digital signal? ;-)
Very different to DAB as is in the same band as the FM and autoswitches. In a way a much better idea.
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Old 13th March 2018, 03:59 PM   #1112
Max Headroom is offline Max Headroom  Australia
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Originally Posted by Tournesol View Post
Did you mean a FM tuner ?
This thing with a 19kHz carrier that carry the stereo signal ?
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 ?
Tornesol, I hear/understand what you are saying......broadcast FM ain't HiFi but it can be pretty darn decent nonetheless, and can happily inspire new playlists/musical interests.
Upstream passive and active devices cause all manner of linear distortion and
non linear distortion behaviours, the final output stage active and passive device behaviours constitute a 'final filter' as does the input device constitute an 'input filter' for the system.
Broadcast FM can be pleasing/pleasant and nicely close to the source CD, but yes it will never be quite the same.

Dan.
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Old 13th March 2018, 04:05 PM   #1113
scott wurcer is online now scott wurcer  United States
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Quote:
Originally Posted by Tournesol View Post
Did you mean a FM tuner ?
This thing with a 19kHz carrier that carry the stereo signal ?
Some of the best sound I ever heard were 15 ips uncompressed tapes played over FM radio. As we often say here the source quality is foremost.

The 19k is the pilot tone for generating the 38k subcarrier. IIRC the absolute best SNR you can get from the system was low 70's but I might not recall correctly. Typically the 19k is notched out if not a small percentage of the population find FM unlistenable.
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Old 13th March 2018, 04:07 PM   #1114
Max Headroom is offline Max Headroom  Australia
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In local shootouts analog FM was well preferred to DAB+....there are Bit Rate issues.
Different distortions, different noises, different rolloffs/dynamics, for me analog FM done right can be better than DAB+.

Dan.

Last edited by Max Headroom; 13th March 2018 at 04:36 PM.
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Old 13th March 2018, 04:28 PM   #1115
gerhard is offline gerhard  Germany
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Quote:
Originally Posted by scott wurcer View Post
Some of the best sound I ever heard were 15 ips uncompressed tapes played over FM radio. As we often say here the source quality is foremost.
Must have been the euphonic diodes in the ratio detector. ;-)
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Old 13th March 2018, 04:29 PM   #1116
jan.didden is offline jan.didden  Europe
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Quote:
Originally Posted by scott wurcer View Post
Some of the best sound I ever heard were 15 ips uncompressed tapes played over FM radio. As we often say here the source quality is foremost.

The 19k is the pilot tone for generating the 38k subcarrier. IIRC the absolute best SNR you can get from the system was low 70's but I might not recall correctly. Typically the 19k is notched out if not a small percentage of the population find FM unlistenable.
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
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Old 13th March 2018, 04:30 PM   #1117
scott wurcer is online now scott wurcer  United States
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Quote:
Originally Posted by gerhard View Post
Must have been the euphonic diodes in the ratio detector. ;-)
I never though of that, the fuzz pedal guys hide their stashes of NOS 1N62 Ge diodes like gold.
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Old 13th March 2018, 04:44 PM   #1118
Tournesol is offline Tournesol  Belgium
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Quote:
Originally Posted by scott wurcer View Post
Some of the best sound I ever heard were 15 ips uncompressed tapes played over FM radio. As we often say here the source quality is foremost.
On my system, FM radio is just awful (trebles). While it sound ok in little speakers.
It is just like the sound of TV: I was obliged to buy a little system for my TV, in my Hifi it was a nonsense: You just listen to hundred of defects, noises, etc...
And the "size" of the sound is ten time the one of the (quite big) screen ;-)
No way.
My FM tuner is somewhere in my cellar.
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Old 13th March 2018, 04:55 PM   #1119
Joe Rasmussen is offline Joe Rasmussen  Australia
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Originally Posted by Max Headroom View Post
Hi Jo, (Rasmussen), quite a while back IRC you mentioned using supercaps for bypassing DAC/OPS supplies....what are your longer term conclusions ?.

Dan.
Hi Dan

I certainly would not use them for coupling audio signals and I am clearly of the best cap is no cap when it comes to signal coupling - but how often do you get away without that, not often. My phono stage design, no coupling caps at all, ultra LF servo though.

Power supply is a different matter, but only to power digital (switching) circuits. Here I use 0.33F/5.5V caps in parallel with largish ceramic layer caps, something I would never do for signal coupling, not in a million years. So 'horses for courses' apply. I only use this on DACs (usually 2 or more are needed, typically 3.3V and 5V) and would love others to try it and report back. Do it also on the 3.3V powered clocks.

I am sure you have something there you could try this on. I won't try do describe the sound, just find out for yourself.

Cheap as chips!

This I believe is about back-EMF noise suppression (switching), and with the clock supply, keeping ULF noise out of the clock.

Joe
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Last edited by Joe Rasmussen; 13th March 2018 at 05:02 PM.
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Old 13th March 2018, 05:11 PM   #1120
scott wurcer is online now scott wurcer  United States
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Quote:
Originally Posted by Joe Rasmussen View Post
Much to agree with you there.
Yes Joe just a comment on my observations, I sense a definite increase in discomfort when someone is in a situation where they realize that they are confronted with a decision and they simply "don't know" that is some process or clue or whatever you want to call it is absent. That is why IMO folks that are used to casual sighted comparisons have strong reactions to suddenly going "blind".
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