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Tuners FM, HD, Satellite |
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Thread Tools | Display Modes |
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#1
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Pulling Good Analog Sound out of Severe HD "Self Noise"?
I just found out my local classical station "uses the Extended Hybrid Mode for HD Radio, which allows us to allocate up to 120 kbps total for all our digital channels combined. We currently only broadcast two channels, our main (HD-1) at 64 kbps, and our secondary channel Viva la Voce (HD-2) at 48 kbps." This must be the worst case for cramping the bandwidth of the analog channel and is almost certainly killing my old tuner with "HD self noise."
I'm looking for guidance on two questions: 1) Is it even possible to get really good sound from the analog channel of such a station? 2) If so, what are the best tuners for the job? I'd guess the IF band-pass would have to have very steep edges -- a digital tuner might be indicated -- but doesn't this imply higher distortion? Other factors? -- Clark2 |
#2
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1.) Yes
2.) Look for a tuner with a good post-detection filter. Narrow IF's with steep slopes will help but also add to distortion as you've noted. Some of the best performing tuners are : Sony XDR-F1HD Sangean HDT-1 They use DSP stereo decoding and have very good HD self noise rejection. Brian Beasley has a lot of good information on HD self noise on his website: http://www.ham-radio.com/k6sti/ Did you run FMFool to see if you have a strong adjacent channel HD station? If you have a strong HD adjacent, it will impact your tuner choices as you'll need a tuner with a lot of IF stages and sharp cutoff ceramic filters. Something like the MR 80 or Sansui TU-X1 will fill the bill. The Magnum Dynalab tuners, as good as they are, just won't work as well in that specific situation.
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Main System: Amati Futura Mains Amati Homage VOX Center, Proac Response 1sc Rears, Three MC2301's for L,C,R MC 602 for the rears C 1100, MX 151, MCD 1100, MR 80 Nottingham Dais with Wave Mechanic Sumiko Palo Santos Presentation SurfacePro 3, RPi 4, ROON, WW Starlight Platinum USB, Schiit Yggdrasil, Benchmark DAC3 HGC MX 151, OppO BDP-95, JVC RS-500 DILA projector, 106" diagonal Stewart Luxus Screenwall Deluxe with Studiotek 130 G3 material. Lake House: Ohm F, MC 275V, C2300, MR 77, Rega P3 OnDeck: McIntosh MAC 4300v |
#3
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I don't think there's any problem with adjacent HD. The nearest that I know of is 2.4 MHz away. Will check... Thanks for the good information. -- Clark2 |
#4
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Don't the HD sidebands actually overlap the bandwidth of an adjacent channel? Is it possible to overcome that even with a narrow IF? -- Clark2
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#5
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Yes, there is overlap into the first adjacent. The extent to which narrow IF filters will help that hinges on a lot of variables - that's the nature of FM reception. But consider that while the first adjacent channel is just 200 kHz away, the FCC typically spaces stations in any market by 400 kHz. To be fair, with today's crowded FM band (in the US), that doesn't always quite work in practice.
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Primary sources: VPI TNT III/SDS turntable, SME-V arm; Bryston BDP-3 digital player; Bryston BDA-3 DAC; McIntosh MVP-881 disc player; McIntosh MR-80 tuner. Preamplifier Audio Research Ref 5SE; Audio Research Ref Phono 2SE; Moon 430 HA. Amplifiers Conrad Johnson Premier 1B; Audio Research D-300; Bryston 4B. Speakers Infinity IRS Beta. Recorders Tandberg TD20A; Crown SX-822; Nakamichi 670ZX; Alesis Masterlink ML-9600. Power Tice Power Block/Titan (x2); McIntosh MPC1500; API Ultra II-20; multiple 20A derated dedicated lines. |
#6
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Narrow IF's help here, as does a directional antenna used to put the offending station in a null. The easiest test to see if you have HD self noise is to switch your tuner to mono. If the noise goes away in mono, you have HD self noise or the signal you are receiving is not full quieting in stereo anyway. You need about 20 dB more signal strength to get full quieting in stereo vs mono. That's exclusive of HD self noise. Tom
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Main System: Amati Futura Mains Amati Homage VOX Center, Proac Response 1sc Rears, Three MC2301's for L,C,R MC 602 for the rears C 1100, MX 151, MCD 1100, MR 80 Nottingham Dais with Wave Mechanic Sumiko Palo Santos Presentation SurfacePro 3, RPi 4, ROON, WW Starlight Platinum USB, Schiit Yggdrasil, Benchmark DAC3 HGC MX 151, OppO BDP-95, JVC RS-500 DILA projector, 106" diagonal Stewart Luxus Screenwall Deluxe with Studiotek 130 G3 material. Lake House: Ohm F, MC 275V, C2300, MR 77, Rega P3 OnDeck: McIntosh MAC 4300v |
#7
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But you had seemed to imply (in your earlier post) that good post-detection filtering (or a better stereo decoder?) could compensate for a wide IF pass-band. That was the reason for my question about (2). Did I misunderstand, or can you get rid of the self-noise by post-detection filtering without increasing distortion by using a narrow IF? The answer to this question would seem important for choosing a tuner to get great analog sound on a station with HD channels... -- Clark2 Last edited by Clark2; 03-07-2019 at 02:54 PM. Reason: clarification |
#8
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While Brian Beasley has done about all that can be done with HD he cannot defy the laws of physics. There is no way to obtain high fidelity from HD radio broadcasts with the available bit-rates. Brian is pretty much a 'voice in the wilderness' in his opinions on the SQ of HD (though I admit to having stopped reading his treatise some years ago - ).
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Glenn... Canton Reference 9 Clearaudio SM Pro Focal Bathys JLA 10" Dominion Kuzma Stabi S w/MC & MM Magnepan 1,7i McIntosh MA8950 & MR88 Oppo 203 Roon Nucleus Rose Hifi RS150B Shunyata Gemini-4 Sony ST-A6B, TA-F6B, ST-J75 & PS-X75 Sorane SA1.2 & TA-1L Stillpoints LP1v2 WW Pt, Au & Ag |
#9
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But having a strong adjacent channel with HD isn't imo the biggest problem, because the HD on your desired signal is likely to be just as big a problem. Quality FM reception has always hinged a lot on location and the antennas, and that's still true. The better the receiving antenna, the higher the gain. The higher the gain, the less you'll notice the distortion inherent in a higher selectivity tuner.
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Primary sources: VPI TNT III/SDS turntable, SME-V arm; Bryston BDP-3 digital player; Bryston BDA-3 DAC; McIntosh MVP-881 disc player; McIntosh MR-80 tuner. Preamplifier Audio Research Ref 5SE; Audio Research Ref Phono 2SE; Moon 430 HA. Amplifiers Conrad Johnson Premier 1B; Audio Research D-300; Bryston 4B. Speakers Infinity IRS Beta. Recorders Tandberg TD20A; Crown SX-822; Nakamichi 670ZX; Alesis Masterlink ML-9600. Power Tice Power Block/Titan (x2); McIntosh MPC1500; API Ultra II-20; multiple 20A derated dedicated lines. |
#10
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That's interesting! I never would have guessed it. Why would that be the case; not enough gain in the internal RF stages? -- Clark2
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