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#1
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Panoramic spectrum analysis
There used to be a really cool tuner made by Sequerra which I saw in
the 1970s which had this amazing feature on a built-in scope. None of the other tuners made at that time which had scopes in them seemed to have that function (I actually bought a Marantz ST600, though for the AMAZING sound, not the scope) Does anyone know why this technology died a death? Surely this could be useful now, as well as being useful for broadband signal detection, showing signal strength as well as how stable the signal is? Or has the concept of having a scope in a tuner died a death for some reason? Surely it should be easier now with the prevalence of LCDs being used for everything in sight? Or are there any WiFi applications which can simulate this function? |
#2
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Panoramic spectrum analysis
On 28 Mar 2009 14:32:59 GMT, DManzaluni
wrote: There used to be a really cool tuner made by Sequerra which I saw in the 1970s which had this amazing feature on a built-in scope. None of the other tuners made at that time which had scopes in them seemed to have that function (I actually bought a Marantz ST600, though for the AMAZING sound, not the scope) Does anyone know why this technology died a death? Surely this could be useful now, as well as being useful for broadband signal detection, showing signal strength as well as how stable the signal is? Or has the concept of having a scope in a tuner died a death for some reason? Surely it should be easier now with the prevalence of LCDs being used for everything in sight? Or are there any WiFi applications which can simulate this function? There's greatly reduced interest in FM overall. So, no market. Kal (who only listens to one station on FM, anyway) |
#3
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Panoramic spectrum analysis
"DManzaluni" wrote in message
There used to be a really cool tuner made by Sequerra which I saw in the 1970s which had this amazing feature on a built-in scope. None of the other tuners made at that time which had scopes in them seemed to have that function (I actually bought a Marantz ST600, though for the AMAZING sound, not the scope) The purpose of the scope was to be a fine tuning indicator. As digital chips went up in performance and came down in price, it became feasible and eventually even more economical to simply build tuners that simply required no fine tuning. Does anyone know why this technology died a death? Then there is that other nasty problem - that FM has largely ceased to be a hi fi medium that is of interest to music lovers. Or are there any WiFi applications which can simulate this function? Webcasts. |
#4
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Panoramic spectrum analysis
On Mar 28, 10:32*am, DManzaluni wrote:
There used to be a really cool tuner made by Sequerra which I saw in the 1970s which had this amazing feature on a built-in scope. *None of the other tuners made at that time which had scopes in them seemed to have that function (I actually bought a Marantz ST600, though for the AMAZING sound, not the scope) Does anyone know why this technology died a death? *Surely this could be useful now, as well as being useful for broadband signal detection, showing signal strength as well as how stable the signal is? *Or has the concept of having a scope in a tuner died a death for some reason? *Surely it should be easier now with the prevalence of LCDs being used for everything in sight? Or are there any WiFi applications which can simulate this function? There is no need for this feature with digital tuners since they tune to exact station frequencies. |
#6
Posted to rec.audio.high-end
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Panoramic spectrum analysis
On Sat, 28 Mar 2009 07:32:59 -0700, DManzaluni wrote
(in article ): There used to be a really cool tuner made by Sequerra which I saw in the 1970s which had this amazing feature on a built-in scope. None of the other tuners made at that time which had scopes in them seemed to have that function (I actually bought a Marantz ST600, though for the AMAZING sound, not the scope) Does anyone know why this technology died a death? Surely this could be useful now, as well as being useful for broadband signal detection, showing signal strength as well as how stable the signal is? Or has the concept of having a scope in a tuner died a death for some reason? Surely it should be easier now with the prevalence of LCDs being used for everything in sight? Or are there any WiFi applications which can simulate this function? Bick Sequerra actually worked on the design of an earlier tuner which sported a 'scope called the Marantz Model 10B. This tuner was state-of-the-art in the mid-'sixties and the Sequerra Tuner, made in the '70's was Sequerra's attempt at updating the idea with solid-state circuitry. While Marantz 10Bs are still around (they command premium prices and when new were, at US$750, the most expensive piece of audio electronics on the market), be advised that if the 'scope isn't working (or, if it becomes non-functional down the line), it cannot be fixed because a replacement CRT (cathode ray tube, or the display tube) has not been available for decades. I'm not sure about the CRT in the Sequerra. There are several reasons why the feature is no longer available. First, of all, modern tuners all use frequency synthesis for tuning, while the Marantz and Sequerra used continuous tuning. IOW, any modern tuner, when tuned to say, 101.5 MHz, synthesizes that exact frequency digitally. There is no need for the tuning feature that was all important in analog or other continuous tuning schemes. But probably, the main reason why these 'scopes have disappeared (and let's face it, with a liquid-crystal display screen these days, one could be implemented on a modern tuner for bupkis) is because FM is pretty-much dead as a high-end sound source these days. The FM dial is so crowded and the stations are so tightly programmed (not to mention heavily compressed and severely limited), that there's really no need for a high-end tuner any more. The days of sitting down in front of your stereo system and tuning in a live symphony (or even a jazz or rock concert) are over. And while a few college and educational stations might still do live concerts, they are relegated to the larger cities and are very few and very far between. Its a shame, but that's the reality. |
#7
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Panoramic spectrum analysis
Slightly off topic but if we are talking about FM and webcasts;
1) Is the bitrate of an MP3 streaming webcast the same as the bitrate of an MP3 file. 2) What bitrate is equivelent to FM quality? I am asking this because I am listening to WGBH FM Boston via the internet and my Squeezebox says it is 24 bit CBR MP3 and it sounds suprisingly good! |
#8
Posted to rec.audio.high-end
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Panoramic spectrum analysis
Sonnava wrote:
The days of sitting down in front of your stereo system and tuning in a live symphony (or even a jazz or rock concert) are over. And while a few college and educational stations might still do live concerts, they are relegated to the larger cities and are very few and very far between. Its a shame, but that's the reality. Luckily this is not totally true. I live in the "sticks" and can tune in to Vermont Public Radio's digital feed. They play classical music 24 hours a day and do the live broadcasts of the Metropolitan Opera on Saturdays. Each weekday evening they present "live" (taped) concerts from around the world. This includes the Concertgebouw, Chicago Symphony, New York Phil, Cleveland Orchestra and others. Each afternoon, "Performance Today" presents concerts from around the world. Sound quality is excellent but somewhat compressed. ---MIKE--- In the White Mountains of New Hampshire (44° 15' N - Elevation 1580') |
#9
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Panoramic spectrum analysis
Sonnova wrote:
The days of sitting down in front of your stereo system and tuning in a live symphony (or even a jazz or rock concert) are over. You could move to Europe. We still do it over here |
#10
Posted to rec.audio.high-end
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Panoramic spectrum analysis
"Doug McDonald" wrote in
message Not so ... it still is useful for adjusting antennas to minimize multipath. I'm not sure that multipath is much of problem with the current generation of DSP-based tuners. And, with digital tuners (DSP based, digitizing the IF) and LCD display, it's simple programming. Latency is a bit of an issue with modern displays. I have an old Sony analog tuner with outputs for this, and actually feed it to a scope. Old school does not necessarily equal new school. |
#11
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Panoramic spectrum analysis
"---MIKE---" wrote in message
... Sonnava wrote: The days of sitting down in front of your stereo system and tuning in a live symphony (or even a jazz or rock concert) are over. And while a few college and educational stations might still do live concerts, they are relegated to the larger cities and are very few and very far between. Its a shame, but that's the reality. Luckily this is not totally true. I live in the "sticks" and can tune in to Vermont Public Radio's digital feed. They play classical music 24 hours a day and do the live broadcasts of the Metropolitan Opera on Saturdays. Each weekday evening they present "live" (taped) concerts from around the world. This includes the Concertgebouw, Chicago Symphony, New York Phil, Cleveland Orchestra and others. Each afternoon, "Performance Today" presents concerts from around the world. Sound quality is excellent but somewhat compressed. ---MIKE--- In the White Mountains of New Hampshire (44° 15' N - Elevation 1580') Yes, VPR is an excellent service (I used to live in Burlington, and visit the Brattleboro area). Now I live in Western Mass and listen to WFCR, which services the area from Amherst and is an offshoot of the UMASS-Five College Consortium. The programing is not as adventuresome, but the offer classical music all day and late night, and three hours of expertly-hosted jazz every night from 8:00 to 11:00. They also have an AM station which carries all the NPR and BBC talk shows morning until night. The big draw for me, however, is the quality of the sound. They use SACD's wherever issued, and so far as I can tell use little or no compression. On recordings I know well, using the Carver TX-11 tuner and my main system (with jerry-rigged outdoor antenae) the sound is sonically almost identical to CD. I know that is heresy to say that here, but it is the truth. I feel truly blessed since I now live on a fixed retirement income and my ability to purchase recorded music and attend live concerts has diminished substantially from what it used to be. |
#12
Posted to rec.audio.high-end
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Panoramic spectrum analysis
On Mar 29, 10:21*am, Steve wrote:
Slightly off topic but if we are talking about FM and webcasts; 1) Is the bitrate of an MP3 streaming webcast the same as the bitrate of an MP3 file. They can be the same but MP3 files can be coded and streamed at any bit rate. For a given codec, the higher the bit rate, the better the quality. 2) What bitrate is equivelent to FM quality? This is a very difficult question to answer given that it is extremely subjective and some here will tell you that any lossy compression at all results in unacceptable quality. You might do a test yourself using an MP3 encoder like lame or other lossy codec and try different bit rates to see where you feel the loss in quality is significant. Note that where the file will be played can be important. What may be unacceptable for serious listening may be fine in a car or for casual listening. Also, some types of music will sound less degraded at low bit rates compared to other types. I am asking this because I am listening to WGBH FM Boston via the internet and my Squeezebox says it is 24 bit CBR MP3 and it sounds suprisingly good! It is not clear exactly what benefits 24 bit MP3 files offer but some internet streams do seem to sound good. |
#13
Posted to rec.audio.high-end
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Panoramic spectrum analysis
On Sun, 29 Mar 2009 07:21:28 -0700, MIKE--- wrote
(in article ): Sonnava wrote: The days of sitting down in front of your stereo system and tuning in a live symphony (or even a jazz or rock concert) are over. And while a few college and educational stations might still do live concerts, they are relegated to the larger cities and are very few and very far between. Its a shame, but that's the reality. Luckily this is not totally true. I live in the "sticks" and can tune in to Vermont Public Radio's digital feed. They play classical music 24 hours a day and do the live broadcasts of the Metropolitan Opera on Saturdays. Each weekday evening they present "live" (taped) concerts from around the world. This includes the Concertgebouw, Chicago Symphony, New York Phil, Cleveland Orchestra and others. Each afternoon, "Performance Today" presents concerts from around the world. Sound quality is excellent but somewhat compressed. ---MIKE--- In the White Mountains of New Hampshire (44° 15' N - Elevation 1580') That's my point. They are compressed and limited and a taped concert is still a RECORDING, no matter how good it is. The excitement of being privy to a performance while it was occurring was simply thrilling. Also, your Vermont Public Radio feed is unusual and you are unusually lucky. I live near San Francisco and can get FOUR NPR broadcasts. With one exception (which is a jazz station) they rarely play any music, and most of the time are filling the airways with political content. |
#14
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Panoramic spectrum analysis
On Sun, 29 Mar 2009 08:20:15 -0700, Iordani wrote
(in article ): Sonnova wrote: The days of sitting down in front of your stereo system and tuning in a live symphony (or even a jazz or rock concert) are over. You could move to Europe. We still do it over here Only useful if it isn't heavily compressed and severely limited. And every time I go to Europe I spend hours scanning the FM radio dial in my rental car looking for decent FM programming. All I ever hear is Euro-pop and other junk. |
#15
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Panoramic spectrum analysis
"Iordani" wrote in message
... Sonnova wrote: The days of sitting down in front of your stereo system and tuning in a live symphony (or even a jazz or rock concert) are over. You could move to Europe. We still do it over here Sadly even here it's less and less. In the UK we only have BBC Radio 3 that broadcasts live classical music and Jazz with minimal compression (in the evenings), all the others just cater for the Kitchen portable or the car. S. -- http://audiopages.googlepages.com |
#16
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Panoramic spectrum analysis
"Steve" wrote in message
Slightly off topic but if we are talking about FM and webcasts; 1) Is the bitrate of an MP3 streaming webcast the same as the bitrate of an MP3 file. Not necessarily. 2) What bitrate is equivalent to FM quality? Probably something around 192 kbps. I am asking this because I am listening to WGBH FM Boston via the internet and my Squeezebox says it is 24 bit CBR MP3 and it sounds suprisingly good! I don't think that there is such a thing as 24 bit MP3. If its 24 kbps then that might be what is meant. |
#17
Posted to rec.audio.high-end
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Panoramic spectrum analysis
On Mar 29, 10:21*am, Steve wrote:
Slightly off topic but if we are talking about FM and webcasts; 1) Is the bitrate of an MP3 streaming webcast the same as the bitrate of an MP3 file. 2) What bitrate is equivelent to FM quality? I am asking this because I am listening to WGBH FM Boston via the internet and my Squeezebox says it is 24 bit CBR MP3 and it sounds suprisingly good! I agree and wonder why all supposed "best tuner" lists all seem to comprise pretty much exclusvely the analogue ones such as the 10b, Sequerra and the MR71 Does anyone now think that this much vanuted digital synthesiser tuning which everyone says gives such precise tuning that panoramic scannere are no longer necessary, produces incrementally superior quality? Sorry to be a bit of a luddite but my old fashioned view is that those older tuners which people still seem to be using to play, yes, their favourite FM stations, do actually produce such better sound that sooner or later, someone is going to start making those tuners much as people have started making valve amplifiers again (even though they dont really pan out on the figures). Am I completely out of court on this and do the cognoscenti really thing that high end users will be able to get the sound they like through the Internet? I have a firend who sells high end HiFi in the sense of everything (eight foot high speakers, three foot high external transformers etc etc) costing over $30,000 and was invited into his living room for a demonstration of his best equipment: I wonder why he chose to demonstrate what was the finest equipment on the face of the earth with a 1960s REL Precedent tuner (with an outboard stereo decoder) if the modern digital synthesized equipment and modern FM stations are so mediochre? |
#18
Posted to rec.audio.high-end
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Panoramic spectrum analysis
"DManzaluni" wrote in message
On Mar 29, 10:21 am, Steve wrote: Slightly off topic but if we are talking about FM and webcasts; 1) Is the bitrate of an MP3 streaming webcast the same as the bitrate of an MP3 file. That all depends on which streaming webcast, and which MP3 file. They can be whatever their designers want them to be within a wide range. 2) What bitrate is equivalent to FM quality? Probably about 192 kb I am asking this because I am listening to WGBH FM Boston via the internet and my Squeezebox says it is 24 bit CBR MP3 and it sounds surprisingly good! I agree and wonder why all supposed "best tuner" lists all seem to comprise pretty much exclusively the analogue ones such as the 10b, Sequerra and the MR71 Does anyone now think that this much vaunted digital synthesizer tuning which everyone says gives such precise tuning that panoramic scanner are no longer necessary, produces incrementally superior quality? Given the low cost, of the XDR-F1HD, all it has to do is be equal. I have 2 friends with them, but neither have owned a 10b, a Sequerra, or a MR71. So a side-by-side comparison is impossible. They describe the little Sony XDR-F1HD as being "Flawless" and "Incredible". The not-so hidden agenda is that the chips that power the XDR-F1HD are a Philips chipset that is destined for automotive FM receivers. In a year or two, the next new car you buy may have an entertainment center based on this chipset. Sorry to be a bit of a luddite but my old fashioned view is that those older tuners which people still seem to be using to play, yes, their favourite FM stations, do actually produce such better sound that sooner or later, someone is going to start making those tuners much as people have started making valve amplifiers again (even though they dont really pan out on the figures). Just as surely as tubed amplifiers have zero sonic advantages but instead have numerous disadvantages, neither do tubed tuners. |
#19
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Panoramic spectrum analysis
"DManzaluni" wrote in message
... On Mar 29, 10:21 am, Steve wrote: Slightly off topic but if we are talking about FM and webcasts; 1) Is the bitrate of an MP3 streaming webcast the same as the bitrate of an MP3 file. 2) What bitrate is equivelent to FM quality? I am asking this because I am listening to WGBH FM Boston via the internet and my Squeezebox says it is 24 bit CBR MP3 and it sounds suprisingly good! I agree and wonder why all supposed "best tuner" lists all seem to comprise pretty much exclusvely the analogue ones such as the 10b, Sequerra and the MR71 Does anyone now think that this much vanuted digital synthesiser tuning which everyone says gives such precise tuning that panoramic scannere are no longer necessary, produces incrementally superior quality? Sorry to be a bit of a luddite but my old fashioned view is that those older tuners which people still seem to be using to play, yes, their favourite FM stations, do actually produce such better sound that sooner or later, someone is going to start making those tuners much as people have started making valve amplifiers again (even though they dont really pan out on the figures). Am I completely out of court on this and do the cognoscenti really thing that high end users will be able to get the sound they like through the Internet? I have a firend who sells high end HiFi in the sense of everything (eight foot high speakers, three foot high external transformers etc etc) costing over $30,000 and was invited into his living room for a demonstration of his best equipment: I wonder why he chose to demonstrate what was the finest equipment on the face of the earth with a 1960s REL Precedent tuner (with an outboard stereo decoder) if the modern digital synthesized equipment and modern FM stations are so mediochre? Why your friend chose what he did is a mystery to me, and has nothing to do with the reality of current FM tuners and stations. FM tuners went synthesised because the same performance could be achieved at much lower cost, and the most important part, with excellent stability. Analogue tuners needed sensitive adjustments at the factory, and if the performance was to be maintained as new, would need regular realignment (say every couple of years). Tuning would drift, hence the need for AFC, as would the centre-point of the discriminator curve, as would the stereo decoding separation. Frequency synthesis coupled with new IC discriminators and decoders made it possible to reduce the cost and improve the stability. Of course there were some, like Sequerra, who built superb all-analogue tuners, but at a cost. Bit like Rolex today, who still build superb mechanical wrist-watches. Also, at the time, radio stations (at least in Europe) broadcast wide dynamic range music, with no processing (it wasn't even permitted by law in the UK up until some time in the 80s, I recall) Then audio processors started being used, leading up to the situation today where every station processes, some to maintain as little as 1dB dynamic range. Listening habits have also changed, up until the late 80s, people did still listen to the radio (wireless as it was known here) sitting at home with few distractions, to hear a complete concert or radio drama. Very few do that now, radio being a medium aimed almost totally at the kitchen portable or the car. Those few serious radio listeners aren't numerous enough for commercial stations to bother to cater for them; we're lucky in Europe that we still have Public Service Broadcasters like the BBC, Radio France, RAI etc who do broadcast complete concerts, dramas and so on to ever-reducing audiences as the oldies die off. FM radio is a victim of changing public attitudes and habits, with new technologies like iPods and mobile internet making FM radio even less relevant as a high-quality medium. Unless we can change the world, I can't see us ever getting back to the golden age of radio listening where quality mattered. S. -- http://audiopages.googlepages.com |
#20
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Panoramic spectrum analysis
On Mar 28, 9:32*am, DManzaluni wrote:
There used to be a really cool tuner made by Sequerra which I saw in the 1970s which had this amazing feature on a built-in scope. *None of the other tuners made at that time which had scopes in them seemed to have that function (I actually bought a Marantz ST600, though for the AMAZING sound, not the scope) Does anyone know why this technology died a death? *Surely this could be useful now, as well as being useful for broadband signal detection, showing signal strength as well as how stable the signal is? *Or has the concept of having a scope in a tuner died a death for some reason? *Surely it should be easier now with the prevalence of LCDs being used for everything in sight? Or are there any WiFi applications which can simulate this function? Maybe it had a spectrum display, I don't recall seeing it. The older S band receivers for astronauts had a spectrum display as the prominent feature, so it would be easy to see carriers turning on and off and general interest. Not much interest in normal FM broadcast. http://www.zekfrivolous.com/goldstone/sub/27.jpg greg |
#21
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Panoramic spectrum analysis
On Mar 29, 10:32*pm, DManzaluni wrote:
... I agree and wonder why all supposed "best tuner" lists all seem to comprise pretty much exclusvely the analogue ones such as the 10b, Sequerra and the MR71 *Does anyone now think that this much vanuted digital synthesiser tuning which everyone says gives such precise tuning that panoramic scannere are no longer necessary, produces incrementally superior quality? A tuner has 2 main functions: 1. Grab the signal from the air in as accurate method as possible, rejecting all other signals. 2. Extract the audio from the carrier wave. Digital synthesizer tuners do part 1 very well, and cheaply. To achieve part 2 very well, a manufacturer has to resort relatively expensive design circuitry. Since no one cares about FM anymore, today's radio manufacturers merely put in what's adequete and cheap to achieve part 2. Yesterday's top end tuners, weaker at holding the signal, did an excellent job of extracting the audio from the carrier wave because at the time, manufacturers were really making an effort back then. The guys over at FM tuner info have lots to say about that; http://www.fmtunerinfo.com/ CD |
#22
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Panoramic spectrum analysis
"codifus" wrote in message
A tuner has 2 main functions: 1. Grab the signal from the air in as accurate method as possible, rejecting all other signals. 2. Extract the audio from the carrier wave. So far, so good. Digital synthesizer tuners do part 1 very well, and cheaply. Not a slam dunk. As page 1 of your reference points out, the spurious response performance of the front end is potentially a problem. All a synthesizer does is provide a very stable and easily tuned local oscillator. There's a lot more to a FM front end than that. There's hope however, given that they guys who wrote your reference (below) found a FM preamp with an IP3 of +20 dbm which is almost enough power to make a light bulb illuminate. ;-) To achieve part 2 very well, a manufacturer has to resort relatively expensive design circuitry. The part you missed is the fact that the designers of the Sony XDR-F1HD found a Philips chipset that was probably designed for car radios. It reduced all of that expensive circuitry to a few chips, using DSP technology. It's all explained in detail right he http://ham-radio.com/k6sti/xdr-f1hd.htm The guys over at FM tuner info have lots to say about that; http://www.fmtunerinfo.com/ But so far they are speechless when it comes to the Sony XDR-F1HD . Contary to the beliefs of some, technology marches on... ;-) |
#23
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Panoramic spectrum analysis
On Sun, 29 Mar 2009 19:32:49 -0700, DManzaluni wrote
(in article ): On Mar 29, 10:21*am, Steve wrote: Slightly off topic but if we are talking about FM and webcasts; 1) Is the bitrate of an MP3 streaming webcast the same as the bitrate of an MP3 file. 2) What bitrate is equivelent to FM quality? I am asking this because I am listening to WGBH FM Boston via the internet and my Squeezebox says it is 24 bit CBR MP3 and it sounds suprisingly good! I agree and wonder why all supposed "best tuner" lists all seem to comprise pretty much exclusvely the analogue ones such as the 10b, Sequerra and the MR71 Does anyone now think that this much vanuted digital synthesiser tuning which everyone says gives such precise tuning that panoramic scannere are no longer necessary, produces incrementally superior quality? I would think that the RF side of things would be irrelevant to sound quality (assuming, of course, that the RF section has sufficient bandwidth for the entire channel). Sound only becomes an issue after the audio has been detected (I.E. stripped off of the RF carrier). Then sound quality becomes important because that's where the "chips" reside which decode the stereo signal, and amplify it enough to drive a line stage. Sorry to be a bit of a luddite but my old fashioned view is that those older tuners which people still seem to be using to play, yes, their favourite FM stations, do actually produce such better sound that sooner or later, someone is going to start making those tuners much as people have started making valve amplifiers again (even though they dont really pan out on the figures). Maybe. I know, for instance, that the Marantz 10B has a problem SCA carrier rejection that makes it "whistle" when tuned to a station simulcasting SCA (Subscriber Carrier Authority - IOW, elevator and in-store music, and Muzak). Also, most older stereo tuners use the complex sum-and-difference or time-switching stereo decoders which aren't as good as a phase-locked-loop decoder. The latter has been around since the 'seventies and is a single chip. You can never get the stereo separation figures from a sum-and-difference decoder that you can get from a phase-locked-loop, and they tend to drift out of alignment and without a proper stereo generator, one cannot re-tune for the maximum separation (which is only on the order of about 20dB under the best of conditions). I used to know a guy whose hobby was refurbishing 10Bs. He would replace the entire stereo decoder with a board he made consisting of a National Semiconductor Stereo phase-locked-loop IC decoder and a power supply which used the 12 volt filament windings on the Marantz's power transformer to power it. It always sounded better than the tubed time-switching decoder that the Marantz employed (he left the tube amplifier stages in place AFTER the decoder stage), had much better separation, and no SCA "whistle". Am I completely out of court on this and do the cognoscenti really thing that high end users will be able to get the sound they like through the Internet? I listen to a number of internet radio stations (including a classical station from London, England) while working on my computer. I cannot say that I have any interest whatsoever in piping these stations through my main stereo system. They simply aren't that good. I have a firend who sells high end HiFi in the sense of everything (eight foot high speakers, three foot high external transformers etc etc) costing over $30,000 and was invited into his living room for a demonstration of his best equipment: I wonder why he chose to demonstrate what was the finest equipment on the face of the earth with a 1960s REL Precedent tuner (with an outboard stereo decoder) if the modern digital synthesized equipment and modern FM stations are so mediochre? There's no accounting for taste. I'll guarantee his (tubed) outboard decoder is inferior to a decoder made with a forty-five cent phase-locked-loop stereo decoder chip and a handful of capacitors and resistors. |
#24
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Panoramic spectrum analysis
On Mon, 30 Mar 2009 07:23:36 -0700, Arny Krueger wrote
(in article ): "DManzaluni" wrote in message On Mar 29, 10:21 am, Steve wrote: Slightly off topic but if we are talking about FM and webcasts; 1) Is the bitrate of an MP3 streaming webcast the same as the bitrate of an MP3 file. That all depends on which streaming webcast, and which MP3 file. They can be whatever their designers want them to be within a wide range. 2) What bitrate is equivalent to FM quality? Probably about 192 kb I am asking this because I am listening to WGBH FM Boston via the internet and my Squeezebox says it is 24 bit CBR MP3 and it sounds surprisingly good! I agree and wonder why all supposed "best tuner" lists all seem to comprise pretty much exclusively the analogue ones such as the 10b, Sequerra and the MR71 Does anyone now think that this much vaunted digital synthesizer tuning which everyone says gives such precise tuning that panoramic scanner are no longer necessary, produces incrementally superior quality? Given the low cost, of the XDR-F1HD, all it has to do is be equal. I have 2 friends with them, but neither have owned a 10b, a Sequerra, or a MR71. So a side-by-side comparison is impossible. They describe the little Sony XDR-F1HD as being "Flawless" and "Incredible". The not-so hidden agenda is that the chips that power the XDR-F1HD are a Philips chipset that is destined for automotive FM receivers. In a year or two, the next new car you buy may have an entertainment center based on this chipset. Sorry to be a bit of a luddite but my old fashioned view is that those older tuners which people still seem to be using to play, yes, their favourite FM stations, do actually produce such better sound that sooner or later, someone is going to start making those tuners much as people have started making valve amplifiers again (even though they dont really pan out on the figures). Just as surely as tubed amplifiers have zero sonic advantages but instead have numerous disadvantages, neither do tubed tuners. I'll certainly agree with the latter. As I said in another post, I used to know a Stanford PHD who re-furbished Marantz 10 Bs as a hobby. He brought one over to my pad one evening that he had re-tubed and "re-aligned" for a client ... We pitted it against my then-new frequency synthesized solid-state Yamaha T-85 (with its FOUR ceramic-filter IF strips, giving different bandwidths from ultra-narrow to ultra-wide). My Yamaha outperformed the 10 B every way that you can think of. It had better selectivity, better sensitivity, exhibited less multipath, had far better stereo separation and even sounded better. So much for 1966 state-of-the-art. BTW, I still have that tuner (20-some years later) and still use it and it is still a dynamite tuner. Too bad there's nothing on FM in this area to listen to..... |
#25
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Panoramic spectrum analysis
Serge Auckland wrote:
Also, at the time, radio stations (at least in Europe) broadcast wide dynamic range music, with no processing (it wasn't even permitted by law in the UK up until some time in the 80s, I recall) Then audio processors started being used, leading up to the situation today where every station processes, some to maintain as little as 1dB dynamic range. What would be the reason for this processing? |
#26
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Panoramic spectrum analysis
On Mon, 30 Mar 2009 15:59:28 -0700, Iordani wrote
(in article ): Serge Auckland wrote: Also, at the time, radio stations (at least in Europe) broadcast wide dynamic range music, with no processing (it wasn't even permitted by law in the UK up until some time in the 80s, I recall) Then audio processors started being used, leading up to the situation today where every station processes, some to maintain as little as 1dB dynamic range. What would be the reason for this processing? Studies (!?) have shown that the stations with the loudest signal catch the "knob-twiddlers". I.E. people tend to stop on the loudest radio signal. Since overmodulating is illegal (most places) radio stations, wanting to get noticed, will compress their audio so that they are modulating as close to 100% as possible all of the time. Severe brick-wall limiting prevents overmodulation. The result, of course, is lousy sound, but they don't care, they just want listeners. |
#27
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Panoramic spectrum analysis
"Sonnova" wrote in message
I would think that the RF side of things would be irrelevant to sound quality (assuming, of course, that the RF section has sufficient bandwidth for the entire channel). Sound only becomes an issue after the audio has been detected (I.E. stripped off of the RF carrier). Then sound quality becomes important because that's where the "chips" reside which decode the stereo signal, and amplify it enough to drive a line stage. There is a possibility that spurious responses will affect sound quality, particularly under marginal conditions. Maybe. I know, for instance, that the Marantz 10B has a problem SCA carrier rejection that makes it "whistle" when tuned to a station simulcasting SCA (Subscriber Carrier Authority - IOW, elevator and in-store music, and Muzak). Interesting. Also, most older stereo tuners use the complex sum-and-difference or time-switching stereo decoders which aren't as good as a phase-locked-loop decoder. A pedantic point, perhaps but the phase locked loop only controlled the frequency of the clock used to run the rest of the decoder. Either type of demodulator could be used. However, by the time that PLLs were introduced, it was already know that the switching demodulator was the way to go. The latter has been around since the 'seventies and is a single chip. Right. I had an AR15 which had a great FM (and AM) tuner for the late 1960s. The multiplex adaptor was highly complex, but required constant adjustment. I eventually spliced a MC1310P chip into the works, keeping only the output audio buffers. It transformed the usuability and the SQ. You can never get the stereo separation figures from a sum-and-difference decoder that you can get from a phase-locked-loop, and they tend to drift out of alignment and without a proper stereo generator, one cannot re-tune for the maximum separation (which is only on the order of about 20dB under the best of conditions). Yup, that was exactly what was wrong with the original AR15 stereo decoder. They had a way to audibly align it for a null from the front panel, but it was a hassle. I used to know a guy whose hobby was refurbishing 10Bs. He would replace the entire stereo decoder with a board he made consisting of a National Semiconductor Stereo phase-locked-loop IC decoder and a power supply which used the 12 volt filament windings on the Marantz's power transformer to power it. It always sounded better than the tubed time-switching decoder that the Marantz employed (he left the tube amplifier stages in place AFTER the decoder stage), had much better separation, and no SCA "whistle". Yup. |
#28
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Panoramic spectrum analysis
"Sonnova" wrote in message
... On Mon, 30 Mar 2009 15:59:28 -0700, Iordani wrote (in article ): Serge Auckland wrote: Also, at the time, radio stations (at least in Europe) broadcast wide dynamic range music, with no processing (it wasn't even permitted by law in the UK up until some time in the 80s, I recall) Then audio processors started being used, leading up to the situation today where every station processes, some to maintain as little as 1dB dynamic range. What would be the reason for this processing? Studies (!?) have shown that the stations with the loudest signal catch the "knob-twiddlers". I.E. people tend to stop on the loudest radio signal. Since overmodulating is illegal (most places) radio stations, wanting to get noticed, will compress their audio so that they are modulating as close to 100% as possible all of the time. Severe brick-wall limiting prevents overmodulation. The result, of course, is lousy sound, but they don't care, they just want listeners. That's right. As well as ruining any dynamics, stations also change the frequency balance to provide more bass, more treble, a sort of dynamically variable "smiley" curve. This again captures the knob twiddlers, and it also serves to create a "sonic signature" so the casual listener "knows" which station they're on by the (appalling) sound. This was massively important before precise push-button tuning in cars and is still important on portable radios and in those markets like the USA where RDS is not ubiquitous as it is in Europe. Radio now is all about capturing audiences for short periods (nobody has the time or inclination to listen for long periods) and stuff as many adverts down their ears in the short time they're listening, give them a few tunes just to leaven the ads. At least, that's what commercial radio sounds like to me. S. -- http://audiopages.googlepages.com |
#29
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Panoramic spectrum analysis
On Mar 30, 6:25*pm, "Arny Krueger" wrote:
"codifus" wrote in message A tuner has 2 main functions: 1. Grab the signal from the air in as accurate method as possible, rejecting all other signals. 2. Extract the audio from the carrier wave. So far, so good. Digital synthesizer tuners do part 1 very well, and cheaply. Not a slam dunk. As page 1 of your reference points out, the spurious response performance of the front end is potentially a problem. All a synthesizer does is provide a very stable and easily tuned local oscillator. There's a lot more to a FM front end than that. There's hope however, given that they guys who wrote your reference (below) found a FM preamp with an IP3 of +20 dbm which is almost enough power to make a light bulb illuminate. *;-) To achieve part 2 very well, a manufacturer has to resort relatively expensive design circuitry. The part you missed is the fact that the designers of the Sony XDR-F1HD found a Philips chipset that was probably designed for car radios. It reduced all of that expensive circuitry to a few chips, using DSP technology. *It's all explained in detail right he http://ham-radio.com/k6sti/xdr-f1hd.htm The guys over at FM tuner info have lots to say about that; http://www.fmtunerinfo.com/ But so far they are speechless when it comes to the Sony XDR-F1HD . Contary to the beliefs of some, technology marches on... ;-) Technology does march on. It marched on right passed analog FM tuners and left it to die. The guys at FMtunerinfo are mightily impressed with Sony's XDR bad boy. But, as usual, they also said that the sound quality of that very same tuner is merely adequate compared to yesterdays tuners. It will pull in the most obscure stations on the planet. If there's an fm transmitter on Mars, you can trust that Sony XDR to pull it in. But to actually sit there and want to listen to the broadcast? Like all modern FM tuners, and like I said earlier, modern tuner manufacturers don't bother. You have to go back to the old school Pioneer F-90, the Yamaha TX-1000, Onkyo T-9090, or Sansui TU-919, just to name a few. They couldn't hold a candle to the new Sony XDR when it comes to finding and grabbing the signal, but when it comes to sitting down to listen and enjoy, the XDR takes a back seat, way in the back of the minivan with 4 row seating CD |
#30
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Panoramic spectrum analysis
On Mar 30, 6:26*pm, Sonnova wrote:
I would think that the RF side of things would be irrelevant to sound quality (assuming, of course, that the RF section has sufficient bandwidth for the entire channel). Sound only becomes an issue after the audio has been detected (I.E. stripped off of the RF carrier). Nope, not the case at all. Phase linearity of the IF stage, for example, translates directly into distortion at the audio stage. This is one reason why the older IF stages are such a bitch to align for audio quality, and why newer FM tuners that used linear-phase IF filters had potentially lower and more stable audio performance. It's also why multipath can sound so nasty: by having multiple delays, you're adding non-linear phase to the whole process and that translates to distortion. RF stage performance in terms of adjacent-channel selectivity, image rejection and more all have direct, measurable and audible influence over the audio output. |
#31
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Panoramic spectrum analysis
codifus wrote:
1. Grab the signal from the air in as accurate method as possible, rejecting all other signals. 2. Extract the audio from the carrier wave. Digital synthesizer tuners do part 1 very well, and cheaply. To achieve part 2 very well, a manufacturer has to resort relatively expensive design circuitry. Uh, not really. To extract the the audio, today one does the following: 1) convert the signal to some intermediate frequency 2) amplify to just below the point of limiting, with a modest bandwidth filter that drop off steeply only well outside the channel of interest (but steeply enough that 2nd adjacent channel signal does not cause terrible overload). 3) digitize the signal at an adequate number of bits at some submultiple of the IF frequency, sufficient to prevent aliasing due to the fringe of the IF frequency filter. 4) calculate what the signal is as audio Note that if the ADC is good enough (and today they are really, really good enough) part 3) is not a serious limit to performance, and part 4) is absolutely perfect. Thus the RF stages and the analog IF filter become the tuner's limiting factor. The real limit is the quality of the incoming signal. and parts 3) and 4) are cheap as the sand they are made from. Doug McDonald |
#32
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Panoramic spectrum analysis
On Tue, 31 Mar 2009 07:29:51 -0700, Arny Krueger wrote
(in article ): "Sonnova" wrote in message I would think that the RF side of things would be irrelevant to sound quality (assuming, of course, that the RF section has sufficient bandwidth for the entire channel). Sound only becomes an issue after the audio has been detected (I.E. stripped off of the RF carrier). Then sound quality becomes important because that's where the "chips" reside which decode the stereo signal, and amplify it enough to drive a line stage. There is a possibility that spurious responses will affect sound quality, particularly under marginal conditions. Maybe. I know, for instance, that the Marantz 10B has a problem SCA carrier rejection that makes it "whistle" when tuned to a station simulcasting SCA (Subscriber Carrier Authority - IOW, elevator and in-store music, and Muzak). Interesting. Also, most older stereo tuners use the complex sum-and-difference or time-switching stereo decoders which aren't as good as a phase-locked-loop decoder. A pedantic point, perhaps but the phase locked loop only controlled the frequency of the clock used to run the rest of the decoder. Either type of demodulator could be used. However, by the time that PLLs were introduced, it was already know that the switching demodulator was the way to go. And so, the PLL stereo demodulator chips used time switching. The latter has been around since the 'seventies and is a single chip. Right. I had an AR15 which had a great FM (and AM) tuner for the late 1960s. The multiplex adaptor was highly complex, but required constant adjustment. I eventually spliced a MC1310P chip into the works, keeping only the output audio buffers. It transformed the usuability and the SQ. I did the same with a Pioneer tuner from the late sixties. I replaced the complex decoder board with a piece of perf board with the Natty chip decoder on it. I don't have the tuner any more but a friend of mine has it and still uses it. Stereo works fine. You can never get the stereo separation figures from a sum-and-difference decoder that you can get from a phase-locked-loop, and they tend to drift out of alignment and without a proper stereo generator, one cannot re-tune for the maximum separation (which is only on the order of about 20dB under the best of conditions). Yup, that was exactly what was wrong with the original AR15 stereo decoder. They had a way to audibly align it for a null from the front panel, but it was a hassle. I had a Knight-kit outboard stereo decoder that I built from the kit. The instructions had a methodology whereby you would tune one coil until the "howling sound" went away. That was supposed to be optimum. I did that, lived with it that way until I went away to college. Our electronics lab had a stereo generator provided to us by H.H. Scott. I put My Eico HFT-90 FM tuner and the Knight stereo demodulator on the thing and aligned the stereo section after first measuring the separation in my "tuned-by-ear" job that I had been living with since I built the thing three years earlier. Before I tuned it with the Scott stereo generator, I got 12dB of separation at 1KHz and 5dB at 10KHz. After using the Scott generator, I got 22dB at 1 KHZ, and 14dB at 10 KHz. That was the best it would give, but boy did that change the listening experience! For the first time I was hearing real stereo FM. So much for the manufacturer's "tune-by-ear" instructions. I used to know a guy whose hobby was refurbishing 10Bs. He would replace the entire stereo decoder with a board he made consisting of a National Semiconductor Stereo phase-locked-loop IC decoder and a power supply which used the 12 volt filament windings on the Marantz's power transformer to power it. It always sounded better than the tubed time-switching decoder that the Marantz employed (he left the tube amplifier stages in place AFTER the decoder stage), had much better separation, and no SCA "whistle". Yup. |
#33
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Panoramic spectrum analysis
On 31 Mar 2009 17:54:11 GMT, codifus wrote:
Technology does march on. It marched on right passed analog FM tuners and left it to die. The guys at FMtunerinfo are mightily impressed with Sony's XDR bad boy. But, as usual, they also said that the sound quality of that very same tuner is merely adequate compared to yesterdays tuners. It will pull in the most obscure stations on the planet. If there's an fm transmitter on Mars, you can trust that Sony XDR to pull it in. But to actually sit there and want to listen to the broadcast? Like all modern FM tuners, and like I said earlier, modern tuner manufacturers don't bother. You have to go back to the old school Pioneer F-90, the Yamaha TX-1000, Onkyo T-9090, or Sansui TU-919, just to name a few. They couldn't hold a candle to the new Sony XDR when it comes to finding and grabbing the signal, but when it comes to sitting down to listen and enjoy, the XDR takes a back seat, way in the back of the minivan with 4 row seating Which is why I was disappointed that the Sony lacked a digital output. Kal |
#34
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Panoramic spectrum analysis
On Mar 30, 6:59*pm, Iordani wrote:
Serge Auckland wrote: Also, at the time, radio stations (at least in Europe) broadcast wide dynamic range music, with no processing (it wasn't even permitted by law in the UK up until some time in the 80s, I recall) Then audio processors started being used, leading up to the situation today where every station processes, some to maintain as little as 1dB dynamic range. What would be the reason for this processing? Yes, it seems to defy logic: Some posts say that you can get better dynamic range, less noise, better separation with the older circuitry, some say that where they live, there is no need. Why did all manufacturers in the 60s and 70s try for the best quality of sound wherever you lived and hope the user has access to quality programs while now a days, they seem to think that no one broadcasts dynamic rance and timbre at the moment so why bother Isnt the solution equivalent to what amp makers now do? Use the best of the old technology but bring it up to date? (I am NOT calling for reintroduction into production of the 10B, MR71 or Sequerra) BTW I an in New York where we get classical on 93.9, 96.3, sometimes on 89.9, occasionally on 90.7 and even more occasionally there is something worth listening to on 88.3 (if you can tune the signal) |
#35
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Panoramic spectrum analysis
"codifus" wrote in message
Technology does march on. It marched on right passed analog FM tuners and left it to die. Rightfully so. The guys at FMtunerinfo are mightily impressed with Sony's XDR bad boy. But, as usual, they also said that the sound quality of that very same tuner is merely adequate compared to yesterdays tuners. I've heard the tuner - they are talking trash. It will pull in the most obscure stations on the planet. If there's an fm transmitter on Mars, you can trust that Sony XDR to pull it in. But to actually sit there and want to listen to the broadcast? It is just fine. It may lack the sonic imperfections of some of the oldies but goodies, so it may sound a bit different from some of them. Like all modern FM tuners, and like I said earlier, modern tuner manufacturers don't bother. Except they do. However, they seem lacking in enthusiasm for putting back in the same sonic imperfections that they worked so hard to remove. The trash talk you're referring to is all about sentimentality and resistance to change. We've already learned that 99.5+ of all music lovers prefer digital, but 25 years after the introduction of the CD a tiny noisly minority are still fighting the battle of the LP. Just like the analog/tube bigots, there are a few people in the southern US who are still fighting the war between the states. Nobody should be surprised or try to form some global truth that we all need to adhere to out of the fact that a few people seem to never get it, and die wishing for something that is (a) inferior on all rational and moral grounds, and (b) will never be again. You have to go back to the old school Pioneer F-90, the Yamaha TX-1000, Onkyo T-9090, or Sansui TU-919, just to name a few. They couldn't hold a candle to the new Sony XDR when it comes to finding and grabbing the signal, So far so good. but when it comes to sitting down to listen and enjoy, the XDR takes a back seat, way in the back of the minivan with 4 row seating Nonsense. CD |
#36
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Panoramic spectrum analysis
It sounds like Internet Radio provides much better content then FM
that is available for many of the contributors to this thread. The problem is the quality but as a practical matter 128 MP3 broadcasts sound better then FM in many cases because there is no interference. At the moment I am enjoying; ABC Classic FM (Australia) 128 KB plenty of classics with some Jazz; find via radiotime.com TSF Jazz Paris (France) 128 KB excellent Jazz but I think they boost the bass a tiny bit. http://player.tsfjazz.com/tsfjazz.pls.php WGBH Boston classics and Jazz but low bit rate http://streams.wgbh.org/wgbh.pls There are also some high bit rate classics not in English such as; Radio Bartok (320 I think) Hungary; http://212.92.28.75:2008/ Netherlands 4 (256 I think) http://shoutcast.omroep.nl:8106/listen.pls And then there is the BBC - excellent content, programs archived for a week so you can listen on demand, unfortunately with a mediocre bit rate http://www.bbc.co.uk/radio/ |
#37
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Panoramic spectrum analysis
On Apr 1, 10:17*am, Steve wrote:
It sounds like Internet Radio provides much better content then FM that is available for many of the contributors to this thread. The problem is the quality but as a practical matter 128 MP3 broadcasts sound better then FM in many cases because there is no interference. I think it would be more appropriate to say that 128 MP3 broadcasts sound cleaner than analog FM due to lack of interference. Of course, though, nothing is perfect. Being digital audio, with some broadcasts you get complete dropout due to network contention issues etc. Times like that make me miss analog FM with its more gentle interference; a little fizz as the signal gets weaker, a gently dropping of high frequency response as the tuner circuitry adjusts to the noise of the weakening signal. With digital its all or nothing, and that abruptness can be quite disconcerting. CD |
#38
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Panoramic spectrum analysis
On Mar 31, 1:54*pm, codifus wrote:
They couldn't hold a candle to the new Sony XDR when it comes to finding and grabbing the signal, but when it comes to sitting down to listen and enjoy, the XDR takes a back seat, way in the back of the minivan with 4 row seating I am not so sure. I have two Revox A720s that from my direct experience will reach to Pluto - even if it has its 'planet' status removed. Our most difficult 'seeing' condition is our summer house, where we are in a valley directly against the side of a mountain towards the nearest transmitters and with two intervening valleys between us and the transmitters we 'want'. It is the only tuner I have tried that locks in without noise or drift or drop-out and in full stereo. Better, even than the car radios. Other tuners tried - in no particular order: Dynaco: FM3, FM5, AF6 - just barely adequate Soundcraftsman: T100 - Sensitivity good, not so good in stereo Revox B760 - adequate to good, weak in sensitivity, good stereo once a station was captured. HK Citation 14, 15, 18, HK500 - good, the 18 being the best of the three Marantz 10B (borrowed for the experiment) - worst of the lot, even the FM3 AR Tuner, AR Receiver - better We use an amplified pancake FM omni antenna in the attic area - between wind, snow and animals, keeping it inside is helpful. The present incumbent is the HK500 - it gets the NPR station that we use for 90% of our listening well enough and the A720 is too nice a unit to live up there unused for 5 months out of the year. But the 720 is flat-out amazing for its receiving capacity. Sound is pretty ****** good, too. If I find a third in good shape... then maybe. Peter Wieck Melrose Park, PA |
#39
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Panoramic spectrum analysis
On Apr 1, 11:16*am, " wrote:
On Mar 31, 1:54*pm, codifus wrote: *They couldn't hold a candle to the new Sony XDR when it comes to finding and grabbing the signal, but when it comes to sitting down to listen and enjoy, the XDR takes a back seat, way in the back of the minivan with 4 row seating I am not so sure. I have two Revox A720s that from my direct experience will reach to Pluto - even if it has its 'planet' status removed. Our most difficult 'seeing' condition is our summer house, where we are in a valley directly against the side of a mountain towards the nearest transmitters and with two intervening valleys between us and the transmitters we 'want'. It is the only tuner I have tried that locks in without noise or drift or drop-out and in full stereo. Better, even than the car radios. Other tuners tried - in no particular order: Dynaco: FM3, FM5, AF6 - just barely adequate Soundcraftsman: T100 - Sensitivity good, not so good in stereo Revox B760 - adequate to good, weak in sensitivity, good stereo once a station was captured. HK Citation 14, 15, 18, HK500 - good, the 18 being the best of the three Marantz 10B (borrowed for the experiment) - worst of the lot, even the FM3 AR Tuner, AR Receiver - better We use an amplified pancake FM omni antenna in the attic area - between wind, snow and animals, keeping it inside is helpful. The present incumbent is the HK500 - it gets the NPR station that we use for 90% of our listening well enough and the A720 is too nice a unit to live up there unused for 5 months out of the year. But the 720 is flat-out amazing for its receiving capacity. Sound is pretty ****** good, too. If I find a third in good shape... then maybe. The main thing I wanted to say was the new car radios seem to be yards ahead in multipath reception compared to the old days. It used to be horrible listening in Pittsburgh driving around. I hardly notice it now. Some of that is due to selective stereo combining. I got a bunch of Nads in my collection, some needing repair, and a whole bunch of others. I finally needed to go push button and could not turn the dial fast enough changing stations indoors. i used a Mitsubishi DA-F10 tuner for a number of years, and liked it. Never had a high end tuner. My first tuner was an Eico tube mono, and was complete garbage. The tuning exclamation point was neat though. greg |
#40
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Panoramic spectrum analysis
On Tue, 31 Mar 2009 20:53:04 -0700, DManzaluni wrote
(in article ): On Mar 30, 6:59*pm, Iordani wrote: Serge Auckland wrote: Also, at the time, radio stations (at least in Europe) broadcast wide dynamic range music, with no processing (it wasn't even permitted by law in the UK up until some time in the 80s, I recall) Then audio processors started being used, leading up to the situation today where every station processes, some to maintain as little as 1dB dynamic range. What would be the reason for this processing? Yes, it seems to defy logic: Some posts say that you can get better dynamic range, less noise, better separation with the older circuitry, some say that where they live, there is no need. Why did all manufacturers in the 60s and 70s try for the best quality of sound wherever you lived and hope the user has access to quality programs while now a days, they seem to think that no one broadcasts dynamic rance and timbre at the moment so why bother It's simple. In the "old days", FM was not popular and stations were far and few between. This meant that nobody cared if a station overmodulated, because the next station was often many MHz away. Today, the FM band is crowded. There are only 100 FM "channels" between 88 and 108 MHz and in some markets, EVERY ONE is in use. In the United States and Canada the channels are spaced 200 KHz apart on "odd" channels, I.E. 101.1, 101.3, 101.5, etc. In Europe, I believe that the channels are even, I.E. 101.0, 101.2, 101.4 etc. (at least they used to be). now, either way, that gives each channel only 200 KHz of bandwidth with a 100KHz guard-band on either side. Stereo requires, IIRC, about 180 KHz, and that doesn't leave much bandwidth. Remember, FM means Frequency Modulation, that is to say that the louder the program material, the further from the center frequency (That's the channel frequency of say 98.1 Mhz) the carrier varies and the carrier can swing plus and minus 100 KHz over the audio range. If a station lets their carrier excursion exceed 200KHz total bandwidth, then they will be straying into the guard-band area between their station the the adjacent station. If the two stations' overmodulation collides It causes a "spatter" type distortion on both. It is therefore illegal in most places for FM stations to overmodulate. In the fifties and sixties, before the boomers discovered FM stereo, the FM airwaves were mostly used as a "prestige" outlet for a radio or TV station and for college radio (there is a section of the dial, at the low end, in the United States reserved for colleges and other non-commercial broadcasting). Mostly you heard classical music and some jazz as well as middle-of-the-road (read that Sinatra, et al) and elevator music. Many colleges ran FM stations with varied programs of talk and music from all genres and around the world. Today, the FM dial is as crowded as the AM dial and just as commercial. The result is that all stations have to use "hard limiters" to insure the licensing agencies of the various governments involved (in the US, its the Federal Communications Commission or FCC) that the station not only WILL NOT overmodulate, they CANNOT overmodulate because the limiter's job is clip any waveform that exceeds the 200 KHz limit. Now, balance this beside the radio station's desire to capture as many listeners as possible and you have a dilemma. Radio station managers want their signals to be the loudest on the dial. The FCC says you must limit your modulation to 200KHz excursion. Enter the compressor. The compressor allows you to set a maximum volume and then amplify all parts of the program to come close to or equal that setting. So, a piece of music that has, say, a 70dB dynamic range (the difference between the loudest and the softest parts) the compressor can reduce that to 10 dB (or 5, or 3, or 1) by amplifying the softest part of the signal to almost equal the amplitude of the loudest parts. This means that common practice is for operators to bang the meters into the red (over 100% modulation) so the signal is good and loud and then let the compressor take care of the softer parts of the program and the limiter just clips any overmodulation which might occur. Loud and legal are the watchwords of modern FM broadcasting. Since it is estimated that most FM listening occurs in cars, the compression, while certainly not what an audiophile wants to hear over his home stereo, is actually beneficial to car listeners. The noise level inside of most moving cars is quite high. without compression, the soft parts of the music would be lost in the road noise. I've often thought that all car radios should include a variable compressor so that the listener could compress not only radio broadcasts, but his CDs and Cassette tapes as well. Is Edwin H. Armstrong spinning in his grave? |
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