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Hydrogenaudio Forum => General Audio => Topic started by: Dude111 on 2012-08-29 20:53:56

Title: Stereo or Mono?
Post by: Dude111 on 2012-08-29 20:53:56
Im curious what you guys prefer??

I have always preferred Mono because everything is combined together and to me sounds the best..

I didnt see any threads discussing it so i thought i'd start one and see where it goes
Title: Stereo or Mono?
Post by: jayess on 2012-08-29 21:21:34
Im curious what you guys prefer??

I have always preferred Mono because everything is combined together and to me sounds the best..

I didnt see any threads discussing it so i thought i'd start one and see where it goes


I prefer stereo, but I did find it interesting recently reading about the Beatles Mono Box Set.

http://www.amazon.com/The-Beatles-Mono-Box...t_mus_ep_dpi_17 (http://www.amazon.com/The-Beatles-Mono-Box-Set/dp/B002BSHXJA/ref=ntt_mus_ep_dpi_17)

http://en.wikipedia.org/wiki/The_Beatles_in_Mono (http://en.wikipedia.org/wiki/The_Beatles_in_Mono)

Mono has its place in music history.

I'm gonna buy this thing after I get out of the dog house for my other recent purchases.
Title: Stereo or Mono?
Post by: LithosZA on 2012-08-29 21:28:28
Stereo, because Binaural recordings require it and those recordings usually sound the most life-like to me. Some people don't like the extreme channel seperation when listening to certain older stereo songs through headphones. For those they can use a stereophonic-to-binaural DSP filter like this one: http://bs2b.sourceforge.net/ (http://bs2b.sourceforge.net/)
Title: Stereo or Mono?
Post by: dc2bluelight on 2012-08-30 05:15:10
There are lots of reasons some people prefer mono.  The big one usually is that the music they love most was originally presented to them in mono, so that's the aural memory, stereo versions will often sound wrong.  Another is that in mono, assuming 1 speaker only, you can move around and the soundstage never really changes much.  Of course, there isn't much to change.  Move your head out of dead-center with stereo, and it all clumps around the speaker you moved toward.  Not a problem Mono has. 

On the other hand, stereo has some advantages too.  Mono recordings contain very limited spacial cues, not zero, but limited. Stereo contains lots of spacial cues, and even if heard with a bad stereo setup (out of balance, etc.) many of the spacial cues still work, and you get a sense of space and dimension you can't have with mono.  If done right, and with your head in dead-center position, the dimensionality can be astounding.  Again, not something mono does well. 

But stereo has issues too.  That tiny listening window being perhaps the biggest, and the fragile nature of phantom image location.  Early stereo researchers concluded that the fewest number of channels required for acceptable stereo was 3, and that included a center speaker (sound familiar?).  Two was not considered acceptable! 

Stereo does some really cool stuff with headphones, though most of it entirely unnatural, its still pretty cool.  Mono ends up in the center of your skull in headphones, which you can learn to like, but it's a perspective that you wouldn't hear in real life.  Binaural stereo takes the image out of dead center and attempts to put you in an acoustic space similar to the one in which the recording was made, but often falls short because binaural hearing characteristics are somewhat individual, and it's hard to provide an accurate binaural experience to every single listener as a result.  And binaural stereo on speakers is just pointless. 

So to move to a more believable soundstage, we add channels.  Every time you double the channel count the change in presentation is easily noticed by everyone, regardless if they think it's better or worse.  Most think its better.  So, mono > stereo was huge.  Stereo > 5.1 is huge.  5.1 > 11.2 is huge.  11.2 to Dolby Atmos and it's ilk is also huge. But we'll probably stop there for a bit.

So the point is, you like what you heard first (mono included) and most people like more channels if they can get them.  The mono-lover's experience is valid for him, and even if his entire love for mono is based on nostalgia or "being faithful to the original", it's still valid.  Personally, I have fewer issues with people loving mono than I do with people claiming stereo is the only "pure" recording method, or the" ultimate" in audiophile experience. 

And yes, I did play a mono vinyl record within the past seven days.  On a speaker, even.
Title: Stereo or Mono?
Post by: greynol on 2012-08-30 05:24:30
When played through a pair of stereo speakers, is the potential for problems associated with the position of the listener different depending on whether the source is stereo or mono?
Title: Stereo or Mono?
Post by: dc2bluelight on 2012-08-30 05:28:27
Just one more comment...I recently heard a mono recording on the thing in the picture, the large cabinet with the horn on top.  That's a phonograph without any electronics, all acoustic.  The recording was made with an all acoustic recorder, no electronics either.  It was, simply, astoundingly good!  Don't think I'd want to hear all my music that way, but it was loud, clear, clean, and quite dimensional.
The thing can be seen and heard here: http://www.pavekmuseum.org/ (http://www.pavekmuseum.org/)

(http://www.titanicjewelry.net/temp/phonograph.jpg)

Title: Stereo or Mono?
Post by: Nessuno on 2012-08-30 08:52:37
Recalling past threads here at HA, a fact is that, AFAIK, the so called "soundstage", or more properly the accuracy of threedimensional space location of sound sources in playback is not objectively measurable, so on those matters, mono vs stereo vs 5.1 vs this or that speaker setup vs headphones etc... there is and maybe there always be room for subjective opinions... and as side effect, like it or not, audiophile slang!
Title: Stereo or Mono?
Post by: derty2 on 2012-08-30 09:27:12
I am not a recording engineer, but I have always assumed that Mono was the only professional recording methodology used in studios all the way until the late 1960s.
Given my taste for authenticity, I expect to only see a Mono recording of things made before 1970 (or so).

However, I recently got a bit confused over this issue. . .
The other day I walked into a record store and casually browsed the Vinyl releases. I saw an audiophile 180g reissue of the album "Kind Of Blue" by Miles Davis (recorded in 1959).
I picked it up, inspected it, and noticed that it was labeled as Stereo !!! I asked the shop assistant how an album from 1959 can be released as Stereo ...and he did not have an informative answer to give me.

If any of you guys reading here have deep knowledge of recording history, technology and distribution, can you shed some light on all of this. Thanks.

I wish record companies and distributors always gave complete notes on the provenance of their releases, rather like the "changelog" you get with a long-standing and respected piece of software (such as foobar2000). Without such info, purchasing music seems like playing an obfuscated game of roulette.
Title: Stereo or Mono?
Post by: itisljar on 2012-08-30 10:05:36
I have read somewhere that some instruments on albums are recorded separately on three mono tracks and then mixed down to mono... later, these three tracks are mixed down to quasi stereo, one track being left, one track right, and one "in the middle".
I think that would be the thing with Miles Davis (and about quite a bit oj older jazz recordings).
Title: Stereo or Mono?
Post by: Nessuno on 2012-08-30 10:32:51
I am not a recording engineer, but I have always assumed that Mono was the only professional recording methodology used in studios all the way until the late 1960s.
[...]
If any of you guys reading here have deep knowledge of recording history, technology and distribution, can you shed some light on all of this.

If memory helps me, first Deutsche Grammophon stereo commercial recording was Bach's Art of Fugue performed by Helmut Walcha in 1956. And it was not actually recorded in a "studio", as it took place in a church (St. Laurenskerk at Alkmaar, NL).

Now one could argue if it's worth recording a big pipe organ in stereo, in the first place.

I owe that recording and as a personal remark I can say that, having also heard that same organ live, I have not the faintest expectation to repeat the same experience with a recording, no matter the recording tecnique and the reproduction chain, but still listening to it moves me to tears every time...
Title: Stereo or Mono?
Post by: Porcus on 2012-08-30 10:34:30
The other day I walked into a record store and casually browsed the Vinyl releases. I saw an audiophile 180g reissue of the album "Kind Of Blue" by Miles Davis (recorded in 1959).
I picked it up, inspected it, and noticed that it was labeled as Stereo !!! I asked the shop assistant how an album from 1959 can be released as Stereo ...and he did not have an informative answer to give me.


Stereo pressings hit the consumer market in 1958 (edit: Nessuno: was the 1956 recording released in 1956? Anyway, stereo pressings were available to consumers before KoB (http://en.wikipedia.org/wiki/Stereo#Consumer_media)), and Kind of Blue was released in stereo (http://www.discogs.com/Miles-Davis-Kind-Of-Blue/release/1353040) (and mono).

BTW, once you had LPs marked “Stereo (also playable on mono)”, the reason being that a mono pickup had a fatter stylus which wouldn't fit every stereo LP. It could very well be that some pressings later were marked “Stereo” because they were pressed for a stereo stylus (i.e., “Stereo” meant “Don't play this with a mono pickup”, not that there was actual stereo content) -- examples, anyone?
Title: Stereo or Mono?
Post by: Porcus on 2012-08-30 10:46:48
No, the Walcha recording was not released in stereo until 1960, according to http://www.allmusic.com/album/bach-the-art...ue-mw0001849213 (http://www.allmusic.com/album/bach-the-art-of-fugue-mw0001849213) :

Quote
Deutsche Grammophon didn't have a way to issue this stereo recording in 1956, but had the foresight to utilize the technology anyway, as relatively few others did at that time; the stereo LP of The Art of Fugue finally made its bow in 1960.
Title: Stereo or Mono?
Post by: Nessuno on 2012-08-30 10:58:48
Quote
Deutsche Grammophon didn't have a way to issue this stereo recording in 1956, but had the foresight to utilize the technology anyway, as relatively few others did at that time; the stereo LP of The Art of Fugue finally made its bow in 1960.


Ok, but the OP asked about recording, not pressing metodology!

BTW: I wonder why such a big firm made its first stereo recording outside a studio. Maybe it was actually easier: a simple two track tape recorder, a couple of microphones and most of all a source that's not so "stereo" in its own?
Title: Stereo or Mono?
Post by: Arnold B. Krueger on 2012-08-30 12:51:53
Im curious what you guys prefer??

I have always preferred Mono because everything is combined together and to me sounds the best..

I didnt see any threads discussing it so i thought i'd start one and see where it goes



Stereo. Some say that the coincident mic recordings that I like are "like mono", but I am unimpressed by the ping-pong and razor-sharp imaging they seem to prefer because I never hear that in the good seats at a live performance. That's true even if your seat is at the edge of the stage, let alone in the middle letters of the alphabet.
Title: Stereo or Mono?
Post by: pdq on 2012-08-30 14:57:34
BTW, once you had LPs marked “Stereo (also playable on mono)”, the reason being that a mono pickup had a fatter stylus which wouldn't fit every stereo LP. It could very well be that some pressings later were marked “Stereo” because they were pressed for a stereo stylus (i.e., “Stereo” meant “Don't play this with a mono pickup”, not that there was actual stereo content) -- examples, anyone?

I actually lived through the period of having to look specifically for the stereo or mono version of a record to match your hardware. My recollection was that you should not play a stereo record on some mono players because unlike a mono record, in which needle movement is strictly horizontal, a stereo record involves vertical movement as well, and some mono cartridges would damage the groove because they were not designed to move vertically.
Title: Stereo or Mono?
Post by: Arnold B. Krueger on 2012-08-30 15:26:40
BTW, once you had LPs marked “Stereo (also playable on mono)”, the reason being that a mono pickup had a fatter stylus which wouldn't fit every stereo LP. It could very well be that some pressings later were marked “Stereo” because they were pressed for a stereo stylus (i.e., “Stereo” meant “Don't play this with a mono pickup”, not that there was actual stereo content) -- examples, anyone?

I actually lived through the period of having to look specifically for the stereo or mono version of a record to match your hardware. My recollection was that you should not play a stereo record on some mono players because unlike a mono record, in which needle movement is strictly horizontal, a stereo record involves vertical movement as well, and some mono cartridges would damage the groove because they were not designed to move vertically.


All true. The good news is that playing mono records with stereo cartridges produced no such excess wear. If you tied the channels together somewhere down the chain, any false vertical signals were cancelled out.

Stereo/mono switches were ubiquitous in those days for this reason, and also because stereo FM could be noisier than the same signal in mono.
Title: Stereo or Mono?
Post by: dc2bluelight on 2012-08-30 18:42:50
Stereo/mono switches were ubiquitous in those days for this reason, and also because stereo FM could be noisier than the same signal in mono.


FM Stereo requires 20dB more raw receiver "quieting" to equal noise performance in mono.  It's a bandwidth thing, the L-R info is centered around a 38KHz suppressed carrier, and in the FM demodulated baseband noise rises with frequency.  L+R (mono) is just plain audio modulation, so the noise issue is far less.  The mono switch is still around today, but it's now called "blend", and is often an active, dynamic, non-user-adjustable reduction in stereo separation based on demodulated baseband noise, or dumber, signal strength. Full blend usually offers at least some mid-band stereo, but not much. This is one area where HD radio wins, it maintains full separation right up until the point where it stops working at all.

I mixed some live music to mono for an AM station to broadcast live a few years back. I found the mono mix to be actually more challenging than the stereo mix, giving me respect for those early recording engineers doing mono.  And they often did it all with one mic, and no mixing!
Title: Stereo or Mono?
Post by: Arnold B. Krueger on 2012-08-30 19:14:00
Stereo/mono switches were ubiquitous in those days for this reason, and also because stereo FM could be noisier than the same signal in mono.


FM Stereo requires 20dB more raw receiver "quieting" to equal noise performance in mono.  It's a bandwidth thing, the L-R info is centered around a 38KHz suppressed carrier, and in the FM demodulated baseband noise rises with frequency.  L+R (mono) is just plain audio modulation, so the noise issue is far less.


Right, and receiver quieting was a far rarer and dearer commodity than it is today. A complete analog FM stereo receiver used to be a formidable collection of circuitry which probably reached its zenith with the early frequency-synth FM receivers with TTL and ECL logic controlling the local oscillator, discrete crystal or LC filters, MSI IF amplifiers and limiters, and full analog implementations of the FM stereo decoder. Classic full implementations like or approaching this included the McIntosh MR 77 and 78, the Heath AR 15 and AJ 1510, and the Marantz 10B.  They filled at least 2 or 3 RUs.  Today it is all encapsulated into a $1 chip operating mostly in the digital domain that needs less than 15 outboard parts, all passive and most trivial. All that and quieting within a dB or two of theoretical max!

Quote
The mono switch is still around today, but it's now called "blend", and is often an active, dynamic, non-user-adjustable reduction in stereo separation based on demodulated baseband noise, or dumber, signal strength. Full blend usually offers at least some mid-band stereo, but not much. This is one area where HD radio wins, it maintains full separation right up until the point where it stops working at all.

I mixed some live music to mono for an AM station to broadcast live a few years back. I found the mono mix to be actually more challenging than the stereo mix, giving me respect for those early recording engineers doing mono.  And they often did it all with one mic, and no mixing!


I've done some 1 mic group work for live events and it can work quite fluidly and effectively when the ensemble is relatively small and very familiar with each other.
Title: Stereo or Mono?
Post by: Porcus on 2012-08-30 19:26:48
BTW, once you had LPs marked “Stereo (also playable on mono)”, the reason being that a mono pickup had a fatter stylus which wouldn't fit every stereo LP. It could very well be that some pressings later were marked “Stereo” because they were pressed for a stereo stylus (i.e., “Stereo” meant “Don't play this with a mono pickup”, not that there was actual stereo content) -- examples, anyone?

I actually lived through the period of having to look specifically for the stereo or mono version of a record to match your hardware. My recollection was that you should not play a stereo record on some mono players because unlike a mono record, in which needle movement is strictly horizontal, a stereo record involves vertical movement as well, and some mono cartridges would damage the groove because they were not designed to move vertically.


All true. The good news is that playing mono records with stereo cartridges produced no such excess wear. If you tied the channels together somewhere down the chain, any false vertical signals were cancelled out.



Yep ... but, here's what I was curious about: in the era where the mono and v-shaped stereo pressings coexisted, did they release old monaural recordings on stereo LPs with v-shaped stereo grooves (only with the same or attempted-same signal) and labeled them as “Stereo” -- without warning users that this is really a monaural signal?
Title: Stereo or Mono?
Post by: Porcus on 2012-08-30 19:31:07
Quote
Deutsche Grammophon didn't have a way to issue this stereo recording in 1956, but had the foresight to utilize the technology anyway, as relatively few others did at that time; the stereo LP of The Art of Fugue finally made its bow in 1960.


Ok, but the OP asked about recording, not pressing metodology!


Oh well, but then we are > 20 years late: http://en.wikipedia.org/wiki/Stereophonic_sound#1930s (http://en.wikipedia.org/wiki/Stereophonic_sound#1930s)
Title: Stereo or Mono?
Post by: lvqcl on 2012-08-30 19:51:44
Im curious what you guys prefer??


A new stereophonic sound spectacular! (http://www.dailymotion.com/video/xd3i0r_audio-fidelity-records-introduction_music)
Title: Stereo or Mono?
Post by: pdq on 2012-08-30 21:25:57
It's a bandwidth thing, the L-R info is centered around a 38KHz suppressed carrier...

Not quite correct. The L-R signal is actually single sideband, from 38 kHz down, not centered on 38 kHz. The suppressed 38 kHz carrier is generated by frequency-doubling the 19 kHz pilot signal.
Title: Stereo or Mono?
Post by: Ron Jones on 2012-08-30 21:37:09
I prefer stereo, but I did find it interesting recently reading about the Beatles Mono Box Set.
Had those mixes been differently, I think I'd prefer the stereo version. As it stands, though, those mixes were poorly done, in my opinion. It seemed as though the mixes were intended to exaggerate stereo, and they become very annoying to listen to on any system with relatively good separation (e.g. headphones, speakers positioned far apart from each other).

Personally, I'm a stereo guy. On every stereo recording I've ever made, the overall effect is just significantly better than a comparably well-recorded mono recording. Granted, I record stereo only in scenarios where stereo recording will bring a benefit, but it does often make an absolutely dramatic difference.
Title: Stereo or Mono?
Post by: dc2bluelight on 2012-08-31 06:47:20
It's a bandwidth thing, the L-R info is centered around a 38KHz suppressed carrier...

Not quite correct. The L-R signal is actually single sideband, from 38 kHz down, not centered on 38 kHz. The suppressed 38 kHz carrier is generated by frequency-doubling the 19 kHz pilot signal.

Beg to differ, it's still pretty much double sideband suppressed carrier centered at 38KHz, always has been.  The SSB (lower sideband) idea is very very recent, and not implemented or standardized yet. The concept was introduced by Frank Foti in 2010, still under test and simulation, though it looks promising.  The issues mostly relate to what happens to the demodulated signal when the rf signal subjected to multipath, and how compatible is the whole idea with existing DSB-based stereo demods.  If you alienate a guy with, oh lets say, a Marantz 10B, what good have you done?  The existing receiver compatibility problem has not had enough attention paid to it for some time, especially with the addition of HD radio.  We really don't need another compatibility issue, so testing is needed and being done now.

Until recent decades ssb has been impractical for high fidelity demodulation, and the DSB SC signal was much easier to recover using either a switching multiplexer, as the cheap and dirty way to do it.  And no, the carrier isn't technically a simple doubling of the pilot, but it is phase-locked to the pilot, and pilot to subcarrier phase is darn critical.
Title: Stereo or Mono?
Post by: Glenn Gundlach on 2012-08-31 08:38:09
Stereo, because Binaural recordings require it and those recordings usually sound the most life-like to me. Some people don't like the extreme channel seperation when listening to certain older stereo songs through headphones. For those they can use a stereophonic-to-binaural DSP filter like this one: http://bs2b.sourceforge.net/ (http://bs2b.sourceforge.net/)


"Extreme channel separation" recordings are often better described as multi-channel mono as the 'stereo' effect is created in the mixing console. When viewed on and X-Y phase display will be mostly an oval. This used to be VERY common given the technical limitations of stereo FM and LPs. True stereo in its simplest form requires 2 channels with some degree of physical separation of the mics and when viewed on an X-Y phase display will show considerable 'out of phase' information. I find it FAR more satisfying to listen to. The absolute WORST in my opinion is 'synthesized' stereo. Some are done by comb filtering frequencies and putting the complement on the other channel. The absolute worst I heard - and the discarded the disc - had most of the lows on the left and the highs on the right. THAT "engineer" didn't have a clue.

Title: Stereo or Mono?
Post by: 2Bdecided on 2012-08-31 11:37:59
Just one more comment...I recently heard a mono recording on the thing in the picture, the large cabinet with the horn on top.  That's a phonograph without any electronics, all acoustic.  The recording was made with an all acoustic recorder, no electronics either.  It was, simply, astoundingly good!  Don't think I'd want to hear all my music that way, but it was loud, clear, clean, and quite dimensional.
The thing can be seen and heard here: http://www.pavekmuseum.org/ (http://www.pavekmuseum.org/)
There are much better gramophones (phonographs)...
http://www.youtube.com/watch?v=_MA957TfmIs (http://www.youtube.com/watch?v=_MA957TfmIs)


Cheers,
David.
Title: Stereo or Mono?
Post by: Arnold B. Krueger on 2012-08-31 11:39:32
It's a bandwidth thing, the L-R info is centered around a 38KHz suppressed carrier...

Not quite correct. The L-R signal is actually single sideband, from 38 kHz down, not centered on 38 kHz. The suppressed 38 kHz carrier is generated by frequency-doubling the 19 kHz pilot signal.

Beg to differ, it's still pretty much double sideband suppressed carrier centered at 38KHz, always has been. 


Agreed.  FM stereo was designed to be decoded by very simple means. I'm not sure that I ever saw a decoder based on just one tube, but definitely saw many based on two (and some germanium diodes).  That's just four sections of gain, which is pretty slim pick ins.

Quote
And no, the carrier isn't technically a simple doubling of the pilot, but it is phase-locked to the pilot, and pilot to subcarrier phase is darn critical.


I have seen a number of FM stereo decoders that full-wave rectified the pilot and bandpass filtered the result to create the 38 KHz. I would call that doubling.
Title: Stereo or Mono?
Post by: Arnold B. Krueger on 2012-08-31 11:43:23
Just one more comment...I recently heard a mono recording on the thing in the picture, the large cabinet with the horn on top.  That's a phonograph without any electronics, all acoustic.  The recording was made with an all acoustic recorder, no electronics either.  It was, simply, astoundingly good!  Don't think I'd want to hear all my music that way, but it was loud, clear, clean, and quite dimensional.
The thing can be seen and heard here: http://www.pavekmuseum.org/ (http://www.pavekmuseum.org/)
There are much better gramophones (phonographs)...
http://www.youtube.com/watch?v=_MA957TfmIs (http://www.youtube.com/watch?v=_MA957TfmIs)



Acoustic phonographs were made through the early 1950s. Some were child's toys, but some were larger and had a more serious intent.  My recollection is that they sounded a lot better than that partially because they could be used to play 78s that were made by more modern means.
Title: Stereo or Mono?
Post by: pdq on 2012-08-31 14:20:39
Quote
And no, the carrier isn't technically a simple doubling of the pilot, but it is phase-locked to the pilot, and pilot to subcarrier phase is darn critical.


I have seen a number of FM stereo decoders that full-wave rectified the pilot and bandpass filtered the result to create the 38 KHz. I would call that doubling.

Agreed. PLL for generating the subcarrier was a relative late comer. I certainly never came across one in the '50s or '60s.

I stand corrected, however, on the SSB vs. DSB issue. 
Title: Stereo or Mono?
Post by: dc2bluelight on 2012-08-31 15:59:20
"Extreme channel separation" recordings are often better described as multi-channel mono as the 'stereo' effect is created in the mixing console. When viewed on and X-Y phase display will be mostly an oval.
I like to describe the display as a "rats nest" because the X and Y inputs are uncorrelated. With true stereo, the greater the physical separation of mics the more random phase is displayed.  To the extreme, coincident "stereo" and M/S shows almost no out of phase material and is heavily correlated, spaced omnis, like you'd use for a big pipe organ recording (private ;-) to GG), shows lots of random and out of phase material.  X-Y displays show LF phase more easily than HF, so the greater the spacing, the lower the frequency that phase differences can occur, and the easier to see on that display.  It's very very hard to make the correlation between an X-Y display and what is audibly "good", except in the extremes.  But you knew that.
This used to be VERY common given the technical limitations of stereo FM and LPs.
Not exactly sure which tech limits you're referring to, perhaps vertical groove limits, but I'll guess that the multi-mono craze of the 60s and early 70s had to do with the invention of multi-track recording and the desire by producers/engineers to gain more control.  The hard-panned "ping-pong" mixes probably helped sell stereos because the effect was so obvious, if obnoxious.

The absolute WORST in my opinion is 'synthesized' stereo. Some are done by comb filtering frequencies and putting the complement on the other channel. The absolute worst I heard - and the discarded the disc - had most of the lows on the left and the highs on the right. THAT "engineer" didn't have a clue.


If by "discarded the disc" you mean "blew it up with a shotgun", I applaud you.  I had an unfortunate brush with a so-called "stereo synthesizer" at an FM station in a small market that desired to present stereo material 100% of the time, but lacked enough stereo hardware to do it.  They stereo-ized mono commercials.  What that was supposed to accomplish still evades me.  I hope the box has long since found its way to the scrap yard.  My only regret is not witnessing its melt-down personally.
Title: Stereo or Mono?
Post by: dc2bluelight on 2012-08-31 16:29:51
I have seen a number of FM stereo decoders that full-wave rectified the pilot and bandpass filtered the result to create the 38 KHz. I would call that doubling.

True, but pilot phase in that topology was a cruel master.  Probably why PLL surfaced as soon as it was practical.  I think I had a Heathkit tuner that did it the rectifier way, separation was terrible. Keeping that circuit aligned within a degree of phase is...oh you get the idea.  It would also suffer more from multipath affects to the stereo demod than a PLL, since pilot to sub phase depends on circuit stability, where a PLL is, well, a phase-locked loop. 

So, ok, technically doubling was used, but it didn't win, and the analog state-o-da-art ends at some form of PLL.
Title: Stereo or Mono?
Post by: 2Bdecided on 2012-08-31 17:13:43
Acoustic phonographs were made through the early 1950s. Some were child's toys, but some were larger and had a more serious intent.  My recollection is that they sounded a lot better than that partially because they could be used to play 78s that were made by more modern means.
But you're in America - you never had the three best acoustic machines over there  Sadly the clips on YouTube don't do them justice.

(HMV 203 / 202, Expert Senior, EMG Xb)
Title: Stereo or Mono?
Post by: dc2bluelight on 2012-08-31 17:29:27
In the US, FM Stereo Multiplex was approved by the FCC in 1961.  The first reference I could find to an integrated circuit PLL demod design was dated 1972.  Assuming no PLL demod existed prior to 1972 (not definite, might have been a discrete implementation), we have 11 years of FM stereo using only pilot frequency doubling demods.  Then we have 40 years of PLL designs.  Sure, it started out slow and there were no doubt a few doubling demods made after 1972, but several things happened then.  For the first decade, FM stereo, and FM in general was shockingly unpopular.  There were very few FM car radios, and most of them were quite poor.  FM listenership was a tiny fraction of the total radio audience, and stereo receivers were available and sold, but relatively few in number.  Then the 1970s started.  First, ICs became common.  But the driving force behind the proliferation of stereo radios and the PLL design was the fact that FM as the definitive music broadcast medium took off finally beating AM roundly for composite listenership numbers. FM in cars became pretty much standard, then required, so FM receivers finally proliferated, putting it mildly.  The automotive market alone would have done the job, but component stereos in the home also became more commonplace too.  They had to be cheap, good, and stable.

Overall, the number of PLL demods that have ever existed in the world is orders of magnitude greater than pilot-doubling demods. The technology has covered 40 years, including the FM boom and IC based designs, is inherently more accurate, stable and cheaper.  Frequency doubling demods were pretty much abandoned with perhaps a few esoteric exceptions.

You guys are correct, pilot doubling was used.  But this is why I reference the PLL method, and didn't give much thought to pilot frequency doubling.  It simply became a non-factor for most of the history of FM, and PLL was/is overwhelmingly the standard.
Title: Stereo or Mono?
Post by: pdq on 2012-08-31 18:05:33
But isn't PLL just one technique for pilot frequency doubling? I don't understand your distinction.
Title: Stereo or Mono?
Post by: dc2bluelight on 2012-08-31 19:18:08
But isn't PLL just one technique for pilot frequency doubling? I don't understand your distinction.

Frequency doubling is using a filter to isolate a harmonic of the original.  So the 19KHz pilot is deliberately distorted so that the second harmonic can be selected, filtered, and used as the missing 38KHz carrier.  The phase of the resulting 38KHz carrier is dependent on the filters involved, which if built with less than ultimately stable parts, can cause its phase relationship with the pilot to change, to the detriment of channel separation.

A phase-locked loop starts with a voltage controlled oscillator at some multiple of the desire frequency, then through a divider chain divides it down to 19KHz. A phase detector compares it to the pilot, detects phase errors and translates the error into a control voltage that is fed back to the oscillator which is then adjusted so that the end result is an oscillator phase locked to the pilot.  A tap on the divider chain at 38KHz is chosen and that frequency used as the required 38KHz signal to control the demodulator.  There are control loop filters, and other filters involved, etc., but that's the general idea.  The entire thing has been on a single chip for decades, but can also be realized with less fully integrated means.  To be fair, a PLL has opportunities for drift too, but they are easier to engineer out.
Title: Stereo or Mono?
Post by: Arnold B. Krueger on 2012-08-31 20:03:39
I have seen a number of FM stereo decoders that full-wave rectified the pilot and bandpass filtered the result to create the 38 KHz. I would call that doubling.

True, but pilot phase in that topology was a cruel master.  Probably why PLL surfaced as soon as it was practical.  I think I had a Heathkit tuner that did it the rectifier way, separation was terrible. Keeping that circuit aligned within a degree of phase is...oh you get the idea.


Yes, yes, yes. An example of this technology can be found here:Heath AR15 Full Schematic (http://www.mcmlv.org/Archive/HiFi/Heath_AR15.pdf)  And it performed exactly as badly you said, really quite horribly especially considering the parts count.

In my case, a MC1310P PLL-based chip replaced most of it. It needed just one non-critical adjustment, when I installed it.  It appears that the MC1310p came out ca. 1976.

Title: Stereo or Mono?
Post by: george84 on 2012-11-16 23:23:48
Hi,

It uses an advance rectifying process that's why the sound is more acoustic and very crystal clear. This new technology was spread all over the world because of the cool sound that it produces. It require a lot of stuff to do this kind of thing.

Thanks