2nd Oct 2018, 8:34 am | #61 |
Nonode
Join Date: Aug 2007
Location: South Bradford, West Yorkshire, UK.
Posts: 2,573
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Re: FM stereo
I remember the quadrophonic broadcast which I think was in 1974. I took my tuner, amp and speakers round to a friends house for the test. I can't remember much about the content of the programme but I think at one point the sound "moved" diagonally.
I wonder if a copy of the broadcast still exists? Keith |
2nd Oct 2018, 10:42 am | #62 | |
Heptode
Join Date: Jul 2006
Location: Winchester, Hampshire, UK.
Posts: 639
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Re: FM stereo
Quote:
I built a Heathkit tuner amp in the early days of stereo, and noted that the de-emphasis components supplied were for the American specification (50us instead of 75uS? - I can't remember after all this time). I wrote to Heathkit UK about it and they not only thanked me for pointing out the error they also sent me the correct R&C components in a small plastic bag to correct my own model. |
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2nd Oct 2018, 11:09 am | #63 |
Dekatron
Join Date: Aug 2013
Location: Wigan, Greater Manchester, UK.
Posts: 9,433
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Re: FM stereo
Quadraphonic sound, we got a couple of units but had to virtually give them away, not a lot of interest from the customers we had. I don’t remember the makes but they were Japanese units, the equipment was decent quality.
Others may have sold lots but not in the shop I worked at.
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Frank |
2nd Oct 2018, 3:03 pm | #64 |
Nonode
Join Date: Nov 2016
Location: Aberaeron, Ceredigion, Wales, UK.
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Re: FM stereo
I remember having to study the Foster-Sealy discriminator in my C&G exams way back in time ( 1960 - 1970 ish or was it later? ).
Cheers John |
2nd Oct 2018, 3:12 pm | #65 |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
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Re: FM stereo
Me too, in the late 1960's at Stockport College.
Lawrence. |
2nd Oct 2018, 3:33 pm | #66 |
Heptode
Join Date: Nov 2003
Location: East London, UK.
Posts: 761
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Re: FM stereo
I remember it well - the upstairs flat brought their stereo down to us and 4 or 5 of us sat huddled tightly together as close as possible to the centre of the 4 speakers - I don't recall the programme content and I can't say we were overly enthralled at the novelty.
According to Genome it was on July 6th 1974 https://genome.ch.bbc.co.uk/5c91d7ea...a8f9f158bb044d Alvin |
2nd Oct 2018, 9:10 pm | #67 |
Dekatron
Join Date: Jul 2008
Location: Kington, Herefordshire, UK.
Posts: 3,675
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Re: FM stereo
Interesting that the producer was Raymond Raikes, who had produced the first stereo dramas for the two-transmitter tests some fifteen years before.
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3rd Oct 2018, 9:35 am | #68 |
Nonode
Join Date: Jun 2013
Location: Surbiton, SW London, UK.
Posts: 2,801
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Re: FM stereo
After the twin transmitter quadraphonic broadcasts were abandoned, encoded quad based on ambisonics was tried, not using proprietary SQ or QS formats but their own standard known as Matrix-H, although I don't remember when these ended. There may be a decoder design somewhere.
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3rd Oct 2018, 11:41 am | #69 |
Dekatron
Join Date: Jul 2008
Location: Kington, Herefordshire, UK.
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Re: FM stereo
Matrix H!
This had little to do with Ambisonics, which was a comprehensive system capable of encoding height information, and led to developments such as the Soundfield microphone. Matrix H was an attempt to combine the least worst features of SQ, QS and Regular Matrix. Chief tweak was the application of a phase shift on centre-front signals, which was played about with over time, but ended up somewhere around 30 degrees. I have some tapes of Matrix H transmissions, which to be frank I haven't listened to closely, but the consensus at the time was that the clarity of the stereo picture was affected, and when I asked Tony Askew, who balanced Proms with it, his reaction was basically " awful thing - waste of time!" If I remember right, Matrix H staggered on through a couple of Prom seasons and was then quietly interred, along with the rest of Matrix quadrophony. |
3rd Oct 2018, 10:29 pm | #70 |
Heptode
Join Date: Mar 2014
Location: Leeds, West Yorkshire, UK.
Posts: 902
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Re: FM stereo
i have this hacker RG200 bought by my parents back in 1968 that has a decoder fitted [as an optional extra]and the stereo beacon although i have never known it to work .There is some mention of stereo broadcasting in the user manual
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3rd Oct 2018, 11:52 pm | #71 |
Dekatron
Join Date: Jul 2008
Location: Kington, Herefordshire, UK.
Posts: 3,675
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Re: FM stereo
That's interesting - is it connected to a roof aerial? It may just be a matter of signal strength.
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3rd Oct 2018, 11:55 pm | #72 |
Nonode
Join Date: Jan 2009
Location: Papamoa Beach, Bay of Plenty, New Zealand
Posts: 2,944
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Re: FM stereo
It’s interesting to compare the UK and US situations, as the US also had a period of twin-transmitter stereo broadcasts before the Zenith-GE system was adopted in 1961. In that case, the norm was to use an FM transmitter for one channel and an AM (MF) transmitter for the other, as indicated in this Wireless World 1958 December item:
The US hi-fi equipment makers developed and offered appropriate equipment, as well. Typical was an AM-FM tuner that had completely separate, and separately tunable AM and FM sections so that they could be used in parallel for stereo broadcasts. Usually the AM section was of the wideband, hi-fi type, and a multiplex signal output allowed the FM side to work with future FM multiplex decoders. Also, some makers also offered multiplex decoders for use with the early experimental multiplex broadcasts. These I think were mostly using the Crosby FM-FM system, which predated most of the other contenders. Such units would have become redundant once the Zenith-GE system was adopted, whereas the AM-FM tuners had ongoing utility even if their combined stereo function was no longer required. I also recall seeing somewhere that one of setmakers offered a matching pair of table radio receivers, one AM only and the other FM only, for use with stereo broadcasts. But I can’t now trace it, so it is unconfirmed. (It might have been in a magazine like Popular Mechanics). In the UK the more limited scope of the experimental twin-transmitter stereo broadcasts would have made it harder to justify the development of specific receiving equipment. Still, for hi-fi applications, the Jason JTV FM & TV Sound tuner, which dated from mid-1958, provided a means of accessing the TV sound channel in a high quality way, that being its primary mission. (I don’t think that Jason mentioned the two-transmitter stereo application in any of its literature. The following JTV2 of late 1959 did have a multiplex output, though.) Lowther catalogued a couple of FM & TV Sound tuners circa 1960, but evidently these did not make it into production. One was said to have “double drive”, although whether this meant that it could simultaneously receive an FM and a TV sound broadcast is unknown. Two valved VHF receiving chains operating in parallel inside a small box would seem to create great opportunity for mutual interference. As in the US, from the late 1950s multiplex outputs were incorporated in British FM tuners. Probably with the export market in mind, Quad arranged the switching in its 22 stereo control unit of 1959 to allow separate FM and AM tuners to be used independently or as a stereo pair. Or a third tuner could be used to form a stereo pair with the first, or a multiplex unit could be used with the FM tuner. Another interesting case was Japan, where two transmitter AM-AM stereo was used for a few years before FM multiplex was adopted. The industry produced hi-fi units incorporating two AM tuners, which evidently had different IFs to avoid mutual interference. Also mirror-image pairs of AM table receivers were available. See: http://www.japanradiomuseum.jp/FMstereo-e.html. A close look at the National SA-32 tuner-amplifier illustrated therein shows that it had two AM tuners. The left-hand one also had an SW band, whereas the right-hand one looks to have been MW only. I’d hazard a guess that the left-hand unit had the standard 455 kHz IF, whilst the right-hand unit had a lower number, perhaps 260 or 110 kHz. I think some care would have been needed to obtain similar overall bandpasses. Cheers, |
4th Oct 2018, 12:01 am | #73 |
Dekatron
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Re: FM stereo
In a Sounds Good programme around 1975, Angus McKenzie spoke about being so impressed with the stereo experiments that he bought himself a TV sound tuner on the strength of it. I imagine this would have been a Jason.
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4th Oct 2018, 12:11 am | #74 | |
Nonode
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Re: FM stereo
Quote:
This was effectively - although probably not formally - part of a series in WW through the 1970s. The attached spreadsheet provides a partial list of these articles and related items. Cheers, |
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4th Oct 2018, 12:16 am | #75 | |
Nonode
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Location: Papamoa Beach, Bay of Plenty, New Zealand
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Re: FM stereo
Quote:
Cheers, |
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4th Oct 2018, 1:24 am | #76 | ||
Octode
Join Date: Jul 2011
Location: Staffordshire Moorlands, UK.
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Re: FM stereo
Quote:
Steve.
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Those who lack imagination cannot imagine what is lacking... Last edited by fetteler; 4th Oct 2018 at 1:24 am. Reason: typo |
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4th Oct 2018, 7:31 pm | #77 |
Heptode
Join Date: Mar 2014
Location: Leeds, West Yorkshire, UK.
Posts: 902
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Re: FM stereo
It was connected to a roof Ariel when it was at my parents house but i dont ever remember hearing stereo radio on it .Sometimes when tuning along the scale the red light flickers but its very faint.As you say it may just need a good Ariel [it wont be helped by the fact that my house has a steel frame]
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4th Oct 2018, 9:59 pm | #78 |
Nonode
Join Date: Jun 2013
Location: Surbiton, SW London, UK.
Posts: 2,801
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Re: FM stereo
Non-PLL decoder beacons could light up on a mono broadcast if a 23kHz tone was present.
I assume this was transmitted for an engineering purpose. |
6th Oct 2018, 3:40 pm | #79 |
Dekatron
Join Date: Jul 2008
Location: Kington, Herefordshire, UK.
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Re: FM stereo
A note on one of the BBC's encoders describes the provision for inserting external 23khz in the absence of pilot tone "for transmitter signalling". Most stereo lights fire on interstation noise, too.
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6th Oct 2018, 4:55 pm | #80 | ||
Nonode
Join Date: Apr 2012
Location: Worcestershire, UK.
Posts: 2,052
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Re: FM stereo
Quote:
Quote:
* found it - DDHB No. 6.179 (80) - yes, the CD2L/4 did the same i.e. 19kHz @ 90mV, 23kHz @ 60mV Guy
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"What a depressingly stupid machine." [Marvin: HHGTTG] Last edited by Nymrod121; 6th Oct 2018 at 5:07 pm. Reason: update re. CD2L/4 |
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