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Old 23rd Mar 2020, 10:39 am   #1
dave walsh
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Default Wireless Relay 1930

Yesterday, Radio 4's "From our HOME correspondent" was an interesting listen with a Northern emphasis perhaps. Andy Kershaw [who lives in Todmorden] reported on a campaign to save the Bandstand in Centre Vale Park, which has now been listed. He mentioned a live BBC relay of the 1930 FA Cup Final. It involved a 6 valve receiver driving a seventeen foot long Horn LS that weighed 3cwt. I've not been able to locate a photo of that but there may well be similar items in the archives!

Dave W

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Old 23rd Mar 2020, 4:53 pm   #2
Hartley118
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Default Re: Wireless Relay 1930

That sounds to be a remarkable speaker. I wouldn't have expected a football commentary to have enough low-frequency content to justify a horn of that length!

On reflection, I wonder whether it was one of these Westrex speakers borrowed from the local cinema. https://www.radiomuseum.org/r/wester..._horn_16a.html . The Radiomuseum reference suggests that the folded horn design is equivalent to a 12-foot air path. Maybe the '17-foot long' claim wss the result of a little press hyperbole. The weight also fits with the Todmorden report

I find it impressive how the commercial incentive of 'talkie' films in the 1920s led to such rapid developments in speakers, largely in Bell Labs (Westrex). By 1930 we had speakers that would bear comparison with today's developments, perhaps give or take an octave or so at the top end. But I don't think their electro-acoustic efficiency has ever been bettered.

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Old 23rd Mar 2020, 5:01 pm   #3
G6Tanuki
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Default Re: Wireless Relay 1930

There's a mention of a radio-relay of promenade-concerts to an audience in a park, and a photo of a large-loudspeaker-equipped van doing this, in "The Setmakers".

Quite a few amplifier/speaker-manufacturers had such 'outside relay' vehicles in the 20s and 30s.
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Old 23rd Mar 2020, 6:13 pm   #4
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Default Re: Wireless Relay 1930

Quote:
Originally Posted by Hartley118 View Post
I find it impressive how the commercial incentive of 'talkie' films in the 1920s led to such rapid developments in speakers, largely in Bell Labs (Westrex). By 1930 we had speakers that would bear comparison with today's developments, perhaps give or take an octave or so at the top end. But I don't think their electro-acoustic efficiency has ever been bettered.

Martin

Quite. 5 - 10W into a decent horn loaded speaker would beat 100W or more into a typical modern PA speaker for acoustic power out.


Of course nowadays high power audio amplifiers with modern speakers are cheaper and less unwieldy than the low power amplifier and efficient horn speaker combo.


High power audio + horn loading, now....
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Old 23rd Mar 2020, 7:51 pm   #5
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Default Re: Wireless Relay 1930

I recall reading that London's Odeon , Leicester Square, managed quite well with a 15W amplifier in the days of optical sound tracks. It was observed in another thread that a much more powerful sound system is required these days to cope with the low frequency range of present- day films.
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Old 23rd Mar 2020, 8:41 pm   #6
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Default Re: Wireless Relay 1930

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I've not been able to locate a photo of that but there may well be similar items in the archives!

Dave W
Perhaps something like this one?

Peter.
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Old 26th Mar 2020, 4:39 pm   #7
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Default Re: Wireless Relay 1930

Edison Studios had a 125' recording horn.
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Old 26th Mar 2020, 6:14 pm   #8
dave walsh
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Default Re: Wireless Relay 1930

Yes the horn can be wonderfully efficient Brigham, as Herald said but you need the space for it The photo dug out by Peter must be pretty much what they had set up in the park at Todmorden. There also were "folded horn" designs and I recall some people mounting down ward facing pairs, using the fireplace alcoves, in the sixties. That was the time of brick built or concrete panel corner cabinet as well. I fancied a pair of those but even my [otherwise very tolerant] parents wouldn't have gone for it

When you look at a sketch of a 30's Radio Workshop, they often have an LS just mounted on a large baffle board maybe angled between the top of the door and the ceiling! Apparently one 5' 6" square, would reproduce the whole fr of an 8" spkr. I suspect Murphy was aiming at that, especially with the larger models in the "Baffle" range. In a way "folding" that big baffle into a smaller efficient box shape sums up one half of the search for audio "perfection".

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Old 26th Mar 2020, 6:20 pm   #9
dave walsh
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Default Re: Wireless Relay 1930

Yes the horn can be wonderfully efficient Brigham, as Herald said but you need the space for it The photo dug out by Peter must be pretty much what they had set up in the park at Todmorden. There also were "folded horn" designs and I recall some people mounting down ward facing pairs, using the fireplace alcoves, in the sixties. That was the time of brick built or concrete panel corner cabinet as well. I fancied a pair of those but even my [otherwise very tolerant] parents wouldn't have gone for it

When you look at a sketch of a 30's Radio Workshop, they often have an LS just mounted on a large baffle board maybe angled between the top of the door and the ceiling! Apparently one 5' 6" square, would reproduce the whole fr of an 8" spkr. I suspect Murphy was aiming at that, especially with the larger models in the "Baffle" range. In a way "folding" that big baffle into a smaller efficient box shape sums up one half of the search for audio "perfection".

Dave W
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Old 26th Mar 2020, 8:21 pm   #10
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Default Re: Wireless Relay 1930

In the 1970's one of my more affluent friends bought himself a pair of massive folded horn Lowther speakers. I helped him unload them from the back of his Ford Capri Ghia, and as he hadn't yet got the rest of his system, we tried them out using his Philips battery cassette recorder. Although it had a stated output power of only 1Watt, and was running on batteries, we got deafening sound before the volume control was even half way.
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Old 26th Mar 2020, 10:35 pm   #11
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Default Re: Wireless Relay 1930

Just goes to show how bad the acoustic impedance mismatch between a "normal" loudspeaker and free air is!
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Old 26th Mar 2020, 10:58 pm   #12
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Default Re: Wireless Relay 1930

One of the most impressive horns I've listened to was the EMG gramophone on a visit to our local museum with a group of ex-work colleagues.

Peter
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Old 26th Mar 2020, 11:48 pm   #13
dave walsh
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Default Re: Wireless Relay 1930

Thanks for putting that up Peter. Kathleen, the blunt Operatic Lancashire Lass plus one my favourite songs! How sad she didn't live longer. Gracy Fields did the working class material and very well. Even Vera Lynn wasn't posh [despite appearances] and neither were the other two extraordinary talents!

What is life? The eternal question? I'm sorry about that duplicated post-so good I said it twice [apparently]. I had problems on another thread with txt disappearing so I'm not sure what happened there.

Dave
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