| |
G0FTD > OLDSET 15.07.09 20:17l 118 Lines 4511 Bytes #999 (0) @ WW
BID : 080183195PZT
Read: GUEST
Subj: Re: Interest in vintage radios
Path: IZ3LSV<IK2XDE<DB0RES<ON0AR<HS1LMV<7M3TJZ<ZL2BAU<GB7PZT
Sent: 090715/1746Z @:GB7PZT.#24.GBR.EU [Kidderminster] #:18308 XSERV410h
Date: Wed, 15 Jul 2009 18:46:20 +0000
From: g0ftd@gb7pzt.#24.gbr.eu (Andy)
To: oldset@ww
Subject: Re: Interest in vintage radios
Nice to hear from you Ray. Thinking about it and packet in general I
think you've earnt the right to be classed as part of the packet world
furniture these days. Stick with it - man!
Here's some of my totally random thoughts.
VK2TV wrote:-
> At age four I used the family radiogram to play my records,
> 78RPM only, of course. This was 1951.
But says:
> Whilst never personally owning a radiogram,
Strewth me ol' fruit! I'm amazed that an old fossil like yourself has
never owned one.
> They were magnificently constructed pieces of furniture.
I remember the units my ancestors had back in the 20th century, and agree
that they really were fantastic pieces of furniture.
The ones that I remember had space for a vinyl collection within it's
own structure. Speeds as low as 16rpm were included.
My grandfather also had a SQUARE vinyl LP in his collection which he
played on it, but I have no info of it's artist.
> Who could forget how "good" a single 12" woofer sounded when mounted in a
> decent cabinet and driven by a single 6V6 output pentode to the dizzy
> heights of 4W RMS? Far from hi-fi but we thought it was wonderful. Listen
> to that bass!
And just think, audio designers design circuits to artificially create
bass these days. (Intermod ?)
> I remember one unit owned by a cousin that featured an AWA (Amalgamated
> Wireless Australia, later to become Amalgamated Wireless Australasia)
> tuner that boasted seven bands and two RF stages.
British units used to have a small cream coloured bakelite tag on their
rear ends proclaiming that the unit didn't require a listening licence.
The UK used to require users to have a licence for a receiver.
I don't know when it ended. All I know is that it was sometine during
the dark ages when the black death killed millions and Britain had
an empire.
They were often had TRF tuners that came with built in 9Khz heterodynes.
My schooldays were filled with the bass from the BBC Light Programme
and it's "Programmes for Schools" on a radiogram.
Of course, radiograms play them funny flat spinning discs too.
As it just so happens, I was researching the old fashioned shellac and
vinyl recording practices, and came across some good stuff on
Wikipedia.
I learnt quite a bit reading it.
For a start, the groove is cut horizontally in accordance with frequency
and amplitude on a disc. But when stereo was introduced the other channel
was cut vertically on the disc.
It is helpful to think of the combined stylus motion in terms of the
vector sum and difference of the two stereo channels. Effectively, all
vertical stylus motion conveys the L-R difference signal, and horizontal
stylus motion carries the L+R summed signal. The advantages of the 45/45
system are:
* Greater compatibility with monophonic recording and playback systems.
* A monophonic cartridge will reproduce an equal blend of the left and
right channels instead of reproducing only one channel. (However many
monophonic styli would damage a stereo groove, leading to the common
recommendation to never use a mono cartridge on a stereo record.)
Conversely, a stereo cartridge reproduces the lateral grooves of
monophonic recording equally through both channels, rather than one
channel.
The development of quadraphonic records was announced in 1971. These
recorded four separate sound signals. This was achieved on the two
stereo channels by electronic matrixing, where the additional channels
were combined into the main signal. When the records were played,
phase-detection circuits in the amplifiers were able to decode the
signals into four separate channels.
There were two main systems of matrixed quadraphonic records produced,
confusingly named SQ (by CBS) and QS (by Sansui).
Commercially they were crap but later became them modern"surround sound"
systems we think of today.
A different format, CD-4 (not to be confused with compact disc), by RCA,
encoded rear channel information on an ultrasonic carrier, which required
a special wideband cartridge to capture it on carefully-calibrated pickup
arm/turntable combinations. Typically the high frequency information
inscribed onto these LPs wore off after only a few playings ;-)
Don't ya just love this old technology ?
73 - Andy, G0FTD @ GB7PZT
Message timed: 19:49 on 2009-Jul-15
Message sent using WinPack-Telnet V6.80
G0FTD @ GB7PZT
Read previous mail | Read next mail
| |
