Sound Quality on 405 Line TVs

[cheerfulcharlie]

Set makers probably gave sound second class treatment because VHF am sound was quite dreadful- taxi's and police cars breaking into Ken Barlow's lines on Coronation Street and that ghostly sound (like the Eurovision show coming down a corroded cable) you got in the Summer Months.

[raditechman]

Cheerfulcharlie, What you describe are reception problems. AM sound on TV in Band 1 or 3 normally was very good. Much better than MW and LW radio in the UK.

John

[Focus Diode]

Originally Posted by paulsherwin

Not 405, but in the early 80s I bought some sort of lightly modified UHF TV front end from Henrys Radio. It had been tweaked to output an IF of about 88MHz, so could be plugged into an FM tuner. The idea was that you could listen to the (mono) sound through your hifi system or record the sound

Sendz Components sold something similar.

Getting back to the quality of 405-line sound quality, on the Philips G6 I had the sound quality on 625 Uhf was awful resembling full bass with the treble turned right down. The push button tone control only made it worse.

Switching over to 405-lines however gave really outstanding sound quality! I was often torn between the excellent colour pictures and poor sound v black and white with outstanding sound quality on using the set!

[Heatercathodeshort]

My 1953 Ekco TC196 15" console, used on a regular basis has incredibly good sound with heavy bass. The loudspeaker is around 8" and marked 'Goodmans specially made for Ekco'.
The output valve is a 10P13 around 4 watts.
Television sound fell to a low level around 1958-62 mainly due to the introduction of the 110 degree tube allowing very slim cabinets and hence tiny speakers. The public seemed happy with the situation and I can't remember a really bad model. It's all about cost and the skin flint attitude of the British public.
It was different over the water with push pull audio amps and high quality speakers.
The VHF sound transmitted on 405 lines was excellent but not reproduced as a rule at the receiving end. John.

[dominicbeesley]

I suspect that many of us on this forum are knocking on a bit and have differing opinions on what constitutes good sound quality. Older tellys (625 and 405) have "better" sound quality to my ears usually due to the absence of horrid resonances and rattles - a function of larger speakers and decent heavy wooden cabinets. Their high frequency response is another matter - I know that when I measured my hearing range last year I was quite surprised at how my maximum discernible frequency was!

What was the sound bandwidth in the spec for 405 lines? I also wonder what the BBC/ITA aimed for in the studio for live broadcasts, OB's and film. I suspect it was a fairly low frequency.

For a while I too had a demodulator that I'd somehow got hold of that I used to record top of the pops until we got a newer telly that had an isolated chassis. Before that I had a radio that could get 405 line AM sound and remember VHF/R2 sounding a good bit better but again that could just be my very poorly lashed together equipment - I was only about 10 years old! Still better than my earlier tapes taken with a microphone held to the TV, usually with children screaming and dogs barking in the background!

[Nuvistor]

Taken from The Television Engineers Pocket Book, edited by Pat Hawker. I always thought the transmitted audio was capable of being excellent.

"The Double sideband as transmitted is 30kc/s representing modulation upto 15kc/s, the Receiver bandwidth is much wider, partly to allow for local ocs drift and to help in the suppression of impulse interference, possible bandwidth 500kc/s".

The wide bandwidth will allow very sharp spikes in impulse interference which can be surpressed by a simple diode circuit.

I may not have the wording exact but that's the essence.

Frank

[Hartley118]

AFAIR, 1950s console TVs like our Pye FV1C sounded much like the better 'large cabinet' radios, which of course sounded much better then than today's band-limited compressed AM transmissions. The FV1C contained a pretty decent 8 inch R&A speaker, but didn't have any pretensions to hi-fi.

Before the advent of FM radio, TV sound was the highest quality live broadcast available. I recall a colleague who was very proud of his high quality home-cut lacquer discs of live TV music programmes.

I recall in my student days in the 1960s connecting a diode detector to a surplus TV turret tuner and getting quite acceptable TV sound recordings, some of which I still have.

AFAIK, the BBC audio spec in the original 405 line days was largely unwritten, being mainly the province of Designs Department. It was with the advent of IBA that professional broadcast requirements were written down. From my experience as a supplier, the studio electronics would typically have been flat from 30Hz to 20kHz.

The limiting factor would have been the link to the transmitter; the best ones, including later digital links, achieved 40Hz -15kHz. However, a run-of-the-mill PO analogue music circuit would have been limited to 10kHz or even 8kHz.

Martin

[Panrock]

Originally Posted by dominicbeesley

What was the sound bandwidth in the spec for 405 lines? I also wonder what the BBC/ITA aimed for in the studio for live broadcasts, OB's and film. I suspect it was a fairly low frequency.

For what it's worth, here is the spec for the sound output of the S.T & C CG1 transmitter, as used in low power stations from the 1950s on and, I understand, to stand in for some of the higher power transmitters at the "end of 405".

From this, it looks like the radiated sound was "good" but not "excellent".

Steve

[1100 man]

Hi Fernseh,
I would most appreciate the circuit of the TV32 if you manage to find it. I have not looked at the set for some years as I don't have a proper workshop set up at the moment. The complete chassis resided on my kitchen table for several years as it was too heavy for me to move!! The complete set is in storage where the woodworm are busily consuming the cabinet! (the cabinet was grim when I acquired it. It is definitely a project I will do at some point when I have suitable facilities again.
Many thanks
Nick

[FERNSEH]

Hi Nick,
the circuit diagram is printed on a A3 size sheet. As soon as it is found I have it photo copied. I looking forward to seeing pictures of this huge set.
There is extracts from the circuit diagram on the link on post #20.

DFWB.

[Synchrodyne]

The audio bandwidth actually transmitted was probably determined mostly by the bandwidth of the GPO lines and links used to deliver the sound programme.

The highlighted item from Wireless World 1951 August, attached, indicates that the GPO lines to Sutton Coldfield were equalized to 10 kHz. That corrected an erroneous reference to 5 kHz in WW 1951 July, the latter also stating that for Alexandra Palace, the bandwidth was 12 kHz.

Actually, 10 kHz was quite good back then. The target number for the radio programme landlines was 8 kHz, not always achieved, although the lines to Brookman’s Park had 15 kHz bandwidth (see WW 1947 October, p.396.) By 1964, 10 kHz was the target (including for the FM service), although still with some shortfalls, and 10 kHz lines were to be used for BBC2 sound. (See WW 1964 January, p.39.) I’d guess though that the Crystal Palace TV transmitters, VHF and UHF, were supplied with full bandwidth (15 kHz) sound signals.


Cheers,

[dave walsh]

This topic comes up from time to time but relative to the general prevailing domestic standard, 405 line sound was pretty good-even with a simple valve output stage. I was recording from TV in the sixties [using a "reversed" OPT to isolate from the live chassis-even with the plug correctly wired] and still have the results. Indeed a 9k to the dizzy heights of 12k top response was very acceptable, especially on the domestic tape recorder market. In the absence of FM radio, listening the "clean" TV sound stood out sharply-especially when you were just focussing on that. This relied on a proper "sound on vision" adjustment though of course.

Even then, letters appeared in PTV or PW suggesting that the quality of the sound output available was being wasted but TV sets were built to a price. I never heard anyone complain very much who wasn't technically interested though. Perhaps it was the Audiophiles on the march

To be honest I couldn't see [hear] much of a problem at the time. Sets were in pretty solid wooden cabinets with a reasonably large speaker and there was certainly none of the later Flat Screen "Sound Bar" codology going on. Perhaps we were just more appreciative of the emerging technology and it's content back then

Dave W

[Nuvistor]

Two snippets from Practical TV Nov 1963.

Underneath the Dipole
Compared with recent importations of sound receivers from the U.S.A. and Japan, the sound side of the average British mass produced television receiver of today shows up badly. In several other parts of the world, hi -fi sound and stereonhony are common place. Really good stereophonic reproduction heard under the right acoustic conditions is quite exciting, and sets are made in both the U.S.A. and Japan, which incorporate every modern refinement of hi -fi and f.m. radiogram. with provision for tape recorder. in addition to 23in. television.


Show Time Round Up
Better Sound
The quest for better sound reproduction is being pursued by many companies. Decca have one model with a 10in. x 6in, speaker in an acoustic chamber; Bush, Murphy and Dynatron have models with l0in. x 6in. speakers, the new Kolster -Brande models have pairs of 5in. x 3in. speakers.

Frank

[Panrock]

There is interest in good sound on vintage television sets to this day.

One of my customers asked for special attention to be paid to the quality of the sound (and vision) during the restoration of his Baird Townsman. This is a 1949 model and operates on Channel 1 with AM sound of course.

I bypassed the set's original sound detector and fitted a modern solid-state audio power amp and a new larger speaker. With some tweaking of the tonal correction at the end, it sounded really good.... deep and imposing but very clear.

The set became known between us as the "Super Baird" and it has now been in use for several years.

Steve

[1955APREN]

I seem to remember from the mid 60's a Pye 21ins console I think based on the
continental chassis but had a differnt sound output stage, feed back from the sound output transformer was applied to the cathode of the sound output valve
(I know a PCL83) . The Speaker was a 10ins sound quality was very good.
Derrick

[suebutcher]

Originally Posted by Nicklyons2

Paul's very much on target there: a friend has just purchased a flat/smart TV, I can hardly discern a word it says & we've spent ages mucking about with it's various (pretentious) EQ settings; STADIUM, MUSIC, SPORT etc etc. Any self respecting TV125 with a PCL82 and a celestion/rola 6X4" speaker would've knocked spots off it for quality and audibility despite being 2W vs 10 + 10W.

In the 90s my parents bought a CRT Philips TV with a button for "Fantastic Sound" that made very little difference to the just-OK audio quality, so this kind of stupidity has a long history.