I am visiting Canada in the autumn. I have a Sony pocket DAM/FM radio.
I understand DAB has been discontinued in Canada. For FM, I understand transmission standards are slightly different, with more pre-emphasis
at the transmitter and de-emphasis at the receiver. Am I right in
thinking that for a small pocket radio (and imperfect hearing) this
will make no practical difference?
I thought pre-emphasis was the same as Dolby in boosting the treble,
but it seems it is not. Could someone clarify?
I am visiting Canada in the autumn. I have a Sony pocket DAM/FM radio.
I understand DAB has been discontinued in Canada. For FM, I understand transmission standards are slightly different, with more pre-emphasis
at the transmitter and de-emphasis at the receiver. Am I right in
thinking that for a small pocket radio (and imperfect hearing) this
will make no practical difference?
I thought pre-emphasis was the same as Dolby in boosting the treble,
but it seems it is not. Could someone clarify?
On 04/06/2025 09:23, Scott wrote:
I am visiting Canada in the autumn. I have a Sony pocket DAM/FM radio.
I understand DAB has been discontinued in Canada. For FM, I understand transmission standards are slightly different, with more pre-emphasis
at the transmitter and de-emphasis at the receiver. Am I right in
thinking that for a small pocket radio (and imperfect hearing) this
will make no practical difference?
I thought pre-emphasis was the same as Dolby in boosting the treble,
but it seems it is not. Could someone clarify?
75 uS time constant is used in the US/Canadia
50 uS in Europe/UK etc
A US broadcast will sound just a little bit 'brighter' on your radio
Not long ago I had some transcription discs to digitise; they dated from
the very beginning of the BBC's F.M.broadcasts from Wrotham and were of unique historic operatic performances on the Third Programme. They had
been made unofficially by an enthusiast at a record company using the
firm's recording lathes, so the recording quality was impeccable .
One or two discs stood out as absolutely wrong, with a harsh sound and excessive 'top'; clearly something wrong with the H.F. characteristics. Eventually I realised that there would have been no commercial high
quality tuners on the British market at the time, so the recording
engineer must have imported an American tuner with a different
de-emphasis time constant.
I re-emphasisd the sound with a 75 uSec characteristic and de-emphasised
it with a 50 uSec characteristic, then it sounded perfectly fine. I
doubt if a random "tone control" would have given satisfactory results.
Mark Carver <mark@invalid.com> wrote:
On 04/06/2025 09:23, Scott wrote:
I am visiting Canada in the autumn. I have a Sony pocket DAM/FM radio.
I understand DAB has been discontinued in Canada. For FM, I understand
transmission standards are slightly different, with more pre-emphasis
at the transmitter and de-emphasis at the receiver. Am I right in
thinking that for a small pocket radio (and imperfect hearing) this
will make no practical difference?
I thought pre-emphasis was the same as Dolby in boosting the treble,
but it seems it is not. Could someone clarify?
75 uS time constant is used in the US/Canadia
50 uS in Europe/UK etc
A US broadcast will sound just a little bit 'brighter' on your radio
Not long ago I had some transcription discs to digitise; they dated from
the very beginning of the BBC's F.M.broadcasts from Wrotham and were of >unique historic operatic performances on the Third Programme. They had
been made unofficially by an enthusiast at a record company using the
firm's recording lathes, so the recording quality was impeccable .
One or two discs stood out as absolutely wrong, with a harsh sound and >excessive 'top'; clearly something wrong with the H.F. characteristics. >Eventually I realised that there would have been no commercial high
quality tuners on the British market at the time, so the recording
engineer must have imported an American tuner with a different
de-emphasis time constant.
I re-emphasisd the sound with a 75 uSec characteristic and de-emphasised
it with a 50 uSec characteristic, then it sounded perfectly fine. I
doubt if a random "tone control" would have given satisfactory results.
On 04/06/2025 21:13, Liz Tuddenham wrote:
Not long ago I had some transcription discs to digitise; they dated from the very beginning of the BBC's F.M.broadcasts from Wrotham and were of unique historic operatic performances on the Third Programme. They had been made unofficially by an enthusiast at a record company using the firm's recording lathes, so the recording quality was impeccable .
One or two discs stood out as absolutely wrong, with a harsh sound and excessive 'top'; clearly something wrong with the H.F. characteristics. Eventually I realised that there would have been no commercial high
quality tuners on the British market at the time, so the recording
engineer must have imported an American tuner with a different
de-emphasis time constant.
I re-emphasisd the sound with a 75 uSec characteristic and de-emphasised
it with a 50 uSec characteristic, then it sounded perfectly fine. I
doubt if a random "tone control" would have given satisfactory results.
Using a modern 75µs US receiver in the UK now would result in too much de-emphasis which means a lack of high frequencies. So not what you
observed.
Brian Gregory <void-invalid-dead-dontuse@email.invalid> wrote:
Using a modern 75µs US receiver in the UK now would result in too much
de-emphasis which means a lack of high frequencies. So not what you
observed.
Hmm - now you've started me wondering if i mis-remembered something.
The recording definitely had too much H.F. and a 50/75 or 75/50 uSec coversion sorted it out - but if it was the other way around from the
way I remembered it, what would explain the initial fault?
Brian Gregory <void-invalid-dead-dontuse@email.invalid> wrote:
On 04/06/2025 21:13, Liz Tuddenham wrote:
Not long ago I had some transcription discs to digitise; they dated from >>> the very beginning of the BBC's F.M.broadcasts from Wrotham and were of
unique historic operatic performances on the Third Programme. They had
been made unofficially by an enthusiast at a record company using the
firm's recording lathes, so the recording quality was impeccable .
One or two discs stood out as absolutely wrong, with a harsh sound and
excessive 'top'; clearly something wrong with the H.F. characteristics.
Eventually I realised that there would have been no commercial high
quality tuners on the British market at the time, so the recording
engineer must have imported an American tuner with a different
de-emphasis time constant.
I re-emphasisd the sound with a 75 uSec characteristic and de-emphasised >>> it with a 50 uSec characteristic, then it sounded perfectly fine. I
doubt if a random "tone control" would have given satisfactory results.
Using a modern 75µs US receiver in the UK now would result in too much
de-emphasis which means a lack of high frequencies. So not what you
observed.
Hmm - now you've started me wondering if i mis-remembered something.
The recording definitely had too much H.F. and a 50/75 or 75/50 uSec coversion sorted it out - but if it was the other way around from the
way I remembered it, what would explain the initial fault?
On 2025/6/5 11:9:0, Liz Tuddenham wrote:
Brian Gregory <void-invalid-dead-dontuse@email.invalid> wrote:I remembered it as being the other way round (we 75 µs, they 50), but
On 04/06/2025 21:13, Liz Tuddenham wrote:
Not long ago I had some transcription discs to digitise; they dated from >>>> the very beginning of the BBC's F.M.broadcasts from Wrotham and were of >>>> unique historic operatic performances on the Third Programme. They had >>>> been made unofficially by an enthusiast at a record company using the
firm's recording lathes, so the recording quality was impeccable .
One or two discs stood out as absolutely wrong, with a harsh sound and >>>> excessive 'top'; clearly something wrong with the H.F. characteristics. >>>> Eventually I realised that there would have been no commercial high
quality tuners on the British market at the time, so the recording
engineer must have imported an American tuner with a different
de-emphasis time constant.
I re-emphasisd the sound with a 75 uSec characteristic and de-emphasised >>>> it with a 50 uSec characteristic, then it sounded perfectly fine. I
doubt if a random "tone control" would have given satisfactory results. >>>
Using a modern 75µs US receiver in the UK now would result in too much
de-emphasis which means a lack of high frequencies. So not what you
observed.
Hmm - now you've started me wondering if i mis-remembered something.
The recording definitely had too much H.F. and a 50/75 or 75/50 uSec
coversion sorted it out - but if it was the other way around from the
way I remembered it, what would explain the initial fault?
ICBW - it's many decades since I read about it! I do remember there was >somewhere where we _did_ use the other setting - might have been TV as >opposed to band II sound.
I re-emphasisd the sound with a 75 uSec characteristic and de-emphasised
it with a 50 uSec characteristic, then it sounded perfectly fine. I
doubt if a random "tone control" would have given satisfactory results.
Brian Gregory <void-invalid-dead-dontuse@email.invalid> wrote:
On 04/06/2025 21:13, Liz Tuddenham wrote:
Not long ago I had some transcription discs to digitise; they dated from >> > the very beginning of the BBC's F.M.broadcasts from Wrotham and were of
unique historic operatic performances on the Third Programme. They had
been made unofficially by an enthusiast at a record company using the
firm's recording lathes, so the recording quality was impeccable .
One or two discs stood out as absolutely wrong, with a harsh sound and
excessive 'top'; clearly something wrong with the H.F. characteristics.
Eventually I realised that there would have been no commercial high
quality tuners on the British market at the time, so the recording
engineer must have imported an American tuner with a different
de-emphasis time constant.
I re-emphasisd the sound with a 75 uSec characteristic and de-emphasised >> > it with a 50 uSec characteristic, then it sounded perfectly fine. I
doubt if a random "tone control" would have given satisfactory results.
Using a modern 75Âμs US receiver in the UK now would result in too much
de-emphasis which means a lack of high frequencies. So not what you
observed.
Hmm - now you've started me wondering if i mis-remembered something.
The recording definitely had too much H.F. and a 50/75 or 75/50 uSec >coversion sorted it out - but if it was the other way around from the
way I remembered it, what would explain the initial fault?
In article <1rdgc50.uprbje977oaoN%liz@poppyrecords.invalid.invalid>, Liz Tuddenham <liz@poppyrecords.invalid.invalid> scribeth thus
Brian Gregory <void-invalid-dead-dontuse@email.invalid> wrote:
On 04/06/2025 21:13, Liz Tuddenham wrote:
Not long ago I had some transcription discs to digitise; they dated from >>>> the very beginning of the BBC's F.M.broadcasts from Wrotham and were of >>>> unique historic operatic performances on the Third Programme. They had >>>> been made unofficially by an enthusiast at a record company using the
firm's recording lathes, so the recording quality was impeccable .
One or two discs stood out as absolutely wrong, with a harsh sound and >>>> excessive 'top'; clearly something wrong with the H.F. characteristics. >>>> Eventually I realised that there would have been no commercial high
quality tuners on the British market at the time, so the recording
engineer must have imported an American tuner with a different
de-emphasis time constant.
I re-emphasisd the sound with a 75 uSec characteristic and de-emphasised >>>> it with a 50 uSec characteristic, then it sounded perfectly fine. I
doubt if a random "tone control" would have given satisfactory results. >>>
Using a modern 75Âμs US receiver in the UK now would result in too much >>> de-emphasis which means a lack of high frequencies. So not what you
observed.
Hmm - now you've started me wondering if i mis-remembered something.
The recording definitely had too much H.F. and a 50/75 or 75/50 uSec
coversion sorted it out - but if it was the other way around from the
way I remembered it, what would explain the initial fault?
If this was very early FM days, might the BBC have not set the fm
premph standard back then?.
On 07/06/2025 09:26, tony sayer wrote:
In article <1rdgc50.uprbje977oaoN%liz@poppyrecords.invalid.invalid>, Liz Tuddenham <liz@poppyrecords.invalid.invalid> scribeth thus
Brian Gregory <void-invalid-dead-dontuse@email.invalid> wrote:
On 04/06/2025 21:13, Liz Tuddenham wrote:
Not long ago I had some transcription discs to digitise; they dated from >>>> the very beginning of the BBC's F.M.broadcasts from Wrotham and were of >>>> unique historic operatic performances on the Third Programme. They had >>>> been made unofficially by an enthusiast at a record company using the >>>> firm's recording lathes, so the recording quality was impeccable .
One or two discs stood out as absolutely wrong, with a harsh sound and >>>> excessive 'top'; clearly something wrong with the H.F. characteristics. >>>> Eventually I realised that there would have been no commercial high
quality tuners on the British market at the time, so the recording
engineer must have imported an American tuner with a different
de-emphasis time constant.
I re-emphasisd the sound with a 75 uSec characteristic and de-emphasised >>>> it with a 50 uSec characteristic, then it sounded perfectly fine. I >>>> doubt if a random "tone control" would have given satisfactory results. >>>
Using a modern 75Âμs US receiver in the UK now would result in too much >>> de-emphasis which means a lack of high frequencies. So not what you
observed.
Hmm - now you've started me wondering if i mis-remembered something.
The recording definitely had too much H.F. and a 50/75 or 75/50 uSec
coversion sorted it out - but if it was the other way around from the
way I remembered it, what would explain the initial fault?
If this was very early FM days, might the BBC have not set the fm
premph standard back then?.
I think they did. The 1954 tests of FM from Wrotham used 50 uS
https://downloads.bbc.co.uk/rd/pubs/reports/1954-36.pdf
Mark Carver <mark@invalid.com> wrote:
On 07/06/2025 09:26, tony sayer wrote:
In article <1rdgc50.uprbje977oaoN%liz@poppyrecords.invalid.invalid>, Liz >>> Tuddenham <liz@poppyrecords.invalid.invalid> scribeth thus
Brian Gregory <void-invalid-dead-dontuse@email.invalid> wrote:
On 04/06/2025 21:13, Liz Tuddenham wrote:
Not long ago I had some transcription discs to digitise; they dated from >>>>>> the very beginning of the BBC's F.M.broadcasts from Wrotham and were of >>>>>> unique historic operatic performances on the Third Programme. They had >>>>>> been made unofficially by an enthusiast at a record company using the >>>>>> firm's recording lathes, so the recording quality was impeccable . >>>>>>
One or two discs stood out as absolutely wrong, with a harsh sound and >>>>>> excessive 'top'; clearly something wrong with the H.F. characteristics. >>>>>> Eventually I realised that there would have been no commercial high >>>>>> quality tuners on the British market at the time, so the recording >>>>>> engineer must have imported an American tuner with a different
de-emphasis time constant.
I re-emphasisd the sound with a 75 uSec characteristic and de-emphasised >>>>>> it with a 50 uSec characteristic, then it sounded perfectly fine. I >>>>>> doubt if a random "tone control" would have given satisfactory results. >>>>>
Using a modern 75Âμs US receiver in the UK now would result in too much
de-emphasis which means a lack of high frequencies. So not what you
observed.
Hmm - now you've started me wondering if i mis-remembered something.
The recording definitely had too much H.F. and a 50/75 or 75/50 uSec
coversion sorted it out - but if it was the other way around from the
way I remembered it, what would explain the initial fault?
If this was very early FM days, might the BBC have not set the fm
premph standard back then?.
I think they did. The 1954 tests of FM from Wrotham used 50 uS
https://downloads.bbc.co.uk/rd/pubs/reports/1954-36.pdf
So it could have been a 50 uSec test picked up on a receiver that had
been set up for 75 uSec in anticipation of the BBC opting for that as
their standard?
As around the one TX, Wrotham, was in use might there have been a
premph switch like there was a stereo encoder on/off in the early stereo days?..
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