Yes, it is the LW service and Droitwich is running on its last pair of valves in the transmitter. Let’s hope a memo will be sent out when it finally shuts down!
Where did you hear it’s on its last pair of valves? So if there is a valve failure… which is not unusual then it’s curtains for Droitwich? Sounds perilous… in more ways than one
Thanks for pointing that out - I’d missed really taking it in, esp that it might be more involved than just “changing a couple of caps”.
To be clear, I don’t have the unit at this time…still trying to get this sorted first.
OK with all that - does anyone have experience of the sonic difference of the deemphasis? Probably hard to generalize. Given that I want to get this just right, seems like not addressing the deemphasis difference isn’t in the cards, but would love to hear anyone’s experience.
” Most FM receivers not designed specifically for the American market sound a bit heavy on the bass end. This is most noticeable as “thumping” on certain types of music. Almost as if there was an un-wanted resonance with the speaker”
It is the eq of the demodulated audio, so it will be like the bass tone control turned up a bit or a noticeably warmer sound… which you might enjoy.
Also from Radiomuseum.org” Pre-emphasis is used at the transmitter end of the FM transmitter to compensate for the inherent increase in high frequency noise in the de-modulated FM at the receiver. By increasing the high frequencies prior to transmitting, when they are decreased at the receiver, the additional (unwanted) noise is decreased as well.
Indeed, it’s like the early days of CD when pre emphasis was a flag enabled on most CDs that the early CDP used to recognise and filter the audio to reduce the noise or the sharpness of the audio from early DACs. If your CDP didn’t support this some CDs could sound rather bright. Note some rippers don’t monitor this and can create bright rips from such CDs.
But on broadcast FM, both Europe and US use pre emphasis to reduce the level audible high frequency noise/hiss , they just use slightly different amounts.
Also from Radiomuseum.org
"Looking at the schematic, The de-emphasis network R80, 47 K and C31, 1 nF have a time constant of 47 uS. (Note, the standard for most of the world except the United States is 50 uS.) Changing C31 to a 1.5 nF capacitor modified the time constant to 70.5 uS. I suppose I could have used a 1.6 nF capacitor, to make it 75 uS, but I felt that just modifying the original value by 1.5 was adequate.
On a similar note: Using American radios in Europe would tend to sound a bit “crisp” and lacking in bass response. The obvious solution here would be to reduce the time constant of the de-emphasis network from 75 uS to 50 uS. "
That may have been for dramatic effect but there aren’t many spares left from what I know - although my association with “aunti” ended back at the turn of the century.
Last project was the extension of Television Centre (which is now luxury apartments, sigh…)
When I think back to how many LS3/5A and the little HH monoblock amplifiers we threw in the skips
Returning vaguely to the topic, the in-house FM channels on the ring main were fully analogue modulation which sounded excellent on the obligatory Denon tuner in every racks room.
The NICAM encoding for distribution that was used for off-air monitoring isn’t quite as bad as you’d think either.
Using a tuner intended for the UK market in the US without changing those de-emphasis capacitors would give you a drop of a bit more than 3 dB from about 2.5 kHz all the way upwards, in fact a serious reduction in upper mid and high frequencies.
That would be impossible to contemplate for me, personally speaking.
I am not 100%, but think AM will go in UK sooner rather than later, although FM is likely to last at least until 2030, but maybe not much more.
More the issue will be broadcasters pulling away from non digital transmission, which difficult to predict but likely ahead of the actual switch off dates?
Blimey! I’ve had my LS3/5a years. They are behind me now because I’ve been through the twelve steps and not touched a pair for years. I’ve taken responisbility for my own midrange and survived. But even so. Blimey!
I think it was only last year ( perhaps the year before) that one of the regional bbc studios shut down and auctioned various Rogers speakers for a very cheap price including many sets of ls3/5a . Also tape machines and various broadcast kit.