Speakers used in DAB Portable radios

[Old Sparky]

I have often noticed that the speakers fitted in these sets are specifically marked 'DAB', and, whilst the majority are a cut above the small speakers used in most portable AM/FM radios, I cannot think of any reason why a special type of speaker is needed for DAB, nor for that matter why speakers intended for DAB cannot be used in other applications requiring 4 or 8 ohm speakes of small dimensions.  In fact very similar speakers are used in the Bose 'Sounddock' amongst other things.  Maybe I'm missing something obvious, but, e.g., if I wanthed a small speaker for a signal tracing amplifier, is there any reason why I shouldn't use one salvaged from a scrap DAB radio?

[Murphyv310]

Of course not. So long as the impedance is correct then go ahead. A speaker is just a speaker, no doubt a way of upping the price to be fair.

[ppppenguin]

Just like there's no such thing as a "digital aerial".

[Mark Hennessy]

They no-doubt have a different speaker for their non-DAB sets that might well be very similar in appearance, but the DAB speaker will be "better" in some performance aspect (usually a tipped-up HF response if my experience of DAB radios is anything to go by - "ohh listen to all that detail - isn't digital great"). So this is just a simple way to avoid mixing them up in production.

Us Hacker aficionados know that many different loudspeakers were fitted to the various sets, and they all sound quite different. Most of the AM-only sets (quite reasonably) ended with with a speaker that has virtually no HF output. The Sovereign I and II had the same speaker, but partway through the life of the Sovereign II that Goodmans speaker was replaced by a Celestion which is a bit more lively at the top end. So in a sense, you could argue that there were "AM" and "FM" speakers

[Raditechman]

Perhaps the fact that DAB broadcasts can have a greater dynamic range than AM or FM is a factor.

John

[Mark Hennessy]

Compared to FM, DAB broadcasts certainly can do, technically, but they rarely do in practice. Not significantly, at least. The Optimod is alive and well in DAB-land, and is an essential tool for stations that employ "less qualified" operational staff. Of course, a reduced dynamic range gives the MPEG encoding an easier ride, which is important given the low bit-rates in use.

So in the context of a 3" speaker in a portable DAB set with only a couple of watts behind it, it's hard to think that is the reason - but anything is possible, of course.

[Murphyv310]

Hi.
In the early days of 405 line TV there were periods of sound only broadcasts. The transmission was of course AM and from Ally Pally on 41.5Mhz, The quality was reckoned to be excellent and from what I've read better than FM.
I have a cassette recorded in 1971 from a Murphy V430 off the volume control, its a recording of Beethoven's Number 6 (Pastorale) with the exception of the 10,125Hz line whistle the quality is first class, from what I remember audio quality on 405 lines was very good on a decent set and of course it was AM, dynamic range was excellent and I'd say it exceeded DAB.

[Crackle]

Back in the 50's TV's had proper speakers, often 8 inches or more in the bottom half of the set.

Mike

[Terry]

Yes, Mike.

Bush used 10" Celestions which gave excellent results.

[Murphyv310]

The 21inch Ekco console I have is excellent even with just a tad over 2 watts RMS. Even the 1946 Ekco gives very good sound with an 8 inch speaker.