I was looking at a Beomaster 5000 (the tuner) listed on eBay, and noticed a red sticker in the rear that said "BEOMASTER 5000 with CERAMIC FILTER". Was this an improvement introduced some time during the production run, of something added later? The label seems very similar to the usual B&O type sticker (which says type 2005 s/n 33597, BTW).

Is there any sense in doing this modification later? I might consider it for my 5000 if it isn't too involved and is reversible.

Hi Mika

My personal preference is for the old style tuners, with the coils, instead of ceramic filters. The ceramic filter was introduced to save costs.

I have restored a number of 1950's Grundig and Saba tube radios (not B&O) with coil filters, and they ALL have far superior reception to modern radios.

The 10.7MHz ceramic filters of those times are really noisy, with noise figures of about 7-10dB.

They also have incredibly wide skirts - between 280-350kHz, which makes it very difficult to receive marginal stations, located between the strong local stations.

Today, Murata's best ceramic filters have noise figures of 3-4dB.

On all my radio equipment (not only B&O), I replace the factory-fitted filters with new Murata units with 150KHz wide skirts.

On the B&O receivers especially, a moderate tuner becomes a powerhouse, being able to pull in previously impossible stations.

A new alignment is essential (easy with the Service Manual), also because the older 10.7MHz filters were usually not manufactured to tight tolerances on exactly 10.7MHz, but sometimes as far off as 10.6MHz, and if you just insert a new accurate 10.7MHz filter (without realignment), you'll be missing a large part of the signal.

And anyway, many times the radio was not aligned properly during production, so a realignment after 30-40 years does wonders.

Bottom line - buy it if you want, but change the filter, and realign. If you have one with a coil tuner, don't change it to a ceramic one.

Menahem

yachadm:

The 10.7MHz ceramic filters of those times are really noisy, with noise figures of about 7-10dB.

They also have incredibly wide skirts - between 280-350kHz, which makes it very difficult to receive marginal stations, located between the strong local stations.

Today, Murata's best ceramic filters have noise figures of 3-4dB.

On all my radio equipment (not only B&O), I replace the factory-fitted filters with new Murata units with 150KHz wide skirts.

Won't that also increase the distortion somewhat? It would be nice to have switchable IF bandwidth, but retrofitting it would probably be a stupid idea...

Bottom line - buy it if you want, but change the filter, and realign. If you have one with a coil tuner, don't change it to a ceramic one.

Thanks, that decides it for me - I'm not going to modify my Beomaster 5000. I haven't actually even looked inside of it yet! I have excellent reception with it, using only a short wire as an aerial, so there will be plenty of other projects next winter before I get to the Beomaster (like its partner, the Beolab 5000)...

I think I will have to start looking on eBay for some radio test equipment to complete my lab... I have some Beolit challenges ahead as well.

Mika,

The narrower filters improve the clarity tremendously, because you are not getting interence from adjacent stations.

In fact, in AutoRadios, which have to deal with rapidly changing signal reception conditions, 150KHz filters are the standard today.

150KHz is the minimum optimum for good stereo reception - but that does not mean that you need more than that. The next size up is 180KHz, and that is already too wide, IMO.

DX Enthusiasts use 110KHz filters for picking out weak signals, but 110KHz is too narrow to receive stereo.

Those old wide filters were probably the best that technology could produce 30 years ago, but like capacitor technology, filters have improved tremendously.

My Meguro FM-AM Signal Generator (bought very used) is probably my most useful piece of equipment after the oscilloscope - it's very satisfying to be able to align these old wonderful radios to their best condition, and to see visually the waveforms of different filters!

Menahem

I seem to remember Frede (the ultimate expert on these) Kristensen saying something about the ceramic filters being for the UK market?

I'd drop him an email for the definitive answer though!!

Lee

There are 2 standards for FM signals in the Western World (I have no idea what the Asian standards are):

In North America, the station frequencies are much further apart, so a radio manufacturer can get away with putting wide, cheap, and "sloppy" (280-400KHz) filters in their radios.

In Europe (including Africa and the Middle East), the station frequencies are much closer together, so the standard filter is 230KHz for general radios, or 150KHz for AutoRadios and Audiophile Tuners.

That's why, if you bring a US Radio to Europe, you will get terrible reception, with much interference from adjacent stations. BUT, if you take a European radio to the US, you'll get crystal clear reception, and also be able to receive weak stations which a regular US radio cannot receive.

It all comes down to costs of production, and the manufacturer (generally speaking) will always use the cheapest component which gets the job done for the target market.

On my 1997 BeoCenter 9300 (the most recent B&O product I own) - bought in the UK - I replaced the stock FM filters with 150KHz units, and improved the reception substantially. I did not bother to measure the skirt width of the original filters (specifically for the UK market), but I would guess that it was in the 230-280KHz range.