Yes, the RIAA preamplifier was an option for the Beogram 1000.
Many were mounted, especially for use with the first versions of the Beomaster 900, but for some reason, they are
not very common today.
The build quality of the module is fairly good, the same goes for the electronic circuits. I am not sure however,
if the RIAA module lived 100% up to the actually RIAA specs given, every producer had their own way of doing it, but
the sound quality is normally very good and pleasant, a good match for the Beomaster 1000 with a pair
of contemporary B&O speakers.
Like everywhere else, electrolytic capacitors dry out and cause problems. This could easily be the cause for the
uneven frequency response, you experience.
Of course, this could also be a problem within the Beomaster 1000 (or both).

When mounting the RIAA module, a "blind" or "short-circuit" plate is removed from the socket in the Beogram and the
module installed instead, held by one screw with a fiber washer.
I think I have some of the blind plates if you need one and I'm sure that many people would be interested in the RIAA
module should you decide to part with it.

Unless an optional RIAA was installed in your Beomaster 1000 (it will sit next to the optional MPX stereo decoder),
your Beomaster should have one phono input WITH RIAA and one WITHOUT. Sounds like you have the RIAA in both inputs.

RIAA options were available also for the Beomaster 900M/K but it's very different from the Beomaster 1000 module.

Martin

Thanks. The sound hums a little as well, so I suppose I will have to recap the preamplifier. Seems like the design will bleed AC to the supply very easily if the filter caps are bad.

Phono 2 on the Beomaster definitely sounded like double RIAA, phono 1 was't quite so distorted - perhaps there is just some connector or switch problem, as I have never tried the phono inputs on it before.

I'll definitely offer the amp module here on the forum if I end up removing it - I'm not quite sure yet which receiver I'll use with the Beogram.

Note that one or two of the electrolytic capacitors are bipolar.

Martin

late question - I've been away too long it seems - can this unit be used with my 1972 'Gram 3000, or was it a different one?

It can't. The Beogram 3000 uses a completely different module.
Rarer of course.

Martin

Hi Mika,

Good to see that you're still tinkering!

You don't need to bypass the Tape input - there are plenty of old KVM (Keyboard Video Mouse) Computer switchboxes around with 5 pin Din Keyboard connectors. Many companies are throwing them away these days.

Ignore the Video and Mouse connectors (if it has those).

Find one with a 1-port input + 4-port output. Open it, and you'll see a single diode on the keyboard wiring - remove the diode, and solder the wire directly to the terminal.

You might want to spray it black to match the vintage B&O colours.

Menahem

yachadm wrote:

You don't need to bypass the Tape input - there are plenty of old KVM (Keyboard Video Mouse) Computer switchboxes around with 5 pin Din Keyboard connectors. Many companies are throwing them away these days.

Ignore the Video and Mouse connectors (if it has those).

Find one with a 1-port input + 4-port output. Open it, and you'll see a single diode on the keyboard wiring - remove the diode, and solder the wire directly to the terminal.

You might want to spray it black to match the vintage B&O colours.

That's a wicked idea! 😁 Actually a PS/2 switch should work as well as PS/2 and AT keyboards are electrically compatible, but the required adapter cables would probably make it a senseless idea in practice...