Beogram 4004 Type 5526: Last minute mod on the Beogram 4004 Turntable #1 from Dallas

The Beogram 4004 turntable number one (of two) from Texas was ready to return home to its owner when a special modification was requested. The owner has a modern integrated Bang & Olufsen system from the late nineties (Beocenter 2500) that is now the intended receiver for this Beogram. That presents a problem because the modern systems do not come with a built-in RIAA preamplifier which is required to prepare raw phono cartridge signals for amplification. The resurgence in the popularity of vinyl records has meant a whole bunch of amplifier systems out there without support for phonographs.

There are quite a few third party solutions of course. Those involve a small RIAA preamplifier box between the turntable and the modern amplifier. That works quite nicely but there is a better way when it comes to a Beogram 4002 or 4004 turntable.

Beolover has designed and built a custom Beogram 4002/4004 RIAA amplifier board that connects right into the Beogram (on the existing output board).

The beauty of this design is two-fold.

1. The modification is internal to the Beogram so it doesn't require an external box and additional cables. The original phono cable is used as-is.

2. The modification retains the original connections so the Beogram can still be used with amplifiers that have their own RIAA preamplifier.

The installation of the Beolover RIAA preamp is quite easy.  Here is the sequence.

In most cases the installation is just to remove the phono output muting relay and solder in the custom RIAA preamp board. For this case I also had to remove the grounding option switch I had installed earlier in the project.

The grounding option is not necessary when using the RIAA preamp connectors. If the owner wants to change the receiving amplifier for this Beogram later, to one that has an RIAA preamp, then the grounding option is still nice to have.  The switch I had installed before would be in the way so it has been replaced with a simple two-pin jumper between signal ground and system ground.

Here is the Beogram 4004 output board with the new RIAA preamp mod re-installed.
This picture shows the board connected up for use as the original Beogram....without any RIAA preamplifier.  I want to test that the original functionality works first.  Then I will switch it to use the Beolover RIAA preamp connectors and test the Beogram in that configuration.

If any other Beogram 4002/4004 owners would like to try this preamplifier for their Beogram just contact Beolover at beolover@gmail.com.