Beogram 8000 cable

I'm actually repairing an old DIN cable and a question just pop off my mind: When I got my 8000 system, only one cable was usable: it was the TP1 (factory original, with a B&O sticker identifying it). I always used it to connect the Beogram 8000 to the Beomaster. (Never had the original Phono cable, and I never use the Beocord anyway)

Though I don't have any problem with it and the sound was, and still is great (at least from what I always perceived), I wondered if that "TP1" cable came with a chassis ground, isolated from the common ground. (a silver wire wrapping around a bronze wire wrapping) Or does it really matters?

But since B&O identified these cables in the 1st place, perhaps it does matter?

Thanks

Guillaume

It DOES matter.
But maybe you just got lucky or maybe the last production cables were made universal - it would work.

The main difference between the original TP and PH cables is the double shielding and the fact that the TP cable is wired
both ways (record and playback), where the PH cable is playback only.

Martin

Thanks Martin,

I verified: there's NO! continuity between the metal casing at each side of the wire. However, looking at the schematic of the Beomaster 8000 inputs, it seems every casing of every inputs should be connectected to chassis ground. So I wonder why my original wire doesn't:

In the Beogram 8000 schematic, the chassis ground seems to share the same symbol as the common ground:

do I understand that they are connected together ?

Two years ago, I had problems connecting that turntable to a beomaster 2400 (with extra pins) and with the same wire. A big hum was heard which could only be solved by keeping the extra pin 7 in the cable (datalink ground) but removing the sixth one.

Perhaps this pin happens to make both chassis at the same ground potential ?

Though I never heard any noises when connected to the Beomaster 8000.

Weird... I definetely need a proper wire connection. Why it took me 3 years realizing it...

Guillaume

Note the different ground symbols in the schematics.
The signal ground (pin 2 in the DIN socket) has a solid black ground symbol. That's the ground reference for the audio signals.
The protective ground (the metal shield of the DIN socket) has an earth symbol. That's the chassis ground = the metal of the record player
and the amplifier = the earth connection if a three-prong mains plug is used.

Both grounds MUST be carried through from the record player to the amplifier and they MUST be kept separate.
Typically (but not always) somewhere in the amplifier, there is a small capacitive coupling between the two and that's how it should be.

Martin

Thanks Martin for the clear explanation,

I definitely need a new cable then. However, they seem somewhat hard to find. Especially with their extra pins. If I would have it, i could even connect the beocord permanently (and finally see how it operates with the beolab terminal.)

Time to start looking for a new cable then..

Guillaume

I'm sure, that Steve at Soundsheavenly can make a good and correct cable.

Martin