Beogram 3000 / Beosound 4 sound quality issues

[CharlieWednesday]

I’ve noticed some sound quality issues with my Beogram 3000 when connected to my Beosound 4.  Because the BS4 does not have a phono input, it is connected via a phono stage.  I have two phono stages, one was quite cheap (but useful as it has DIN input) and one more expensive Pro-Ject one.  I’ve tried both, but I’m getting some poor quality.  I’m no audiophile but it’s just not right – it’s not separating well and there is some distortion at the top and bottom.

I was worried it might be the turntable or the MMC4 (which I recently had re-tipped at some expense), so to test it, I connected it to my Beocenter 8500 instead (which I usually use with a Beogram 8500, in a different room), and connected my Beolab 6000 speakers to that too, so I could do a real comparison.  It sounded so much better – at least I know from this that it is unlikely to be the turntable or cartridge that has the issue – it’s got to be the phono stage, the BS4, or the cabling.

However, to perform a true test with the Pro-Ject phono stage, I need to ground it.  Can anyone tell me, on the DIN plug, is it the ring that provides the ground?  Or, could I just ground the BG3000 by connecting a wire to one of the two screws on the back (there is one either side, at the back of the lid), leading to the ground on the phono stage?  It may be that the cheaper of my two phono stages is the problem, I’m hoping so anyway!  It does cause a lot of interference and the quality varies if you move the phono stage at all while in use, so I’m guessing it might just be quite poorly built.

The Pro-Ject one is already in use on another (non B&O) HiFi in the house but if I can get it connected and grounded via that one, and it sounds good, I’ll just buy another the same.

[Madskp]

Based on this post the outer ring in the DIN connector has a separate wire on a Beogram 2000, so pretty sure that must be a ground connection https://forum.beoworld.org/forums/topic/how-to-wire-7-din-plug-to-beogram/#post-53422

My parents has the same cheap Riaa amplifier as you have (you mentioned in another post). I remember  the  first time I connected it there was some hum. I noticed that because the DIN connectors on the RIAA is recessed the outer casing on the wire DIN plugs can be a little fidely to get into the the connector. It was like it had to be alligned very precisly to get the connector get to the bottom. Hope that makes sense

I know your problem is not hum, but a bad connection can make all sorts of trouble, so maybe worth to try

[CharlieWednesday]

You were right – the DIN connection was quite poor because of the recess in the casing.  If I pushed it in more firmly, it gave a better connection.

I also switched the output cable from the phono stage to the BS4 for another one, just in case there was an issue there (though they were both good quality RCA cables).

It does sound much better now; not as good as when connected with the Pro-Ject phono stage, still a bit flat, but not bad.  I still think I’ll buy another Pro-Ject one th0ugh, now that I know how to earth it!

[Madskp]

CharlieWednesday wrote:

You were right – the DIN connection was quite poor because of the recess in the casing. If I pushed it in more firmly, it gave a better connection.

Good to hear that was also the case with yours and ended up making it better

[CharlieWednesday]

Also you were right about the ground being in the ring of the DIN.  I got a proper DIN female to RCA male adapter today, and connected it to the phono stage via RCA (the phono stage in question having both DIN and RCA inputs and outputs).  I made the ground connection by just jamming a pierce of thin shielded wire into the edge if the DIN ring, and connected that to the ground connection on the phono stage.  The earth hum was definitely gone.

I will play test it for a few days and see if I am happy with the sound quality of the cheap phono stage.  If I’m not, I’ll buy a better one – at least now I’ll know how to earth it.

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