Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Meridian - Systems 502 input switching noise

Hi all,

I've been happily using my 502 with a pair of M2s for a few months now.

I recently bought a new (to me) phono stage, a Roksan ArtaXerxes X, and now when I switch to the input for the phono stage I hear a moderately loud pop. I previously had another external phono stage (Musical Fidelity X-LP) connected on the same input with no such noise. In addition this is the only channel on which I get any noise when switching inputs.

So my question is: is this anything to worry about? Has anyone else had experience of this?

Thanks in advance!

Peter

It’s not necessarily a solution; but, many years ago I suffered from a similar popping noise from my 500 Series kit.

The culprit was a twin set of wholly carbon constructed VanDenHul RCA interconnects. Replacing them with something less ‘esoteric’ from VanDenHul resolved the issue.

That's interesting, thanks for the reply. Did you find it was particular front-end gear that was affected, or more widespread?

They connected my 506 to my 551/555: as the volume was increased or decreased there was a constant popping noise heard through my A500’s.

Replacing them with VanDenHul D102 interconnects totally eliminated the problem.

A helpful audio dealer might be willing to loan different interconnects to you to ascertain if that is the issue (or not).

If that is not the cause of your problems then it might be related to when you initially switch-on your external phono unit.

FWIW, when I switch-on my DSW.2 I always hear a momentary low-level ‘bump’ through the device.

YMMV

After doing a few tests earlier I left the system on for a few hours. I tried switching inputs again and now I hear no popping noise. So it must be something to do with the period of time the phono stage has been left on (charging up caps??). I have heard some people recommend leaving phono stages on anyway so maybe that's what I'll do to work round the problem.

This could be a difference in ground levels, or a DC offset in the phono stage.

As above, the offset may have levelled out over time, this points to (very) tired power supply capacitors.

You could try linking the earth points on the phono stage and the 502 to make sure there is no difference in ground levels, but this could lead to an earth loop hum, but cheap and easy to try.

All the best,

Steve

Thanks for the info on this Steve. So would the ideal solution be to replace the capacitors you mentioned?

Ideally you should get the power supply capacitors checked on the Phono Preamp by a tech who knows what to look for.
My suggestion was an educated guess that the capacitors are worn and gradually have enough charge to be stable and not have any DC offset etc.

I'd try linking the ground pins on both to see if that cures the pop first, any wire would do to test, a 'speaker cable off-cut for example.

Have you tried it again without the phono preamp being left on to see if it persists?

Guess you are using the Roksan ArtaXerxes X with the DS-U (little square black box the same shape as the phono stage) power supply?

I had one of those DS-Us let go so they are not totally reliable. IIRC, they come from a time when one left all equipment constantly power up. One friend left his turntable spinning 24/7. Those behaviours tended to put a strain on the electronics. The DS-U has an on-board power switch but that controls the output; the box stays active when connected to live mains - at least mine does - so it gets switched off at the outlet.

Roksan offer alternative power supplies but it is a long time since I dabbled and cannot remember what is compatible with what.

Touraj will advise or probably be able to fix your current unit if it is indeed faulty.

Thanks Steve - I will dig out a length of wire later and test linking the ground pins. I just tried it again after the phono stage had been left off overnight and it's exactly the same as before with quite a loud pop.

That's right, it's using a DS-U. Coincidentally I have another DS-U which is powering my Xerxes's speed controller, so I could theoretically swap them over to see if that makes a difference. Visually the two DS-Us look identical other than the matt finish on the one I bought with the ArtaXerxes. I've had no trouble with the other DS-U/XPS3 over the ~20 years I've owned the turntable, although maybe powering the phono stage is more demanding.

I did consider contacting Roksan but I think Touraj is now with another company - Vertere? - not sure whether they support old Roksan gear or not.