Marantz cd600ose hum/buzz

[safe1]

Dear all,

I have a Marantz CD600OSE player and one problem with it which i never managed to get rid of.

To the point:

My CD player is sit one shelf below the top shelf of my rack, where (at the top) sits a Rega P3 turntable.

If the CD player is powered on it introduces hum and buzz to my Rega turntable (amplifier input selector is in Phono/Rega's input position...).

- I disconnect the CD Player's interconnects and still get the same hum/buzz from my turntable (i don't have to spin a record to hear it, it's audible even if the turntable is idle and i simply turn the amplifier volume up).

- I power-off the CD Player and the hum/buzz from the turntable is gone

- I power-on the CD player and take it off the shelf, moving it about 1 meter away and the hum/buzz is gone.


I'm convinced that it's something wrong with the CD player. It introduces hum/buzz to the turntable even without interconnects attached to it. It only happens if it's powered on and near the turntable (one shelf below it actually).

Any ideas how to fix it?

(in another thread i posted that i believe that the problem might be Marantz's transformer. I'm not sure though).

[Fidelity Audio]

I don't think the cd is actually faulty, you possibly have a bad gnd / earth on your deck. Check the interconnects on the deck and the cartridge + the arms gnd.

The pickup is either being picked up by the cartridge or the interconnects, the noise will more than likely be picked up from the cd players tx.

Brent

[safe1]

Is there an explanation why this phenomenon happens only when the cd player is powered on?

There is also an amplifier, a tuner, a phono preamp and a Musical Fidelity X-10D line conditioner on the same rack...

None of them causes any hum/buzz to the turntable.

[Mooly]

Have you tried rotating the CD in the position it is in... it's not the answer but may help to show you the problem is caused by the lines of force from the transformer.

I agree with with rowemeister, and really it's the Rega that's at fault, rather than the Marantz.

How to fix it... first determine if the Rega is compromised in some way with regard to shielding and grounding. Is there a separate ground wire from TT to amp ?

Free space between the two is the easiest and cheapest solution. The only material that might help for shielding is mumetal (but where are you going to get that these days)

Mu-metal - Wikipedia, the free encyclopedia

[safe1]

Hi Mooly,

There is a ground cable running from the turntable tonearm to the Creek phono preamp ground post.

My TT interconnect cables are a single run from the TT cartridge to the phono preamp (and considering the ground cable it runs from the TT tonearm to the phono preamp).

Then i have another interconnect running from the phono preamp to my amplifier. That's it.

Should i try to connect the TT ground straight to the amplifier grounding post by-passing the phono preamp's grounding post ?

[Mooly]

What happens if you don't connect the TT to the preamp at all including disconnecting the separate ground wire, and perhaps just put shorting plugs in the input sockets on the preamp . Any hum present now ?
Now leave the shorting plugs in place and recoonect the separate ground to the preamp . Any change ?

Also make sure the arm really is grounded... measure it on ohms to the ground post.

Depending on the outcome have you tried different interconnects, bit of a long shot but some can be poor.

Problems like this can have odd causes. oes the TT also have a mains earth in the supply lead.

[safe1]

Originally Posted by Mooly

What happens if you don't connect the TT to the preamp at all including disconnecting the separate ground wire, and perhaps just put shorting plugs in the input sockets on the preamp . Any hum present now ?
Now leave the shorting plugs in place and recoonect the separate ground to the preamp . Any change ?

Also make sure the arm really is grounded... measure it on ohms to the ground post.

Depending on the outcome have you tried different interconnects, bit of a long shot but some can be poor.

Problems like this can have odd causes. oes the TT also have a mains earth in the supply lead.

Hi again,
i did some further tests as advised...

(amplifier's source selector to the phono-preamp output all times...)

Test 1: disconnected all TT cables from the phono-preamp inputs.

Outcome: Marantz cd player does not introduce any buzz when powered on.
I can hear hiss though (unnafected by the cd-player) through the speakers.
Must be because phono-preamp does not have anything connected to its input.

Test 2: disconnected all TT cables from the phono-preamp inputs but now connected RCA shorting plugs to the preamp inputs.

Outcome: Very loud (and different) buzz coming out of the speakers which is totally different and irrelevant to the power state of the Cd-Player (on or off).

Test 3: same as test 2 but now connected the TT's ground on the phono-preamp ground post.

Outcome: same as in test 2. nothing changed.

Test 4: removed the shorting plugs from the phono-preamp and reconnected the TT RCA left/right channels on it (ground is still connected on the phono-preamp post).

Outcome: for as long the Marantz CD-player is powered off eveything is fine.
When i power it on the buzz is back -> this is the original problem.

Test 5: Left anything as in test 4 but now removed the TT ground from the phono-preamp post and connected it straight to the integrated amplifier ground post.

(yes it has one and it also has phono inputs but misses the phono preamp daughter card which is at extra cost -> Exposure 2010.)

Outcome: same as in test 4.
If i power on the Marantz cd player the buzz comes in. If not, everything is fine.


Note that i did test 4 and 5 before while i had completely removed the Marantz cd-player interconnects and left only the power cable connected to the mains outlet. So Marantz interconnects are irrelevant to the problem.


Any ideas?


EDIT: i also checked with a multimeter the TT's ground cable for continuity from the arm to the pre-amp ground post and it appears OK.

Turntable's mains cable does not have mains earth
Phono preamp's power supply does not have mains earth
Tuner's mains cable does not have mains earth
CD-Player's mains cable does not have mains earth
X-10D line conditioner's power supply does not have mains earth
Integrated Amplifier's mains cable DOES have mains earth.

[Mooly]

That was good timing lol

Test 1... result as expected OK

Test 2... Something amiss... it shouldn't hum if the signal and ground are shorted at the input sockets.

Test 3... you need to find why test 2 is doing what it does

Test 4 and 5... Is the interconnect lead captive from the TT or can you swap it ?

The result of the shorting plugs is odd, I'm sure you agree... can you recheck that, first one channel shorted, then the other, then both. Are they normal RCA/Phono inputs ?

[Mooly]

Originally Posted by Mooly

Are they normal RCA/Phono inputs ?

And you are shorting the centre pin to the outer ground with a blob of solder, using a couple of old phono plugs with no other wires attached ?

[safe1]

i will recheck asap