[alexerwu]

I have just received the RKV II 2 days ago from
Meier-Audio. However, it has now developed a hum in
both channels. I have tried switching power cords,
switching the position of the tubes and switching
amplifiers. My Sugden headphone amp placed in the
same configuration (same power cord, interconnects
...etc.) does not exhibit this hum.

Any opinions/suggestions?!

Please note that I do not think this is a power source problem as my AC source is obtained through a PS Audio 300.

 

[wallijonn]

have you tried listening to it connected directly to an AC socket (bypassing the PS Audio power distribution unit)? (and with the PS Audio 300 completely disconnected from house wiring)?

 

[alexerwu]

Quote:

have you tried listening to it connected directly to an AC socket (bypassing the PS Audio power distribution unit)? (and with the PS Audio 300 completely disconnected from house wiring)?

Yes I have. There was no discernable improvement in the hum.

 

[lextek]

Serving in Ecuador had a similar problem. He noticed if the headphone plug was pulled slightly out of the jack. The hum would go away. He later found out the problem was caused by something else. i can't remember what it was now. Try a search.

 

[Hirsch]

Is the hum in both channels?

Is your source plugged into the same outlet?

Are you using a three prong power cord?

 

[alexerwu]

Quote:

Is the hum in both channels?

Yes. I have also tried both of the 1/4" headphone jacks with same results.


Quote:

Is your source plugged into the same outlet?

Yes. Back of the PS 300 has 4 outlets. However, I have also tried connecting the RKV to a separate outlet and have encountered the same hum.

The PS 300 is set at sin wave 60 Hz. 117 V (i.e. standard setting)

Quote:

Are you using a three prong power cord?

Yes. Standard IEC cord.

Thanks for everyone's responses so far...

 

[Hirsch]

Quote:

Originally posted by alexerwu Yes. Standard IEC cord.

You might want to try floating the ground. My RKV came with a two-prong cord. You can get a "cheater plug" that will convert a three-prong cord to a two-prong cord at Radio Shack, IIRC. This can sometimes clear up ground loop issues. A bad ground connection inside the unit is going to be more difficult to find.

Also check to see that your source is connected properly in the rear. There are two sets of jacks in the rear. They are arranged horizontally in pairs. Once an input is connected to one set of connectors, the other pair becomes a passthrough automatically. Vertical or diagonal connections would be bad...

 

[wallijonn]

the most prudent thing to do would be for you to email Jan and ask for his suggestion. chances are he's already heard all the different symptoms, and his techs have told him all the fixes (like tightening or loosening the toroidal transformer screw 1/4 turn, checking the rectifier tubes, checking for loose capacitor screws, etc). He may want you to return the unit if he feels that it needs a toroidal transformer replacement.

btw, I am going through the same thing with my Monarchy SM70. The manufacturer is sending me some cheater cables. I don't know if I want to keep it even if the hum problem is rectified, since I specifically asked that the unit not hum before it was sent to me. supposedly he checked with sensitive speakers. my problem is that i want to use it with headphones.

and make sure you've turned off all flourscent lights in the vacinity, don't put near a computer, etc. test for hum with no inputs or shorted rca inputs. chances are that your hum is in the power supply. why mess with it if Jan can repair it under warranty?

 

[joelongwood]

Quote:

Also check to see that your source is connected properly in the rear. There are two sets of jacks in the rear. They are arranged horizontally in pairs. Once an input is connected to one set of connectors, the other pair becomes a passthrough automatically. Vertical or diagonal connections would be bad..

I agree with Hirsch......this is what caused Servingecuador's hum.

 

[alexerwu]

Thanks for everyone's suggestions so far.

I have contacted Dr. Meier and Helmut concerning this problem and will keep everyone posted.

One thing that I neglected to mention was that the inputs are properly connected. I used the lower pair (horizontal). Also, I have been able to enjoy the use of the amp the first day in the same configuration. It was only on the 2nd day that the hum manifested itself for no apparent change in system configuration.

 

[ServinginEcuador]

Make sure that you connect the RCA jacks to different connectors on the back of the amp. I had the same problem until I realized that the RCA's are shorted together internally, and if you hook up to the same one with both outputs from your source you'll get this problem. You'll have to connect one input to the top connection, and one to the bottom. Not two across from each other.

If you are connected to the lower pair still, as you stated, move one RCA to the upper jack and your problem will go away immediately.

 

[wallijonn]

SE,

I think I may have to start calling you Mighty Mouse

 

[ServinginEcuador]

Here's a quick photo of the inputs that are internally shorted on the RKV. You'll notice that the shorting bar goes horizontally, thereby making the hum when connected in that manner. We should make sure that we post some info on connecting the RCA inputs on this thing as it is confusing. It always has to be connected using one top connection, and one bottom connection.

 

[joelongwood]

I dunno, Serving. Mine is connected horizontally, using the two bottom inputs. The manual states this is the way it should be done. And i have no hum whatsoever......silence.

 

[Hirsch]

Quote:

Originally posted by ServinginEcuador Here's a quick photo of the inputs that are internally shorted on the RKV. You'll notice that the shorting bar goes horizontally, thereby making the hum when connected in that manner. We should make sure that we post some info on connecting the RCA inputs on this thing as it is confusing. It always has to be connected using one top connection, and one bottom connection.

That's not a shorting bar. Note the piece of plastic on the top set of jacks separating the right and left connector leads going to the board at the side.

Have you tried using both top connectors, or checking for a possible short on the bottom set only? Mine works fine using either set of connectors, with the other set working as outputs.