Jay's Audio CDT2 MK3 hum


Hi all! Greetings from Poland. My first post here after years of reading the forum!

 

Recently I have purchased Jay’s Audio CDT2 MK3 (230V European version), actually following the comments and recommendations read at Audiogon. All is great with it except the hum it emits from its casing. I should say “hums”. The one that was occasionally audible from the left side (where transformers sit) I eliminated by using a DC-blocker. However, there is audible hum peaking at 300 Hz coming from the right side. Its level is dependent from line voltage which at my place sometimes reaches and exceeds 260 V (230 V is nominal voltage) for short periods during sunny days (lots of PV installations around and old power lines). I tried on-line UPS with selectable voltage output and there was no hum at 220 V, neglectable at 230V and audible from my listening position at 240V. At 250V and above it is really bad. Of course I can’t hear it while music plays but it is annoying when in standby. It is kind of fake standby as in fact the unit seems fully powered except for the display. It takes 12W playing and 9W in standby or turned on (not spinning) with display off.

 

Obviously, I tried it disconnected from my DAC, different lines in the house, turning off all the lines except the one feeding my audio. The hum from the right side of the unit is ONLY dependent on the voltage. My old Copland CSA14 and new CSA100 and old Roksan Kandy amps don’t hum. My Copland CDA266 and Roksan Kandy CDPs don’t hum. Does not matter how low or high the voltage is.

 

I contacted Beatechnik and they said it should not happen and advised to check it in their service in Slovenia. Paid, as I purchased it from a private importer, so it is not covered by their warranty. In the meantime I bought a voltage controller with servo motor which keeps the voltage right. Not really a correct hi fi approach I guess.

 

So, my question to Jay’s Audio CDT2 MK3 owners, preferably from the EU, can you hear any hum from your units, coming from the right side of the casing? Does it fluctuate depending on mains  voltage?

Thanks for reading and looking forward to read about your experience!

tomasz1964

@tomasz1964 

I am in the US and never seen my voltage exceeding 122V, but it seems that you have solved the problem with regenerator, congratulation. Now, stop worrying🙂

BTW, my name is Tomasz as well.

@knock1 Hi Tomasz! So you must have Polish roots :)

Been traveling a bit but finally got the transport to the seller. He's borrowed an autotransformer to play with higher voltages than nominal and confirmed my observations. He's found that once the top lid is off there is no hum audible. He experimented a bit with the transformers, which don't produce any audible sound when the lid is off. With the lid on the screws needed loosening to silence the hum. So, the whole thing that bothered me whole summer is the transport housing resonance amplifying otherwise inaudible vibrations of the transformers. Hell knows why it is the strongest on the right side. I am relieved that it is only a mechanical "issue" and nothing wrong in the electronics. Although I fixed it by using a cheap voltage stabilizer, I might try to put some  anti-vibration insulators under the trafos, So there would be no rigid connection between the transformers and the transport housing. 

Again, thanks for all the comments.