The hum in my Prima Luna Prologue Premium integrated sounds like a constant 60hz. It is in both channels equally, Its amplitude is not affected by the volume control and muting the amp does not make it go away. My guess is that it's coming from the rectification circuit or some shielding did not get installed during manufacture. I bought it to power some 105db speakers. It is useless in this application.
- ...
- 72 posts total
| Post removed |
The hum in my Prima Luna Prologue Premium integrated sounds like a constant 60hz. It is in both channels equally, Its amplitude is not affected by the volume control and muting the amp does not make it go away.Now that sounds like a typical ground loop hum. For the test below feed all the associated audio equipment from only one wall duplex receptacle outlet circuit. You can repeat the test later if you have more than one circuit you are using to feed your equipment and then check for hum again. First disconnect all the source equipment from the inputs of the amp. With nothing connected to the inputs of the amp check for the hum. (I assume the amp uses a 3 wire grounded plug and power cord). No hum? Add/connect one piece of source equipment to the amp’s inputs. Check for hum. (In most cases the source equipment will use a 3 wire grounded plug and power cord that may be causing the ground loop hum). Hum? Disconnect that piece of source equipment from the amp’s inputs and then try another piece of source equipment and connect it to the amp’s inputs. Check for hum. Hum? If yes, good chance it is the integrated amp causing the ground loop hum problem. If no hum, then it’s a good chance it is the first piece of source equipment you connected to the amp’s inputs. Try all other pieces of source equipment and check for hum. If no hum, then start reconnecting the source equipment, that did not cause the hum, back to the amp one piece at a time to the amp’s inputs checking for the hum. If by chance you have a CATV cable box or a SAT dish box connected to the audio system in anyway start there first. Disconnect the incoming coax cable from the receiver box. This a prime suspect for a ground loop hum problem. What happens is there is a difference of potential, voltage, from the incoming coax cable shield and the safety equipment ground at the wall AC power outlet. In most cases the coax cable shield is not ground properly outside at the grounding block on the outside of the house. |
I’ve worked with the national distributer trying most of what you suggest (cheater plugs, with source, without source etc.). The only thing I haven’t done is unplug everything in my house. I’d bet green money that the integrated is the source of the hum. My Balanced Audio Technology integrated is silent using the same electrical circuit. The noisy amp is under warranty. It works well with normal speakers so I may try to trade it in for some quite tubes or the new Pass Labs 25 watt SS amp. Thanks for your concern and advice. |
dweller, Does the integrated amp hum with nothing connected to any of the inputs? Does the hum sound like this? 60Hz. https://www.youtube.com/watch?v=SVZ2P0KsLic https://www.youtube.com/watch?v=Lnd57eOyesk . Or like this? 120Hz. https://www.youtube.com/watch?v=pC4Uzt0qm2E . Check this out. A tube causing a 60Hz hum? https://www.youtube.com/watch?v=GrVtX0QGNls |
- 72 posts total