Hum from Descent i

[dutiel]

Just fired up the Descent i sub today and noted a (60 cycle?) hum. This is unchanged whether or not anything is hooked up and is unaffected by the volume control.

Have not been able to get to service and am at a loss. Any ideas out there?

Thanks!

Greg

 

[Necrosuit]

What is hooked up to it? Amp, Music server? any wireless devices? grounding?
the reason I ask is because I had a similar issue and it was from my Sonos device being above my amp, even 3 feet above my amp! soon as I put that thing on the floor all the noise was gone.

 

[dutiel]

Descent i hum

The hum is there even with nothing except the power cord hooked up; I tried a ground lift and it did nada. I hooked in the line in and, until I attached the other end to the pre-out on the amp, the hum was perhaps 80% reduced but once I attached to the amp, it worsened. Ordered an Art's Clean Box to address this but it is still disappointing in something so expensive as this

 

[Necrosuit]

Have you tried differnet power cables? different outlets? move the sub from that area to another?

 

[dutiel]

The hum

could not find another power cable - the one supplied does not have ground, so I will need to go out and find another but I did try several outlets with no difference noted.

 

[churchill]

Contact Melody at ML service, her email is [email protected]

 

[dutiel]

many thanks

 

[Hauger92]

It could be a 75ohm RG6 coax cable that's giving off RF. Unplug the coax from your cable/satellite/VCR and see if the hum goes away.

 

[autoformer]

I had the exact same problem

I had a brand new Descent i with the exact same problem that I'd purchased in December with precisely the same symptoms you describe. Everyone I talked to, including my dealer, had me chasing down ground loops. None of my other equipment was making noise. The Descent i itself does not use a ground, so a ground lift did nothing.

My sub was powered by a PS Audio Power Plant Premiere. I tried different electrical circuits within my home. I tried using power from the neighbor's house. I tried a UPS running on battery power. I tried a Honda generator. The sub behaved the same in all cases with just power connected. The sub was not connected to any other components. Just the power plug.

Finally, the dealer agreed to ask Martin Logan to send a replacement. The replacement arrived from UPS trashed, with the grilles dented and the chinks in the cabinet. Martin Logan was very apologetic and sent a third unit via air freight. Plugged it in and it works just fine.

Mine was just a defective unit.

The hum is there even with nothing except the power cord hooked up; I tried a ground lift and it did nada. I hooked in the line in and, until I attached the other end to the pre-out on the amp, the hum was perhaps 80% reduced but once I attached to the amp, it worsened. Ordered an Art's Clean Box to address this but it is still disappointing in something so expensive as this

 

[dutiel]

The hum

Thanks for all the input! Looks like it is a defect, so I will be pursuing with ML.

Greg

 

[Speedskater]

On Ground Loops

Ground loops can only happen when multiple cables (be they AC power, interconnects or cable TV in any combination) are connected between units. In simple systems speaker cables are probably not part of the problem.

So if the only connected cord is the power cord, you can't have a ground loop.

 

[dutiel]

I agree - finally got with ML and through trial and error, the culprit turned out to be the servo within one of the speakers (no, I never heard a speaker hum when it was not induced by the amp or the wire but they were familiar with this trait).

Thanks again to all.

 

[jshowalter]

I'm really glad I found this thread. This is exactly the symptom our right Descent-i is exhibiting. Thank you!

 

[Stefan_DR3]

Glad I found this thread too! Just picked up a brand new Descent i and there is a quiet humming noise coming from all 3 woofers, regardless of connection or settings.

This thread suggests it was a common problem about 2 years ago. I was told by my dealer it is the last one in Canada. Not sure how long it was sitting in the distributor's warehouse. Any way to decipher a build date from the serial number?

 

[Stefan_DR3]

Got the sub replaced with a much newer build and the hum is gone, but still a slight noise up close.

The box was different (cube instead of hexagonal) and serial number has more characters that doesn't fit the old decoder posted in the sticky thread. Is there a new decoder?