Not a ground loop hum???

Sean, the MR1200 does indeed convert the AC from the wall into balanced power provided at its outlets. Are you saying that it should not hum regardless of how dirty the incoming AC may be? That was my assumption when I purchased the piece, given the filtering that it is supposed to perform and the positive reviews that BC has garnered for their balanced power line conditioners.

I've got the product designer/maker telling me that the noise is due to really dirty AC and that there's nothing to be done except have one of their power cords fitted with a quiet device that will resolve the noise issue in the MR1200. On the other hand there is the possibility of a QC issue with my unit.

I'm going to test the MR1200 in the new house next week and see what happens. If it's still noisy, perhaps I'll send it to BC for a check-up. Beyond that, I'm just not sure what to do.

Danny, I'm guessing the main difference is that the HT1000 does not have a transformer, or at least not one that converts the incoming AC of 120v in relation to ground into balanced AC of 60v from the hot and 60v from the neutral, so there is no possibility of transformer hum. The purported advantage of a balanced power line conditioner, such as the Blue Circle Music Rings among others, is that it offers even greater benefits in terms of lowered noise floor, etc. Not in my set-up though.

Thanks once more for the input. Much appreciated.

Max

Check out the Granite Audio website for a product called Ground Zero. I bought one of these units after going through the same process you have with no luck and lots of frustration. Ground zero took about 20 minutes to connect to my system and it completely eliminated the humming altogether. What remains is the darkest background and lowest noise floor I've ever had in my system. Simply amazing! It was worth every dollar spent. Check it out!

Completely forgot to provide an update on the situation with my MR1200. Well, after trying it out in our new house and hearing the same level of noise, I sent the power conditioner back to Blue Circle, paid for shipping and about $60 for the filter add-on. They also checked it for mechanical and QC issues. Once I had it back home and inserted into the audio system, no more noise/hum from the unit!

Now I have two other noise isses to resolve. One is hum from the speakers, which increases in intensity as the volume is turned up. Could this be the inherent noise from the tubes in the preamp and or CD player? I've read in a couple of places about the noise from high gain preamps being audible through high-efficiency speakers? My speakers have a rated sensitivity of 101dB.

The other noise I recently discovered when I tapped the chassis of my preamp by accident. I gave the middle of the face plate a a light rap and heard distortion out of the left channel speaker. Any ideas?

Thanks again for any advice and suggestions.

Max

Your hum could easily be residual hum from the tube pre-amp, although in my system it sounds more like tube rush/hiss. Do I assume correctly that this hum is well below the level of the sound of the music you are playing? Tapping the chassis, probably a microphonic tube in the left channel.

Hi Newbee,

Thanks for your response. That's correct, the hum is not audible when music is playing.

Damn that tube! I don't know a lot about tubes, but I should have thought about the possibility of it being microphonic. Time for a new pair I guess.

Regards.

Max