HUMMING Through Speakers

[nmastrandrea]

I am getting a humming noise. I haved tried everything i can think of. Monster line conditioning, seperate outlet from a different line in the house.

I have Classe' amps CA400 for the Requests and CA75 for the Cinema center and for the script rears. Not sure if they are the culprits or this is an inherit problem with Martin Logan.

any suggestions are welcome

Nick

 

[Dreamer]

The guy I bought my Krell preamp from was running Classe' amps, and he had a SERIOUS problem with ground loops. I'd suggest that it's not your speakers at all, but a ground loop issue somewhere further back up the chain.

Classe' amps (and to some extent, my Carver amps too) are sort of notorious for this, especially the ones with 2-prong power cords, when mixed into a system with other components that have 3-prong cords. I know that using a "cheater" plug on other gear is a big no-no, but it is the only way I (and the guy I bought the Krell from) could get the hum out of our systems when we put the Krell in the loop. Almost all my other gear (Amps, Carver C-400t, CD players) use 2-prong power cords, and the Krell has a 3-pronger. Using a "cheater" plug on the Krell eliminated the hum., and I'd tried everything--even running a long, heavy-duty extension from another part of the house that I KNOW was on a different breaker...

If you have a powered subwoofer, that can be a major culprit too.

One more thing is your TV cable. If you are using an AV pre/pro, with your cable feeding into it (in ANY way except HDMI or TOSLINK, which seem to be immune to this) and I mean any way--F-connector, composite, or component for video, Digital coax OR analogue stereo for sound--it can cause hum in your system due to strange grounding issues in some cable systems. You can put "ground loop isolators" in the line before it comes into your cable box, or right before the connection enters the pre/pro--different approaches work better for different setups.

Isolating a hum can become a VERY expensive and mind-numbing crusade--buying isolators, transformer, and filters, re-wiring your mains, etc. I know there were a few times when I was ready to throw my Velodyne sub off the deck into the trees when I first hooked it up. But a lot of logical thinking, and some diligence with power filtering, cable layout, connection logistics, and some creative multimeter probing finally got the problem solved...

Tracking down and eliminating the dreaded hum can drive you absolutely nuts. Good luck!

--Richard

 

[mikesinger]

.

One more thing is your TV cable. If you are using an AV pre/pro, with your cable feeding into it (in ANY way except HDMI or TOSLINK, which seem to be immune to this) and I mean any way--F-connector, composite, or component for video, Digital coax OR analogue stereo for sound--it can cause hum in your system due to strange grounding issues in some cable systems. You can put "ground loop isolators" in the line before it comes into your cable box, or right before the connection enters the pre/pro--different approaches work better for different setups.

Disconnect your cable from the pre and and see if it goes away. If it does then you have your culprit. I had to add a Aragon Magic ground box to my cable feed.

 

[nmastrandrea]

The guy I bought my Krell preamp from was running Classe' amps, and he had a SERIOUS problem with ground loops. I'd suggest that it's not your speakers at all, but a ground loop issue somewhere further back up the chain.

Classe' amps (and to some extent, my Carver amps too) are sort of notorious for this, especially the ones with 2-prong power cords, when mixed into a system with other components that have 3-prong cords. I know that using a "cheater" plug on other gear is a big no-no, but it is the only way I (and the guy I bought the Krell from) could get the hum out of our systems when we put the Krell in the loop. Almost all my other gear (Amps, Carver C-400t, CD players) use 2-prong power cords, and the Krell has a 3-pronger. Using a "cheater" plug on the Krell eliminated the hum., and I'd tried everything--even running a long, heavy-duty extension from another part of the house that I KNOW was on a different breaker...

If you have a powered subwoofer, that can be a major culprit too.

One more thing is your TV cable. If you are using an AV pre/pro, with your cable feeding into it (in ANY way except HDMI or TOSLINK, which seem to be immune to this) and I mean any way--F-connector, composite, or component for video, Digital coax OR analogue stereo for sound--it can cause hum in your system due to strange grounding issues in some cable systems. You can put "ground loop isolators" in the line before it comes into your cable box, or right before the connection enters the pre/pro--different approaches work better for different setups.

Isolating a hum can become a VERY expensive and mind-numbing crusade--buying isolators, transformer, and filters, re-wiring your mains, etc. I know there were a few times when I was ready to throw my Velodyne sub off the deck into the trees when I first hooked it up. But a lot of logical thinking, and some diligence with power filtering, cable layout, connection logistics, and some creative multimeter probing finally got the problem solved...

Tracking down and eliminating the dreaded hum can drive you absolutely nuts. Good luck!

--Richard

thanks for the reply and the suggestions. I have a ground loop isolator (looks like a matching transformer). I also have the amps plugged into the two "cheater" plugs. Just figured it was the speakers since they are plugged in for the panels were more prone to HUM. I have an old Bryston amp i can try. I like the picture. I will list my stuff soon and take a picture if you are interested. I had to build a custom wall unit to accomidate the reQests to keep the wife happy!

 

[VanDaRo]

I have seen/heard this issue with several amps over the years. The usual culprit is dimmer switches. It could be one just about anywhere in the house, especially if the ground is on the other side of the home. Lousy and/or old bonding of the dwelling being the second most likely.

As a last resort -- and I do mean last -- open up the amplifier(s) and lift the chassis ground (green one) and tape them off so that they won't make contact with anything.

This is a very irritating problem, and I hope you resolve it soon !!

~VDR

 

[bigbanger]

I had a similar hum when driving my SL3s with my Plinius SA-103 - but only when the Plinius was in Class A mode (go figure). Anyway, it didn't bother me that much so I didn't spend too much time diagnosing the exact source of it. But I recently switched to a pair of CLS IIzs and now there's no hum! FWIW, I do have Halogen recessed lighting in my listening room on dimmers, so the dimmers may be the culprit (as someone else suggested in this thread).

 

[tsmooth]

My experience was a problem with my interconnects. I switched to Nordost Blue Heaven RCA from Monster THX 1000 and I experienced a TERRIBLE hum. I thought the amp went bad, but I tried hooking the monster interconnects back up and all I heard was DEAD QUIET. I don't know if it was the shielding, but it was night and day between the two. I would recommend (you probably already have) moving any current or power carrying wires from the signal carrying wires as much as possible. It is an 1/r squared relationship, so just a few inches can make a world of difference, it did for me.