having a problem with hum with my le amps

foxylady · « **on:** 21 Jul 2004, 04:09 pm »

does anyone know what the problem might be? i've tried swapping cables, switching off lights, unplugging my cable tv box but the hum still persists.

i'm pretty sure its from the le amps cuz it hums even when the pre amp is switched off. its like a low volume buzzzz with the occasional high pitched eeeeee kicking in.

has this happened to anyone else before?

Curt · « **Reply #1 on:** 24 Jul 2004, 02:54 pm »

This post should really be in the nOrh owners fourm.

But, since Leamps are rebadged IRD MB-100s I will try to help you find the problem.

Try unplugging your amps RCA IC input (turn amp off first). You can plug a shorted RCA in place of the IC (if you have one) but that's not necessary. If the hum stops, after removing the amps input and turning the amp back on, it's coming from upstream not the amp.

If the hum persists please e-mail me and we will trouble shoot further. E-mail is best for these matters.

foxylady · « **Reply #2 on:** 24 Jul 2004, 11:01 pm »

Hi Curt,

Thanks for the reply even though its a norh product. I figured I'd head straight to the amp makers to get a better answer.

I have emailed you on this, maybe we can continue this via email.

Curt · « **Reply #3 on:** 25 Jul 2004, 02:41 pm »

I just replied to your e-mail.

djklmnop · « **Reply #4 on:** 25 Jul 2004, 08:46 pm »

Check any electrical appliance too. In my room, I have a pair of MB-100s running. I light the room with one of those cheap Halogen floorstanders which points up to the ceiling. When I turn the lamp halfway up, i hear a hum through the speaker, so now I'm left with no choice but to listen to music in complete darkness.

Andy

Curt · « **Reply #5 on:** 26 Jul 2004, 09:37 am »

Quote from: djklmnop

Check any electrical appliance too. In my room, I have a pair of MB-100s running. I light the room with one of those cheap Halogen floorstanders which points up to the ceiling. When I turn the lamp halfway up, i hear a hum through the speaker, so now I'm left with no choice but to listen to music in complete darkness.

Andy

Very good point. Some cheap dimmer switches are also real offenders.

truant · « **Reply #6 on:** 28 Jul 2004, 03:59 am »

Upgrading the powercords for my MB-100s has done the most to reduce noise so far. I just started using SIGNAL CABLE Magic powercords and can't recommend them highly enough...and they are not even broken in yet. A great deal at $59 especially since us monoblock owners have to pony up for two cords. Stepping up to higher quality cords also allows more of Curt's amps' potential to shine through. I'm convinced that there is even more in there wanting to get out. And Curt is definitely right about those dimmer switches.

jqp · « **Reply #7 on:** 29 Jul 2004, 02:03 am »

Why would a different three-wire cord make a difference in noise of the amp? Maybe poor current isolation in a cheaper cord? I am a little foggy on this one.

foxylady · « **Reply #8 on:** 29 Jul 2004, 05:47 am »

Quote from: jqp

Why would a different three-wire cord make a difference in noise of the amp? Maybe poor current isolation in a cheaper cord? I am a little foggy on this one.

I think truant is referring to a reduction in the noise floor as opposed to actual noise that I am hearing from the speakers.

Curt · « **Reply #9 on:** 29 Jul 2004, 08:56 am »

Quote from: jqp

Why would a different three-wire cord make a difference in noise of the amp? Maybe poor current isolation in a cheaper cord? I am a little foggy on this one.

Perhaps his environment is noisy (lot's of gear, some digital gear, many wires near the amps power cord) and the new power cord is a shielded one (which most 3rd party cords are).

A shielded power cord can sometimes reduce the incoming noise level (if the system is in originally in a noisy environment) that enters on the power lines. Reduced noise does make the music sound better.

jqp · « **Reply #10 on:** 29 Jul 2004, 05:14 pm »

Ahh ok that does make sense. Curt do you use a sheilded cord?

Curt · « **Reply #11 on:** 29 Jul 2004, 06:32 pm »

Quote from: jqp

Ahh ok that does make sense. Curt do you use a sheilded cord?

No, not with our low gain (26dB) MB-100 amps.

Actually, most systems are not noisy enough to require a shielded power cord for the amplifier.

High gain systems with high efficenct speakers can wind up with high noise levels. If I sold a high gain (>30dB) amp I would probably use a shielded power cord and a mild input filter.

Line level is a bit easier, our preamps have a serious EMI/RF input filter that we believe works better than a shielded power cord for controlling noise entering on the AC mains.

jqp · « **Reply #12 on:** 29 Jul 2004, 06:40 pm »

Well my 26dB gain amps are doing great...they tell me that they want a PT-3 to keep them company

truant · « **Reply #13 on:** 30 Jul 2004, 02:16 am »

I do happen to live in a notoriously NOISY neighborhood. Whenever I've upgraded a cable in my system it has increased the level of quiet. I've also upgraded outlets and removed dimmer switches from the circuit used by my audio system. I used to be able to hear a hum through my speakers from across the room and it drove me nuts. Now when I put my ear up to the speaker drivers I hear only the slightest hum. To be honest I never tried to determine the exact source of the noise in my system. I did a little research then started upgrading and replacing.

truant · « **Reply #14 on:** 10 Aug 2004, 02:11 am »

foxylady...did you ever find out what was causing your amp hum?
I turned on my system tonight and was greeted with a very loud hum coming from one of the channels. I checked all of the connections then unplugged my amps from my Monster power strip(had already planned to replace it with a SIGNAL CABLE power strip later this month)and plugged them straight into the outlet(PS audio). This did the trick though logistically is a real challenge considering outlet placement in my apt. I hope you have already solved your problem but if not perhaps my situation will be instructive.

foxylady · « **Reply #15 on:** 10 Aug 2004, 09:45 am »

Quote from: truant

foxylady...did you ever find out what was causing your amp hum?
I turned on my system tonight and was greeted with a very loud hum coming from one of the channels. I checked all of the connections then unplugged my amps from my Monster power strip(had already planned to replace it with a SIGNAL CABLE power strip later this month)and plugged them straight into the outlet(PS audio). This did the trick though logistically is a real challenge considering outlet placement in my apt. I hope you have already solved your problem but if not perhaps my situation will be instructive.

still in the process truant. intending to test the amps at a friend's place so I'm having to wait till he is free. In any case I have just returned from a short holiday in Bangkok, haven't even listened to my set up since touching down.

I did however, receive an email from a MB100 owner who lives here also, and he mentioned experiencing what I am. So it might not be an isolated case, we are all living in public housing with the same mains supply, and I shall have to test it at a friend's place where the supply might be different.

foxylady · « **Reply #16 on:** 17 Aug 2004, 06:46 pm »

Just an update guys...... I finally lugged my amps over to a friend's place. Plugged them in and they were dead silent. So the problem does not lie with the amps. I think its something to do with the mains, which the amp might be picking up. There was absolutely no hum at my friend's place.
Thanks to all for the help!