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Anoying humm in my LFR1100
#406269 07/20/14 09:09 PM
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I refused to believe that Axiom would send out new
speakers or components with a defect. So for the past 2 months I have been listening to my LFR1100 with a definate humm coming from the mid and woofers.

I have tried replacing my RCA interconnect cables just to make sure it was not them.

I have tried a different amp and pre-amp setup

If I unhook the LFR DSP from the amp, the speakers are dead quiet. If I hook just the front speakers up, and go directly from the pre to the amp and bypass the DSP all together, they are dead silent.

it sounds like a ground feedback loop humm.

is there any thing else to try before rattling the doors at Axiom to get a new DSP sent out to me as the one they sent seems to be DOA?


Anthem: AVM60
Axiom: ADA1000, LFR1100, VP180, QS8, EP500, M3, M3comp
AudioSource: Amp One/A
Re: Anoying humm in my LFR1100
MatManhasgone #406270 07/20/14 10:33 PM
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Originally Posted By: oakvillematt
I refused to believe that Axiom would send out new
speakers or components with a defect. So for the past 2 months I have been listening to my LFR1100 with a definate humm coming from the mid and woofers.

I have tried replacing my RCA interconnect cables just to make sure it was not them.

I have tried a different amp and pre-amp setup

If I unhook the LFR DSP from the amp, the speakers are dead quiet. If I hook just the front speakers up, and go directly from the pre to the amp and bypass the DSP all together, they are dead silent.

it sounds like a ground feedback loop humm.

is there any thing else to try before rattling the doors at Axiom to get a new DSP sent out to me as the one they sent seems to be DOA?


Sounds like nothing is defective and that the real problem is a ground loop in which you will have to solve methodically yourself.


I’m armed and I’m drinking. You don’t want to listen to advice from me, amigo.

-Max Payne
Re: Anoying humm in my LFR1100
MatManhasgone #406271 07/21/14 12:57 AM
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If the plug is a 3 prong try lifting the ground. I use a modified 2 prong extension cord . Ground loop hum can be a real sob. My phono preamp picks up all kinds of stray EMI . Try moving the dsp as far away from everything else as you can as a test.


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What others think of me is none of my business.
M80 V3 MY GLOSS Cherry
Re: Anoying humm in my LFR1100
MatManhasgone #406272 07/21/14 12:59 AM
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Do you have Cable TV/Internet connected to that system?

If so, that is a good place to start as troubleshooting found that was the culprit. My EP800s hummed as did my previous Velos. It was easily fixed on the 800s by unscrewing the Chassis Ground screw. With the Velos it was much more complicated...

TAM

Re: Anoying humm in my LFR1100
MatManhasgone #406274 07/21/14 03:20 AM
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Matt, if I followed, the LFR DSP appears to be the only factor causing the hum. All your changes, including a different amp and pre-amp, didn't affect the hum problem as long as the LFR DSP was still in the circuit.

There isn't any apparent way that simply inserting an additional component(e.g., the DSP)in the middle of a circuit could create a ground loop which previously wasn't there. Therefore it seems that the problem is likely to be internal to the DSP, which would need repair or replacement.


-----------------------------------

Enjoy the music, not the equipment.


Re: Anoying humm in my LFR1100
MatManhasgone #406275 07/21/14 03:54 AM
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A few more questions that might help to herd the problem into a corner...

- Is the DSP plugged into the same circuit as the other equipment ? Just checking on this one...

I wanted to ask "how about switching off or unplugging the DSP and waiting for the P/S to bleed down" but a bit worried about spikes/noise going out to the amp & speakers so maybe skip that.

- Do you still get the hum if DSP is connected to amp inputs but preamp is not connected to DSP ?

- Is the hum on both L & R channels ? On both front and rear channels ?

Last edited by bridgman; 07/21/14 03:59 AM.

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8
Re: Anoying humm in my LFR1100
bridgman #406280 07/21/14 04:44 PM
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The hum is there when the DSP is connected to the Amp. It does not matter if it is turned on or off. Even unplugged with not power cord attached to the back of the unit, and completely disconnected from the pre-amp. I still get the humm.

I did not budget nor do I have very long RCA cable to try and put the DSP on the other side of the room from the rest of the equipment. It was never discussed with my by Brent when I inquired about the unit that it would humm if connected.

I get the distinct feeling that there must be some form of short inside the DSP that causes this buzzing humm on the speakers.


Anthem: AVM60
Axiom: ADA1000, LFR1100, VP180, QS8, EP500, M3, M3comp
AudioSource: Amp One/A
Re: Anoying humm in my LFR1100
MatManhasgone #406281 07/21/14 05:57 PM
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OK, that's very clear. And very weird.

The part I really don't get is that it hums both with and without the power cord. It's easy to come up with explanations for one or the other but not both.


M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8
Re: Anoying humm in my LFR1100
MatManhasgone #406282 07/21/14 06:03 PM
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I would call Axiom. It's always possible that something was jarred during shipping!


::::::: No disrespect to Axiom, but my favorite woofer is my yellow lab :::::::
Re: Anoying humm in my LFR1100
MatManhasgone #406283 07/21/14 07:38 PM
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spoke with Brent and I am shipping back the DSP for them to take a closer look at. It is really weird. But I am not worrying as Axiom is top notch on their support side of things and I am sure that they will figure out what is going wrong.

They have no control over how the unit gets handled when UPS gets it. So it might have been something getting whacked out of spec in shipping from some nob dropkicking the box to the other end of the shipping dock so he doesn't need to walk the extra 18 feet. ?? who knows.


Anthem: AVM60
Axiom: ADA1000, LFR1100, VP180, QS8, EP500, M3, M3comp
AudioSource: Amp One/A
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