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ADA1250 feedback
#420770 10/20/16 10:22 PM
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brendo Offline OP
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Hi all.
On my third day with my new ADA1250 3channel. Totally awesome unit. First day cranked it so far seems a little more dynamic{details in the music} than my previous A|B pro power Amp.

But now I have a noticeable noise floor from the ADA.
It's not a ground loop as I'm already using an isolator through my cable box{had that issue with my old Amp}.
It's similar to the feedback from a guitar amp just a quiet buzz in the background.

Also it seems to be through the center channel or 3rd channel unplugged it to see in stereo and buzz was not noticeable. And gone when I turn of the power switch

Any ideas greatly appreciated.

Now in the process of organizing the mess my cable monster put behind the entertainment center. To funny how they can get to a holly cow state so easily.

Re: ADA1250 feedback
brendo #420779 10/21/16 02:44 AM
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Oh boy!

Did you try swapping one of the L/R channel boards into the center channel?


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Re: ADA1250 feedback
brendo #420791 10/21/16 12:12 PM
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When you said that you unplugged it, are you talking about removing the cable from your pre-amp to your ADA center channel?

I would as mojo said, try moving the center channel cable to either the left or right channel and see if the hum moves to that speaker. Likewise, try running the left or right channel cable to the center without the center cable plugged in. Does it make the hum. If it was a power problem inside the ADA then it would more likely be system wide and the hum would come from all your speakers.

You also didn't say if you are using RCA or XLR to connect between the pre-amp and your ADA. It should not make a difference, but if there is something up inside your pre-amp then this might help isolate the deficiency


Anthem: AVM60
Axiom: ADA1000, LFR1100, VP180, QS8, EP500, M3, M3comp
AudioSource: Amp One/A
Re: ADA1250 feedback
brendo #420815 10/23/16 01:08 AM
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brendo Offline OP
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I'm using RCA Monster ultra audio cables.
So I switched the channels around and swapped the RCA's and as I was doing so the hum went to almost gone, as long as the one on my center stayed stretched. As soon as I pushed it back on my stand the hum becomes very noticeable.
With that RCA removed from the ADA nothing just clean sound from my M80s. On any channel that I have tried on the ADA. My remaining surround channels through my AVR are not getting this hum at all.{Front height and sides}

It's pretty easy for my to try an RCA to mic.{XLR} though I've read that that can actually degrade the sound quality

Re: ADA1250 feedback
brendo #420816 10/23/16 01:31 AM
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Confused?

So what speaker is the hum coming from? is it just the center speaker or is it all the speakers?

I get that when you have just the left and the right hooked up, it sounds silent. That is what is should sound all the time.

I think you are saying when you hook up the center channel RCA that you start to get the hum. I am going to gather that you have tried moving the RCA connectors to different plug spots on the back of the ADA to see if that changes the characteristic or amount of hum that you are hearing.

Have you tried just hooking up the center channel RCA only and seeing if you are getting any hum.

Just trying to figure if it has anything to do with a signal or ground issue coming from your Pre-Amp that the ADA is sensative to that perhaps any of your prior amps were not.

Also, have you tried pulling all your other inputs from your pre-amp to see if the sound goes away. These would all be steps to look into before you can start to diagnose what to do. You really need to isolate what is connected. For instance, I had a wicked hum with an Rotel amp that went away when I unplugged the HTPC media player computer that I was using for music streaming.

And BTW, going from RCA to XLR doesn't reduce the sound quality, it just reduces the gain by about -10db

Last edited by MatManBobbleHead; 10/23/16 01:36 AM.

Anthem: AVM60
Axiom: ADA1000, LFR1100, VP180, QS8, EP500, M3, M3comp
AudioSource: Amp One/A
Re: ADA1250 feedback
brendo #420820 10/23/16 08:10 PM
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brendo Offline OP
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It comes from all 3 L,C,R, though only when I connect my center.
haven't tried only the center yet. When I put the ADA back in my rack the hum gets louder so possibly EMI/RFI.
Swapped through all the inputs on my ADAs RCAs

Re: ADA1250 feedback
brendo #420822 10/23/16 11:51 PM
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If you have a spare speaker you could substitute it for you center as a test.

In my last house which was older 1960ish I had to do all kinds of dumb stuff because of noise in my bedroom system. I had to run a separate extension cord from the hall way outlet into the bedroom for certain things like all the wall warts and used ground lift so no loopback . My newer house is dead silent , has a really well designed electrical system. Can you run a cord from another room and only power up the pre/pro and the amp with all else turned off. Like you say maybe some EMI.


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Re: ADA1250 feedback
brendo #420823 10/23/16 11:57 PM
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sorry

Last edited by Socketman; 10/23/16 11:59 PM.

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What others think of me is none of my business.
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Re: ADA1250 feedback
MatManhasgone #420826 10/24/16 12:17 AM
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[quote=MatManBobbleHead]Confused?

So what speaker is the hum coming from? is it just the center speaker or is it all the speakers?

I get that when you have just the left and the right hooked up, it sounds silent. That is what is should sound all the time.

I think you are saying when you hook up the center channel RCA that you start to get the hum. I am going to gather that you have tried moving the RCA connectors to different plug spots on the back of the ADA to see if that changes the characteristic or amount of hum that you are hearing.

Have you tried just hooking up the center channel RCA only and seeing if you are getting any hum.

Just trying to figure if it has anything to do with a signal or ground issue coming from your Pre-Amp that the ADA is sensative to that perhaps any of your prior amps were not.

Also, have you tried pulling all your other inputs from your pre-amp to see if the sound goes away. These would all be steps to look into before you can start to diagnose what to do. You really need to isolate what is connected. For instance, I had a wicked hum with an Rotel amp that went away when I unplugged the HTPC media player computer that I was using for music streaming.

And BTW, going from RCA to XLR doesn't reduce the sound quality, it just reduces the gain by about -10db [/quote

If you used an adapter from unbalanced to balanced this could limit your amp since balanced connections have much higher output voltage on pre/pro's and higher input impedance on the amp. Is that what you meant to say or am I talkin out my backside.


DOG is GOD spelled backwards.
What others think of me is none of my business.
M80 V3 MY GLOSS Cherry
Re: ADA1250 feedback
Gr8_White_North #420827 10/24/16 12:53 AM
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Originally Posted By Socketman

If you used an adapter from unbalanced to balanced this could limit your amp since balanced connections have much higher output voltage on pre/pro's and higher input impedance on the amp. Is that what you meant to say or am I talkin out my backside.


Yes. And I found when you work it out it comes in at around -10db loss of sound level.

I was using for a long while a Pioneer receiver that only had RCA pre-outs and had to use RCA-XLR cables as there was something that caused a wicked hum between the LFR1100 speakers DSP and the Anthem amp that I had purchased. If you play with the room correction sound levels you can compensate by putting the channels to +db for the ones that are on the RCA-XLR and -db for the ones that are not.


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