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Adam A7 electrical hum (help please) Studio Monitors
Old 15th April 2009
  #1
Here for the gear
 

Adam A7 electrical hum *solved*

Hey guys so today I bought a pair of Adam A7s. My right A7 has a very noticeable hum coming from the tweeter. My first instinct was that it was picking up hum from a surrounding power source so i tried switching all cables (both audio and power cables) into the speaker and the problem persisted. I then tried taking the speaker to a different part of the house and plugged it into a different outlet with no audio cable in the input and still the same issue.

So based on my trouble shooting so far I have narrowed it down to the fact that it is actually a problem with the speaker itself and not any of my other gear (which was all working fine with my old speakers).

These speakers were bought used so they cant just be taken back. My question is if this is a known issue and possibly an easy fix for the A7s? I am more than willing and comfortable opening up my gear and working on it if someone can point me in the right direction as to what I should be looking at being the source of the problem.

Additional info: The hum does get louder as the input gain is raised etc (and no this is not just standard tweeter hiss that most speakers have this is an actual hum). I have tried adjusting all the EQ settings at the back to make sure it wasn't some sort of scratchy connection. The input knob on this particular speaker does make some slight noise as its adjusted but not consistantly whereas the other speakers input gain knob is silent.


Any help you guys can give me is much appreciated

Thanks
Brad

Last edited by brad808; 22nd May 2009 at 02:04 AM.. Reason: Problem resolved
Old 15th April 2009
  #2
Gear Maniac
 
narapo's Avatar
 

I had a similar problem with one of my new A7's ; loud hum, even with the A7 plugged alone without any audio input. The unit was faulty and had to be replaced under warranty ; so have your Adam inspected and serviced...
Old 22nd May 2009
  #3
Here for the gear
 

Just an update for anyone having a similar issue:

The problem turned out to be that on the faulty speaker there was an unshielded cable from the front panel to the amplifier at the back. To temporarily fix this I soldered on a new shielded cable and it solved the problem. I emailed Adam tech support and they sent out two replacement front panels.
Old 12th December 2014
  #4
Here for the gear
 

Adam A7 Electrical hum

I had exact same problem (and symptoms) as brad808. I opened the rear panel and did some troubleshooting. It turned out to be a faulty potentiometer (volume control). I did not replace the potentiometer just disconnected the potentiometer cable from the rear panel and the hum was gone.

As I don´t use the volume control on a daily basis, this is not a huge practical problem. If so, I will just remove the rear panel, connect the cable, turn the volume to preferred level and disconnect the cable again.

A good advise could be to turn the volume to 0 db (straight up) before disconnecting the cable. This way you know at which db level the potentiometer is calibrated for.

Hope this could be helpful if someone struggle with the same irritating problem.

All the best!
Old 24th September 2015
  #5
Gear Head
 
Vex One's Avatar
Does anyone hear a hum in their A7s if you put your ear to them?
Old 25th September 2015
  #6
Quote:
Originally Posted by Vex One View Post
Does anyone hear a hum in their A7s if you put your ear to them?
Yes.
Similar problems as described above.
Old 25th September 2015
  #7
Lives for gear
 

Hi
Almost all monitors will 'hum' or 'hiss' if you listen to them in a 'silent' room with your ear to the speaker drivers.
A proper and more realistic 'test' would be in a 'silent' room with your ears at least half a metre (18 inches) away from the speakers.
Matt S
Old 25th September 2015
  #8
Gear Head
 
Vex One's Avatar
Quote:
Originally Posted by Matt Syson View Post
Hi
Almost all monitors will 'hum' or 'hiss' if you listen to them in a 'silent' room with your ear to the speaker drivers.
A proper and more realistic 'test' would be in a 'silent' room with your ears at least half a metre (18 inches) away from the speakers.
Matt S
My listening position is about a metre away from each speaker and when both speakers are on I can hear the hum clearly in a quiet room. I hear the typical hiss which doesn't bother me, the hum is definitely louder.

Funnily enough I have a Behritone (Behringer's version of an Auratone) and that makes no hum what so ever, yet that is a crappy thing that's meant to sound crap.
Old 25th September 2015
  #9
Lives for gear
 

Hi
Hum from monitors when the audio input is disconnected (and the input is 'terminated' with a resistor for example) is unacceptable. When audio cables are connected the setup becomes dependent of good grounding practice for which responsibility is shared by several parties so more difficult to define.
Matt S
Old 25th September 2015
  #10
Gear Head
 
Vex One's Avatar
Matt, that was the answer that I was looking for.

My AC is pretty good (no dimmers or anything around), I use basic power conditioners and have never had a problem with ground loops.

I was preparing for the line 'these monitors hum, just deal with it' but from what you've it sounds like there is a fault with the speakers.

Thanks for your input.
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