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Author Topic: Humming in speakers  (Read 2917 times)

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electricd

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Humming in speakers
« on: October 01, 2002, 11:02:50 pm »
Ok here is the setup.  I have 2 12W 4" sheilded speakers in my cab (the ones from HAPP).  I have a 10W stereo amp that I built from a kit from electronickits.com.  The amp works fine, but I can hear the hard drives spin in my speakers, and a constant humming sound.  I have tried moving the amp away from the power/computer but it didnt help.  I have seen this before in car stereo installations and have solved with with a ground loop isolator.  Do you think this is what I need to do in this case??  Thanks in advance!

ED7

Chris

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Re:Humming in speakers
« Reply #1 on: October 01, 2002, 11:35:24 pm »
Better speaker wire?  Shielded speaker wire?
--Chris
DOSCab/WinCab Jukebox: http://www.dwjukebox.com

rampy

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Re:Humming in speakers
« Reply #2 on: October 01, 2002, 11:46:34 pm »
could be 60 cycle hum... is your florescent light on.lighting your marquee?  is there a florescent light on overhead (try shutting those off and if the sound persists or not)

if it is a ground loop the islationtf thing might work...

shielding the wires couldn't hurt... you could also shield your circuit board too if it still won't go away...

good luck...
rampy

Chris

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Re:Humming in speakers
« Reply #3 on: October 01, 2002, 11:50:28 pm »
Hey, Rampy, was that you I was fighting with on eBay today for that broken Star Wars yoke?

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rampy

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Re:Humming in speakers
« Reply #4 on: October 02, 2002, 08:31:46 am »
you dirty rat! ;D yeah that was me...

I had been watching the broken one and the more complete one as they were like 9 bucks and 15 bucks going into the last day... I was totally blown out of the water on the complete one (I tried to bid 20 something and it said sorry minimum bid 46.06 or something)

Did you actually end up with it, or is that someone else that got it at the last minute.  I'm not sure if I regret not bidding more or not, though... but not sure what good half a SW yoke would do me...

rampy

electricd

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Re:Humming in speakers
« Reply #5 on: October 02, 2002, 09:39:49 am »
I do have a 22W blacklight hanging above the speakers.  I have sheilded speakers, but regular speaker wire.  How do you go about sheilding the speaker cable (I have never heard of dong this?).  I really hope the ground loop isolator works, as it would be MUCH easier to accomplish.  Thanks!

ED7

Chris

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Re:Humming in speakers
« Reply #6 on: October 02, 2002, 11:58:13 am »
Does the hum go away if you turn off the blacklight?

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Chris

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Re:Humming in speakers
« Reply #7 on: October 02, 2002, 11:59:25 am »

you dirty rat! ;D yeah that was me...

I had been watching the broken one and the more complete one as they were like 9 bucks and 15 bucks going into the last day... I was totally blown out of the water on the complete one (I tried to bid 20 something and it said sorry minimum bid 46.06 or something)

Did you actually end up with it, or is that someone else that got it at the last minute.  I'm not sure if I regret not bidding more or not, though... but not sure what good half a SW yoke would do me...

rampy

No, someone beat us both by a few cents.  I was at rehearsal when it ended, though...
--Chris
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hyiu

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Re:Humming in speakers
« Reply #8 on: October 02, 2002, 02:08:35 pm »
up to my very limited knowledge.... if a speaker has those "weee"ing / "hummm"ing noise.....

especially in car audio.... if you turn it on and have no music... it'll have those "weee"ing noise... and the harder you step on the gas (the engine runs faster), the louder (higher pitch) that "weeee"ing noise is....

if I'm not wrong... (cannot guarantee... heard from some electrican some time ago...) its mainly caused by some kind of feedback to the amplifier.... (not really the speaker...)

but how to take care of that.... sorry... donno....

but that gound loop isolation solutions sounds like a reasonable approach to solve this.... you ground loop the amp ?!?!

Another Brilliant mind ruined by education....  :p

BobA

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Re:Humming in speakers
« Reply #9 on: October 02, 2002, 05:03:17 pm »
There is a bit more useful info that might be helpful in this troubleshooting exercise.

1.  What is used to power your amp kit.  Is it regulated DC? and if so from what source. Does the amp hum with no input? Does it hum with the light turned off?

2.  What is the level of the signal you are feeding the amp? Can it be increased by increasing the volume of your PC? A higher level signal is more able to overcome noise.

3. Are all your grounds connected?  What are you using to connect the PC to the amp? Is this wire sheilded or at least twisted?  This is a low level signal and could be picking up noise.  

4. You can get sheilded audio cable.  Most of it for speakers is quite expensive.  It is more likely that your amp is picking up noise and amplifying it then the speaker wires picking up the noise where the signal is at higher levels.

BobA

electricd

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Re:Humming in speakers
« Reply #10 on: October 02, 2002, 05:09:50 pm »
Im gonna try the ground loop isolator this evening.  I will keep you posted and let you know if it works.

ED7

electricd

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Re:Humming in speakers
« Reply #11 on: October 03, 2002, 12:57:55 am »
Ok tried the ground loop isolator tonight and it didnt make any difference.  So I hooked up my NXG NX-VM80 volume control knob between the speakers and the amp and VOILA!  Perfect sound!  No idea why this is, because even with the knob at 11 (max output) there is no humming, hissing, or popping.  This thing cost me a pretty penny ($35 I think) but it works flawlessly.  I recommend the amp kit/vol knob solution for anyone who wants REAL arcade speakers and not the usual PC speaker hack.  Looks better, sounds better (IMHO of course).  Thanks for all the suggestions!

ED7

SirPoonga

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Re:Humming in speakers
« Reply #12 on: October 04, 2002, 11:18:57 pm »
How is everything powered in your cabinet?

The volume knob introduces a new resistance.  So it does change things.

  
 

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