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Discussion Starter · #1 ·
End of last year I purchased a new, boxed Velodyne HGS-18 (Series I) from an authorized dealer. When powered and there's no source output (e.g. DVD has ended), the sub emits a low hum/hissing sound. Clearly audible across the room.


Anyone else experience that on their HGS-18 and/or know of any fixes?


Velodyne has not yet responded to my calls or online "warranty registration".


RTW
 

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Velodyne makes great subs but, you are absolutely right, there is a low hum. I will assume that you have heard this sound with no interconnect connected to the sub (ie. eliminating possible ground loop hums). From what I remember, basically it is the servo device that is causing the hum. It is fairly low and definitely can not be heard through most of a movie especially an action movie. However during very quite passages, especially if you are listening for it, you can definitely hear it.


However you should also realize that the servo device is used by Velodyne to obtain clean distortion free loud low levels - hence the trade off for the slight low hum.


Also realize that some people are not bothered by this hum and do not even notice it while others like yourself notice it from across the room.


If you do get a hold of a Velodyne representative ask them if their newer updated subs still have this hum.
 

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Discussion Starter · #4 ·
So, it sounds like this is a known issue that I can take up with Velodyne. Does anyone know of instances where Velodyne has remedied the problem and, if so, how it was remedied?


As for ground loop issues, could you provide a bit more explanation as to what to look for in my connections?


The sub is simply connected to the audio sub out of my Ref50. No further connections to amplifier, speakers, etc.


Thanks

RTW
 

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Murphy's Law! :(

The B&K Ref50 ALSO has a known issue with hum or whine but I think it occurs at ultra high frequencies (not low).

See other threads regarding this.

May or may not be related.

Unplug sub from pre/pro to narrow it down.

It if continues contact Velodyne.

If it stops contact B&K.

Hope this helps.
 

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the ground loop issue could be the problem if you still have the hum when it is pluged into the wall (pwr) and nothing else. Disconnect all rcas etc....do you still have it? If so...it is an internal amp issue. If not then it most likly is ground loop. Go to home depo and by a three to two connector to plug into your sub power cord and then into the wall. Worked for my sub that had a hum
 

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Discussion Starter · #7 ·
I'll try the ground loop tests. Don't think that's the issue. Thanks.


Not related to Ref50 noise (non-issue in my book, since not audible on my system during any playback), as it continues even after processor and amp are powered down.


RTW
 

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Discussion Starter · #8 ·
Update:


Velodyne called me back and said they'd take care of the issue. Most likely a component in the amplifier board for which they have a simple fix/replacement.


Hopefully it works.


RTW
 

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Discussion Starter · #9 ·
Just to close the loop here...I drove down to the Velodyne HQ today and had them update a component in my HGS-18 amplifier. The tech told me it wouldn't completely remove the hum, but that it would bring it down to being audible up to at most 3-4 feet. BTW, this is the same goal stated for the Series II HGS-18. They haven't figure out how to completely remove the hum.


After about a 20-minute operation, we tested it (on their equipment, as I only took in the amplifier/controller board) and, sure enough it was reduced. And, at home, it's significantly reduced as well. Still audible, but instead of it calling out to me, I have to listen for it to hear it at any distance (e.g. more than 4-5 feet).


Apparently, it's related to the servo-control -- which, as I think I understood the tech to say -- is the feedback mechanism that tightens up the bass response by measuring the woofer's displacement in real time versus the music footprint. Pretty cool, actually. He demonstrated how by tapping on the woofer cone without the power up, it sounded much less muted than with the servo-control in action.


So, anyway, I'm happy. Velodyne was very nice on the phone and in person and the hum is, if not gone, virtually un-noticeable now.


RTW
 
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