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Author Topic: Sound Deadening for Henry 2K-2 Amplifier Case.  (Read 9405 times)
K1ALN
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Posts: 17




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« on: March 04, 2016, 08:52:38 PM »

I am looking for a product to use to reduce case vibration on my Henry 2K-2 amplifier (Console Model).  Blower air sound is not objectionable, but the running blower causes case vibration hum.

Holding a knee against the case greatly reduces the hum, but is not a comfortable or long term solution.

I do not want to use any of the foil covered automotive-style sound deadening mats as the thought of their aluminum in proximity to 2700 volts gives me the willies.

Spray, non-foil matting, or Huh

Thanks for the assist, Alan  K1ALN
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K8AXW
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Posts: 5137




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« Reply #1 on: March 04, 2016, 09:01:09 PM »

I don't have the information at hand right now but I researched the same question a couple years ago.

Google "sound deading material" or a variation of this. This stuff is made in various thicknesses and is fireproof.  It's used in the audio industry. 

It can be attached to the cabinet with contact cement after cutting the sizes you need.

I didn't consider gluing carpet inside the cabinet because of it being a dust collector.

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JS6TMW
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Posts: 707




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« Reply #2 on: March 04, 2016, 10:13:26 PM »

I would try to eliminate the cause of the vibration rather than the symptom. It's likely the fan (or blower) has a bad bearing, or somehow got out of balance. Replacement is often the easiest solution.

Steve
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ZL1BBW
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Posts: 865




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« Reply #3 on: March 04, 2016, 10:53:54 PM »

You can buy spray on sound deadening for cars.

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ex MN Radio Officer, Portishead Radio GKA, BT Radio Amateur Morse Tester.  Licensed as G3YCP ZL1DAB, now taken over my father (sk) call as ZL1BBW.
K1ALN
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Posts: 17




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« Reply #4 on: March 05, 2016, 04:28:33 AM »

The blower seems to run smoothly enough.  I think that part of the problem is me.  I have exceptional good hearing and find the low pitch hum very annoying. Another approach that might work is to stiffen the large rear panel. And although this amp came from the estate of an SK and was  part of a multiple set of backup amps ( he had four and this one is a 9 out of 10 in condition) I'm not an amp collector and may fabricate a stiffening brace for the back panel. I'm reluctant to drill for pop rivets as an errant metal chip might cause havoc, so if I go that route I may try a tight fit coupled with some two part epoxy rather than mechanical fasteners.

I am continuing my look at automobile acoustic deadening materials, but do not want the aluminum foil facing in there.

Thank You for the replies!

Alan,  K1ALN
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JS6TMW
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Posts: 707




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« Reply #5 on: March 05, 2016, 05:10:17 AM »

Yes, a stiffening brace might work. You could even try it out on the outside of the back panel, maybe a strip or two of wood with double-back tape.  A suggestion - don't bother with epoxy if you want to make a permanent installation - my universal adhesive choice is Marine Goop.

Also check out Amazon. I got some rubberized pads from them last year to cushion a loud motor. Not exactly what you're dealing with but they carry a pretty good variety. (They also sell Marine Goop!)

Steve
« Last Edit: March 05, 2016, 05:22:49 AM by JS6TMW » Logged
N8CBX
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Posts: 343




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« Reply #6 on: March 05, 2016, 05:55:46 AM »

I am continuing my look at automobile acoustic deadening materials, but do not want the aluminum foil facing in there
The aluminum foil backed material is for heat insulation, besides acoustic, you don't want that.
You want what they call "Q-pads" made by Evercoat. It has a contact adhesive coating on one side. Heat up the panel with a hot air gun and then apply the Q-pad.
(Besides my ham radio hobby, I restore British sports cars as a hobby too, and use the pads inside the door skin to dampen the "tinny" sound closing the door.)
Jan N8CBX
« Last Edit: March 05, 2016, 12:45:27 PM by N8CBX » Logged

Dayton Ohio - The Birthplace of Aviation
K6AER
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Posts: 3858




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« Reply #7 on: March 05, 2016, 08:55:22 AM »

Any thing you add to reduce noise is at the caveat of reducing cooling which is most important. Low frequency noise has almost no effect by sound deadening material.

Balancing the cage is the best way to take care of the noise. Granger also has replacement blowers.
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K8AXW
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Posts: 5137




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« Reply #8 on: March 05, 2016, 09:43:59 AM »

Perhaps the term "sound deadening" should be replaced by "sound absorbing."  That's actually what is desired.  If this stuff is applied to the walls of the cabinet without restricting any vents, then there isn't a heat retention problem.

The stiffening with wood strips with foam weather striping (adhesive one side) between the wood and cabinet might have the desired effect.  Try it first because it's possibly a cheap solution.
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K6AER
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Posts: 3858




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« Reply #9 on: March 05, 2016, 05:11:03 PM »

You did not mention the frequency of the hum. If it is below 300 Hz sound deadening will not help. Like a car with big woofers you can feel the noise 5 cars back.

Find the source of the noise and stop it there.
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WX7G
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Posts: 6835




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« Reply #10 on: March 06, 2016, 03:04:07 AM »

It sounds like the sound is not air movement but blower motor vibration exciting the enclosure. Thinking outside the box, the blower can be moved outside the box. A suitable blower can be mounted elsewhere in the room and the air ducted to the amp. The blower in the amp is then disconnected from AC power.

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K8AC
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Posts: 1600




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« Reply #11 on: March 06, 2016, 05:09:11 AM »

Check out some of the materials being used to silence desktop PCs.  You can get acoustic insulation in a variety of thicknesses and without the foil layer.  Here's one example: http://www.quietpcusa.com/Acoustic-Insulation.aspx

I've used similar material in my desktop PCs and was able to quiet things down considerably.  Also, take a look at some of the websites dedicated to acoustic insulation for autos.  Some of them go to great lengths to explain how to apply deadening material to doors and floor panels so as to deaden the vibration without completely covering the area with insulation.  Only a certain percentage of the area needs to be covered in order to deaden the panel vibration. 

73, K8AC
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