[Amps] Ducting Suggestion

[Jim Barber]

If there's room where the duct exits the rear of the amp, a "noise 
sweep" will reduce noise - at least that conducted through the air in 
the line - substantially.

Take a 90-degree dryer hose coupler and line the inside with an acoustic 
dampening media. For larger systems I've used asphalt sheet, which along 
with other materials is available from
http://www.parts-express.com . You *can* use spun fiberglass or polyfill 
glued to the inside wall of the coupler, but it'll be trap dust and add 
resistance to the airflow. If you use asphalt sheet, cut it into small 
enough squares and rectangles so that it will lay flat when you glue it 
in. Adding a foot or so of hard tubing lined with the same stuff on 
either or both sides or the sweep will improve performance somewhat.

On larger HVAC systems we can get 20+dB acoustic loss above 150hz or so 
with a properly constructed sweep. Below 150hz is mostly motor vibration 
and/or conducted vibration in the line itself; you need to isolate that 
at the source by isolating the motor mount as Bob mentioned.

My .02, adjust for local currency as appropriate.
Jim N7CXI

On 3/20/2012 1:18 PM, Bob K6UJ wrote:
> The dryer exhaust hose would be excellent I think, you are avoiding sound conduction down to the blower with the non metallic hose.
> Also it would be a good idea to isolate the blower from the power supply chassis with rubber pads for sound dampening.
> The only thing left to consider is the noise from the exhaust air coming out the blower.  If it is going to be six feet away in the same room, probably
> on the floor ? , there will still be exhaust air noise, but should be reduced quite a bit.  Maybe this is a dumb idea but if it is still too loud for you liking,
>   you could use more of the exhaust hose over to he outside wall and go thru the wall with a regular dryer vent.  Just brainstorming.................
>
> Bob
> K6UJ
>
>
>
>
>
>
> On Mar 20, 2012, at 12:48 PM, Mr Mike wrote:
>
>> SLOOOOOOwwwllly workeing on a single gs-35b amp.
>>
>> I puchased a blower that is rated at 110 cfm @ .5" SP
>>
>> I am planning to make the HV p/s a seperate unit and am toying with the idea of remoting the blower as well, to reduce noise.
>> In this design there would be a 3" diam flexible tube running from P//S blower cabinet to remote amp chassis, about 6 feet long.
>>
>> I know flexible exhaust pipe would work, ants certainly tough enough, but has anyone any more aesthetically pleasing ideas?
>>
>> AC2Q
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