Super quiet compressor? WTF?

I tested this Quincy compressor that I bought at auction today:
http://goo.gl/OCpa3
It is almost identical to my own Quincy compressor:
http://igor.chudov.com/projects/Quincy-340-Compressor/
It has the same pump, of the same vintage, etc. The difference is that this one has a 3 phase motor (mine has single phase 10 HP motor), and also, that it has a different muffler and oil bath filter. Also, my compressor has a belt guard and this one, does not.
What really shocked me was just how much quieter this compressor is, compared to mine! WTF?
Could just an intake muffler and oil bath filter make that much of a difference? Or does a belt guard add that much to noise?
i
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The intake muffler certainly could. A large part of compressor noise is from the intake - one of several reasons that plumbing the intake to the outside is often a good idea (though muffling it is probably _also_ a good idea if doing that in a residential neighborhood.)
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wrote:

That also was a large part of the noise from old VWs, even the very first water-cooled ones. Intake noise can be suprisingly loud, especially if you have a good muffler on the output end.
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Well, I tried swappnig my Solberg intake filter/muffler for the Burgess muffler that is on the Quincy that I bought the other day.
Made very little difference. I think that the noise is due to "everything else".
i
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wrote:

'Could be. Go to a pet shop and puy a few feet of plastic aquarium hose. Stick one end of it in your ear. d8-) Hold the other end in different places where you think the noise may be generated.
That's what I've used in place of a mechanic's stethoscope for close to 50 years, and it works great.
Or, buy a mechanic's stethoscope and go pro.
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On 7/8/2011 7:43 AM, Ed Huntress wrote:

Just for grins, I once fitted a small forklift carb to a Ducati 350 at my Dad's suggestion. As he predicted, off-idle and low throttle response was fantastic (at great loss to high end). One thing quite surprising was it would idle very steadily and reliably, slow enough I could hear the air rushing in through the intake. I'd never heard intake noise before on a bike.
That combo would light off with one kick, hands off throttle and at once settle down to a slurp-thump, slurp-thump idle.
Jon
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Ha! Was that the single-cylinder, DOHC Ducati with the countershaft drive to the cams? IIRC, they had a concentric Amal carb, right?
They were pretty slick, but giving that engine asthma with a little forklift carb probably gave you much better atomization at low flow rates.
I once put a single-carb (SU) manifold from a Morris Minor onto my friend's AH Sprite, just to get him back and forth to school while he learned to rebuild those carbs. It would pull stumps, but it was out of wind in a hurry.
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On 7/8/2011 8:50 AM, Ed Huntress wrote:

SOHC, but yes, driven by bevel gear train off the crankshaft. Never saw one with an Amal, all early models I've seen had Dellorto side bowl carbs, later builds had a square slide Dellorto..

Yeah, it was awesome putting around, a very smooth linearity to throttle input with oodles of torque. Up to a point... <G>
Jon
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Eh, boy, memory is going. Yes, I remembered the separate valve covers and DOHC stuck in my memory. Also, the desmos from the late '60s and on. There was a lot of stuff going on, on top of those cylinder heads.

Well, Amals were somewhat popular as retrofits (they flow better than Dellortos) but the OEM use of Amals on Ducatis came with later models, as my memory jogs. Some of the V-twins had Amals from the factory, too.

My favorite stump-puller was a BSA Victor 441 that I had for a short while, until I realized, at about age 20, that I would soon have the kidneys of a 60-year-old if I kept it. You could go up a steep hill with it and count the cylinder firings.
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