Umarex How do you quiet a Notos down?

Probe oring missing? Mine is tuned to 15fpe and very quiet with oem shroud

igolfat8 said:

I removed the OEM moderator and installed a 1/2-20 adapter. Then i tried several different LDCs from Donny FL and Rocker 1 and this thing is just rudely loud. I don’t have a dB meter but it’s easily 2x louder than my other airguns. it’s detuned to 582 FPS running CPHPs. Any suggestions?

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Something is wrong, I get 64dB with Subscribers Tesla valve moderator. The stock mod is 72dB.

You definitely have a leak. The Notos is pretty darn quiet with the factory moderator. Even at 20ft lbs.

igolfat8 said:

Running the stock HS and reg is turned in 1-1/4 turns which is around 900 psi-ish, Yielding 582 FPS. Previously I was using a weaker HS but it had a nasty blaaaaaap sounding report. Put OEM HS back in and the blaaap sound went away but it’s always been louder than any of my other moderated PCPs.

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Blaaaaapp is hammer bounce.

900 psi?

This is a phenomenon mostly based on your lowering the reg much below the point where the gun is balanced.

To run the reg at a pressure less than 1/2 the manufactured setting, you will need to replace the preload spring, hammer spring, hammer and start a new tune.

The Notos was designed around 20fpe, you have a completely different animal now.

I dropped my reg alittle bit, then cut my spring alittle also. All the way backed out I'm at 15fpe. Honestly my reg is very very consistent like that and very quiet. I'd need to look at my old posts as I did I think write down exactly what I did. I'd suggest raising the reg pressure at least to half way back to original. Your likely wasting A LOT of air with that low of a reg pressure and heavy hammer and such.

Edit: Here's what I found

Before I shot the gun I tore it apart and took off the air tube to adjust the regulator down. Impressed with the machining. I adjusted the reg down one half turn. I then removed hammer spring and cut off 3 coils off the spring. This got me right at 695fps with CPHPs.

the stock notos is very quiet for me

igolfat8 said:

Running the stock HS and reg is turned in 1-1/4 turns which is around 900 psi-ish, Yielding 582 FPS. Previously I was using a weaker HS but it had a nasty blaaaaaap sounding report. Put OEM HS back in and the blaaap sound went away but it’s always been louder than any of my other moderated PCPs.

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Mine is loud too. Even with a big can on it.

Just put your hand or a couple of fingers over the area where the magazine goes, over the bolt probe, ideally without the mag in place. Your hand /couple of fingers will 100% detect a leak and its severity better than Kleenex in this region. Many instances with airguns where you don't want to use your hand, but in this area its safe. I used to do Kleenex / TP, but then last few times I was like, why am I using my visual sense opposed to my sense of touch? Lol

A little wisp of air shouldn't contribute much to the guns report, but a violent one certainly may. If you could isolate a muzzle report from your leaks report, if it were a wisp it would sound quite literally like a mouse fart. If it were a larger violent leak, it would be violent and air would escape fast enough to vibrate / shock enough atmospheric air to become loud, akin to having to muzzle blasts.

-Matt

igolfat8 said:

I've had my barrel out several times and it has two teeny tiny O-rings around it to seal the transfer port area. My O-rings didn't look great the last time I had it apart so I wonder if I am loosing some air around them. Today I am going to try a Kleenex test to see if I have any air escaping there and from the probe O-rings and I will report back my findings.

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I put new barrel orings on mine as I did the plenium and mod adapter kit.

you need a moderator that's about 200mm or a bit longer with a bore that's not too over sized.

Also try raise the regulator.

You will likely need a much lighter spring or try to drill the hammer lighter. I believe with your reg setting as low as it is, it's wasting alot of air.