HOG D2 metallic whistling on exhale

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John12

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Stuart, Florida
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I am a new diver, just open water certified. Wasn't happy with my MARES MV12s regulator, so after reading a lot of great things here, decided to get a HOG d2 second stage, to pair with the MARES 1st stage. Just got it today from Dive Right In, great dealer price shipping etc. Hooked it up to my air cylinder. Have no way to test it in water so strictly dry breathing.. It inhales great, but a distinct sound like a harmonica with each exhale. Its not restrictive just noisy. Will this change if I dive with it, do others have the same noise under these conditions. I know its a great product from a great dealer, just wondering if its an indicator of a problem or I should just wait and dive and see what happens. Could it be because of the first stage, if so I'll pair it with a EDGE 1st stage, (don't want to use din) I did call the dealer customer service, the young man said to dive and see if it goes away, if not they will replace it. I just wanted to make sure there was no problem that might make it better toreplace it before I get under with it. Know its redundant, I did e mail customer service at EDGE with this question, just looking to this forum for real world experience. As a side note, my wife has a Legend it doesn't make any noise when breathing under same circumstances.
 
All my regs make funny noises above water, but underwater is another story. Usually it is a sound like blowing across the edge of a piece of paper. Don't worry about it and go dive it.

The only thing that matters is for the first stage is that the IP is set in the correct range. Do you own an IP gauge? If not I would highly recommend getting one, and routinely check it to catch an issue before it becomes a problem underwater.
 
I would say that it is the diaphragm vibrating when you exhale. Normally the hydrostatic pressure of the water stops the vibration and allows the exhaled air to escape from the exhaust, but because you're dry breathing, there's no pressure against the diaphragm.
 
I have exactly the same issue with a Hog D1. In fact, I have it on both my D1s - to a much lesser extent on one than the other. This is the sole thing I am disappointed about with these regs. They breathe very well, if a little wet while inverted (on both). So yes, the problem resolves just fine underwater. It is, as Phuong rightly points out, the diaphragm vibrating.

The one other quirk I found was with a replacement yellow purge cover. The spacer on the back of it was too long and pressed against the diaphragm when installed, resulting in a slow but significant leak. I shaved a few mms off it with a craft knife, and it resolved the issue.
 
I have exactly the same issue with a Hog D1. In fact, I have it on both my D1s - to a much lesser extent on one than the other. This is the sole thing I am disappointed about with these regs. They breathe very well, if a little wet while inverted (on both). So yes, the problem resolves just fine underwater. It is, as Phuong rightly points out, the diaphragm vibrating.

The one other quirk I found was with a replacement yellow purge cover. The spacer on the back of it was too long and pressed against the diaphragm when installed, resulting in a slow but significant leak. I shaved a few mms off it with a craft knife, and it resolved the issue.

I have run into a few seconds that do this and it is as was already stated. No problem with diving them and a couple actually resolved themselves after a few dives. I have had sherwoods, oceanics, and aqualung seconds do this. On one I fixed it by taking the cover off, removing the diaphragm, and reseating it.

As to the soft covers there were some that got sent with a stem that was too long. The quick fix was to trim the stem. It was also possible to adjust the lever height for the cover. But if you went back to the original cover the lever height needed reset. The new soft covers seem to be fine.

Sent from my DROID X2 using Tapatalk 2
 
Oh man I am glad I am not the only one. Second dive with rental gear last week in Roatan my reg was making a humming noise when I exhaled until I was more than 20 feet under. Noone else seemed to hear it, and I was not losing air, so all was fine.
 
CoasterFreak, as Jim points out this is not uncommon with regulators, no matter the marque. It's by no means just a HOG thing :)

I did try reseating the diaphragms on both, but it made no difference as the issue seems to be the exhaust diaphragm rather than the front one. In fact, if someone knows a fix I'm all ears. The regs breathe beautifully - much nicer than the ($$$) oceanic zeta they replaced for me. But the harmonica noise has raised more than one eyebrow when doing pre-dive buddy checks on boats. The regs work just fine, so it doesn't bother me enough to send them anywhere, but if there is an easy tweak I'd be happy to make it.
 
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normally a harmonic is a spring, if your harmonic doesn't stop in the water after a dive or two and is bugging your dealer will be happy to move the springs that 98% of the time will eliminate the harmonic, or we will be happy to as well. The other 2% we will still be happy to figure out and stop. :)

On a happy note, this thread has more reports of harmonics than we have gotten in the last 4 years.
 
normally a harmonic is a spring, if your harmonic doesn't stop in the water after a dive or two and is bugging your dealer will be happy to move the springs that 98% of the time will eliminate the harmonic, or we will be happy to as well. The other 2% we will still be happy to figure out and stop. :)

On a happy note, this thread has more reports of harmonics than we have gotten in the last 4 years.

Thanks for stopping by, cerich! I never contacted you guys directly, but did post the same issue here back in May:

http://www.scubaboard.com/forums/edge-gear/419962-2nd-stage-accordion-noise.html

The consensus was to dive with it, which I have been doing ever since. The noise maybe eased up a little, but did not resolve over 15 or so dives as primary before I started using it as my secondary. I like the reg enough to have bought another since. It has the same issue, but not nearly as loud.

I came to the conclusion it was the exhaust diaphragm. Taking the front of the reg off, removing the diaphragm, and covering the front with my hand, exhaling I get the same noise. If I put the tip of a bamboo skewer in through the exhaust and gently lift the lip of the exhaust diaphragm to break the seal, exhaling out I get no noise. If it is of use to anyone I can take a video.
 
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normally a harmonic is a spring, if your harmonic doesn't stop in the water after a dive or two and is bugging your dealer will be happy to move the springs that 98% of the time will eliminate the harmonic, or we will be happy to as well. The other 2% we will still be happy to figure out and stop. :)

On a happy note, this thread has more reports of harmonics than we have gotten in the last 4 years.

My original HOG seconds never did this but now I swapped them all over to the new style case all seven of my HOG seconds do this. I thought it was the exhaust valve making noise but the benefit of the if the new style case far out weights the noise it may make out of the water, all I care about is how they perform in the water. If people give you funny looks when they hear the noise just say the HOG regs are supposed to sequel like a pig!
 
https://www.shearwater.com/products/teric/

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