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Model 15 hum

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Model 15 hum

Postby Skotchi » Sat Aug 26, 2017 5:49 pm

Hello,

Forgive me if this is a stupid question, but I'm a first-time Moog modular owner. I've just turned on my Model 15 for the first time, and there's a very noticeable hum. Is this normal?

Thanks for any insight!
Skotchi
 
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Re: Model 15 hum

Postby Rarecomponentadsr » Mon Aug 28, 2017 6:21 am

No ...not normal.

I once had this problem . The only thing you can do is check your power connections, make sure it is properly earthed. Check you haven't got any loose connections.
Also where is your set up ? Isolate it away from anything where it could pick up external interference .

Is there anything you have plugged in near the Modular that could be affecting it ?

Finally, do not plug any patch cables in. Test the Modular without any cable connections apart from PSU.

...and if this doesn't work..try the synth in a different room on a different floor to see if it's a mains loop fault.
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Re: Model 15 hum

Postby Skotchi » Mon Aug 28, 2017 4:25 pm

Really appreciate the detailed response-- I'll try these suggestions.

Thanks!
Skotchi
 
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Re: Model 15 hum

Postby EMwhite » Thu Aug 31, 2017 11:04 pm

Depends the type of hum.

When I got my Model 15, I noticed a... um, noticeable 'hum' except it was the hum of the power supply vibrating (as they do) against the wood cabinet. Apparently the power supply was mounted directly to the wood and not insulated with rubber grommets as I've seen used in the past on other, similar types of modulars.

Is your hum coming from the PS or is there a ground loop issue / coming through the VCA output?

thanks.
'76 Minimoog, Taurus 3, Oberheim FVS + Son of 2-voice; Sequential ProOne; Juno 106; Moog Model 15; Kurzweil 250; Hammond M3; and a handful of Fender Basses Flickr!
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Re: Model 15 hum

Postby Skotchi » Fri Sep 01, 2017 10:50 am

Hi EMwhite,

Really appreciate your help.

I don't believe the 'hum' is coming through the VCA output-- it seems to be most noticeable in the area of the on/off switch. Is this where the PS is located within the cabinet? Or is the PS on the back where the power cord attaches?

I should add that I have a surge protector that is supposed to indicate issues with grounding, and that particular indicator is not lit.

I sent an email about this to Moog support about 5 days ago, but so far, crickets.

Again, my thanks.
Skotchi
 
Posts: 21
Joined: Mon Aug 21, 2017 10:21 pm
Location: Austin, Texas

Re: Model 15 hum

Postby EMwhite » Sat Sep 02, 2017 12:31 am

My bet is that it's the same thing that I've experienced.

A sure fire way to find out is to turn your 15 around and put your hand on the power supply as you turn it on; you'll feel the vibration that I'm talking about. it's subtle but you'll feel it. Note that you will need to pull the back panel in order to do this; unlike the vintage 15, the power supply components are not exposed.

I've been meaning to take mine apart to install the rubber grommets that I'm talking about. The power supply is mounted with standoffs; others use 'L' brackets (the latter is preferred but Moog went this route in order to make it more sturdy; there really isn't any difference from a power supply performance perspective; it's just mechanical engineering.

Confirm the vibration/hum and that will motivate me to take mine out/apart, fix it, and take some good pictures.

I did email Moog when I first experienced this (in September of 2015) and their feedback was that they would discuss my concerns with their design team. I had a few other QC issues, nothing major.

Thanks.
'76 Minimoog, Taurus 3, Oberheim FVS + Son of 2-voice; Sequential ProOne; Juno 106; Moog Model 15; Kurzweil 250; Hammond M3; and a handful of Fender Basses Flickr!
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Re: Model 15 hum

Postby Skotchi » Sun Sep 03, 2017 9:27 pm

Hi,

I’ll try removing the back to confirm your observation in the next week or so when I get a chance.

Regarding QC issues, I’ve also had a *very* minor issue: one of the small screws on the 904A was missing and another on the 921 was loose. Again, very minor, but it does call into question Moog’s much vaunted QC process.

Thanks
Skotchi
 
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Re: Model 15 hum

Postby thedangore » Fri Sep 08, 2017 12:42 am

Skotchi wrote:Hello,

Forgive me if this is a stupid question, but I'm a first-time Moog modular owner. I've just turned on my Model 15 for the first time, and there's a very noticeable hum. Is this normal?

Thanks for any insight!


If it makes you feel any better, I also had the same "issue" when mine arrived. The hum was noticeable for sure, but doesn't seem to do anything sonically to the signal. The actual unit had a very light but constant hum noise as soon as you flipped the switch. The sound does seem to eminate from the power button area which i can only assume is where the power supply is located. It very well could be a vibration like EMwhite suggested.
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