F212 Transformer Hum - Problem solved.
 

Ever since getting my F212, I've been plagued with audible 60 Hz. hum coming from the F212's internal toroidal power transformer. The hum was elusive and would come and go without warning. Sometimes the hum was persistent for many minutes at a time. At other times, it was cyclical and would come and go with a periodicity of a three or four seconds between peaks and valleys. I reached out to several people who said it could be dimmers installed on the lighting or that it could be D.C. riding on the A.C. line. Disconnecting the dimmers didn't help and selectively powering down various circuits at the breaker panel didn't help. I also ran separate 10 AWG feeds from the breaker panel to the sub. I even tried both sides of the A.C. line to no avail. Heck, I even invested in a toroidal isolation transformer only to find the isolation transformer itself hummed quiet loudly.

At my wits end, I decided to invest in a little $100 device known as the Emotiva CMX-2 AC Line Restoration and Common Mode Filter. I also investigated a PS audio device that I found info on only to find that it was no longer being manufactured. The CMX-2 arrived several days ago and appeared to be a well-built and solid unit. To my utter surprise the problem has been resolved! The F212 is dead quiet even with my ear pressed against the cabinet of the sub! I can highly recommend this little gadget if you suspect you may be fighting D.C. riding on your A.C. line.

Joe.......This is good news. Thanks for letting everyone know about the Emotive CMX-2 AC Line Restoration and Common Mode Filter. Retail $119 isn't bad if it solves issues like yours.


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>Precision DC offset eliminator.

>High-quality common mode and differential mode L-C noise filtering.

>Continuous line-status monitoring - provides continuous real-time indicators that show the status of Hot, Neutral, and Ground lines.

>Power Direct Connect™ mounting system, which connects the outlets directly to the circuit board.

>Premium high-quality components and a heavy-duty double sided FR4 circuit board with high current paths on both sides.

>Two commercial grade AC outlets.

>Detachable IEC high current, 14 gauge, 2 meter power cord included.

>High reliability resettable magnetic circuit breaker.

>Constructed from machined aluminum.

>Can be mounted vertically or horizontally.

Joe thanks, my 212 has some hum too, I have tried ground lifts and even a Furman outlet strip higher end unit and even all of that into my PS Audio conditioner, WW silver cable no help :no:

I will order one of this asap and keep you and the thread posted.

PS Thanks so much, this will be a game changer.

My 212 even seems to add some noise when I use my MX150 but not when I am in pure 2ch mode on my C500 rig. For some reason my MX 150 even though on the same circuit as the C500 and both these even on a diff breaker and a diff PS Audio conditioner have given me fits. Sounds like your issues in similarity.

I did run another dedicated 120 circuit and another 20 amp breaker, got rid of light dimmers etc went all LED nothing and I mean nothing has helped.

When the audio system is off I power of the power to the 212 to keep it out of the loop and then even pull the power cord uggg....:sigh:

Again Thanks Joe :)

WOW I sure hope this helps! :thumbsup:

Can you tell me where to order at? Amazon 2-4 weeks I want it yesterday!

Order update, OK I ordered direct from manufacture, nothing else has helped so hope this does not sure if it will be here this week or next?

But with the new Oppo 205 on the way Wed I use it running the MX150 so I really want this hum gone.

All my other items not to hi-jack this thread helped maybe 10-20 percent each, but hum is still bad enough it is annoying and I love the F212 so i sure hope like help this does the trick. For $119 I think it is cheap investment relative to everything I have into the system, yet alone the F212.

I stock them! :yes:

That's a great find and great that it has worked. I'm considering a JL sub. Is this hum a common issue?

Not at all; I have about 10 pairs of subs, zero hum.

Good! Thanks.

Ivan wish I knew this I would have ordered direct from you Sorry... I ordered from company direct :(

I had the same problem several years ago. Either the Emotiva wasn't available yet or I just didn't know about it. Audio by Van Alstine sells the "HumDinger," which removes DC from the line, and it did the trick at $125 per sub (a little more now, I think).

And the verdict is.........?

F212 Transformer Hum - Problem solved.
 

It did minimize the hum to a point that is very low. So in between songs you have to be very still and if you put your head within four feet it barely audible now. So for my installation I would say the hum is 80% less. Note it was not loud enough to ever detect while listening before installing the Emotiva, only with nothing playing was a hum present.

I tested even with the xlr cable disconnected and it had no effect. I think and maybe it is normal unless it is my crappy power company, a slight issue that goes with the territory of these large amps on the F212.

All in all I am more pleased now than before with the performance of the sub. Thanks guys [emoji41]

Good to hear (or not)! It's a shame that little nits like this bug people like me to death but, then, I guess this what make the audio world go round.

Also, I apologize for any part I may have played in causing you to notice something that didn't bother you prior to all of this!

A friend had the same issue with his F113 and the dealer recommended that same Emotiva unit. His hum disappeared as well.

Hello! I've an F113 v2 with this very annoying problem, but Emotiva CMX-2 AC Line Restoration and Common Mode Filter doesn't exists for sell anymore...
Something replaced it?
And one more - I need it for 220v - some body has experience with such kind of filters?
Thanks!

I believe Emotiva may no longer have these in production and I've never seen one built for European voltage and frequency standards.

If you are handy with tools of the trade and have access to an electronic parts supplier, there are schematics on the internet that would allow you to construct your own DC offset correction circuit that don't appear to be to difficult to make.

Good luck!

Shoot Frank Van Alstine an email and he may be able to help you. https://avahifi.com/collections/acce...c-line-blocker

Ron