AMP & Passive Subwoofer Recommendations?

[drvnbysound]

If you're going to go the component crossover route, I'd suggest a 6dB (first-order) low-pass crossover. This would only consist of a single inductor wired in series with the speaker/subwoofer.

Having said that, it's hard to say that this will actually resolve the issue. Here's why... I assume that the subwoofer used (the one humming) has a LPF built-in already; that should be filtering any high frequency that's on the line already... so this may just end up being pre-filtering, which may not even have an effect. Particularly if the frequency of issue is in the band that you'd want your sub to reproduce (e.g. 60Hz).

 

[RAL]

The trouble is that a typical subwoofer has a frequency response of 20 Hz to 200 Hz.   The 60 Hz AC hum is almost smack in the middle of it's range.  A typical filter doesn't have a sharp enough cutoff to remove just the 60 Hz frequency and nothing else.  It would end up removing much of the frequncies on either side of 60 Hz that you do want to hear.

 

[Del91574]

After speaking with "an advisor" with cruthfield.com...  I'm told that manufactures don't make passive subwoofers (at least not ones that are free standing/floor type) for residential use.  I stubbled across a passive sub model VAS12SUB from VM Audio which is a "pro audio" passive sub.  I was going to pair that with a sub amplifier Behringer NU1000 but apparently that equipment is designed to have a mixer board and other crap (e.g. designed for DJ's or studios).
 
I'm about to pull my hair out
 
If any of you have a passive subwoofer please share the make/model as well as the amp you're using.

That's your issue...you spoke to the wrong "advisor".

 

[ccmichaelson]

That's your issue...you spoke to the wrong "advisor".

 
I spoke to multiple "advisors" - they all have different ideas/thoughts/solutions as do people here ;-)
 
The local AV guy suggested I contact our electrician and ask him for an "iron thingy" that we could clip on the speaker wire to eliminate the 60 hertz hum...  say what?  

 

[drvnbysound]

I'd guess that he's referring to a ferrite core: http://parts-express.com/ferrite-core-1-4-cord-noise-suppressor--110-450

 

[Del91574]

I spoke to multiple "advisors" - they all have different ideas/thoughts/solutions as do people here ;-)
 
The local AV guy suggested I contact our electrician and ask him for an "iron thingy" that we could clip on the speaker wire to eliminate the 60 hertz hum...  say what?  

And facts aside, I've experienced the worst advice by those whose name contains a "field" in it. They're a retailer similar to Best Buy or others. They do offer assistance on the automotive side, but as far as home and pro audio, some of the worst published advice I've seen.

 

[ccmichaelson]

yeah I trust you guys more than any local AV guy or online store...  that said, there didn't appear to be a group consensus on a solution but appreciate all the "try this/that".  Given that I'd like to dual-purpose my sub's (sonos connect amp + AVR) I decided to try the Russound P75 which supports auto-sensing between two sources (sonos + AVR) and it should amplify the line-level across my speaker wire to a Russound ADP1.2, a speaker to line-level adapter.
 
I have a 100% guarantee from Crutchfield that this will solve the hum or my money back...  can't beat that I guess...
 
So my connection will be sonos/AVR sub outs -> Russound P75 -> speaker wire in wall -> Russound ADP1.2 -> subwoofer.
 
As an interesting side note, I plugged my subwoofer into the AC outlet and plugged in an RCA cable (one that doesn't connect to anything else on the other end) and there's a slight hum...  If I unplug the RCA jack there's no hum.  Perhaps that's normal...

 

[pete_c]

I have a 100% guarantee from Crutchfield that this will solve the hum or my money back...  can't beat that I guess...
 
Been years now here purchased my first LCD TV's from Crutchfield.  I purchased matching LCD TV's of different sizes at the time.
 
Delivery / customer server was great.
 
Perhaps that's normal...
 
I do not get a hum here using microphone cable from one side of the room to another with my powered subwoofer.

 

[mikefamig]

As an interesting side note, I plugged my subwoofer into the AC outlet and plugged in an RCA cable (one that doesn't connect to anything else on the other end) and there's a slight hum...  If I unplug the RCA jack there's no hum.  Perhaps that's normal...

 
Assuming that the RCA plug was connected to a shielded cable, both ends of the shield needs to be connected to earth or the shield will not work to protect the data wire from noise. If the far end of the cable was not attached to anything then the cable can act as an antenna and pick up noise.
 
Mike.

 

[mikefamig]

I have a 100% guarantee from Crutchfield that this will solve the hum or my money back...  can't beat that I guess...
 
Been years now here purchased my first LCD TV's from Crutchfield.  I purchased matching LCD TV's of different sizes at the time.
 
Delivery / customer server was great.
 
Perhaps that's normal...
 
I do not get a hum here using microphone cable from one side of the room to another with my powered subwoofer.

 
Probably because microphone cables are shielded.

 

[pete_c]

Yes it is.
 
Just looked at the old spool of Radio Shack cable.  It is just labeled 2-conductor plus shield.  It has to be some 20 years old now.

 

[RAL]

Not only is microphone cable shielded, it is twisted pair, so any hum that is picked up by one wire will be cancelled out by the other.

 

[pete_c]

It's been a couple of years back here that I did install a Russound zoned amp (in a com closet) with keypads in a dental office pro bono for a friend.  I tried the catxx low level baluns to carry audio to a ipod in the front of the office (reception desk).  The cable ran way high up above but adjacent to much conduit some 100feet plus (large offce) and no noise was picked up by the Russound amp which amazed me. 

 

[Del91574]

Probably because microphone cables are shielded.

And balanced to the source.

 

[ccmichaelson]

The hum is gone - hooray!  The Russound P75 amp and the Russound ADP-1.2 were the ticket to my problem and as a bonus, I can dual-purpose my subwoofer - 1) When playing music through our Sonos Connect AMP 2) When watching TV/movie and sub audio coming from our AVR.
 
Appreciate all the comments/feedback!