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Trouble with home theater, any audio guys here? Subwoofer recommendation needed (1 Viewer)

fantasycurse42

Footballguy Jr.
Background:

Wife ordered a new credenza that houses our entertainment center. Unfortunately she didn't take measurements and my old receiver didn't fit in it, so I had to get a new one. While doing this I picked up a Harmony Companion to make everything compatible with my phone and eliminate the remote. 

Outside of a new Denon receiver, I kept my old speakers as they still worked well. I have Definitve Technology 5.1 Pro Cinema system with the sub, bought it in 2008. I had a theater dude set up the new receiver and hook up the Harmony hub to everything.

The whole thing was working great for two weeks with the old speakers/sub and new receiver. Last night I was on the couch and heard a repetitive sound. The best way I could describe it was; I live in an apartment building, the noise sounded like my neighbor was running a washing machine or dryer at a distance. Kinda at a distance like a flight up or down, but very noticeable constant tapping, like the wheel of the machine running in circles and kinda loose. I shut the TV and still heard it, so I ruled the system out and assumed laundry was being done by a neighbor.

Same noise again tonight, I got up and investigated, it's coming from the sub, all connections appear okay and the noise even continues when I turn the TV off.

Audiophile forum info I found says it might be the amp in the sub? This isn't my background and I have no clue. It's a Definitive Technology Pro Cinema sub, about 8 years old. These things are supposed to last 15-20 years, no?

Any suggestions?

TIA

 
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Chaos Commish

Footballguy
Audioguy here. Guessing that's the 600 series with the 8" sub? There is a bit of troubleshooting to do before calling it the amp, but the fact everything was great for a couple weeks with the new receiver does point to the amp failing. DT has great customer service and even way past warranty might ship a refurb amp cheap if you're willing to install the plate. Give them a call. It's pretty simple.  If not Parts Express sells subwoofer plate amps that will drive your sub fine from $50 to way more. But you can spare yourself that troube because Amazon has Polk Audio's 10" powered sub for $99 right now. It is better than your original, and if the new receiver is 5.2, then two is like thunder in a good way. Just sayin'... the best part of your system to upgrade is the 8" sub. It's pretty limited. 

Rule a few things out, you might get lucky. Make sure the sub is plugged into the same outlet as the receiver. You could have a ground loop if it isn't. This could solve the problem. Press down on the sub when it's playing. If you hear weird sounds it's the voice coil or the driver... toast. Pick it up and shake it for loose wires. Turn off and move any wifi and bluetooth transmitting devices. You could be getting interference. Remove the rear plate and make sure there isn't a tiny washing machine in there. 

 

fantasycurse42

Footballguy Jr.
Okay, I have no idea what any of this means... The sub has an LFE wire that plugs into the receiver "sub out" and a power cord that plugs into a multi outlet surge protector. 

What do I do to try and resolve? Removing the back of this credenza and adjust wires is a nightmare.

Speak to me like I don't know anything about home theaters please.

 
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belljr

Footballguy
Unplug the sub from the wall for a minute.   Does the noise stop?  THen plug it back in, any changes?

How are your speakers wired? Banana clips?  Loose wire possible

 
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fantasycurse42

Footballguy Jr.
When I turned everything off, still heard the noise from the sub. I unplugged it, then replugged, noise came back about 30 seconds later.

The sub has an input like an rca cable, just one wire that goes from sub to receiver. The speakers are all wired with those audio wires where the wires are out and touch the thing and are then screwed in.

I'll post some pictures later, I'm pretty lost on this stuff.

 

belljr

Footballguy
When I turned everything off, still heard the noise from the sub. I unplugged it, then replugged, noise came back about 30 seconds later.

The sub has an input like an rca cable, just one wire that goes from sub to receiver. The speakers are all wired with those audio wires where the wires are out and touch the thing and are then screwed in.

I'll post some pictures later, I'm pretty lost on this stuff.
Best description ever.   

I agree with others.   Does the sub work at all?

 
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moleculo

Footballguy
ground loop has to do with the power cords.  Make sure the power cord from the subwoofer is in the same outlet (or power strip) as the receiver.

 

belljr

Footballguy
:lmao:

Yes, works well except for that stupid noise.
Unhook the LFe (RCA PLUG) from subwoofer.   Do you still hear the noise

ground loop has to do with the power cords.  Make sure the power cord from the subwoofer is in the same outlet (or power strip) as the receiver.
This also.  Also try sub directly into wall.   Check your manual (some request not to use a power strip/surge)

 

belljr

Footballguy
I'll post wire pictures when I get home, maybe that'll help.
Just keep describing them..... :P

Pretty sure the answers won't change. We are trying to isolate your issue 

If the Powered sub had no incoming line from the receiver and still making the noise than it's a pretty specific issue

 
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belljr

Footballguy
  1. If the subwoofer is plugged into its own outlet, plug the subwoofer's power cord into an outlet shared by the other components. Use an extension cord if necessary.
  2. If the hum persists, and your system includes a cable TV, disconnect the cable line. If the hum stops, install an isolation transformer on the cable.
  3. If the hum persists, disconnect the remaining component cables one at a time until the hum stops. Install a coaxial isolation transformer on that cable.
  4. If the hum persists, install a line-level ground loop isolator on the subwoofer's line-level feed cable. This usually solves most hum problems.
  5. If nothing helps, disconnect all the audio cables from the subwoofer. Leave the subwoofer plugged in and switched on. If the subwoofer hums, it points to a defective unit. Contact the company's customer service to technical support 


I've made an assumption it's a "hum"

 
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moleculo

Footballguy
I don't think it's a ground-loop hum, but that's the easiest thing to check and fix.  might as well rule it out first.

 

fantasycurse42

Footballguy Jr.
probably not a ground loop then, probably a blown amp.
This is what a lot of audiophile forums have brought me to believe with my minimal knowledge. 

If I troubleshoot and can't fix, is my best option just buying a new one? 

Any recommendations to replace this one? The room is not very large if that helps, think NYC family room 18x17.

 

Fat Nick

Footballguy
If you end up wanting to just replace them, I've got a pair of Polk PSW250's I'll sell you for cheap.  Ported box.  Big boom.  Great for movies.  I just built a home theater with all in-wall Def. Tech stuff, so I don't need them anymore.

 

eoMMan

Footballguy
Rollin down my windows yeah I have a air-conditionerBut I got the sound I want the whole world to listen ta

 

Fat Nick

Footballguy
fantasycurse42 said:
Can I get some recommendations? Need a new sub, 100-400 range, the lower the better.

Room is about 17x18
Seriously man, I hate to sound like I'm just hawking my used stuff here, but consider my pair of PSW250's...that pair would sound fine in a 17 x 18 room.  They look basically brand new.

 

Hawks64

Footballguy
Seriously man, I hate to sound like I'm just hawking my used stuff here, but consider my pair of PSW250's...that pair would sound fine in a 17 x 18 room.  They look basically brand new.
Yeah for your price range ie under 400 FN's pair will sound better than the Polk you linked. Both don't go really low and you have more space than a single 10" can handle IMO.

 

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