7.6 cu.ft Maelstrom- X 18" build

**sub_junkie** · **10-09-09, 01:28 AM**

Yep. It still looked the same as with the Insignia receiver. The amp's not clipping, and is at what looks like 20mm or so Xmax. Just an estimate haha.

**Mike P.** · **10-09-09, 02:08 AM**

Are the #3 and #8 dip switches on the amp set to the right hand side which is the off position?

**sub_junkie** · **10-09-09, 02:18 AM**

Yep. They are set in the "right" switch position.

**Mike P.** · **10-09-09, 03:13 AM**

One last question. What were the gain controls set at on the amp when you had the EQ unit in the loop and when you took it out?

**sub_junkie** · **10-09-09, 11:05 AM**

The amp gain has been turned up all the way up. I had the MIC2200's output knob set anywhere from 0dB to +5dB and the preout channel on my receiver set around +5dB also. My mains were set at -10dB, and they could overpower the sub at 70dB's on the receiver due to it "bottoming out".

**Kevin Haskins** · **10-09-09, 11:21 AM**

Pull the driver, support it with a pair of 2'x4's on a saw horse. Run a sine wave 20-30Hz signal into it in free-air. At that point, you can see/hear everything that is going on with the driver under excursion. If it doesn't make mechanical noise in free-air, it won't in the box and your problem is something other than the driver. If you get noise in free-air, you have eliminated clipping as a problem because the driver won't take near as much power to get to full stroke.

Trying to troubleshoot it in the box with music as a test signal is not going to get you anywhere.

Kevin Haskins
Exodus Audio

**sub_junkie** · **10-09-09, 12:21 PM**

Its making noise on the 30hz tone but it just sounds like distortion. What is it supposed to sound like though? I also ran a 10hz wave through it and it had very low noise. There's a slight whistling noise, but that's probably from the pole vent, right?

**sub_junkie** · **10-09-09, 03:01 PM**

I forgot to mention that I did the free-air test in Bridged Mono. Would that matter?

**Kevin Haskins** · **10-09-09, 05:31 PM**

Quote:

sub_junkie wrote:

I forgot to mention that I did the free-air test in Bridged Mono. Would that matter?

Give me a phone call and I'll walk you through some testing. The forum is useful for troubleshooting something but it can be cumbersome for multiple exchanges.

360-452-9373

Kevin Haskins
Exodus Audio

**mlkmgr** · **10-09-09, 11:45 PM**

why do you have the boost at +5dB through the receiver? do you know what frequency it is boosting it at?

when i thought my shiva was bottoming out, it was my onkyo receiver's audyssey settings of +5dB that was causing my sub to hit xmax around 25-28Hz. my box was built to spec, my amps hpf set accordingly at 18Hz but i was still having issues. someone at avsforum told me to turn the boost down in the onkyo settings and the problem went away. (it was applying the +5dB boost around 25Hz) figure out where the +5dB is being applied in your frequency range. could be the reason you are having issues.

oh, and did you call kevin like he requested?

**sub_junkie** · **10-10-09, 02:43 AM**

As far as I know, my receiver boosts all of the frequencies, but I don't remember. I don't see why all receivers wouldn't boost all of them rather than just 20-30hz etc... But it still have the problem when its at 0dB, or lower. I only did that so I didn't have to have the gain way up on the MIC2200, because the hum noise is annoying.

I called Kevin, and he helped me run the sub through a few tests, and it all checked out. The noise is still there though. I will post the video here and email it to him as he requested. Note that my camera amplified the noise that its making. It's not quite that loud in person. The amp isn't clipping in the video, and it is on one channel (of the EP2500 in 4Ω) like I say in the video.

Here is the video. I think I sound funny in videos lol:

**Mike P.** · **10-10-09, 03:13 AM**

So far you have taken the EQ out of the loop, swapped out the receiver and the sub checks out. Next thing to do is eliminate the hum issue. Maybe that has something to do with it.

**Ryan Anderson** · **10-10-09, 03:27 AM**

Quote:

Mike P. wrote:

So far you have taken the EQ out of the loop, swapped out the receiver and the sub checks out. Next thing to do is eliminate the hum issue. Maybe that has something to do with it.

out of curiosity, most noise, esp ground issues, are 60Hz in nature due to power supply being 60Hz AC? Can harmonics go down as well as up, 30Hz being 1/2 of 60Hz... so the hum being the culprit because of this?

**sub_junkie** · **10-10-09, 12:55 PM**

The noise is either coming from the Pre-Out channels on both of the receivers, or its a bad RCA to XLR cable. I think its the XLR cable because when its disconnected from the EP2500, the hum is gone.

**sub_junkie** · **10-13-09, 10:51 PM**

I found out today that the replacement cable that I'm getting is out of stock. So, I won't be able to try it for a while. And, my dad is saying that I need to put the amp away until Christmas. It is an early Christmas gift anyways. This thing is awesome with the EP2500. Plain and simple.

**sub_junkie** · **10-22-09, 04:20 PM**

Well I got the new cable and tried it and the noise is still there as with the old one.

**mlkmgr** · **10-22-09, 06:49 PM**

try a different brand of cable. if it is the same brand of cable as before, the cable you are getting is all manufactured the same way. this will help to eliminate the cable as the culprit.

go to your local audio store and find one. if it is the culprit, problem solved. if it is not, return the cable to the store and move to the next piece of equipment in the chain.

**sub_junkie** · **10-23-09, 09:41 PM**

Would it make sense that the hum noise I'm getting increases in volume when I turn the gain up on the MIC2200?

**sub_junkie** · **10-25-09, 10:20 PM**

Sorry for another double post...
Anyways, I did a few more tests for the ground issue. I unplugged my LCD TV, and that didn't help it any. I unplugged everything in my room, and that didn't help. Finally, I unplugged the Cable/Sat cable for my tv in my room, and the noise practically is gone. There is just a slight noise with the gain turned all of the way up on the MIC2200, and with the EP2500's gain all of the way up. You can only hear it about 7 feet away, then it is inaudible.

How do I go about fixing this cable issue? (for cable tv by the way)

**robbo266317** · **10-26-09, 05:55 PM**

This seems to be a common problem over there.
If you do a search you should find a couple of threads with the same issue.

**sub_junkie** · **10-26-09, 06:36 PM**

I found a few threads that mentioned the cable box being a problem, but none of them adressed how to fix them.

I forgot to mention that I ran my cable through a Monster Cable Clean Circurity system, and the noise was still there.

**robbo266317** · **10-26-09, 06:56 PM**

I am not familiar with the Monster Cable system, maybe someone else can give advice on it.

Hum is typically caused through grounding faults and can be a real pain to pinpoint.
Is all the equipment on the same outlet/circuit, is the cable box grounded properly or is the cable box on a different mains circuit?
We don't seem to have as much problems these days down here in Oz. All the wiring is grounded back to the meter box and each room is on the same circuit.

Hopefully someone will come up with suggestions or you could pm the the members in the other threads and ask how they resolved it.

**sub_crazy** · **10-26-09, 08:35 PM**

I used to have the same problem when I had cable TV and the only thing that worked was the Mondial Magic box ground loop eliminator. There was also the Tributaries Ground Guard which was said to do the same thing but I never tried it. They were like $99 each back in the day but since I don't think they are made anymore you may be able to find one cheap on ebay.

I would call your cable company first and complain to them that the cable is not properly grounded. All they have to do is install a ground and your hum should be gone.

**sub_junkie** · **10-26-09, 10:10 PM**

Ok, cool. Would it cost anything for me to have them come out? And, how would I be positive that it isn't grounded properly? I could try to get COX or whoever to come out, but my parents would be weary of anything happening haha

**sub_crazy** · **10-26-09, 10:19 PM**

The cable should be properly grounded so if it is not then they have to correct that with NO additional cost.

I have never done it but basically it is a coupler that goes between the cable coming in from the street which has a ground wire attached to the house ground. I have seen the one they used for my Directv install and it is a simple device. You can just explain to the cable company that your amplifier has a ground loop hum and the only way to stop it is by unplugging the cable TV so that means it is not properly grounded.

Your only other option would be to try and do it yourself or buy one of the ground loop eliminators I mentioned above.

After moving to Directv I have never had another ground loop but I remember the hum horrors when I had cable.

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