Strange Issue

[Hi Ho]

I was messing around with my system today (what's new? ) attempting to find the best settings to make do with my receivers' terrible bass management until I can get a new one (crossover won't go below 100hz while sub has rolls off around 100hz). I did get it to sound better by setting the front/center speakers to large, which sends bass to the speakers but oddly, keeps the subwoofer in action. This setup definetly fills the void that was there.

Anyway, I am kind of getting off topic. The issue I experienced is with my subwoofer. It is a DIY job (seen HERE) with a Parts-Express 250w plate amp. I was messing with the phase dial to see if it made any difference... It did... though not in a normal way. I noticed, after turning the knob back to 0, that the sub was no longer making any sound. I was getting a little jumpy because the last thing I want is a dead sub. I turned up the volume on the sub and I could heard a little bit of sound. I started turning the phase knob back and forth and the sound came back. I turned it again and the sound went away.

I have now concluded that if I turn the phase knob away from 0 the sub will stop working until I turn it all the way to 180 and rapidly turn it back to 0. Even though it is now working, I swear it isn't as loud as it used to be, but that might just be my mind.

What could cause this?

 

[mtrycrafts]

I was messing around with my system today (what's new? ) attempting to find the best settings to make do with my receivers' terrible bass management until I can get a new one (crossover won't go below 100hz while sub has rolls off around 100hz). I did get it to sound better by setting the front/center speakers to large, which sends bass to the speakers but oddly, keeps the subwoofer in action. This setup definetly fills the void that was there.

Anyway, I am kind of getting off topic. The issue I experienced is with my subwoofer. It is a DIY job (seen HERE) with a Parts-Express 250w plate amp. I was messing with the phase dial to see if it made any difference... It did... though not in a normal way. I noticed, after turning the knob back to 0, that the sub was no longer making any sound. I was getting a little jumpy because the last thing I want is a dead sub. I turned up the volume on the sub and I could heard a little bit of sound. I started turning the phase knob back and forth and the sound came back. I turned it again and the sound went away.

I have now concluded that if I turn the phase knob away from 0 the sub will stop working until I turn it all the way to 180 and rapidly turn it back to 0. Even though it is now working, I swear it isn't as loud as it used to be, but that might just be my mind.

What could cause this?

Not sure why it fades as you dial in a different phase. The loudness may be, most likely that the driver is not totally linear in both directions of travel. So, when you apply the phase shift with music, you may have volume issues.

 

[Hi Ho]

Well, the thing is, it is completely random the way it fades. It might drop out half way up, 3/4 way up, or anywhere in between. Then, I have to turn it to 180 and quickly turn it back to 0 in order to get the sound back.

 

[agarwalro]

Well, the thing is, it is completely random the way it fades. It might drop out half way up, 3/4 way up, or anywhere in between. Then, I have to turn it to 180 and quickly turn it back to 0 in order to get the sound back.

Since you have the rest of the speakers running as "Large", you are probably cancelling out certain frequencies when you change the phase on the sub. It is the result of the room responce changing with you changing the phase of the the sub and not the rest of the speakers.

The best way to overcome this problem is to go through the speaker calibration steps repeatedly changing the phase of the sub each time. The settings that gives you the best intergration of speakers and sub with flattest response is the one to keep.

 

[MacManNM]

Since it appears to be random, I'd say you have a dirty pot, or a bad pot on the amp. Try some spray cleaner in it, it should clean it up.