Dahlquist Subwoofer 'popping'

[Viro]

Man, it's crazy what forums you can find on the 'net these days....

So I have a weird problem...

I have a Dahlquist subwoofer with the following specs...

8" high-power woofer with 1.5" voice-coil
reflex rear ported front-firing cabinet
Class-D (digital) pwer amplifier, 90W RMS - 250W peak power
system optimised amplifier equalization

This is hooked up through a single RCA digital jack cable to my Kenwood VR-6060 home theatre receiver...

Here's the problem.....out of nowhere the sub starts 'popping'. If I unplug it and replug it in it goes away.

It'll do it if I'm watching tv with the audio going through my home theatre or it'll just start popping in the middle of the night with the receiver off.

I'm reasonably handy and if I'm directed to a solution that'd be great....I'm past the warranty now and really don't want to dip into the cookie jar to get another one yet.

 

[Viro]

er...uh....um....

I just plugged 'er in to give it a look and I just got a humming noise and then no power....

I was thinking this is a power problem from the start, now obvioiusly it is.

It has always plugged in to a monster surge protector power bar .... so no surges of sorts that I would know of.

 

[MacManNM]

Sounds like..

Sounds to me like the auto on circuit is malfunctioning. Does it have this feature? If its not that then i would say there is a problem with the feeback circuit in the amp. Is the woofer going to the rails when its making this noise?

 

[Viro]

not sure what you mean....

it's almost like it's 'overheating' something and then it won't work right...(that might not be the case, just how it appears to me)

When it fails or whatever it just puts out a steady 'pop........pop.......pop.......pop......pop'...(steady, like a drum beat, same tone too)

When I unplugged it yesterday and then put it back in it worked just fine while I was listening to the boob tube, and then in the middle of the night last night it starting doing it.

I've got to get a new fuse (it blew today when i put it in today.....the sub was humming first and then I unplugged and then when I plugged in there was no power).

It is a dahlquist QX10t model sub (part of the Orbit 5.1 micro home theatre series)....the sub is always powered but will put out sound when the receiver is kicked on. (is that what you mean by auto on)

The board looks ok (no apparent bad parts and such)....if I knew what to do I could probably fix it myself...

I don't feel like I abuse the speakers at all, sure sometimes I got the volume up but I have the bass setting on the subwoofer set in the middle and the receiver settings have the subwoofer 'normal'.

I found a link to the EXACT system I have....(just fix the http part)

hxxp://www.dahlquistcorporation.com/DQp9%20_Orbit_no_box.pdf

 

[MacManNM]

Does it do it when the rca input is unplugged? You said it did it in the middle of the night, was the receiver on or off?

 

[Viro]

the receiver was off last nighh when it was doing it before it rudely awoken me from my deep sleep.....I can't remember for sure but I think i did unplug the RCA and it still 'pop....pop....popped' before I unplugged.

I don't feel like I abuse the speakers at all, sure sometimes I got the volume up but I have the bass setting on the subwoofer set in the middle and the receiver settings have the subwoofer 'normal'.

Can't be for sure but I'm pretty sure I did....i didn't try the other channel on the woofer I know that....currently it's hooked up through the left channel to the receiver

 

[MacManNM]

I think the problem is probably in the "auto on circuit". That is the circuit that tells the amp to go into low power mode when it's not being used. If there is a switch that defeats that circuit (something marked "powersave" or the like) I would try switching it.

The other possible problems could be:
1. Bad cable causing some kind of ground loop
2. a feedback problem in the amp circuit itself.

Try the switch, and changing out the cables, anything more than that, you will have to have it repaired. But chances are it would be cheaper to go out and buy a replacement sub. I'd recomend the Cadence, prob would be an upgrade to that little 8" you have now.

http://www.ubid.com/actn/opn/getpage.asp?AuctionId=601412458

Check it out.
Good luck

 

[Viro]

So what's your explanation to the subwoofer popping when I'm listening to music/watching TV (as in the receiver is on)?

I think I understand what you're saying when it's off, but don't forget it's doing it when it's 'on' (as in receiver on, producing sound).

 

[MacManNM]

the auto on also turns it off when not in use, I'd say that one of the sensors is bad and is cycling the amp power on and off, at random. Perhaps a thermal effect

 

[Viro]

man this bites....after I get a fuse I'll plug 'er in and see if anything is overheating in the circuitry...

nothing labelled powersave or of the sort....i've got 'lo-pass', 'high level', and 'diode bridge' labelled, that's it

 

[Viro]

So I put in the new fuse.....now nothing....no bass what so ever.

The power LED light is on but nothing......another weird thing I never noticed before....the led light first came on red and then after awhile went green....but still no bass!!

Booooo!

 

[Audioholics]

Something very similar happened to my Dad. Not to make this potentially more complex than it needs to be, but the popping would completely go away if we disconnected the sub from the receiver.

The popping woudl happen whether the receiver was on or off, but if disconnected it would stop. On a whim I checked the AC line and found DC on it (can't remember how many volts but it was more than 2.) My guess is that the receiver was damaged as a result (in my Dad's case).

No idea if this coudl be related as thre are so many variables and this doesn't exactly fall under the Occam's Razor solution.

 

[Viro]

don't drag my receiver into this !!! .... unfortuneatly the sub isn't putting any sound out now so I don't know if it's the cable, the sub, or like you suggested, maybe the receiver connection

usually when i would plug my amp in I would get a little pop, like the amp kicked in and everything worked on it's own from there...

I don't get that now....just my power light goes from red to green after awhile