Newbie here - sub dead

 

cudabob
Unregistered guest
I have a 200 Watt 12 inch KLH sub driven by a Harmon/Kardon Surround amp which has been working fine. All of a sudden, the sub produces no sound - the power light comes on when on manual, but the auto setting doesn't work. Can a cable just go bad (cheap)? Can there be another reason?
 

cudabob
Unregistered guest
Update - I found an old set of cables which didn't help. The power will stay on if turned on manually, then switched to auto. The cone is vibrating, but essentially no sound coming out.

?
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 6632
Registered: May-04


If the woofer cone is vibrating, the sound is likely to be very low frequency or very low level. Either way, there is probably nothing that you can do to solve the problem other than take it to a repair center. This sounds like an internal problem in the amp and not the driver itself or the cables.

 

just trying
Unregistered guest
Well, you say it works in the "on" position but it does not work with the "auto on" function? If that's the case it probably does work, but the sub is just not receiving a strong enough signal to auto turn it on. On my H/K Avr-330 I need to turn the master volume to about -50 to get the sub to kick on. I am not happy about this so I have to get a new sub that has manual/always on. Good luck with it.
 

cudabob
Unregistered guest
It stays on when turned on manually then switched to auto, but there is no sound either way!

My guess is it is TU.
 

Silver Member
Username: Mixneffect

Orangevale, Ca. USA

Post Number: 533
Registered: Apr-05
I am not familiar with your Harmon/Kardon Surround amp, but if I may, I would like to suggest the following easy tests;

Process of elimination;

Remove the sub from your system, and wire it from another source (walkman with mini to RCA adapter, or other recievers). This will determine if it is your sub (plate) amp or your Harmon/Kardon amp at fault.

If it performs the same, then its your sub (plate) amp.

If it doesnt perform the same and functions normally, the it is your Harmon/Kardon Surround amp.

"It stays on when turned on manually then switched to auto, but there is no sound either way!"

Some plate amps have a fuse inside the box. Unscrew the plate amp off, and check that fuse. Unplug the unit before you remove any screws, and do not short out anything on the amp board. I would even replace the fuse with another NEW same size fuse. Sometimes fuses look good accross the poles, but they are not completing the circuit because they are broken at the ends where you cannot see because of the end caps. I have had that one happen to me before (lol).

If something is bad with your Harmon/Kardon Surround amp, I would take it to a qualified repair shop and have them check it out for you. I do not recommend for consumers to get into those kinds of diagnostics. The same goes with the sub plate amp. If the fuse is ok, then let the pros check it out.
 

cudabob
Unregistered guest
Thank you for the information! I'll check it out tomorrow
 

cudabob
Unregistered guest
I hooked up an I-pod (I used the headphone jack) to the sub and the auto turned the sub on, but even setting the gain at full (both I-pod and sub) the sub was audible but not loud in the least.

I took the amp off the box - no fuses inside. The power fuse on the outside looks good - it does power-up.

The H/K is a AVR 20 II. Is there an easy way to test the amp?
 

just trying
Unregistered guest
So when you took out the plate amp did you check the wiring from the amp to subwoofer? I've heard of sub enclosures having "air leaks" as well, maybe that's it!? I don't know, maybe it's just not loud enough for you heh. How long have you had it? Maybe it's time for an upgrade...
 

cudabob
Unregistered guest
There is a plastic wire connector between the plate and the cone. It snapped back together after I took it apart.

I've had the sub for several years. It used to work great-I could shake the dishes in the kitchen cabinets.

Before I upgrade I want to know what is wrong!
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