Blown amp

How do you know if you have a blown amp?


I play my sounds and maybe after a hour my subs start to have this high pitch sound. the h/u is 4 volts.

 

Wait....your SUBS start to get a high pitch sound? Sure it's coming from them? If you have an iphone download some RTA app and figure out what frequency it is. Then make sure your LP filter ON THE AMP is set to something like 80hz. If the LP filter is set below the frequency of the noise being produced that will be a sure sign your amp is involved in the fuckery.

 

Yes it comes from the sub and the amp. It happen after i pound my system for a hour.My gains are only 1/4 turned up.My amp is set between 30-80 hz. it a mono amp ssf is at 30hz and the lpf is at 80hz

 

If your amp was blown it wouldn't work at all, you have other problems.

 

what would that be sir? i thought the 3 40 amp fuse would have gone first?

 

The gain knob is not a volume knob. Where it is set should have no bearings on it being blown.

If your amp is working for an hour, then you start hearing a noise, I would bet it is something else.

Swap subs, disable inputs (or unplug them), etc. Start trouble shooting.

Or call the MFG and return it for repair, but I doubt it is the problem.

 

If the sub is being thrown a high frequency signal to play, from somewhere up the signal chain, it has to be the amp. Since the LP filter on the amp filters out anything higher than the set frequency, if the high frequency noise being played by the subs is HIGHER than the chosen frequency on the LP filter then this means one of three things...

1) The filter is functioning and the amp is making the noise after the filter.
2) The amp is receiving the noise from somewhere upstream (headunit) and is not filtering it out. This means the filter on the amp is broken.
3)The filter is not functioning and the amp is making the noise.

All three mean the amp is on the fritz to some degree.


I don't think the sub could make a noise that it's not receiving but you could also do the following. Wait till it's making the noise. Then hook up a midbass speaker to the amp and see if that noise comes out of the midbass speakers.

 

Do you see what I mean though? If that noise is getting past the filter something is wrong.

 

If the speaker wire from amp to sub is close to the power wire could that cause something?

 

I am 100% on board with this, except it is not doing it from the start - thus the hesitation. I have never heard of a LP filter failing after 1 hour of use. Possible, but odd.

I would
1) find out if it does this after a set amount of time, or randomly.
1a) find out if it comes back if I shut down the radio/truck, and turned it back on (quickly, not 20 minutes later...)

If it does come back when you restart the truck, when the noise starts, disconnect all other amps/speakers, and try to isolate it.

After knowing it was the sub/amp, I would try a different amp or different sub.

But you have to isolate before you can fix.

 

Yeah Pinky.....go try some shit and experiment. Let us know what you find.

 

It happens mostly after a hour after a hard run at almost full tilt.
It goes away after 20 min when I turn my truck back on.

 

ok?

 

no help? my gain on the amp is about half way

 

You're joking right? We gave you all sorts of stuff to try so that you could report back and we could solve the problem. You didn't do ANY of it.

How do you expect us to help you?