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-   -   Parasound amplifier problem? (http://www.diyaudio.com/forums/solid-state/80198-parasound-amplifier-problem.html)

Original Burnedfingers 24th May 2006 10:49 PM

Parasound amplifier problem?
 
A guy I know has a Parasound HCA-2200 11 amplifier driving a pair of Polk speakers. This guy has taken out several pair of tweeters in short time.

I believe the guy is clipping the amp and this is why the tweeters are being taken out. Other people are telling me there is a problem with the amplifier.

Anyone have any ideas/ suggestions?

anatech 24th May 2006 11:06 PM

Hi Joe,
I'm with you, clipping would be my guess. We did warranty service for Polk and also found their tweeters didn't take that much abuse to go open.
It is possible for amplifiers to oscillate, also the signal source. It's always wise to check everything. Let me know what you find out.

Just curious, what makes the other people so sure it's the amp? To finish that argument, just hang a 'scope on the output.

-Chris

Original Burnedfingers 25th May 2006 12:53 AM

Chris,

If my memory hasn't gone too far south wasn't there a light bulb fix for the polk speakers?

I'm 100% positive the amp is A1 shape. You know how it goes.. its never the operator its always the equipment.

anatech 25th May 2006 01:47 AM

Hi Joe,
I'm guessing the light bulb fix was not a factory authorized modification. :shhh:

A fool and his tweeters are soon parted. Anyway, both tweeters would normally point to clipping. I'd still hang a 'scope on the output. Everything else is pure conjecture. Well, maybe a theory, or educated guess in this case. Best to rule out system issues before you end up with egg on your face.

-Chris

jleaman 25th May 2006 02:13 AM

Just a question. Does putting a light bulb in there act like a fuse ? I've seen these in yourkville speakers.

anatech 25th May 2006 02:17 AM

Hi jleaman,
No, as the average current rises, the resistance of the bulb goes up. Mind that the bulb also has an inductive characteristic. These bulbs are great for the warranty program. Good for tweeters, but not exactly hi fi. This will also change the crossover frequency (load resistance is changing).

The speakers appear to become more bass heavy as the tunes get cranked.

-Chris

Original Burnedfingers 25th May 2006 02:30 AM

Chris,

I have always used the bulbs in series with the hot leg. Mainly in commercial applications I use a tail light bulb. It turns on at 60 watts so no more power goes to the driver. I have done frequency sweeps both with and without the bulb and the response is the same.

Quote:

The speakers appear to become more bass heavy as the tunes get cranked.
From the standpoint that no more high frequency material is passed when the bulb turns on I will have to agree with you.

There are other manufacturers that use bulbs as standard equipment in their speakers.

Not a bad fix when your going to beat the sh*t out of things.

anatech 25th May 2006 02:44 AM

Hi Joe,
I agree in a non-home enviroment. When the job is not professional and the tunes are cranked, a light bulb keeps the crowd dancing.

There are times when you can't win with a customer at home. Light bulbs installed for those individuals. What else can you do?

Still, you normally only bake tweeters when you clip the amp.

-Chris

Original Burnedfingers 25th May 2006 03:00 AM

We use limiters in professional applications and they work quite well. In addition to limiters there are occasions where extra measures need to be taken and that is where the light bulbs come into play.

It is unfortunate that the average home user cannot use logic to govern their judgement. The outcome of course is broken devices.
Many tweeters, midranges and woofers will suffer as a result.

anatech 25th May 2006 03:09 AM

Hi Joe,
Quote:

We use limiters in professional applications and they work quite well. In addition to limiters there are occasions where extra measures need to be taken and that is where the light bulbs come into play.
Exactly! But your friend's system is not actively crossed over. ;)

Quote:

It is unfortunate that the average home user cannot use logic to govern their judgement. The outcome of course is broken devices.
Home users are always confused between warranty and insurance programs. We all pay more because of this.

So are you going to have a look at his system? Take the scope to the amp if you can to watch things in their natural enviroment. I want to hear you tell him "I told you so".

-Chris


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