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fongman 21st May 2010 12:22 AM

Earthquake PHD2 amp
I've had the amp for a while. I bought it working and put it away for some years now. So i decide to put it in my truck and the amp won't produce full power? I check the power and its reading 12v. Nothing seems burn. Just not push as hard. All the power and outputs transistor are fine. I've check the 4424 and the 8040 ic and they are ok. The only thing i can see wrong is the outputs reading are: pin 123


on the first 3 and next 3 to the speaker side are


Those last 3 don't look right? Any help please...

Perry Babin 21st May 2010 12:36 AM

That all looks OK.

If this was in a different vehicle or was connected to different speakers/enclosure, those could make the difference.

I'll assume that you've checked the gains and crossover point.

Do you have a scope?

fongman 21st May 2010 01:00 AM

I was going to buy that scope I talk to you about but it was missing parts so I pass up on it. I try it with two different speaker and it did the same thing. When I used a different amp, it was good. Are the readings ok?

Perry Babin 21st May 2010 01:09 AM

I don't see anything wrong with the voltages you posted. I would have expected the pin with 3v to be nearer 5v but since the output is precisely 1/2 of the rail voltage, I don't see a problem. There could be a problem with the preamp section that's not allowing the output to reach full power.

fongman 21st May 2010 01:19 AM

I have the gain control too. I will used that and see if it helps?

ppia600 21st May 2010 02:33 AM


Originally Posted by fongman (
I have the gain control too. I will used that and see if it helps?

I noticed on my phd2 that the amplifier seemed to have higher sensitivity with the gain knob plugged in, kind of weird IMO

fongman 21st May 2010 04:23 PM

With the knob plugged in the bass did get louder, but i'm going to test it in the truck. I will let you guys know?

fongman 3rd June 2010 05:58 PM

Hello, I want to update you guys that i did put the amp in the truck for testing but the sound was still low. I found that one of the cap by the speaker out was leaking. I will replace the 100v 47uf and retest. I was having a hard time to find a replacment in town.

AlieNWarE 30th November 2016 12:59 PM

Hello, I hope someone has to answer. I need help, look for remote contrl of the EArthquake PHD2

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