Rockford Fosgate Punch 250M

[Perry Babin]

If the op-amp is defective, I'd expect R2 or R20 to be getting hot also. If they are not, I'd suspect C8.

 

[seankane]

I changed the op-amp and the resistor is no longer burning in half and the voltage is positive now. The amp still has tons of noise and back ground static on the output.

The other op-amps have a couple volts on the outputs as well.

Any ideas where all this noise is coming from?

 

[Perry Babin]

Is it noisy with the crossovers set to low pass?

Is it noisy on all switch and crossover combinations?

Is your signal source ground connected to the amp ground?

 

[seankane]

The noise is sensitive to the left RCA jack. I changed the RCA jacks and put new ones in. There is no solder bridges or broken connections as they are all fresh. When I touch or wiggle the left rca the amp pulls current and makes terrible noises. Maybe something on the board associated with the left rca jack has a bad solder connection or is bad?

 

[seankane]

I had a bad rca patch cord.

The amp still has a slight background frequency noise if you will. You can hear it only at low volume idle it does not seem to affect the output.

What could I check in the input path to eliminate this noise?

 

[Perry Babin]

Is your signal source ground connected to the amp ground?

 

[seankane]

Yes it is I turned the gain down and the sound went away, is it because my source unit has 8 volt pre-outs and its sitting on top of my power supply and possibly picking up interference from the power supply?

I am going to install today in my work truck with an HX2 10" sub in low pass mono at 2 ohms and see how it does. Should give me about 600-700 watts. The amp says 500 watts at 2 ohms on the back but I am sure I could add 25% to that knowing older Rockford amps.

The sound quality of this amp is amazing just like the 250m2 do you think its the way the amp is set up from the CT of the torroid? I have never heard an amp as clean as the 250M, 250M2, 250.1, and the 250.2.

Thoughts???

 

[Perry Babin]

If your 12v supply is a switching power supply, it could generate noise. Did you try moving the head unit off of the supply?

I can' comment on the quality of the sound. I wouldn't expect it to sound any different. I've only heard those amps used on subs so SQ wasn't an issue. Many times, the perceived quality is better simply because the amp has more rail voltage and is less likely to be driven into clipping.

 

[seankane]

I ran the amp all day at 2 ohms and ran it hard, got very hot could not even touch it. Didnt shut down and sounded great and gave me no issues.

I think this one is ok. Thanks for the help Perry this one was a basket case.

 

[seankane]

Its been 2 weeks now and I have been running the heck out of this amp at 2 ohms and beating that little HX2 10" sub to death. I have had no issues, no shut downs, to say the least I am very pleased with this amp.

 

[seankane]

Its been running hard @ 2 ohms daily for many hours for over a month now. I think it may be time to let it go to a new home, I just wanted to be sure it was going to be reliable and that it has!