Need Help with 4 Channel amp's sound qualtiy diminishing at higher volumes

[Speedyed]

Hello Everybody,

Due to an incorrect install from a local stereo shop one the channels of my Alpine PDX-F4 is no longer working.
I was told something may be lose inside. Anyhow I have a 4ga power and ground cables and have just had my back up amp US Acoustics USX4085 amp installed.
Previously I have all 8ga power and ground when I had this same US Acoustics amp installed and it sounded great and even at very high volumes and kept the same settings, gain is at about 3/4. Currently it sounds great, crystal clear and detailed until i play music at high volumes for over 5 minutes (Volume 25 of 40 ) from my Kenwood Excelon XR997 heaunit. The Sound qulaity, dimishes and loses some clarity almost blury and no longer clean and detailed. After the instal i did notice right away that this amp sounded more powerful and louder at lower to high volumes compared to previously with all 8ga power and ground. Should I start by lowering the gain on this amp or ?

Any help would be greatly appreciated

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[1aespinoza 10+ year member]

Any help would be greatly appreciated

Start off by making sure the ground is making contact with bare metal. Then check that the fuse holder wires by the battery are snug. When I have had this same issue it has been low power going to the amp. It just seemed to me as if the capacitors in the amp were not being recharged fast enough. I do not know if that is a thing but finding those power faults led me to assume that.

 

[Speedyed]

Start off by making sure the ground is making contact with bare metal. Then check that the fuse holder wires by the battery are snug. When I have had this same issue it has been low power going to the amp. It just seemed to me as if the capacitors in the amp were not being recharged fast enough. I do not know if that is a thing but finding those power faults led me to assume that.

Thank you, I did check the ground and and fuse holder wires and everthing is fine. All I did was swap amps and the previous Alpine pdx sounded strong and clean until 1 channel stopped working. I had this US Acoustics amp in my previously a bout a year ago before i upgraded to 4 ga power and ground it it woked flawlessly. I was adviced to do a factory reset on my headunit as that may help clear old settings etc. I guess i can give it a try but not convinced that will solve the issue.

 

[Old_Slapper]

Also, it depends on the type of wire they installed. Copper will carry a lot for power than aluminum. How much power is your US Acoustic amp? You might have a speaker going out. That might be what fried your Alpine and is making your US Acoustic amp sound crappy.

 

[audiobaun 5,000+ posts]

What model and brand speakers are you using on the amplifier?

 

[Speedyed]

Also, it depends on the type of wire they installed. Copper will carry a lot for power than aluminum. How much power is your US Acoustic amp? You might have a speaker going out. That might be what fried your Alpine and is making your US Acoustic amp sound crappy.

Using Sky High copper OFC wiring and Stinger 8000 series rcas. The US Acoustics usx4085 is rated at 85X4 @ 12.9 volts and proably close to 100w X 4 rms. Running CDT NEO 6.5"compnents (100 watts) & Apline S69 (6X9 85watts) rear deck,

 

[Speedyed]

What model and brand speakers are you using on the amplifier?

Using Sky High copper OFC wiring and Stinger 8000 series rcas. The US Acoustics usx4085 is rated at 85X4 @ 12.9 volts and proably close to 100w X 4 rms. Running CDT NEO 6.5"compnents (100 watts) & Apline S69 (6X9 85watts) rear deck

 

[Old_Slapper]

Using Sky High copper OFC wiring and Stinger 8000 series rcas. The US Acoustics usx4085 is rated at 85X4 @ 12.9 volts and proably close to 100w X 4 rms. Running CDT NEO 6.5"compnents (100 watts) & Apline S69 (6X9 85watts) rear deck,

Using Sky High copper OFC wiring and Stinger 8000 series rcas. The US Acoustics usx4085 is rated at 85X4 @ 12.9 volts and proably close to 100w X 4 rms. Running CDT NEO 6.5"compnents (100 watts) & Apline S69 (6X9 85watts) rear deck,

I'm guessing you were using 8g before the upgrade. Did your Alpine get pretty hot, and how long is your power run?

 

[Speedyed]

I did have 8ga previously and now 4ga. The Alpine Mono amp didn’t get too warm and neither the US Acoustics. Last night i turn down the gain on the US Acoustics from 3/4 to a gair over 1/2 and it sounds better.
I believe the x-over from my 6.5” components (driver’s side) is faulty and not producing clean, clear sounds like front passenger’s side.

 

[audiobaun 5,000+ posts]

I did have 8ga previously and now 4ga. The Alpine Mono amp didn’t get too warm and neither the US Acoustics. Last night i turn down the gain on the US Acoustics from 3/4 to a gair over 1/2 and it sounds better.
I believe the x-over from my 6.5” components (driver’s side) is faulty and not producing clean, clear sounds like front passenger’s side.

I would suspect the amp at this point. Caps may be leaking or getting old. ? Amp may need rebuilt. Those mosfets may even need be checked on the rails . I used to collect that series. I still have White Man Machines, BTS Blue and Black Badge series and SX series left

 

[Speedyed]

I would suspect the amp at this point. Caps may be leaking or getting old. ? Amp may need rebuilt. Those mosfets may even need be checked on the rails . I used to collect that series. I still have White Man Machines, BTS Blue and Black Badge series and SX series left

I had this same amp installed about 9 months ago with no issues whatsoever which make all this odd