Amp Hiss (even when RCAs unplugged; disappears when sound is played)

[fleas2016]

Hi audio peeps! I need advice. I just received my 900W PA D5000.5 amp from Amazon and installed it yesterday. Before the installation of the PA D 5-channel amp, I had our temp amp (an old 300W Fenton 4-channel to power my MM6501 seps (front) and DB651 coaxials (rear) - no sub yet. With the temp amp, I had no noise besides the high-pitched powering off sound when amp is turned off

But with the PA D5000.5 amp, I'm getting some hiss/whine even if:

1) Radio is OFF (same scenario if my volume is set to 0 or fader/balance set to extremes)
2) RCA inputs are NOT plugged to the amp
3) Engine is OFF (I get engine whine in addition when engine is on).

Here's the thing: when I turn on the radio and adjust the radio volume/fader/balance so a speaker plays a sound. The hiss from that particular speaker is gone even I turn the radio off (and on again) afterwards or just the particular speaker "off" using fader/balance controls. This is true even when I start the engine.

But any speaker that hasn't played a sound since initially switching the car from OFF to ACC will have the hiss/whine

The hiss doesn't increase with the volume.

NOTE: My remote on wire is connected to the car's ACC so the amp turns on immediately even when my radio is OFF. Unfortunately, my factory head unit doesn't have a remote out.

But then again, with the temp amp, this doesn't matter, I don't have this noise at all.

What to do?

We're thinking of the following possibilities:

• Static
• Amplifier Ground Cable placement (Gauge 4 na as it is) - With the Fenton it's OK but with the more powerful Polk hindi siguro?
• Other Ground? - Kaso hiss is there even when the RCAs are unplugged
• Defective Amp - Huwag naman siguro, I had this shipped from the US

[fleas2016]

[UPDATE] Let's say the car is on ACC with my HU off and I am getting this buzzing sound. If I open the driver-side door, I get this alarm that my key is still in the keyhole. This is pretty standard for most cars now. But once I close the door, the alarm stops.. AND so does the buzzing from speakers

Previous Amp:



New Amp:

[oj88]

Does your stock radio have a power lead going to a motorized antenna or an active antenna pre-amp system? If so, you can use that as the remote amp trigger.

If I would venture a guess, I would think that it may have something to do with the input automatic gain. With no signal coming in initially at the inputs, the amp may have automatically increased the gain to compensate. But when you turned on the radio, the amp readjusted the gain to a lower level, almost eliminating the white noise.

As with the connection with the door closing, I would think that there was enough spurious or transient noise coming into the input, possibly caused by the dome light control circuit, to introduce a "pop" into the amp input and allowing the input gain to adjust its level.

The best workaround is to somehow tie up the remote power to the HU.

[fleas2016]

My unit have the fixed antenna on the middle of the tail-end of the roof so motorized antenna is out. I'm not sure about the active antenna pre-amp system. My installer said he can't find a remote turn on wire. I'm inclined to believe him.

I did buy an active LOC Audio Control LC2 which has a remote turn on feature for HU's without the remote turn on functionality. I'm just waiting for my subwoofer so everything will be installed one-time. I just couldn't wait and installed the amplifier first since it's just removing and reattaching of the individual wires from the old amp to the new amp. I'll have my amp checked out at the same time na din.

I'm just wondering why my old amp doesn't have this noise but the new amp has it is the "automatic gain adjustment" a new feature of new amps? could it be turned off?

[fleas2016]

Just an update guys, hoping someone can give suggestions?

So I went back to the installer for subwoofer installation and at the same time, get them to help me resolve my issue.

The first thing we did was remove the amplifier from the car and connect it to a test speaker and battery away from the car. Each individual channel was good and no noise. So that rules out the amplifier

When brought back to the car and connected to my speakers and power connections, the noise is there, obviously.

So I wanted to pin-point the issue so we tried different combinations when the amp is already connected to my car's audio setup and found out that if the amplifier's power, ground and +12v remote are directly connected to an external battery, the static noise is NOT present.

However, when the amplifier's power and ground was connected to the external battery BUT the +12v remote was connected to my car's ACC, the noise was there. This led us to a faulty conclusion that its a problem with my remote write connected to the car's ACC tapped from the HU, so I asked the guy to tap the remote wire to another source directly in the fuse box. To our hearts dismay, the problem was still there

Next, we tried connecting the ground directly to the battery using jumper cables hoping to eliminate any grounding issues. The noise was still there. However, now that I am reflecting on it, the guy connected the jumper cable to the end of my existing ground wire. Were as when we connected the amplifier to the external battery, we used a different set of wires.

I might go back and ask them to use the jumper cables directly and use a new set of power wires to eliminate if its my power and ground wires and their placement

Any more troubleshooting ideas is certainly appreciated

PS. The guy used a volt meter to check the voltage of the power+ground and the remote+ground, the result came up with a stable +12.4v.

[userfriendly]

It is most likely your remote on wire. It really should be connected to your HU. Some things to check:
1. Is your ground connected to bare metal? You really should scrape the ground point to metal and remove all paint for a proper ground.
2 Are your wires and cables free from connections (dugtong)?
3. Are your rca and power cables away from each other?
4. Has your installer checked for ground loop?

You have a very nice amp. Sucks that its giving you problems. BTW, who is your installer? Static is a pain in the behind to trouble shoot. Maybe you should try some other shop or installer.