Buzz when the sub turns on

Recently got done installing an audio control D4-800, some upgraded speakers, and a sound ordnance b-8pdt powered sub. I'm having issues with the sound ordnance sub. Almost every time it turns on, it buzzes for about 1/2 second at close to max volume. Not sure what frequency, but it sounds like white noise during startup.

I'm wired from the stock head unit through speaker level inputs to the audio control amp. I'm using the bass output from the audio control amp(RCA's) to the sound ordnance. I'm using ignition switched power as the remote turn-on signal for both amps since the stock head unit doesn't have one.

I've also added in a 10 second delay timer to the sound ordnance remote turn on. I thought maybe the head unit or the audio control was outputting noise during their boot up. Now the radio and audio control are fully booted and playing music and the sound ordnance will still buzz when it turns on. The only time it doesn't buzz is if I have the truck on, turn it off, then turn it back on within a few seconds. I've never had a sub that makes white noise during startup. It's really annoying. Any ideas?

 

Power up the sub with audio lines disconnected. If it still buzzes then you know it's a sub problem and contact support accordingly. If it doesn't buzz, you might have to choose a different input.

Edit, also, I don't know how your 4 channel outputs to RCA. Are you sure they are low level outputs? If not, you need a converter.

 

The 4 channel audio control has programmable line level outputs (either full range or subwoofer). They're programmed for sub outputs right now.

 

Does the amp auto convert from speaker level input to line level output? I would almost be tempted to put an external converter and tap the sub directly to the front speaker inputs, for sake of troubleshooting simplicity.

 

Yes it does. It has a built in DSP and as I understand the manual, it sums the front and rear speaker inputs, applies it's internal "accubass" logic to correct for the factory head unit roll-off, uses the internal low pass filter, and then outputs the preamp signal to an external subwoofer amp. There's a lot of options for what can come out of the line outputs, it's all programmable in the audio control software.

I'll disconnect the inputs from the sub today and see if that helps, but I'm really hoping it's not the audio control amp that's causing this. I bought it specifically for the DSP and control in correcting for the factory head unit. The sub also has high level inputs, but it won't correct for factory roll-off, so I'll be losing some capability going that route.

 

I’ve seen LOTS of installs with that amp and never seen anyone mention the problem you’re having, so I’m leaning towards the sub.

If you test the sub while it’s disconnected and it doesn’t do that, I would start double-checking the amp settings because like you said, it has a lot of them.

Also check your RCA cables from the amp to the sub. If you have a spare laying around the house, hook it up to see

if you still don’t get anywhere, it’s time to break out a multi-meter

 

It does it even with no signal input to the sub, but now it gets even stranger.

When you turn the key off, there is a 30 second delay and then a relay clicks off somewhere on the truck. For the life of me I can't figure what relay it is. If I turn key off and then back on within this 30 second window, the sub won't buzz when it starts up. If I let this relay open and then turn the key on, the sub will buzz when it powers up.

There is also very faint white noise coming from the speakers when the head unit is at zero volume. Not enough that I would worry about fixing it, but when I turn the key off the white noise continues for 30 seconds (even though the head unit and the audio control amp are off), and goes away when the relay clicks open.

So what relay stays on for 30 seconds after you turn the truck off and would affect the speaker output on an unpowered system?

 

For shits and giggles try turning on the gto function of the audio control. Unwire the ign turn on switch you have and take the turn on from the audio control amp to the sub amp. If I have read your post right you have the audio control amp sending signal to your sub. That’s the way I have my audiocontrol d6.1200 wired to my sundown sfb1500 and I do not have this issue

The issue might be the sub amp turns on first and as the audio control amp boots up it back feeds through the rca outs

 

This was one of my first thoughts, so I added a 10 second delay timer on the sub amp. Everything is fully powered and booted before the sub turns on now. It still does it. It even does it if the RCAs aren't connected, so it's not feeding anything through the input.

 

Where do you have you’re amps grounded since both of the amps are admitting white noise you said

 

Underneath the center console. There's a few 10mm bolts there that hold various brackets. I removed one that went into a nut welded to the body, scraped the paint off and grounded them both to the same bolt. I then upgraded the body to battery cable from it's stock wire to a 2 gauge cable.

What I don't understand is where the white noise is coming from, because it persists after both amps are turned off.

 

Check all your grounds. If your amp or other component are grounded to a painted surface, the paint should be sanded/ground away to expose bare metal. Then reground. I've seen this effectively eliminate buzz noise, but that's If I'm reading your trouble correctly

 

O

I'm fairly convinced it's a ground issue, I just haven't had time to pull the center console back out and try to fix it. I put the grounds from both amps on the same bolt, trying to avoid a ground loop between them, but I think I'll separate them to give a larger surface area and see if it helps at all.

 

Try the ground just under the seat where the carpet is cut here...


Also depending on which OEM head unit you have there might be a remote turn on/power antenna wire you can tap.

 

Couldn't find a remote turn-on wire. I regrounded everything and it still does it. The original grounds had ~1.8 ohms to the battery. The new wiring has 0.3-0.4 ohms to the battery. I think I'm going to call sound ordnance and see what else I can do.

Even with the speakers disconnected from the amp, there is still white noise in the speakers. This can be eliminated by moving the included kicker external crossovers out from behind kick panel. So it looks like I get to find a new spot for those far away from anything electronic. Glad kicker cheaped out and didn't shield those.

 

Sadly, kicker is known for loudness/volume. Not sound quality.
I'd say their best SQ speaker is their Q class. Nothing else

 

Yeah I've had em before and they sounded a lot better in other vehicles. I'm into this upgrade over 2k and I'm not happy with the sub or the speakers.

 

i think your blame is misplaced. i don't know of any car audio crossovers of any brand, or cost level, that come shielded from the factory.

 

Your probably right. I was quite pissed earlier. But also, needing 6+ inches of physical separation between the cross over and any other wire in the truck seems excessive. There's tons of people that have put external crossovers in the kick panel, but mine seems to be the only one where it's a problem.

I gotta find another car I can install the sub into as my last chance effort to isolate the buzz before I send it back in for a warranty replacement.

 

Man, nothing worse than getting deep into a project and less than satisfied with the outcome.
Hope you can find a way to make it more acceptable