Amplifier pop / DC output on turn-on (Pioneer PRS-D4100F) - VIDEO

[GuySmily 10+ year member]

I don't know what the deal is, but BOTH of my amplifiers are having issues in bridged mode. This one, a Pioneer PRS-D4100F, puts out a pop every time it turns on. After the pop, it looks like it's putting out DC voltage, pulling the speaker cone in one direction) and holding it there for a second before it starts playing music (after another small pop).

It might pull the sub about has far as Bass I Love You can, and I'm afraid of damaging the sub because of how it sits there.

If it's not bridged, the startup is faster and there's no pop at all.

Any suggestions?

You'll notice the door speakers turn on while the sub's amplifier is sitting there holding the subwoofer cone pulled in:

Click to read more...

 

[Side Show 10+ year member]

what ohm's is your sub? what have you got it wired too?

looks like the amps going into protect, i'd say it's wired down to 1 or 2 ohm and he amp cant take it, or the gain is maxed out aswell as bass boost, also make sure you have a lpf set

 

[Side Show 10+ year member]

post of of the amp and how it's wired

 

[GuySmily 10+ year member]

Thanks for all the tips.

The sub is an SA-8 D4, which is two channels at 4 ohms each (right?). Each channel from the amp powers one voice coil - no parallel hookups or criss-crossing or anything like that. I read somewhere that this was a bad idea, but I didn't see any explanation for it. Do some music producers feed equal but opposing waveforms into the L/R channels?

Here's a picture of the amp:

high resolution: https://picasaweb.google.com/lh/photo/SjQlJXavCqjKQNAqinHUh9MTjNZETYmyPJy0liipFm0?feat=directlink

AL+ and BL- go to one side of the sub

BR+ and AR- go to the other side

Come to think of it, I should probably be using the "mono bridge" instead... I still had this problem when hooked up to two separate speakers though. Regardless, double checked the manually, and I guess for a sub I would want mono output from the amp, so I'll go swap it and report back.

 

[Side Show 10+ year member]

duel 4 ohm sub can be wire to either a 2 or 8 ohm load only.

your wiring is wrong.

 

[Side Show 10+ year member]

it is wired up correctly if you had 2x single 4 ohm woofers... also you want to wire them for mono, try that it might work for ya..... do you have the manuel of the amp? have a quick read on how to wire duel voice coil subs too.

whats plugged into the rca pre-out too?

 

[GuySmily 10+ year member]

Fixed the wiring to use mono output. Definitely a lot more volume coming from the sub - sounds a lot better. Unfortunately, it still has the startup pop and apparent DC output as seen in the videos.

This should be 4 ohms per channel, right?

Thanks for the quick reply, btw. Already made a big improvement thanks to you:toast:

 

[Side Show 10+ year member]

yes, whats your lpf set at on both sides? also turn the gain down and bass boost off

 

[Side Show 10+ year member]

that amp isn't suited to this sub, how you have it wired up is not the correct way of doing it, each voice coil sounds like it is getting a different signal, whats your subs rms?

 

---------- Post added at 02:35 AM ---------- Previous post was at 02:34 AM ----------

 

hope the subs okay still and your amp

 

[GuySmily 10+ year member]

I've been experimenting with the LPF set at 60-80hz on the amp. No headunit at the moment, and no LPF or bass boost settings on phone/laptop.

Just for kicks, I tried unplugging all RCA cables. No difference - still get the pop.

Gain is set to "normal" (500mV), but have tried it at the minimum (6.5V), ~25%, 50%, "normal" (0.5V), and max (0.4V). One thing I didn't notice until checking just now: The lower the gain is set to (rather, the higher the voltage), the shorter the DC output period lasts. At 6.5V gain, the subwoofer moves maybe 2mm less than at normal/0.5V gain, and it stays there for maybe 1/2 or 2/3 as long as at "normal" (~2/3) gain.

 

[GuySmily 10+ year member]

Missed your 2nd post. I believe both channels are getting the same exact signal now that I'm using the "mono bridge" wiring instead. That definitely helped a lot.

The SA-8 v.1 sub is good for 400W RMS. The amp is a bit big at 300W x2 RMS continuous @ 4 ohms), but apparently people overdrive these things all day and I don't push it that hard anyway.

I just read in the manual that if no RCAs are hooked up to Input B, the gain for Input B needs to be set the same as Input A. I'll go do that, and make sure A/B are both set to LPF at the same frequency. Will post back in a sec.

 

[Side Show 10+ year member]

so you have turn on pop only now? from both a laptop and phone... whats the volume on those set up at? this is really weird.... prob would work fine if you had a headunit

 

[Side Show 10+ year member]

I would bridge one side only of that amp, and wire your sub to 8 ohms. and see if that gets rid of the pop (do you understand what I mean by this?)

 

[Side Show 10+ year member]

you are trying to run 1 sub/speaker off a 4channel amp. you should have got a mono or two channel amp. that amp isn't build for that

 

[GuySmily 10+ year member]

Still have pop and then DC power going to sub for a short time before music kicks in.

Gain and LPF were already set identically for both input channels, so no luck there. Thought I was on to something for a second. Oh well.

I had the exact same problem with 3 different headunits, so that's a no-go.

I'm using this amp because I already had it on hand. Trying to minimize spending, being a semi-poor college student and all that. I ordered the D4 sub specifically so that I could use it with this amp in bridged mode, which supports 2 channels at 4 ohms each.

I understand how to wire the coils for 8 ohms (I'm a computer engineering major), but instead of bridging one side and cutting my power in half, I could just use it in unbridged mode on Channel A only. There's no pop that way (instant turn-on, no weird DC-hold), but having half the power output just isn't good enough.

Might have to throw in the towel and check with Pioneer on this one, or I'll take it apart and see if there's anything wrong internally. I'm pretty confident that the install is correct, especially now that it's wired for mono output instead of stereo.

Worst case, I'll ask for a new 2-channel amp for Christmas.