Hi,
everytime I turn my engine on, I get a loud thump over my speakers. I'm searching for a way to get rid of this, since I don't want to damage my audio equipment. Please help!

Bam.

Wait, you've got a 2a.

Okay, now we're looking at wiring problems and such.

First of all... You have the amplifier's remote turn-on wire connected properly, right? For instance, it's not connected to the ignition wire?

I thought the negative spike bug only appears if you turn the engine off, not when turning it on!?
Yes, I have everything wired properly. In my opinion the problem is related to the empeg's amplifier-remote-out.

Btw. thanx for your fast reply!

So let me get this straight...

- You have a Mark 2a.

- It is wired properly. For example, its orange wire is connected to the car's ignition-sense wire. Its yellow wire is connected to +12v constant. The blue wire is connected to the amplifier's Amp Remote wire. The amplifier's power is run straight to the battery through a fuse block.

- Your car's ignition wire only goes live when you turn the ignition key (in other words, you don't have one of those cars where the radio is always-on).

- You have checked for blown fuses, including a blown fuse inline in the yellow wire (IIRC there's a little block there).

- You have checked for other wiring problems, such as crossed wires, the old connector problem etc.

- You insert the empeg into the sled with the ignition turned off. The empeg is off when you insert it because the key is off.

- You start the engine.

You're saying at that point you get a thump from the amplifier?

If so, that's extremely odd. The amp remote wire should not go high right away like that. The situtation you're describing should only happen if the amp remote wire is hot before you turn the key. And unless something is wired wrong or there are crossed wires somewhere, that should simply not happen.

Ok, all points you've mentioned are not the case of the problem.
In my car, the key has several positions. If the key is not plugged in, the empeg is off. If I turn the key to position one, the empeg starts playing, engines are still off. In this position I can also use some electrical systems in my car, e.g. the electric windows. If I turn the key further, the engine starts and I get the thump. I think the reason is that car voltage breaks down for a short time and so does the empegs sound output stage. The voltage on the remote line also drops, but it's still enough for the amplifiers to be not muting. When the empegs sound output stage comes back to live the thump is born...

Btw. I'm not sure if the thump also comes if I turn the key quickly to the engine-start-position, so the empeg has not enough time to boot completely. I have to test that tomorrow.

If you start the engine while the empeg is playing, a thump is normal. The amplifier is live when the empeg is playing. Dunno how they could prevent that from happening. I'm pretty sure other aftermarket stereos with a powerful external amplifier would do the same thing. I recall my CD players in the past doing that, too.

"Doctor, it hurts when I do this."

Now that I think about it: Maybe a circuit could monitor the voltage of the empeg's amplifier remote, and if it drops below a preset value drain the remote down to zero volts for one or two seconds, so that the amplifiers are muted for that moment.

You might be able to prevent the thump just by putting your empeg and the amplifier on a capacitor so that there's no voltage drop issues when your starter motor engages. Not sure.

Or maybe your car is designed so that the ignition line goes off-on briefly when you start the engine, and as such causes the empeg to go off-on really fast thus causing the thump. So perhaps a small cap on the ignition wire might do the trick. Again, not sure.

Hm.

Anyone else got ideas?

Do you think that a small cap would be sufficient? I've just calculated that it would need a 16,7 mF cap to power the empeg for 0,1s (running @ 1A)...

Yeah, I've got the same "problem" and I've been thinking about fixing it for quite a while. My "fix" at the moment is to simply turn my key all the way back to off before starting the engine, so the empeg turns off and then back on again.

What you need to do is do some experimenting. I suspect the culprit is that your car's constant power is cut when the starter is engaged. This could be fixed by running a seperate constant power lead to the battery.

To check if it's just your amp, try connecting a small wire from constant power to the amp remote input on your amp. Then while your amp is forced on, try starting the engine while the empeg is playing.

Matthew

Why can you tell it's the amp if you force the amp to be on? The amp would of course amplify everything that comes from the empeg - even a thump.
Btw. I don't believe that there's something that cuts constant power or ignition power as long as the starter is engaged - I think it's just the battery voltage that breaks down.

I didn't want to say anything because I'm not really certain when it comes to this sort of stuff, but you might want to invest in one of those heavy-duty batteries that are supposed to not get so bogged down when the starter engages. I remember some folks saying that they helped, I think. I think I also remember folks saying they didn't.

So, in conclusion, you should try this thing that's likely to be expensive that I have no firsthand knowledge of and little theoretical knowledge of based on some things I think I remember as being inconclusive to begin with. Good luck!

I tried it a while ago and found that I didn't get a thump with my amp forced on. I'm not really sure why. I also found that one of my amps thumped and one of them didn't, so it seems like it can be influenced by amp design too. Really you just need to mess with it untill you get a better idea of where exactly the thump comes from.

Matthew

I suppose it's possible that the amp could cut itself off due to low power earlier than the empeg, the empeg keeps the amp switch line on, so the amp powers off and back on. It's supposed to avoid the thump because the empeg won't have told it to cut on yet, but the empeg never saw the power dip far enough to tell the amp to cut off.

I wouldn't really know how to fix that. Maybe a cap in the amp's constant line? Seems like it'd have to be a pretty big one, though.

That's plausible. I'd expect a good amp to be designed to prevent thumping when this happened though.

I had a problem like this in my crew cab. One of the amps would get power as soon as I hit the key, the others had a built in mute delay to prevent this. I solved the whole solution by putting a timer circuit on the amp remote turn on circuit. Only 10 seconds or so will keep it from happening. Check http://the12volt.com for a circuit.

max_

I think my car already has a heavy-duty battery installed from stock, since it has a big engine...
What do you think about my idea to monitor the empeg's amplifier remote and set it to zero Volt if it drops beneath e.g. 11V? Would it be difficult to develop a circuit for that?

Thank you for all your answers!

i got a bmw same thing happens so i start engine then insert empeg but i got a big diesel so amps drawn by the stater and glow plugs is just silly.

You're saying at that point you get a thump from the amplifier?

I have this problem in my Focus. I assume that it's properly wired, since Cambridge Car Audio did it. Generally, I avoid pushing the empeg into the sled until I've turned the engine on.

Maybe I should look at getting a delay circuit like the one suggested installed.

In case it helps....

It varies for different cars, but the radio usually uses either an ignition sense line or an accessory line (often dual-labelled on audio pin-outs just to confuse!). Ignition sense stays on during cranking, but accessory might not.

For instance, Fords like the Focus use the accesory line which will drop to zero while the key is in the crank position and it will come up again when the key springs back to RUN/IGN. There is no ignition sense at the radio connector.

Also for example, VW/Skodas do not usually drop the accessory line during cranking.

I do not know about BMWs off-hand but I'll have a look

Perhaps delay the empeg turn-off for a few seconds to be sure the accessory line going down means turning the car off? Same way as you notice some radios don't turn off right away when you key off the car.

Nick

For instance, Fords like the Focus use the accesory line which will drop to zero while the key is in the crank position and it will come up again when the key springs back to RUN/IGN. There is no ignition sense at the radio connector.

Yeah, that's exactly what I meant in an earlier post. One could test if their car was doing this thing by simply looking at the ignition sense wire with a multimeter and fiddling with the key.

Question. Let's suppose my car works this way. Let's say I want the ignition sense wire to have a slight capacitance delay so that a voltage loss didn't make it go "low" for, say, a second or two.

Can I do that with a relatively small capacitor? Perhaps small enough to be done internal to the empeg itself? How would it be wired?

One could test if their car was doing this thing by simply looking at the ignition sense wire with a multimeter and fiddling with the key.

...which means that one would have to open up ones dashboard in order to do this .

...which means that one would have to open up ones dashboard in order to do this .

Yeah, I know what you mean. I've been going through in my head all the ways I could get around having to do that. I'm even considering opening the empeg and running a couple of leads out the front temporarily, because it's easier for me to mod the empeg than it is to dig into my dash.

How long does the empeg take to respond to the ignition line going off? Could you keep cranking the car and see whether the empeg goes off? (oh for my old cars which didn't start so well!!).
I have a Focus too, so I know how that behaves..

Or could you probe the sled connector with some long probes?

I think I am too blase about taking my poor car dashboard to pieces! I do have the luxury of some tastefully (apparently only to me!) coloured spare dash pieces to play with!

Nick

Wait, never mind. It's got nothing to do with the ignition wire.

I just checked it, and the problem is the sudden voltage loss on the overall electronics of the entire car because of the starter motor. There's a whole different thing that happens on the empeg when I turn the accessory position on and off fast. No thump that way, only when I actually engage the starter and the whole car voltage drops a bunch to power the starter do I get the thump.

Back in the old days, I had some big capacitors on the 12v constant wire from the battery to prevent this from happening. Didn't keep the empeg playing during a starter motor run, but it stopped the thump. I took it out a long time ago as part of a ground loop diagnostic and never put it back in.

So, Warp10, if you want the thump to go away, your empeg yellow wire and your amps have to be on the constant power line from the battery, and that line has to be protected by bigass capacitor(s).

How long does the empeg take to respond to the ignition line going off? Could you keep cranking the car and see whether the empeg goes off?

I just went out to the car and tried it. The behaviour is exactly as you describe -- the empeg comes up when I turn the key to the RUN/IGN position, and then drops out again when I crank the engine. There's a really small pop when the empeg comes up, and then a much larger one when the accessory line drops out.

The empeg drops out pretty much instantly when I crank the engine.

While I was out there, I took some photos.

Warp10, if you want to wire your own capacitors (and a diode is also part of this scheme), it would be as described in this thread, which, by the way, is about a Mark 1 player which does not have a separate ignition-sense wire.