(hopefully someone can answer before my installer calls back)

First: AUX Input Voltage Specs

I am having him wire an existing factory CD player into my empeg, and he just called and said that the CD player line-out is probably under-spec, since he needs to crank the empeg volume way up to hear it at all.

What voltage is the empeg expecting on the AUX line? 1V like what the empeg puts out itself, or less? Installer tells me 0.5V is average/standard. He can throw a line-amp in there to bump up the signal, he says, but I'd rather not have to.


Second: Headlamp Sensor Line

What voltage is the empeg expecting on this line to indicate that the car's headlamps are on? Maybe its my dimmer settings on the empeg, but he says it seems to behave opposite of what he expects. Says it goes bright with headlamps off, goes dimmer with headlamps on. I would expect that the empeg looks for +5V on that line to indicate headlamps are ON, yes?


Third: Common Ground

Also, he says that the empeg, on its own, in the car, does not have any ground-loop noise, but when he adds my factory unit back into the equation, there is ground-loop noise. Is there any way of grounding the CD player some other way? I am wondering if "ground-loop noise" is the magical term stereo shops use, sometimes justifiably, to get more $$$ out of the install.

- - - - - - - - - - - - - - - - - --
MK2 #141, green, 12GB

Headlight sensor problem: This is described in the FAQ section of this BBS. He has it wired correctly, there's just two separate dimmer settings: One with lights on, one with lights off. Set 'em both and you'll be happy.

Ground loop when adding the factory head unit: Every time you add another component to a car audio system, you create the possibility of a ground loop. This counts whether you're adding an amp, a passive crossover, an equalizer, another head unit, whatever. Each component increases the possibility that one of the components will have a different ground potential than the others. Debugging this one is just like debugging any other ground loop. Check the FAQ section under "common installation issues" for links to some good ground-loop-debugging documents.

Quiet head unit: Don't worry about it, you won't be listening to the CD much anyway. But probably what's going on is that the head unit is 0.5v or 1v, and the Empeg is 4v. If that's the case, then yeah, the Empeg's gonna be louder. The only work-around is to adjust the volumes or boost the head unit. Before you panic, check it out and make sure that he's really playing the CD player at 0db when he says it's too quiet.

___________
Tony Fabris

I can tell you that for question 2 it doen't matter. You just need to set the dimmer level you want with the lights off and then with them on.

Brian

-Finally received my Mark2 no thanks to customs.

Thanks, Tony.

1 AUX Voltage: The CD player was actually less than 0.5V (it only had fixed line-outs), but he put a couple line-amps on (I traded in some high-low adapters) and its fine now.

2 Dimmer Line: Me stupid. RTFM!

3 Common Ground/Noise: No, I won't be using the CD player very often (its better than having a hole in my dash, marginally) but I'm going back in a week to try out a ground-loop isolator.

4 (new): I *did* discover a bug though...I think...

- - - - - - - - - - - - - - - - - --
MK2 #141, green, 12GB

AUX: You need probably 1v+ to get good level on aux input.

Headlamp sensor: The empeg has 2 dimming levels, one for lights on and one for lights off; both are settable, so it sounds like your unit is set for dim with lights off and bright with lights on! To set the level, go to the dimmer menu with the lights off, set the level requied. Turn lights on, go to dimmer menu again, set level required for this state. Done!

The empeg aux inputs have a floating ground, to adjust to your CD-head's ground level, so it should be ok. What do you mean "when he adds the CD head into the equation" - when AUX is selected on the empeg, or when the CD head is in the car at all?

Hugo

My CB radio in my Jeep has a 4 Watt mono speaker output. The speaker on my CB mic unit is horrible. I was wondering if the Empeg's AUX input could handle a 4 Watt input? Is it pretty safe to try without harming the Empeg? I can start with the volume turned down on the CB and raise it until I hear it through the Empeg.

This is a good application for mixing the Empeg output with the AUX input. I don't know if the DSP can do that or not.

Thanks and I'm looking forward to the tuner module,
-Ryan.

My CB radio in my Jeep has a 4 Watt mono speaker output. I was wondering if the Empeg's AUX input could handle a 4 Watt input?

No, but you can get some speaker-level to line-level converters from Crutchfield that'll do the job for you.

This is a good application for mixing the Empeg output with the AUX input. I don't know if the DSP can do that or not.

Even if the DSP couldn't do it, I'll bet that it could be done in software. There's a limit to the sampling frequency, but it could theoretically sound decent with the sounds from the CB radio output. I wouldn't hold my breath on Empeg writing such a mod, though.

Then again, now that I think about it, voice-response navigation systems could benefit from such an Aux-Mix as well, so maybe the idea isn't really that farfetched.

Another option is to mix the two signals (CB and Empeg) using a line-level mixer, then send that result directly to the amplifier. That would work immediately and wouldn't require any work on Empeg's part. Does anyone know if there are line-level mixers like that designed for car applications? Or perhaps there's just a simple way to combine the two sets of signals without using a mixer?

___________
Tony Fabris

Aw heck, as long as we're talking about features that someone else would have to implement, a ducker would be even better.

For those who never worked in a studio or radio station, a "ducker" is a device that has two inputs. Normally, input A is just copied to the output. When a signal is present on input B, it gets added to some fraction of input A and presented to the output. The audible effect is that of the announcer (usually) talking, and the music "ducking" under his voice. It's usually implemented with a noise gate with separate control inputs, but it's also possible to code in DSP.

Yeah, I'm familiar with duckers, having worked with guitar effects (I've got a digitech unit that implements a modular ducker in the effects chaing that's pretty nifty). I just didn't mention it in my post because I thought things might get confusing.

But it's a good idea. If the Aux mixing was done in software, you could definitely implement a ducker. It could work for nav units, hands-free cell phones, whatever.

___________
Tony Fabris

I figured you would be, living in Grass Valley and all. Lots of great audio processors came out of that neck of the woods.

Boy, we should really be working, eh?

I figured you would be, living in Grass Valley and all. Lots of great audio processors came out of that neck of the woods.

Yeah, but Digitech is in Utah.

___________
Tony Fabris