(to spark a little discussion in here)

Simply, my Alpine is too loud and my empeg is too quiet. What do I do?

I've got a bit of a quirk with my dual head unit install. It's empeg + simple Alpine AM/FM/CD deck. The RCA's for both go to a "source switcher" which runs one set of RCA's to the amp.

With the gain on the amp set wherever my installer set it, my empeg set to -20dB is decent but a bit quiet. My Alpine set to 18 (of 30) is comfortably loud. At 0dB, I can tolerate the volume of the empeg. The Alpine, let's just say I've never gone to volume=30 for fear of damaging my (stock) speakers and my ears.

Maybe I shouldn't, but I think this is a problem. I want my empeg to be barely tollerable at 0dB. I'm convinced that a range of volume like that would allow me more accurate EQ settings (so I could make them -dB instead of all +dB like I have now because it's too quiet). And I want my Alpine to calm down a bit, so I don't kill myself if I accidentaly spin the volume knob.

But there's only one gain on the amp. What can I do:
Could the installer have hooked up the Alpine output from the speaker level outs? No, that's impossible, right?
Could I get a de-amplifier for the Alpine so I could get more gain on the amp?
I thought I read reasons for max gain settings on amps. Any links so I can avoid hurting my amp?
Or am I just using my empeg incorrectly as always? Am I SUPPOSED to only have audible sound from -20dB to 0dB, leaving the myrad of volume increments below -20dB to be too quiet to hear? (no, it's not broken, just too quiet).

Eventually, I want to add better speakers and a sub to my system. But I think I should get this worked out first. Thanks.

Could the installer have hooked up the Alpine output from the speaker level outs? No, that's impossible, right?

Unlikely if he's any good, but way to many "professionals" just aren't... So I wouldn't totally rule it out.

Could I get a de-amplifier for the Alpine so I could get more gain on the amp?

Sure, look for RCA attenuators or build your own (they're nothing but simple voltage dividers)

I thought I read reasons for max gain settings on amps. Any links so I can avoid hurting my amp?

Too high a gain setting (same as too low a sensitivity setting, which is what the gain knob normally is graded with... for instance 8 to 0.25V) will make the output signal clip (bump the output signals "head" into the roof / the max voltage it can do; and flatten the normally rounded tops and bottoms of the sinus shaped signal, making it look more like a square wave) Clipping can lead to the amp putting out twice the RMS rated power (a square wave with amplitude X volts has got twice the power of a sinusoid signal of the same amplitude) which the spake rmight not be rated for. It can also generate a fair amount of harmonics (a perfect square wave is made up of an (infinite) series of sinus waves of decreasing amplitude as the frequency goes up; so your tweeters might also be receiving more power than the system normally feeds them...

Or am I just using my empeg incorrectly as always? Am I SUPPOSED to only have audible sound from -20dB to 0dB, leaving the myrad of volume increments below -20dB to be too quiet to hear? (no, it's not broken, just too quiet).

Depends - if the 0dB setting is as loud as you ever care for, well then you're golden... But to me -20dB is a bit early to have no audible response...

/Michael

Thanks for the info. It's just a shade over my head (the amp stuff is, I get the audio signal stuff), but it gives me a few "key words" to search for and keep an eye out for.

> Clipping can lead to the amp putting out twice the RMS rated power.
Ok, but aren't there "degrees" of clipping? Check out the attachment; I'm more visual so maybe this will help describe it. Looking at the upper peaks only in the examples:
A - The input
B - Amplified output with gain set just a bit too high. Two peaks.
C - Gain set just a little bit higher still. Now, "the clips are wider"; they are above output range for longer because they are amplified more.
D - Gain set to "disturb the neighbors", creating tons of peaks.
So, when you say clipping can lead to twice RMS being put out, does that mean one clip will lead to 2x RMS? Or does the amount of unnecessary output power increase as clipping increases, as shown in the pictures?

And about the range of available volume. Am I wrong in assuming that I should increase the amp gain so that 0dB is very loud because: That way, I can properly set the EQ (be diminishing the levels instead of increasing them), which lowers the overall output, and still have a large number of volume increments between "conversationally quiet" and "very too loud". If I set the EQ to diminishing levels now, I'll have to run at -12dB just to hear it, which gives me only a few volume increments before I hit 0dB.

Thanks again for the tips.

With the gain on the amp set wherever my installer set it, my empeg set to -20dB is decent but a bit quiet. My Alpine set to 18 (of 30) is comfortably loud. At 0dB, I can tolerate the volume of the empeg. The Alpine, let's just say I've never gone to volume=30 for fear of damaging my (stock) speakers and my ears.

I wish you'd provided like for like values. 'decent but quiet' != 'comfortably loud' != tolerable.Maybe the Alpine has 8V pre outs vs the 4V outputs of the empeg. Assuming that is the case, with a flat EQ/Bass/Treble on both units, I'd expect the Alpine at 15 to be roughly the same volume as the empeg at 0dB. (Obviously, check on the same song - use a CD that you've already ripped and put on your empeg.) That 18/30 Alpine volume equates to 4.8V, or about +1.5dB in empeg terms. 30/30 would be +6dB in empeg terms. You might want to uncap the empeg's volume and confirm this. (Can't remember offhand where that setting is... config.ini?)

Buy an attenuator for the Alpine and boost the gain at the amp.

> Clipping can lead to the amp putting out twice the RMS rated power.
Ok, but aren't there "degrees" of clipping? Check out the attachment; I'm more visual so maybe this will help describe it.

Yes, there are degrees of clipping - from the barely audible to the painfully obvious. Yes, the power increases as clipping increases - 2x rated RMS (given that the stated rated value is honest - which one can't always be sure of) power happens only if the clipping is extreme and the output signal is effectively a square wave (ie effectively no slope at all)
The clipping in "D" is severe but you're still not up to 2x the power.

Am I wrong in assuming that I should increase the amp gain so that 0dB is very loud because: That way, I can properly set the EQ (be diminishing the levels instead of increasing them), which lowers the overall output, and still have a large number of volume increments between "conversationally quiet" and "very too loud"

Nope, that is correct. Just as you say above: I'd increase the gain on the amp to get a wider useful range volume range on the empeg, and get (or build) an attenuator for the other HU. But beware that you probably don't want to use full the full range of the other HUs volume control - most other HUs start to distort their own output at around 75% of the max (remember that the empeg too will distort the output if you go above 0dB on the volume setting, and the signal from the mp3/wav/... is full scale.), so check what volume you have from the other HU at 75% or so after adjusting the amp before getting/making the attenuator.

/Michael

Something to consider is Audio Control's device at http://www.audiocontrol.com/caraudio.htm - called their "four.1i". It's an in-dash half DIN item with two sets of inputs, and one "master volume control" output. The thought is that you put two different sources into it, use the sources and the gain adjustments to set the levels you want, and afterwards the single knob on this four.1i product is your new volume control.

I've never used one, and am not really familiar with it. But that's the gist of it, something I'd suggest taking a look at and see if it does what you're looking for or gives any more ideas.

Interesting stuff, all around. Thanks for the links and tips and more tips.

At this point, I'm pondering if I should satisfy my desire to learn all All ALL this stuff about car audio or if I should just accept my crappy sounding system and be pacified by the cool visuals of the empeg. Only time will tell.