I was wondering what some possible causes of distortion would be? I am currently in the process of installing a component system (Boston Acoustics SR60) and an amplifier(An Alpine MRX-F30) onto the headunit I already installed (Sony DSX-S310BTX) (as the previous owner had some kind of setup that he ripped out before sale, leaving me with 3/4 speakers connected and a lot of random wiring in the car...). Last night I decided to rip out his previous amp wiring kit (which he had wired down the passenger side) and install a new Revopak 4gauge kit that I wired down the drivers side of the car. After wiring it into my amp and securing a ground on the rear cross brace, I then finished off the wiring to the passenger side speakers (as I am still having issues snaking the wires into the drivers door) to give it a test.

The result that I have is what I would call about 80% clear audio with 20% distortion coming across. I thought maybe I wired the wrong speakers into their respective crossovers (as, like an idiot, I forgot to mark the wires so that I would know which is which) and found that I guessed correctly the first time, as only the tweeter seemed to be putting out sound. I did not make any adjustments to the Amplifier in terms of settings, and honestly I didn't really look at what it is set at as by the time I finished it was way past my bedtime... But the main question I have is why I could be getting distortion at low levels of volume (volume level 10 out of 50)....

Thanks in advance for helping a car audio newbie out!


Edit: Just to help out, the speakers are rated at 85 watts RMS with 250W peak, the Amp is rated at 50W RMS x4, or 150RMSx2 in bridged mode (but I also don't really know anything about bridging...) Also, I assume I wouldn't select either the high-pass or low-pass filter setting on the amp as I have external crossovers?

 

i wonder if the gain is set too high. if it is, you might be clipping at a low volume. give this a try:

http://www.the12volt.com/installbay/...TID~85479~PN~1

and here's a quick pictorial on bridging your four channel amp:

http://www.wikihow.com/Bridge-an-Amplifier

 

Ok cool, I'll check out the gain when I get off of work, and hopefully I will finally be able to snake the last two wires into the driver's door... it is a huge PITA compared to the passenger...

 

heres how i snake wires into the door, first unlcip any connectors blocking access to the rubber boot in the kick panel area(make sure the key is not in the ignition when doing this) and cut a slit or remove the electrical tape wrapped around the rubber boot. shoot a little bit of silicone spray into the rubber boot, then feed your wire runner(i use a 48" zip tie with the connector cut off) through the boot with your wires taped to the other end. the rigid yet flexible wire runner along with the silicone lube to should make it a piece of cake to feed the wire through the boot.

 

so last night I turned the gain way down, and everything seems to be great now (I haven't spent much time trying to calibrate it like explained in that link, was really busy last night), but what concerns me is that the gain was only at 50% when the distortion was being caused at volume level 10 (out of 50). Given the relatively low output of the amp, coupled with the fact that the RMS capability of the component set is higher than the max output of the amp, is it normal that I would get distortion at 50% gain?

Also, I'm going to try and snake those last 2 wires into the driver's door tonight, the passenger's side was a breeze when I sprayed WD40 into the boots and then snaked through the wires by taping them to a wire hanger... only issue I see with the drivers side is the fact that it's a little more cramped and for some reason it seems the boot from the door to the footwell is more curved/bent? I'm really just hoping I get lucky lol...

 

yeah, if your gain is set high enough that your headunit's level 10 volume is pushing the amp too hard, then you will clip. the clipping isn't coming from the speakers being overpowered, but rather from the amp being asked to send more power than it can handle. turning down the gain is the way to make sure that, even when you turn up the headunit volume all the way, the amp never hits that ceiling.

 

but my main concern is that it seems strange to me that the amp's gain set in the middle of the scale, at an output of 50W RMS max, would overpower speakers rated to 85W RMS? Or am I misunderstanding what the gain actually is?

 

you can think of gain as the ratio of input voltage from head unit to the amp's power output to speakers. this allows an amp's power output to be adjusted appropriately based on the headunit you're using. for example, an alpine headunit's pre-out sends 2v max to the amp at full volume, and a pioneer sends 4v max to the amp at full volume. the gain would need to be set higher for the alpine and lower for the pioneer.

if an amp's gain is set relatively high (e.g. for a 2v pre-out headunit), but it receives over 2v from a different headunit (e.g. from a 4v pre-out headunit that sends over 2v at mid-volume), then the amp will be sending full power to the speakers well before the headunit's at max volume, and pushing it past that point will cause the audio to start clipping. in other words, clipping happens when the amp is pushed beyond its max, not when the speakers are overpowered.

that's sort of a rough explanation, so folks can feel free to jump in and clarify.

also, you can read up on gain at the first of two links i posted above.