Need help with Amp Install.

[Rich]

Just yesterday, my sub amp died in my car. Anyways, I had extended warentee on it, and when I brought it back, they gave me a better one as they didnt have any of mine in stock.

Before we get into the details, im definitly a newbie here. I like building enclosures / boxes and stuff, but I dont have much technical knowledge of this stuff. When I wired up the 1st amp, I followed the directions to the letter, but used bigger wires than reccomended incase I wanted to upgrade.(4 gauge power and ground is what I have in.) This amp had bad instructions.

The new amp is an MTX 4202. Its still quite a low end amp, but its definitly better (Its 200w x 1 compared to my old 120w x 1), and should pound my car much more than my old one did.

I could probably put it in with about 15 min cause the wires are already there. I want to have my subs back!! Anyways, Ive yet to hook it up cause im confused. This amp has a "GAIN" knob that im not quite sure what to do with. My old amp did not have one. My question is, do I need this GAIN? There are no numbers on the knob itself, so how do I do this? I think it has to do with the headunit preout voltage, right? How much do I turn the knob? Is this some sort of guessing game?

According to the manual that came with my headunit:

Preout maximum output level / output impedence = 2.2 V / 1Kohm

Heres a pic of the amp that I found on the web, so you can understand about the GAIN knob.



Audiophiles....no laughing at my amp / subs setup. The old one sounded pretty good to me, and this should be even better. Im on a pretty tight budget, and not looking to give the whole street a headache from my bass.

Any and all help appreciated.

[KatWoman]

I don't know much about the technical side of things, but if memory serves me correctly, the "gains" knob controls how much power (bass) the amp puts out...in layman's terms, if you turn it all the way up and blast your system you stand a good chance of blowing your sub. I had this happen to me before I met Alex...a shop installed my amp with the gain all the way up and less than 2 weeks it blew my sub. When I took it back they said "Oh your amp volume was all the way up".....IF A SHOP EVER REFERS TO IT AS VOLUME, GET THE HELL OUTTA THERE!!

You might wanna check MTX's website www.mtxaudio.com or call their tech support dept, which is supposed to be pretty good. The # should be on their site or on the box.

[Rich]

Thx for the help, Kat.

I took a look at there website from the link you provided, but it wasnt very helpful, so I checked the box and gave them a call a few minutes ago and they were quite helpful and were able to explain it to me. I also told them what subs I had, and they told me where to set it to start (approx 1/4 - 1/2 turn) , and then I can make small adjustments from there.

Basically exactly as you said, in my configuration it controls how much bass the amp puts out. According to the tech guy at MTX that I spoke with, If I ran the gain to the max all the time, I would definitly blow the subs I have after a while, as the "performance certificate" that came with the amp shows it to be putting out quite a bit more than advertised! Also, if I keep the gain turned down a bit, it will also keep the amp running cooler which will avoid cutting out due to high heat.

So, to summarize, im shaking with anticipation As soon as I finish class for the day, ill be heading home, then out to the car to install it, and if all goes well, I should have a big grin on my face

[KatWoman]

Awesome...let us know how it sounds

[Rich]

Originally posted by KatWoman
Awesome...let us know how it sounds

Good news, and bad news. If I keep the gain fairly low, so the subs hit about the same amount as they did with my old amp, it sounds ok. Good clarity, but kinda crappy SPL. Of course with a bigger amp now, and I checked my subs and they can handle the power, I turned the gain up a substantial amount.

It sounds AWESOME as long as I keep the trunk open. Definitly more than I expected and not even close to full gain. Only problem is, when driving with the trunk shut and the gain up, it rattles and shakes a TON, and the SQ goes all to shit. So bad that its not really good to listen to like that, and when im driving, ppl turn and look expecting to see a swarm of bees from all the buzzing from my trunk, but instead they see my rattling car