Setting gains on my amp

AustinKP

OK, after about 3 days, I'm finally done installing my amp! If I do say so myself, I did a freaking awesome job. NO wires are visible until they come straight up to the amp on the back of the seat. Also, when I was going to buy a fuse, I found a Dynamat Original speaker kit on sale for $7, so I put that on around my speakers. Except for the tweeters on the doors and my HU, my car still looks completely stock. Unless you folded the back seat down, you'd never know I have an amp back there. This is very exciting. Now, this is the part where I'm stuck. I don't know how to adjust my amp. I turned the gain all the way down, then started to turn my HU almost all the way up so I could adjust the gain until I heard distortion. But even with the gain all the way down, at about 2/3 volume, any kind of bass distorts horribly. I have my HU crossover set at 63Hz, and it does the same thing at 80. Turning the gain up or down doesn't seem to make any difference at all. I thought turning the gain up would make it louder. Am I doing something wrong?

MacLeod

Hmmm, thats odd.

Make sure your bass control on the head unit is also at 0 db or flatline or off then try it.

This may also be an issue of too much power. PPI amps are very powerful and very underrated. Thats why earlier I recommended you not go with the bridged configuration because I felt that the 160 watts would be more like 200 and that would be more than the MM's could take. You may want to bi-amp the speakers and see how that sounds. That would be about 55 watts to the tweet and 55 to the mid at least and that would push em pretty good.

Now are you saying that turning the gain up or down has no effect at all? If so then it could also be that youve been had. If I remember right this was supposedly a display model and you snagged it for $150 or so. This could be a returned model and they just stuck it on the wall until they could unload it. I remember you saying they made a big production of how they were losing money selling it to you that cheap and that had me wondering. So you may have gotten an open box amp with a faulty gain control.

However, PPI amps are unbelievably well built and the chances of one being messed up are low.

Thats about the only reasons I can think of.

exalted512

i would check if your amp has anytype of bass boost on it, or if your HU has any type of bass boost, like bbe or any of that and turn it off
also my HU has different EEQ settings, like flat, natural, and one of them is like super bass or something, make sure your HU doesnt have any of that on
other than that, its supposed to make it louder to a point, then thats where your gain and your HU voltage match and it doesnt get that much louder
at about 2/3 to 3/4 volume is when most cheaper HU's voltage starts to clip, that might be what youre hearing
-Cody

AustinKP

Well, I don't think there's much of a chance of it being a returned amp. The salesman actually seemed kinda surprised when he went to take if off the wall and it wasn't hooked up. Also, it wasn't a big production about them losing money, the salesman also found that out when he went to ring it up. The manager is the one who kinda made a fuss, but he had nothing to do with the sale. He was just in the center of the store where the register was and just came over to put in his code authorizing the 10% off. Also, none of the screws or knobs had any sign of wear or marks. There are tiny screwdriver marks on the screws now since I've installed it, but it looked brand spanking new before. I don't think it's my HU clipping, I have the Alpine 9815. When I was looking at it, my amp has two different gain knobs. I dont' know which one does anything, I need to read my manual again. Neither one seemed to make much if any difference when I turned them though. My HU eq settings are flat. No bass boost in the HU or amp is turned on.
Only thing I can think of so far...does the speaker hole have to be sealed? I had 5x7 speakers before, and just put my 6.5" speakers in the same hole. There is a very small gap above and below my MM6's where they don't fill the whole 7". Could that make a difference or can they run free-air? I sure wish I knew more here...

MacLeod

The should be fine in free air but would perform better if you had an adapter and sealed the hole. However this shouldnt make your speakers distort with bass with the gains all the way down. Im at a loss on this one.

AustinKP

I dont' know how high the volume actually goes on my HU, but anything above around 25 distorts a ton. It doesn't really come on gradually, but goes from pretty good quality to audible distortion in about 4 or 5 clicks, so around 28-29ish...

MacLeod

Just pull the plug on your amp and turn the HU all the way up to get the max number than multiply that by .75 and that will give you the number you should set your gains for.

For instance, my Alpine goes to 35 so I set my gains for 27.

AustinKP

Good idea, thanks. I'm going to read my amp manual again, and go play with it some more to see if I can figure out whats wrong...

AustinKP

It's still not working...HELP!!!

neomagus00

okay, that's really weird that the gains don't function at all; have you tried keeping the hu really low and adjusting the gains, to see if that makes a difference? if that doesnt do anything, i vote something's wrong w/ the amp.

AustinKP

Is the gain essentially the volume switch? It seems to make it a little louder when I turn it up, but not like I expected. I didn't want to turn it up a lot because it starts to distort...

neomagus00

yeah, the gain's like the volume; technically, it tells the amp how much voltage it's recieving, and the amp does its thing accordingly; i.e. if the gain says "here's 2 volts" the amp will amplify that signal twice as far as if the gain says "here's 4 volts". how much voltage is coming out of your HU? i've got 6.5 V, and with my gain at minimum and my mm6's xovered at 100 Hz, i can get to maybe 22 out of 40 on my HU before distortion. distortion here being over-excursion on a 100 Hz signal.

AustinKP

4v preouts. Amp takes up to 8v it says...

AustinKP

MM6's are supposed to get loud enough to make your ears bleed, right? Mine are only almost as loud as they could get on my HU, before the bass starts to distort...the xovers are set to Full, maybe I should mess with those instead of using the xovers on my HU?

AustinKP

Ok, I've made a couple advancements, but I'm not much closer to the solution. Apparantly, if you have "High Voltage" pre-outs from 4v-12v, you have to hit a -12dB button. I did that and it made it quieter, but it still distorts at the same volume when I turn it up. Also, I found that the gain knobs DOES INDEED affect the volume, I just hadn't turned it up past like 1/3 so the difference I was noticing was very small. I had stopped because it was distorting, so I didn't want to screw anything up. I put the HU crossover at like 120Hz, so it doesn't distort much now, but of course, no bass response. Over on CAF, they say it's probably the gaps between the speaker and the panel...something about separation of waves... I guess now, I just have to seal the door better somehow. Hope i have room. It was already a pretty tight fit behind my door panel. I want to keep it looking stock. Any better ideas?

neomagus00

well, since you've got the "-12 dB" switch activated, and that changes the range of the gain from 12v-4v, you SHOULD be able to turn the gain to very near the maximum without distortion (assuming the amp is putting 150 W to each channel). less than 1/3 is strange. you're using the xover on the HU? it's set at 120? slope doesn't really matter here.... um.... we've already made sure there's no equalization going on anywhere, so that's not it.... perhaps switch where you're doing your xovering, if its on the HU now try it on the amp?

on bass: it's only a 6.5 speaker, so bass isnt really its thing, but it should be able to keep up with its own midrange as long as it's not playing too low (45 is too low here), so that is definitely (sp?) strange....

as a note, i just went and metered my MM6s at 99 dB at 100 Hz right next to my head, with no processing at all. that's at 35/40 volume, with gain set for 8v instead of my 6.5, so i know they can go louder. do you have a meter (mines just the one from radioshak)? maybe you're just deaf

exalted512

how flat are your doors where the speakers are?
you could always get a piece of MDF, cut a hole for the speaker, carpet over it, then screw it to your door panel
ive seen it done to a jeep on sounddomain but dont remember where i saw it...its very easy to do, but truthfully, i dont think thats your problem, my guess is the amp...im sorry to say, but i dunno
its next to impossible to 'trouble shoot' over the internet...
-Cody

MacLeod

I still think you should either bi-amp your speakers or just hook up the front channels and see how that sounds. Im tellin ya that PPI is putting out a whole lot more than 160 rms and its probably more grunt than your speakers can handle. If you bi-amp it then theyll be getting about 110-120 watts per channel and thats a little closer to optimum. Hook up just the fronts or bi-amp them and see. It cant hurt. :cool:

AustinKP

Well, I called PPI tech support today. Turns out that there's something wrong with my amp. Depending on how it's set up, I either get sound out of just my left side, or both sides with no ability to fade or balance. I gave the place a call where I bought it, and they'll send it in for service for me, so I dont' have to pay for shipping. I just have to go w/o an amp until it gets back:mad:

exalted512

i was thinking it was probably the amp...
sorry to hear that dude...
if it makes you feel any better...ive blown like 3or 4 times as many amps as you have...ive lost count...haha
-Cody

AustinKP

Thanks Cody, I feel MUCH better that my amp is broken because you've had more break than I have...:rolleyes:

Well, to pour salt in the already open, bleeding wound, this morning when I was coming to work, I had the power plug pulled from my amp since I wasn't using it. I think I experienced what it lovingly referred to as "alternator whine" coming through my right tweeter. It wasn't so much a whine, as a sort of quiet clicking sound. My stereo was turned completely off, and my amp was unplugged. The sound raised in pitch with my engine rpms, kinda like a playing card in the bicycle spokes. Where the crap is this coming from!? At no point do my speaker wires nor rca's cross my power wire. I thought it might be cause my amp wasn't grounded, so I plugged it in, but the sound continued. This sucks!!! Can someone please come here and fix my car? Please?

MacLeod

Dude, I have the exact same thing. I can turn the hu off and disconnect the amp and STILL get a slight whine. Its been there since I bought the truck new and with the factory tape deck. I dont know what the hell it is. Maybe some power line or something in the door that puts out some wierd mojo or something. Im just too lazy to do any trouble shooting since the only time you can hear it is when there is no music playing and even then its very slight...plus Im lazy, did I mention that?!

exalted512

if you can, next time it does it, disconnect the RCAs really quick, if it still does it, itll will narrow it down to the amp
when i had my old JVC head unit everytime i got a call on my cell phone my back speakers would make noise
it would always do it like 2 or 3 seconds before it would ring
i keep my phone in the little cubby hole in my dash and id hear that noise and pick up my phone and it would ring...my friends always wondered how i did it...lol
-Cody

MacLeod

If its a clicking sound its not the amp. An amp will not make any kind of sequential noise. It will always be a constant thing so the problem lies elsewhere.

It very well could be a cell phone or something. Whenever one transmits, your HU picks it up and transmits it downstream. To test this, the next time it starts clicking or tapping, hit the mute button or turn the volume all the way down. If the noise stops then you know all the components down from the HU are innocent and it lies in your HU.

AustinKP

Ok, I've narrowed it down to my car being posessed. I completely unplugged the Amp, Rca's and even the speaker wires at the amp. It STILL makes that noise. The pitch increases with the engine rpm's. I've only tried this once on the way home tonight for lack of more time, but when I started my car, it was making the noise, but as soon as I turned on my HU(and thus my amp, it was hooked up at the time)the noise quit, then the music started playing. While the music was playing, I couldn't tell if it was making the noise because of the music, but in the couple seconds of silence while the CD player was searching for the track, I think the sound stopped. It sounds kinda like a motorcycle or something from an old Nintendo... B/c it makes the noise w/ nothing hooked up, it can't be my HU or Amp causing the noise. Somewhere the speaker wire is picking up noise, even if it's only hooked to the xover on one end, and nothing on the other end. Is this strange?

exalted512

i say replace the speaker wire b/t the crossover and the tweet
-Cody

LittleCar_w/12s

I know it's a PITA, but it couldn't hurt to re-wire the speakers, at least you'd find the problem on the way (I hope). Also as for Xovers, It's possible they could be making the noise. If it's broken, or not it could be making a resonant electrical noise caused by the Xover capacitors and the speaker coil as an inductor, it can be set off by a bad spot in the wire touching the car chassis. I would make sense that it'd go away as soon as the Xover has something on both sides... ie the amp on. It's a piss in the wind idea, but i hope it helps.
-Jerry

AustinKP

Well, I confirmed today that the noise DOES go away when the amp is on. As soon as my HU powers up, the noise stops immediately. I put it on pause so it was silent, and there was no noise at all. I'm pretty sure it's not my speaker wire having a bare spot. The jacket on that wire from KK is pretty dang thick. There's no way it could have worn through. The sound might be coming throught the woofer as well, I haven't listened very closely to it. I need to check that...

MacLeod

Check your x-over location. It could be close to a source of power and transmitting it. Say from like a power window lead or something.