Amp blowing fuses...

[hatrix 2]

I have a 18" Fi SSD d2 running off of a Powerbass ASA 400.2.

The sub is wired at 4 ohms right now and was actually only running on one channel of the amp and getting 100 watts. I just changed it to bridged because I just now realized it supports 4 ohms. It's rated at 400 watts when bridged.

My gain when only running it on one channel had to be almost all the way up for the sub. Is this because it was only getting 100 watts ? I still wouldn't think it would have to be turned up so high. I was really worried about clipping but never had any burning smells when playing full blast for extended periods of time. The amp gets kinda hot but never overheats. When it is wired bridged I only need the gain a tad less than half way, maybe half way at the most. It still gets slightly hot but it doesn't seem as hot as before.

So I changed it today and was trying to set the gain by ear for now. I had it around half way up and it was fine at a decently loud volume level. I turned my HU up from 48 to 52 and not even 2 seconds after being at 52 the sub just stopped. I checked the fuses and both of the 15A fuses were blown. I tried turning the gain down very slightly and was playing at the HU at 54 volume, even higher, to test and see if they would pop again. Everything was fine for about 20 minutes until I changed songs and they popped again after 15 seconds or so.

Is it because the gain is set to high ? The sub is only seeing half of the power it wants, if that as I'm not sure what the amp truly puts out. My lights dim slightly when idling and playing it at max volume. If I'm driving there's practically zero dimming. I also have another amp hooked up for my mids and highs, a Hifonics HFi100.2 but it's not blowing any fuses.

[Impious 1,476]

My gain when only running it on one channel had to be almost all the way up for the sub. Is this because it was only getting 100 watts ?

No, it's because you didn't properly set the gain.

In this case you were using the gain as a volume control. Since the power output to the subwoofer was relatively low (100w), you cranked the gain up way too high to get decent volume out of the subwoofer. Nothing bad happened because luckily, even clipped, the power output was still well below what the subwoofer could handle thermally & mechanically.

When it is wired bridged I only need the gain a tad less than half way, maybe half way at the most.

That's because you are getting more volume out of the subwoofer due to the higher power output from the amplifier.

Has nothing to do with where the gain control actually needs set to be properly adjusted, but rather because you are setting the gain improperly & using it as a volume knob.

Is it because the gain is set to high ?

Maybe.

The sub is only seeing half of the power it wants,

Subs do not "want" power. They can handle a certain amount of power, thermally & mechanically. But they don't "want" anything. They don't have emotions.

Grab a DMM & a test tone, set the volume to just below where the fuse blows & measure the voltage from the amplifier.

Does the amp have any other settings; bass boost, etc?

Does you headunit have any settings; bass boost, subwoofer level control, etc?

Please learn to properly set your gain. Unfortunately the "by ear" method does not work for you. One of the few instances I would highly recommend the DMM method for setting the gain.

[hatrix 2]

I realize everything you said about gain... I know it's not a volume control. I have read all the stickies and such about setting the gain. I wasn't to afraid having it all the way up when it was getting such little power because I figured it wouldn't get enough power even if clipping to burn it up... I don't have a DMM on hand to use to set the gain right now. I'm going to get one to set it but for now it is what it is. If the gain wasn't all the way up there was honestly no bass. I wasn't just trying to have it incredibly loud. It was seriously quiet if not turned up.

My amp does have bassboost but I have it set to 0. My HU has bassboost also but it's off there too. I also have the bass set to 0 on the equalizer.

But there's an update on my situation. I went to drive somewhere and just got back. I was driving for about 50 minutes back and forth total. Had the HU at 50 and was listening to music just about the entire time. Around 40 minutes or so my amp shut off again and I thought I had blown the fuses again. I turned down the volume and kept driving but it eventually turned back on. So I'm thinking oh it must have gone into protect and it turns out it did. I get home and feel the amp. It is incredibly pucking hot. Like burnt my hand feeling it hot. Obviously over heated.

I don't understand why it's getting so hot. I'm going to turn the gain down and test how hot it gets tomorrow. It's never overheated before but I guess giving my sub 4 times the power it was is making a lot more heat. NOW I'm afraid the sub is clipping or going to clip and destroy itself a lot easier.

Edited April 17, 2012 by hatrix

[Impious 1,476]

Double check & make sure you actually have the sub wired to 4ohm instead of 1ohm.

Just an idea.

[hatrix 2]

I'll have to tomorrow just to make sure. But last time I had it wired to 1 ohm the bridged connection wouldn't even power the sub at all. It just wouldn't accept the ohm load.

Thanks for the help. Much appreciated.

[hatrix 2]

Well yea I'm dumb. It was wired down to 1 ohm. I must've been half asleep when I wired it a couple weeks ago. So it ran fine at 1 ohm on a single channel even though it still isn't stable at 1 ohm even on a single channel. The amp doesn't get hot now.

Only thing I still don't understand is the gain. My head unit goes to 64 max volume and with the gain almost 3/4 way up it's not even very loud until I have the volume at about 58. I don't really feel comfortable having the volume that high but I also don't want to turn the gain up higher. I can turn the gain to max though and the sub never gets warm. It stays cool to the touch even after 30 minutes of abuse. Could this be because the pre amp out on my HU have a low voltage ? My HU only has one pre out and it goes into my highs/mids amp first then from the out on that amp into my sub amp.

Edited April 17, 2012 by hatrix

[Notorious97200 339]

You can do what you want, but 400 is 400 ! Maybe it can't be much louder with this power.

What h u do you have ? If the voltage is too low from the h u, you will need to have the gain high enough.

Ooh it's a Pioneer.Try to turn the bass level to the max before setting the gain on the amp. It's what I did on all my Pioneer h u.

Good luck.

[hatrix 2]

You can do what you want, but 400 is 400 ! Maybe it can't be much louder with this power.

What h u do you have ? If the voltage is too low from the h u, you will need to have the gain high enough.

Ooh it's a Pioneer.Try to turn the bass level to the max before setting the gain on the amp. It's what I did on all my Pioneer h u.

Good luck.

Yea it's the DEH-1200MP.

I really wouldn't want to turn the bass level up on the HU though. Wouldn't that cause clipping to occur much easier ? I mean it'll make it louder and help with the gain but in the end might hurt more with clipping.

[Impious 1,476]

Depends on how the headunit works. On some of them, the subwoofer output needs to be set at maximum to output rated voltage.

If you had a DMM & a test tone you could measure them to verify.

[hatrix 2]

Unfortunately my headunit doesn't have any subwoofer control because it only has one pre out. It just has a EQ for treble, mid and bass.

Edited April 18, 2012 by hatrix

[Impious 1,476]

Then yes, don't crank up the bass control.

[hatrix 2]

Figured as much. Leave it at zero ?

Edited April 18, 2012 by hatrix

[ricksi30 923]

Figured as much. Leave it at zero ?

Correct. Glad you guys figured it out.

[hatrix 2]

Yep thanks guy. Must be because of a low pre out voltage of only 2.2V, regarding the gain being up. I'm planning on upgrading to a AQ750 when I can.

Edited April 19, 2012 by hatrix

[Briggiboy33 2]

I have the same amp and i feel pretty comfortable giving it a lower ohm load now! Haha... But yeah i think the input voltage is low. Ifyou could increase your input voltage i bet you would have a lot better like signal to amplify. I have my signal split right now and its a noticable difference in my sub.. But it sounded alot better before i split it.