scott87 Posted April 9, 2014 Share Posted April 9, 2014 I have a small 12" subwoofer connected to a cheap amp. I didn't want anything fancy and wasn't fussed of make as its hidden in the boot. However, i've installed it as i have with every install i've done in the past and im getting a lot of distortion at pretty low volumes. I have the amp bridged as there was a little image of bridged connection on the amp. The equaliser on the low range from the headunit is turned down and the amp is set to the lpf mode. I have disabled the loud mode on my headunit as well. The rca is the opposite side of the car to the power cable and the earth is bolted to the floor of the boot. Should i try the amp wired to a single channel on the amp? I know my old jbl amp and sub had to be like this for some reason even though it was a bridgeable amp. I have a pioneer deh 1430r, the entry range jbl 12" subwoofer and the really cheap bit of kit a 2 channel mutant amp. Quote Link to comment Share on other sites More sharing options...
Kaan W Posted April 9, 2014 Share Posted April 9, 2014 Have you chanted anything from when you say it was working fine before ie headunit, amp etc? What's the make and model of the headunit? Quote Link to comment Share on other sites More sharing options...
scott87 Posted April 9, 2014 Author Share Posted April 9, 2014 Have you chanted anything from when you say it was working fine before ie headunit, amp etc? What's the make and model of the headunit? Nope i've not used this sub and amp before but did hear it working. The head unit model etc is above. If the speaker has gone pop ill get another 12" but was just wondering if there was something i was overlooking. Like running the sub from one channel rather than bridging or swapping the rca round etc. Quote Link to comment Share on other sites More sharing options...
mattdavies Posted April 9, 2014 Share Posted April 9, 2014 Check the filter selection on the AMP, you want LPF or low pass filter as it may be playing music through it instead of justthe Bass Quote Link to comment Share on other sites More sharing options...
scott87 Posted April 9, 2014 Author Share Posted April 9, 2014 Check the filter selection on the AMP, you want LPF or low pass filter as it may be playing music through it instead of justthe Bass Yer its set to lpf Quote Link to comment Share on other sites More sharing options...
Kaan W Posted April 9, 2014 Share Posted April 9, 2014 What's the input voltage set to on the amp? This must be the same as the RCA output on the headunit. People treat the voltage input as a volume, it's not. If it's set to its lowest voltage of say .5v (the most clockwise position) and the headunit already has a high signal output (6-12v) the amp is multiplying what's already a high output signal thinking it's at .5v to meet its requirements thus trying to pump out more power than it should be even at low volumes resulting in a very distorted clipped signal. Make sense? Quote Link to comment Share on other sites More sharing options...
scott87 Posted April 9, 2014 Author Share Posted April 9, 2014 What's the input voltage set to on the amp? This must be the same as the RCA output on the headunit. People treat the voltage input as a volume, it's not. If it's set to its lowest voltage of say .5v (the most clockwise position) and the headunit already has a high signal output (6-12v) the amp is multiplying what's already a high output signal thinking it's at .5v to meet its requirements thus trying to pump out more power than it should be even at low volumes resulting in a very distorted clipped signal. Make sense? Yer that's makes sense thanks. However I have no idea what the head unit is doing. It is a very primitive unit. Quote Link to comment Share on other sites More sharing options...
skippyboyo1 Posted April 9, 2014 Share Posted April 9, 2014 Is the sub boxed? It will sound shocking if not? Quote Link to comment Share on other sites More sharing options...
scott87 Posted April 9, 2014 Author Share Posted April 9, 2014 Is the sub boxed? It will sound shocking if not? Yer its in a box. :/ Quote Link to comment Share on other sites More sharing options...
skippyboyo1 Posted April 9, 2014 Share Posted April 9, 2014 Personaly I think the answer is in the question. Your using cheep gear. Granted it worked before but for the sake of a few hundered quid the difference will be massive! If the budget will stretch get a bottom of the range audison amp (although bottom it will be better than a lot!) a jl audio sub with a large power cable and you will be amazed at the difference. Obviously if the problem persists you will have to change the head unit out. I can back this set up as it's what I have.... Mine rattled the rear window loose however I've had this set up or ages and yes it sounds good but more importantly it's lasted! Unlike cheep alternatives. Quote Link to comment Share on other sites More sharing options...
scott87 Posted April 9, 2014 Author Share Posted April 9, 2014 Personaly I think the answer is in the question. Your using cheep gear. Granted it worked before but for the sake of a few hundered quid the difference will be massive! If the budget will stretch get a bottom of the range audison amp (although bottom it will be better than a lot!) a jl audio sub with a large power cable and you will be amazed at the difference. Obviously if the problem persists you will have to change the head unit out. I can back this set up as it's what I have.... Mine rattled the rear window loose however I've had this set up or ages and yes it sounds good but more importantly it's lasted! Unlike cheep alternatives. I know its cheap but the problem seems more than just because the gear is cheap, it seems very signal orientated or amp settings. I think it may be the headunit as it really doesn't seem to allow much control. However im going to remove the sub and inspect it. I wasnt wanting insanely good quality audio, just something to take the low range away from the speakers in the car so they didnt sund so bad. Can i run the sub from one of the channels rather than bridging? I'd lioke to try a few things before binning it. Quote Link to comment Share on other sites More sharing options...
skippyboyo1 Posted April 9, 2014 Share Posted April 9, 2014 I know its cheap but the problem seems more than just because the gear is cheap, it seems very signal orientated or amp settings. I think it may be the headunit as it really doesn't seem to allow much control. However im going to remove the sub and inspect it. I wasnt wanting insanely good quality audio, just something to take the low range away from the speakers in the car so they didnt sund so bad. Can i run the sub from one of the channels rather than bridging? I'd lioke to try a few things before binning it. You sure can, as long as it's off the amp Quote Link to comment Share on other sites More sharing options...
Al Massey Posted April 9, 2014 Share Posted April 9, 2014 All bridging does it double the power going to the sub. Quote Link to comment Share on other sites More sharing options...
scott87 Posted April 9, 2014 Author Share Posted April 9, 2014 You sure can, as long as it's off the amp Cheers dude Will try this and then see if that makes a difference at all. Im also going to turn the input voltage to the lowest and use the bass boost/gain and make sure everything else is to the lowest and on low pass. If its still there then i know there is an issue with the components. - - - Updated - - - All bridging does it double the power going to the sub. Oh so if i have a low power sub this will be sending way to much power! Quote Link to comment Share on other sites More sharing options...
Kaan W Posted April 9, 2014 Share Posted April 9, 2014 Not enough power is usually the cause of distortion. It's best to match the subwoofers power with an amp then have it running at 50-75% load. Quote Link to comment Share on other sites More sharing options...
scott87 Posted April 9, 2014 Author Share Posted April 9, 2014 Not enough power is usually the cause of distortion. It's best to match the subwoofers power with an amp then have it running at 50-75% load. Ok well the speaker looks fine. Its a 1000w jbl or 250w rms anyway. The amp is the older 2 way mutant one. Its purple and has black bars over it. The model number is rubbed off. Ive played with the settings and taken it from bridged to normal connection. I have also turned everything off on the headunit. The voltage oin the amp i then turned all the way up with the bass boost/gain db reading to 0 and turned the voltage back till the distortion went. I then moved the gain up a bit and voltage down if it needed. I got this to a level that sounded ok. But the bass isnt booming at all. I then turned the feed from the headunit to the low pass filter to +6 from zero. And then adjusted the gain and input voltage again until there was no distortion. Its sounding fine but its not rattling the doors off as my old jbl did. I have the frequency turned up a little from 40hz, probably more like 60. I have also turned the others to zero as they were high pass ones. There is also a mid something setting that seemed to be best put in the middle. Basically this is the best i can get it, So if anyone is local that can have a look that would be grand. Or at least tell me i've done it all wrong and try again. All of this was done with the cd player set to the highest volume i listen to as any louder an ill blow my other rear speaker. That reminds me, anyone have some rear speakers please? Quote Link to comment Share on other sites More sharing options...
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