Slow sub response???

[IanGT99]

I didn't really know what to search for on this, but I was hoping some of the extremely knowlegable people on here could help me out. I know a pretty good deal about systems, but unfortunately, not enough to solve this problem. I have a Jensen, 300 watt amp. It's cheap, but has still worked well for me for quite a while. I have 2 JBL 12" subs that are pretty decent also. When I have the bass turned up loud for a while, sometimes the bass won't hit exactly on the bass note. For instance, on the rap song "Bia Bia" (we all know that one for it's great bass tones), there are many low, punchy notes. As soon as one of them hits, there will be nothing coming from the subs for a split second, then they'll come in full force. It's almost as if my amp is shorting out from the power, then recovering. Is it the amp or could it be something else. I have a custom made, sealed box and monster wire all around. Any ideas???

Ian

[rocketfast123]

Sounds like a power problem. Are you running at least a 8 gage wire from the battery to the amp?

my $0.02

[MattBatt]

It's the fact that sound travels at 1,130 ft/s and your subs are further away from you than your mid range speakers. The mids are producing the upper end of the bass hit so you are hearing them more in time than the subs.

[2002GT]

Sounds like my problem... I had it hooked to the amp wrong... I was running 2 ohm instead of 4 or w/e... check wiring

[IanGT99]

Sorry MattBatt, that's not the problem. It's very noticeable that the subs just don't hit when they're supposed to. I'm running 8 gauge wire for the power and the ground wires. I have it set all wired correctly, too. I think it may just be a short in the amp or something. My RCA's are plugged into the front output from my CD player. I have the Pioneer P6000. It's about 4 years old, and the sub outputs were starting to go bad. Instead of spending money to have it repaired, I just switched the RCA's to the front. Would that have anything to do with it?

[quinton]

does it do it on alot of songs or just that one? youre box could be producing one hell of a group delay, but i doubt it would be as extreme as it sounds like youre describing.

[IanGT99]

No, it doesn't do it on just that song. It's just the songs where there is very punchy bass. Like, there is no bass, then all of a sudden, there's a note that hits extremely hard and low. I have no idea what could be causing it. I guess i'll just struggle with it for a few months and get new subs and an amp. If it still does it, then i'll be mad.

[jmckinney]

What kind of H.U. are you running?

Could be that the RCA preout running the amp is starting to go out

Or if you are a line output converter, then that would definately be the issue.

A few other things to try would be a better ground and maybe some better RCA's

[MattBatt]

I don't understand Why is everyone blowing off my theory like I'm and idiot? This kind of thing happens every day you see lightning and then you hear it. Your mids are 4 feet away and your subs (if pointed backwards in the trunk) are like 8 feet away. Most PA gear for shows they line up the voice coils for the woofer and the tweeter so that there are no time delay issues.

Also if you want to get technical if you have a crossover hooked up to your subs then the front of the waveform (above the crossover point) could be going to the mids (if it's tight bass then there might be some freqs above the crossover point) and the rest comes through to the subs after the first part of the transient. Take for example the hit of a kick drum there is the initial impact of the mallet on the drum head (above the crossover) and then the resonating frequency of the body of the drum.

Also just as a final question how do you know that it doesn't sound right do you have access to another high quality stereo system that reproduces the song correctly to compare your system to? It might just be the way the Artist/Engineer made the song Jazz artists play "out of the pocket" all the time.

[jmckinney]

i was not trying to ignore you MattBatt, i was simply stating from my experience what i thought it could be. I have seen the same issue that they are speaking of many times. As for Pro Audio... that is a completely different world than car audio. I've been an installer for 5 years, but I have the sound tech for many of the churches in my area for over 8. Everything you said is true, but the problem Iangt99 is describing is a common issue.

[IanGT99]

Yeah, MattBatt, I wasn't dismissing your input either. I'm just saying that this is a recent problem. It never did it before, so it must be that something is shorting or going bad. I have the Pioneer DEH-P6000 H.U. It's a really great HU and it's worked really well for me the past 4 years. The sub output on it recently was giving me troubles. It almost sounded like it was power surging because there would be these low, quaint pounds of bass about a half second apart all the time. It was really strange. I switched my RCA's (which are monster wire, by the way, so I'm fairly certain it's not the wire) to the Front outputs. Now, I'm only running a 300 watt Jensen amp, and I'm thinking this may be the problem. The RMS factor of that amp may not be strong enough to handle the amount of power needed to accurately produce the extremely low, loud, bass tones. From my understanding, the lower the notes, the more power it takes to produce them. I doubt it could be the front output on the HU because they have never been used before until now. I'm going to upgrade to a 1000 watt Sony amp and two new P5 octagonal shaped Sony 12's over the winter. Hopefully that will quell the problem. jmckinney, since you've been installing for 5 years, maybe you could put in some more information??? Got any ideas of what it could be???

What's your crossover point set at? Could it be that it's set to low and the songs your talking about only have small areas with frequencies low enough to play through the subs? Remember subs only play a small percentage of the music, maybe as small as a 40 Hz range, where as mids may play as much as 5000 HZ. If your frequency range is set to narrow, the subs could have long pauses where there is nothing for them to play. In a SQ car you would'nt hear that, but most of the systems here the subs overwhelm mids and highs, this could be very noticeable. . . I think.

[IanGT99]

Good point. The HU has a feature where I can control how low the frequencies are that go to the front speakers. Since my sub's RCA's are plugged into the front output, I've had to set it at it's lowest setting of 50 Hz. If I put it to 80 or 120, the subs loose a great deal of power because they're not getting the really low notes. I'll probably have to end up getting my sub out fixed or get a new HU, but for right now, the front out is my only option.

[MattBatt]

Ok I understand now. Do you have another amp to hook the subs up to to see if that is the problem and if it isn't hook up your rears to the amp and see if it continues.

Originally posted by IanGT99
Good point. The HU has a feature where I can control how low the frequencies are that go to the front speakers. Since my sub's RCA's are plugged into the front output, I've had to set it at it's lowest setting of 50 Hz. If I put it to 80 or 120, the subs loose a great deal of power because they're not getting the really low notes. I'll probably have to end up getting my sub out fixed or get a new HU, but for right now, the front out is my only option.

I'd definitely move it to 80Hz, I might even try 120 just to see how it sounds. If your worried about getting deep bass - don't, a very small fraction of what you hear is below 50Hz. Most people can't even hear below 20-25. People competing for SPL will often tune their ports above 50Hz because the really low notes just require too much power to get really loud.

I'd also check all connections esp. the ground (because I've found a bad ground connection can just cause all kinds of funky sh!t). Then maybe, like MattBatt said, try another amp - Jensen isn't known for it's reliability and could very well be the problem.

[IanGT99]

I got the Jensen amp when I was 17...young and stupid high school kid, right? . I guess I was all about saving a buck or two back then and went with the cheaper brand instead of getting something that would last. I really do think it's the amp. Unfortunately, I don't have another amp to hook the subs up to. If I did, the Jensen would have been out the door long ago. I'm gonna try tuning it to 80 Hz and then see what that does. Like I said though, I'm hoping to land all new stuff in the winter months.

[MattBatt]

Your Headunit speaker amps might be able to push the sub a little ( probably just enough to check and see if it's the am that is wrong.

[quinton]

dont change the front setting to 80 or 120.. turn the thing off.. its a HIGH PASS FILTER as in right now you are cutting out the freqs below 50 by atleast 6 db/octave depending on the deck.. turn it off. make sure your LOW PASS FILTER is set between 80-100 on the amp.

(if its a pioneer deck, press the down arrow when you are at the setting)

[IanGT99]

I could do that, however, I really don't want all those low frequencies going to my front speakers. So, I guess I'm screwed either way...I'll give it a try and see what happens.

[quinton]

Originally posted by IanGT99
I could do that, however, I really don't want all those low frequencies going to my front speakers. So, I guess I'm screwed either way...I'll give it a try and see what happens.

dont you have a rear output?