folsep

I need some help. Last year, I replaced the stock Sub in a 98 GS400 with a JL 10" IB sub (M10IB5 Marine- its a free air sub primarily used on boats) powered by a Older Fosgate 250a2. Everything else remained stock. It sounded great.

a couple of weeks ago the stock amp went out and I had no sound, good excuse to upgrade right?

Instead of buying a new amp, I decided to purchase a new head unit and use that as an internal power supply to the interior speakers. I bought and had "professionally" installed the new 7 inch in dash DVD pioneer 4200.

Result...everything is great except the sub is about half as "punchy." it doesn't hit hard like it did with the stock head unit??? Everything else sounds and works great, it's just the sub isn't performing the way I liked before.

I've adjusted the LPF on the amp, internal sub adjustment on the head unit, messed with "bass boost" and played with all different eq levels.

When I finally get it to where I think it sounded like before, a new track comes on and it's totally distorted. This never happened with original head unit.

Any thoughts?

Of course, I will get in touch with the installers and have them try to "fix it" but I have a feeling where it might go because when I picked my car up he said that he new head unit made the sub sound so much better???


I understand that sound taste is relative and I'm not implying that he's wrong. However, it is apparent that I am not gettin the level of deep bass that I was previously. It sounds like I went from a 10" to an 8.

I'm a new member and would appreciate any input from forum members, seeing as they do not have a direct interest in the contents of my wallet.

(I tried a topical query and since I'm not really sure what I'm looking for it has limited my results).

Big Mack

iTrader: (1)

First off, welcome to the club.

If you had everything stock but the sub and the new amp, it was receiving the signal from the old amp. This is certainly going to provide much more signal to the RF amp because it was amplified by the factory amp, then converted to a signal for the RF to use. Does the Rockford have high level inputs, or was a line output converter used? Either way, the RF was getting much higher levels before, thus allowing the gain to be set low. The new deck simply doesn't allow for this much signal, and would require you to raise the gain on the RF amp to better match the output of the deck. It shouldn't really make the sub sound horrible, though. If it's distorting, the gain is set far too high. You need to get it set up properly using a test tone at a pretty decent level.

Big Mack

folsep

Thanks for the quick reply.

A line output converter was originally used in the "factory" setup so that it could be played on the factory head-unit.

(I believe it just "patched" in to the rear speakers wire?)

So if I understand correctly:

The stock head unit went to the factory amp which sent power to the aftermarket amp which then sent power to the sub. Now we have taken out the factory amp and so the sub is not receiving the benefit of that power.

Makes sense. It sounds as if it's not as "powerful." I guess I should increase the gain. Could too much of an increase cause damage to the sub ?

The distortion only occurs at higher volumes and only after I increase the head unit sub level to the max and then add "bass boost" and "loud." So....to be expected I assume.

I will add a little to the gain in the am and see if that helps.

Oh, and the amp is pretty primitive. The only controls are gain, "punch"- which is essentially a bass boost at about 45 hz- and a high and low pass switch with accompanying ***** for adjusting the frequency. If you stop the switch in between switching from high and low there is a "Full." Could setting it to Full and then setting to a higher frequency like 120hz or so allow the sub to capture more frequencies and essentially play more bass notes resulting in a possible deeper effect?

Thanks for your help.

Big Mack

iTrader: (1)

Yes, you need to match the gain to the deck's output level.

You should decrease your sub level to 0, turn off the bass boost, and turn off the loud. This will set your output as flat as possible and allow the gain to be properly set. If these are each maxed out, you are sending a very high (and usually distorted) output to the sub amp.

Make sure you read above first.

That's not really primitive. It has all the features needed, but not very flashy with them. You should leave the crossover on low pass, setting it for about 80 Hz and below. I would leave the punch off as well. This allows you to use the bass boost on the deck for those times when you want more low end. Using all of those "boosting" features together is what usually creates a lot of distortion and kills subs when they get overdriven. Fine to use one or two occasionally, but if you want more volume on a consistent basis, buy more amp, buy more subs, or both.

You're welcome, mang.

Big Mack

folsep

A minor adjustment to the gain helped. Thanks.

Big Mack

iTrader: (1)

Glad to help, mang. Amazing how one little thing can throw everything off kilter, isn't it? Thankfully, you're learning from others mistakes, not paying for them yourself.

Big Mack