Sub Line Driver

[rampage101]

I'm after a subwoofer line driver for my current system, I'm currently running:
JVC AVX2 Headunit (think its the problem, see below)
DLS UP36 (3-way fronts)
DLS IR12 (Iridium 12" Sub, 65L-/+, ported)
DLS RA10
2x Jaycar 150wrms (1 per front speaker triplet, until I get my 2 amps for active front stage)

My problem is I don't seem to get a lot of bass, don't get me wrong, its loud but it just doesn't seem like its as loud as it should be, and I believe its because the headunit only has the 1 rca line for sub out, so I've got it bridged into the amp, but I think because of this the amp only see 1/2 the signal compared to a normal 2rca output of another headunit.

Thoughts, suggestions? I know Audiocontrol do a line driver, but I'd rather just grab some op-amps and build one if its not that hard.

[Dan2]

Im guessing the front loader has a sub line out (the one you are using) and normal line out. if your sub has a built in low pass filter, try use stereo line out with amp's LPF - that should give better signal.

[rampage101]

Well, I have a spare pair of rear-out rca's, but I get the same volume as the sub out (assuming sub out is max vol.), so its pointless because I also loose sub control. Hence, why I need a line driver.

[Dan2]

ok cool - then op-amps are probably the way to go. i will get back to you with a design as soon as i can.

if your sub line out has the same volume as your rca jacks then you should hav enough signal going to the amp - are you sure your gain on the amp is max???

[richie00boy]

It does seem like you have a problem with your system, there should be enough signal to get loads of bass. Splitting your sub signal will actually give near-as-dammit just as much level as if the sub-out had two connections.

If you build a line driver you need one with gain, probably at least 10dB going by what you have said. But then again as I said at the start, I think you need to look elsewhere.

[pinkmouse]

Unless your amp is very strange, splitting the mono signal into the two sub inputs will not decrease the level significantly. Adding gain with an opamp line driver will likely just drive the amp into clipping earlier. Unless there is a major mismatch in signal levels from the head unit, (which your experiment with connecting the sub to the rear outputs seems to disprove), then only answer is a more sensitive driver or a bigger amp.

[rampage101]

Yeh, thats whats got me all confused, the amp is 500w @ 2ohm, which is what the sub should be getting (dual 40hm sub, running is parralel), and I've heard other stuff that seems to output more, and the only thing I can put it down to is the headunit output.

I do work in car audio, and Audiocontrol does do a line driver, but as yet I don't know who the australian importer is. I will get around to actually testing a Alpine headunit, and see what happens then.

The amp is definetly on max gain, the sub level controller is disconnected (but the option is set correctly, so it maxes the level anyway).

[Dan2]

i agree with the other guys - a stronger input signal shouldn't be needed. just to clarify - are you running amps on your other speakers??(midrange and tweeters) if you have those amps on max gain, your head unit could be running at a low volume, making the bass sound quiet. try setting the gain down on other amps so u can turn the volume up more on the head unit

[rampage101]

The gain on those is very low, and I generally listen to the headunit at around 30, it only gets to 50.

[Dan2]

well then you can try this small pre-amp

http://www.uoguelph.ca/~antoon/circ/audio/audio1.html

it should do the job