[fdriller9]

Hey I'm looking for the individual who ran their stock L7 woofers at 150W each.

How long did you have them running like this? Did they last? Any problems?

I'll be helping someone do a sub install and I want to bandpass the under seats. But I'm wondering if I should amp them @ 80W or 125W per channel.

I have mine amped @ 75W per channel and they have been fine but 125W is almost double the power.

[Titanium3Series]

did running them on an aftermarket amp help at all? i thinking about ditching my 10in and doing this...

[kaigoss69]

I was, for a little while. When it comes to selecting an amp for these, remember that they are midbass drivers, and not subs. The goal is (or should be) to give them enough power that the MIDBASS can keep up with the rest of the system. The goal should NOT be to overpower the mid and high frequencies, as these are not the right drivers for that. As long as that is understood, the amp max output, from personal experience, does not need to be higher than 150 watts per woofer, but should be higher than 70 watts per woofer. I know this because a) the OEM amp puts out around 70 wpc before clipping (measured myself) and b) the aftermarket amp I used, capable of 150 wpc, was not maxed out when I used it. So the required amp power lies somewhere in-between.

What also needs to be understood is that the signal going to these woofers contains bass and sub-bass frequencies. As soon as you amplify the signal to get better midbass, you are also amplifying the lower frequencies and I know for a fact that the OEM woofers cannot handle it. You will need to use the amp's high pass filter to filter these potentially damaging frequencies out. IIRC on my Blaupunkt amp I set the HP to 50Hz with a 12dB/oct slope.

So you can use them with added power, but you need to be careful. Remember how much these cost to replace.

[fdriller9]

Originally Posted by kaigoss69

I was, for a little while. When it comes to selecting an amp for these, remember that they are midbass drivers, and not subs. The goal is (or should be) to give them enough power that the MIDBASS can keep up with the rest of the system. The goal should NOT be to overpower the mid and high frequencies, as these are not the right drivers for that. As long as that is understood, the amp max output, from personal experience, does not need to be higher than 150 watts per woofer, but should be higher than 70 watts per woofer. I know this because a) the OEM amp puts out around 70 wpc before clipping (measured myself) and b) the aftermarket amp I used, capable of 150 wpc, was not maxed out when I used it. So the required amp power lies somewhere in-between.

What also needs to be understood is that the signal going to these woofers contains bass and sub-bass frequencies. As soon as you amplify the signal to get better midbass, you are also amplifying the lower frequencies and I know for a fact that the OEM woofers cannot handle it. You will need to use the amp's high pass filter to filter these potentially damaging frequencies out. IIRC on my Blaupunkt amp I set the HP to 50Hz with a 12dB/oct slope.

So you can use them with added power, but you need to be careful. Remember how much these cost to replace.

Thanks. My plan is to bandpass the underseats. I know they are actively low passed around 200-150hz so I was going to high pass them, around 70Hz. Then low pass the sub. This is actually how I have my system now but I have my underseats run with a Alpine M500. But it's running @ 8ohms, 75W per channel. I didn't want to run them @ 2ohms, 250Wpc for fear of blowing them.

I'm thinking about using an MB Quart ONX4.125. I was going to use channel 1 and 2 for the underseats which will give them 125W @ 4 ohms. And bridge channels 3 and 4 for 500W @ 4 ohms for a Alpine 1242D.

I have the 1242D running off a JL 500/1 now @ 2 ohms and I love the way it sounds. Do you think sound will change much when I wire it to 4 ohms?

[fdriller9]

Originally Posted by Titanium3Series

did running them on an aftermarket amp help at all? i thinking about ditching my 10in and doing this...

Well bandpassing them helped alot. When you just add a sub, it will play some of the same frequencies of the 10in. So that's why I added an external amp so I could bandpass them.

[kaigoss69]

I have to revise the output of the OEM amp. I mistakenly used 2 ohms resistance in my earlier calc, using 4 ohms yields 35 watts per channel, not 70.

[fdriller9]

Originally Posted by kaigoss69

I have to revise the output of the OEM amp. I mistakenly used 2 ohms resistance in my earlier calc, using 4 ohms yields 35 watts per channel, not 70.

I thought it was 70W per channel @ 4 ohms? I think you were right the first time around.

Specs of the OEM amp are 2 x 70W @ 4ohms and 7 x 40W @ 2 ohms.

I don't know if that's RMS or peak though.

[kaigoss69]

Originally Posted by *********

I thought it was 70W per channel @ 4 ohms? I think you were right the first time around.

Specs of the OEM amp are 2 x 70W @ 4ohms and 7 x 40W @ 2 ohms.

I don't know if that's RMS or peak though.

Peak!

[rcurley55]

Originally Posted by *********

I'm thinking about using an MB Quart ONX4.125. I was going to use channel 1 and 2 for the underseats which will give them 125W @ 4 ohms. And bridge channels 3 and 4 for 500W @ 4 ohms for a Alpine 1242D.

This can't be done. The 1242D is a dual 4-ohm coil sub. Your options are:

1. Wire the coils in parallel, presenting the amplifier with a 2 ohm load
2. Wire the coils in series, presenting the amplifier with an 8 ohm load
3. Power each coil separately from an individual amplifier channel, presenting a 4 ohm load to each channel.

Option 1 is not compatible with that amplifier (from what I can see), Option 2 is the safest and would give you something around 200W to that sub. Option 3 is tricky, but can be done if you know what you are doing, but you are looking at 250W to your sub, which is not all that different then running Option 2, the easier option.

I have the 1242D running off a JL 500/1 now @ 2 ohms and I love the way it sounds. Do you think sound will change much when I wire it to 4 ohms?

Again, this is impossible...You are better off keeping the 500/1 and getting a 2 channel amp to power the underseat woofers.