L-Pads for car audio?

[edouble101 314]

If have been thinking about this for too long and my brain is no longer able to figure this out on it's own Are L-pads ever used in a car audio application? I understand their use in a passive setup for home audio but what about an active setup in car audio? Hmmmmm adjusting the amplifier gain will not change sensitivity so an L-pad would be used to attenuate a higher sensitivity driver?

Reason I am asking is that it can be difficult to match mid/tweeter/midbass sensitivities for an active 3-way setup. Let's say that the midbass and tweeter sensitivity is 88db 1w/1m (4 ohm). And that the midrange sensitivity is 91db 1w/m (8 ohm). I think 91db 1w/1m@8ohm is the same as 88db 1w/1m@4 ohm (see how I get myself all f'd up!)? Could an L-pad be used to attenuate the midrange if needed?

I think there is a simple answer. But like I said my brain is fried from thinking about this for weeks on end

[Tirefryr 1,742]

Yes.

[edouble101 314]

Yes.

Why haven't I EVER seen a build log or even mention of an l-pad for car audio?

[Tirefryr 1,742]

Because the only people who would consider using them don't use them. They either switch drivers, application, or pad some other way.

You would actually see them quite a bit in the early 90s.

[Impious 1,476]

If you are running active you have no need for an L-pad. Adjust the gains on the necessary amplifier channels or adjust the level settings on the active crossover to properly level match the drivers..

91db 1w/1m sensitivity is 91db 1w/1m sensitivity regardless of the impedance of the driver because it's a proper 1w/1m measurement. The only time you need to "correct" the sensitivity rating is if it's a 2.83V rating, because 2.83V results in different wattages depending on the impedance of the driver. But if it's measured at 1w, then 1w is 1w regardless of the driver's impedance.

[edouble101 314]

Because the only people who would consider using them don't use them. They either switch drivers, application, or pad some other way.

You would actually see them quite a bit in the early 90s.

What other methods are there to "pad"?

I am finishing up the design on a 3-way active and the midrange has been always "padded" by other builders that used the driver for home audio use. I am concerned that I will need to do the same.

[edouble101 314]

If you are running active you have no need for an L-pad. Lower the gain on the necessary amplifier channels or adjust the level settings on the active crossover.

91db 1w/1m sensitivity is 91db 1w/1m sensitivity regardless of the impedance of the driver because it's a proper 1w/1m measurement. The only time you need to "correct" the sensitivity rating is if it's a 2.83V rating, because 2.83V results in different wattages depending on the impedance of the driver. But if it's measured at 1w, then 1w is 1w regardless of the driver's impedance.

Ah ha! Do you see a huge difference between a tweeter/midbass at 88db 1w/1m and a midrange at 91db 1w/1m?

[Impious 1,476]

Yes.

Why haven't I EVER seen a build log or even mention of an l-pad for car audio?

Because most people doing the build logs are either using a prebuilt passive crossover (which either has an L-pad/attenuation or it doesn't), or they are running active (where a passive L-pad isn't really necessary).

Over in Europe there are some SQ competition formats which are 100% passive crossovers........those competitors probably use L-pads as they custom build all of their passives.

[Tirefryr 1,742]

Because the only people who would consider using them don't use them. They either switch drivers, application, or pad some other way.

You would actually see them quite a bit in the early 90s.

What other methods are there to "pad"?

I am finishing up the design on a 3-way active and the midrange has been always "padded" by other builders that used the driver in for home audio. I am concerned that I will need to do the same.

You pad by adjusting the gain or level on the processor. You can throw out what has been done for HT. It in no way relates to response characteristics in the automotive environment.

[Tirefryr 1,742]

And Brad beat me to it.

[Impious 1,476]

If you are running active you have no need for an L-pad. Lower the gain on the necessary amplifier channels or adjust the level settings on the active crossover.

91db 1w/1m sensitivity is 91db 1w/1m sensitivity regardless of the impedance of the driver because it's a proper 1w/1m measurement. The only time you need to "correct" the sensitivity rating is if it's a 2.83V rating, because 2.83V results in different wattages depending on the impedance of the driver. But if it's measured at 1w, then 1w is 1w regardless of the driver's impedance.

Ah ha! Do you see a huge difference between a tweeter/midbass at 88db 1w/1m and a midrange at 91db 1w/1m?

I see 3db of difference

Audible difference is something that you can't determine just from looking at the listed sensitivity specifications. It's going to have a lot to do with the installation (driver location, aiming, etc) and the actual FR of the speakers a long with their operating bandwidth. I wouldn't worry about a 3db difference in sensitivity, that's easily enough corrected for if necessary.

[edouble101 314]

Thank you for the very fast replies Impious and Tirefryr. I am very happy that I asked the question instead of mixing up more ideas in my head.

[Skullz 8]

With the better processors today you don't see much use in pads for car audio.

[Impious 1,476]

You can throw out what has been done for HT.

I missed the part where he was specifically referencing HT crossover designs for his midranges.

As Ryan said.....most of what happens in HT isn't going to transfer to car audio as our environment and other constraints are so much more challenging and so much further from ideal.

[edouble101 314]

With the better processors today you don't see much use in pads for car audio.

Gotcha. I plan on using either the MS8 or the 3SIXTY.3 if it comes out in time.

You can throw out what has been done for HT.

I missed the part where he was specifically referencing HT crossover designs for his midranges.

As Ryan said.....most of what happens in HT isn't going to transfer to car audio as our environment and other constraints are so much more challenging and so much further from ideal.

Thanks again for your help.

[///M5 2,833]

They'll be a lot more control in either of those processors than the sensitivity differences you speak of.

[edouble101 314]

They'll be a lot more control in either of those processors than the sensitivity differences you speak of.

Good to know. I do not want to be elbow deep in a build to realize I didn't have the design properly figured out.

[///M5 2,833]

Both of those should easily be able to deal with 10dB differences if not more

[Tirefryr 1,742]

That's the beauty of the electronics. It's almost infinitely adjustable.

[edouble101 314]

Both of those should easily be able to deal with 10dB differences if not more

That's the beauty of the electronics. It's almost infinitely adjustable.

The 3SIXTY.3 should be amazing from what I have been able to gather. I am very anxious to hear more about it.

[///M5 2,833]

And if for some RIDICULOUS reason they didn't have enough its real easy to build an Lpad in particular if you don't have to be exact

[///M5 2,833]

And I REALLY doubt that ridiculous reason can exist

[///M5 2,833]

However, I expect someone from FL will prove me wrong but with a stupid reason

[Tirefryr 1,742]

Padded supertweets, LOL.

I got 50 supertweets in my dash and they are too "bright." How can I tone them down?

[Shogen 325]

lol... good info, good laughs...