Matching speaker sensitivities

[Khron]

Ok.. In a few weeks' time, i'll start work on my most ample project to date: 5 (five) bi-amped, 2-way cabinets, with a 35/50W mid-woofer and a silk dome tweeter. Now, the mid has an SPL of 82dB @1W/1m, while the tweeters are around 90-92 dB.

My question is: How can i (measure, if needed and somehow) equalize the sensitivities of the speakers??? (i.e. reduce the tweeter from 90-92 to 82 dB, to match the mid-woofer)

Note that i intend to use a 4th order Linkwitz-Riley crossover before the power amps for each cabinet, and the output buffers have a level control for each frequency band (mid and high, respectively).

[simon5]

You can do that with a L-pad.

You could also use several mid-woofers to need less EQ,

If you use 4 mid-woofers per tweeter, you'll have 88 dB versus 90-92 dB tweeter.

82 dB is really poor efficiency, I hope that mid-woofer is worth it...

[Khron]

Well, i don't want to build anything like a PA system, so 4 woofers per tweeter is out

The thing is that i wanna come out pretty cheap, so i'm gonna be forced to do some compromises. This mid-woofer is something like 7$ so...

Umm.. getting back on topic, know any links to something related to L-pads?

http://sound.westhost.com/project09.htm

Or better yet, some data about the relationship between the output buffer 's pot's travel and the actual SPL (if there is a remotely linear relationship...)

[megajocke]

If you cross over actively you don't need the same sensitivity. Just turn down the level on the tweeters.

[Khron]

I KNOW THAT THAT IS ALL I HAVE TO DO!!! I just want to find out (as objectively as possible) just HOW MUCH to turn down the tweeter level. Subjectivity isn't good enough for me

[carlosfm]

Originally posted by Khron
I KNOW THAT THAT IS ALL I HAVE TO DO!!! I just want to find out (as objectively as possible) just HOW MUCH to turn down the tweeter level. Subjectivity isn't good enough for me

8 to 10 db.

[simon5]

L-pad calculator at the end of this webpage...

http://ccs.exl.info/calc_cr.html

[Khron]

Yeah, thanx carlosfm, i figured that much by myself..

Damn.. When i ask questions, i ask questions

[John Sheerin]

Measure, adjust the appropriate pot, measure again, etc. This also lets you compensate for variation between units somewhat. Of course measuring will open up a whole new can of worms about the crossover, but you can cross that bridge when you get to it.

See my webpage for some info on a cheap measuring setup.

[phase_accurate]

Subjectivity isn't good enough for me

You might be astounded how accurate this works sometimes !!!!

OTOH you can use a soundcard-based measurement program and a simple measurement mic to do so.

Regards

Charles