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View Full Version : Please Help Out This Poor, Unsophisticated Rube (question about testing crossover).



CheeseGrits
09-13-2008, 06:55 AM
My apologies for being so basic, but I'm no electrical engineer. I'm also pretty new to speakers and crossover design, etc. I did some searching on the forum, and I didn't see anything that directly answers my question, so here goes:

Can I use my multimeter to determine whether the components of my L110 crossovers are all within spec? If so, do I have to physically remove the components from the circuit before testing them?

If there is a good article or thread about this, a link would be appreciated. I don't mean to ask you guys to retread familiar ground.

Thanks in advance!

Mr. Widget
09-13-2008, 10:08 AM
Can I use my multimeter to determine whether the components of my L110 crossovers are all within spec?No.

You need an LCR meter and you need to know how to use it. It is fairly basic stuff, but you'd be best off if you could find someone in your area to help you figure this stuff out.


Widget

grumpy
09-13-2008, 11:29 AM
Feeling in a contradictory mood this morning... :)

Sure... you'll also need a set of test tones (online or on CD), make sure
the AC voltage function on your DVM is accurate in the audio range (say
20Hz-20,000Hz), and a few eight ohm resistors. Depending on the interval
of your test tones, you could patiently build up a series of measured voltages
that you could plot over frequency... do this at each driver's leads with the
8 ohm resistor put in-circuit in place of the driver being measured.

This will give you three voltage drive plots (one per driver), which could be
compared in shape and amplitude to what's expected for the N110 crossover.
Convert the voltages to decibel ratios 20log(Vout/Vin)... if you set Vin to be 1.0Vac
the conversion is a little simpler.

The voltage drive plots might even be available here:

http://audioheritage.org/vbulletin/showthread.php?t=4552

(scroll down to Figure 8).

Are there other ways to do this without pulling your crossover all apart?
Sure. The "simpler" and perhaps more accurate ones require more than a
DVM though... and then if the plots don't match, you're back to checking
individual components.

Cheers.

Mr. Widget
09-13-2008, 12:05 PM
Feeling in a contradictory mood this morning... :)
:applaud:



Sure... you'll also need a set of test tones...I had to read your post twice to figure out where you were going with it... and I understand what you are talking about, and while I certainly don't have the patience to do it, you are correct.:blah:

I am not sure a self professed unsophisticated rube is going to get it. :D


Widget

grumpy
09-13-2008, 12:49 PM
...gotta start somewhere :) Computers and a bit of hardware sure make the
plots prettier to look at (and a whole boatload faster), but with some care,
the accuracy using simple tools can be perfectly adequate.

U.Rube: all of that was to just check that the entire network was "in spec"
rather than checking the individual components. A bit of work and learning
either way.

I'd be a little surprised if the N110 (L110 networks) components were failing
unless there are l-pads (level controls), or they've been abused (there would
be other signs like burned out drivers, or if one speaker sounds much different
that the other (which could still be a driver problem).

Just trying to tweak the system, e.g. adding small value bypass capacitors is a different story... another set of threads.

Hoerninger
09-13-2008, 01:10 PM
... but I'm no electrical engineer. I'm also pretty new to speakers and crossover design, etc...
Depending on the interval of your test tones, you could patiently build up a series of measured voltages that you could plot over frequency... Learning by doing - the hard way. But didn't we start somewhere too, without a PC or ambitious(?) tools?
And there was no Internet!
___________
Peter

Ian Mackenzie
09-13-2008, 03:06 PM
Im a just wondering why the L110 crossover would not be within spec?

Perhaps the L110 does not sound right?