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-   -   avoiding the l-pad (http://www.diyaudio.com/forums/multi-way/34170-avoiding-l-pad.html)

smak 16th May 2004 11:43 PM

avoiding the l-pad
 
i'd like to avoid using an l-pad but would like to tone down the highs my lpg 26t tweeter are producing.

its working in cahoots with an eton 5-880 midrange but its severely outshining it.

the eton is rated at 87dB while the lpg is 90dB. both 8ohm units.

i've been told using a 4 ohm resistor in series with the lpg may help my cause but i'll need to re-calculate the cap i have limiting anything below 2k reaching the tweeter. i believe its an 11mF cap.

what resistor do you think i'll need to tame this tweeter and what new capacitor value should keep it x'ed over at ~2K?

Andy G 17th May 2004 01:38 AM

there is nothing wrong with an L-pad
 
so long its hard wired with quality resistors.

for approx 3dB drop use 18 ohms across the tweeter, and then 2.2 ohms in series.

Jay 17th May 2004 02:51 AM

If you change the cap because you add a series resistor, you can calculate the value (based on increased tweeter impedance), but believe me, it will be the same as designing a new crossover.

The parallel resistor as suggested by Andy will bring back the original impedance.

Hi Andy, can you recommend 2 or 3 brands of resistor for use with crossovers? What do you think of that gold metal shielded vishay commonly used in tube applications?

If Andy thinks that L-PAD has no problem, I guess it is because he never has an inferior amplifiers. IMHO, most problem with speaker is because the amplifier is not up to the task. The L-PAD resistor (or any kind of compensation components) will take away the power (current) out of the drivers, leaving the speaker with inferior sonic quality. But if you cannot avoid the L-pad, what else can you do.

Mudge 17th May 2004 12:45 PM

Quote:

Originally posted by Jay
But if you cannot avoid the L-pad, what else can you do.
Active or passive bi-amping, with a different gain on the treble amp? :confused:

There are always options.

Jay 17th May 2004 02:08 PM

Quote:

Originally posted by Mudge
There are always options.
Including buying Martin Logan ;)

Ouroboros 17th May 2004 02:59 PM

Why avoid the L-pad? If your tweeter has higher sensitivity than the woofer, then an L-pad (with fixed resistors) is a very good way to attenuate it. It also helps to keep the load more constant on the XO output.

Sheldon 17th May 2004 03:16 PM

Quote:

Originally posted by Mudge
There are always options.
Transformers? I gather that these are not commonly used because appropriate ones (power, frequency response) are not so readily available?

Sheldon


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