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Danieln

My new LaScala crossovers.

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Finally, after a year with my 1988 LaScala, I replaced the AL type crossovers with a constant impedance set.

I took good care to simulate and then measure the results and i am now an happy camper :-)

 

I decided that a fix L Pad will be my preferred way to attenuate the mid range.

The original attenuation was 6 DB, but in order to make them more lively, I opted for a 4 DB pad.

 

What are your preferred attenuation?

 

Dan

Cross1.jpg

Cross2.jpg

Cross3.jpg

Cross4.jpg

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What does your schematic look like?

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Man... makes me think dean's autoformers really look nice.

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Claude, here it is, nothing very exotic except for the lack of the autoformers :-)

This is a slightly modified ALK universal. I measured the low crossover at 430 and the high at 5700 Hz,

Considering the mid driver fall as a rock at 6000, crossing a bit lower is a plus imho.

 

What is your preference for the mid attenuation in term of DBs?

 

Cross5.jpg

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28 minutes ago, Schu said:

Man... makes me think dean's autoformers really look nice.

 

Wha ...

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Here is the spice simulation : It shows crossovers at 417 Hz and 6100 Hz. 

Measurement were 430 Hz and 5700, Hz close enough.

Cross6.jpg

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2 minutes ago, Deang said:

 

Wha ...

It was just a small insult, no biggie 

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Now that the autoformer shock is (almost) passed, what is your opinion concerning the attenuation level?

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6 minutes ago, Deang said:

Lmao  🤣 

Have you been drinking today?  🍻😁.  Do you have a response?   😂

  • Haha 1

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Per your original post, Your preference is for a positive 4db?

I think anywhere from -3db to a -6db is cool and the gang. A -4db would probably be just about right depending on room influence.

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Sober ... for now.

 

4dB is perfect. But you should have cut bigger boards and lined up the air cores. 

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Always take your time ...

196D995E-7608-4B5B-BDCD-36ACA302175C.jpeg

5B7B2F07-5DDA-45F2-8F01-4CA8F5E08C03.jpeg

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Thanks for the answers,

yes I was referring to  -4 DB, and it is quite a bit more lively than -6DB.

The more I listen to it, the more I prefer -4.

Oh i see Deang, you lined-up the center of the cores. i thought that been 90 degrees apart was sufficient at these low frequencies.

 

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Check your low pass on the woofer.  The horn loading of the woofer essentially doubles the woofer impedance.  That's why Klipsch used a 2.5 mH woofer inductor.  La Scala's bass horn can comfortably go well above 400 Hz. 

 

post-2142-1381931825092_thumb.jpg

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My spice simulation models the woofer as a 6.2 Ohms in series with a 1mH voice coil inductance. Adding my 1.25mH (Essentially two 2.5mH in parallel taken from the AL type crossover) brings the total to 2.25mH for my simulation. The resulting crossover is simulated at 417 Hz. Now, when I look at the actual electrical response of the crossover, I measure 430 Hz which matches quite well the simulation. Increasing the inductance lowers the crossover point in fact. Which crossover frequency is optimum from your point of vue?

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I see Deang, L2 is about 2.5mH. The point is that part of this is in the voice coil.

Else, how can I explain my measured point is 430?

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