Help with under 300Hz for Monsoon MM-700 Planars

[adason]

Bfb1963, do you plan using one sub under the table? Or two small woofers on the desk under the planars flanking the monitor?

 

[planet10]

impedance of the planar panel

dave

 

[adason]

Thanks Dave.

 

[bfb1963]

View attachment 1174623

dave

Thanks for the impedance curve. I measured it at 3 Ohms at static, and assumed it would 4 Ohm driven.

Bfb1963, do you plan using one sub under the table? Or two small woofers on the desk under the planars flanking the monitor?

I will be going with two small woofers under the planars and flanking the monitor. No subwoofer. The Monsoons have holes on their bottoms for the metal peg legs that I can use for dowels to connect it to the woofer module.

I originally was going with a 3rd order at 300Hz, because that is what the guy I bought them recommended. But if they were meant to be 250Hz, then I will go with the Bessel 3rd order at 250Hz you posted. I wont consider the Butterworth because one of the inductors needed is on backorder from PE.

 

[bfb1963]

I've never built a crossover from scratch before. Some of the inductor specifications are off a little. Is that OK? I do not want to do any unwinding since I can't measure inductance. And I understand that capacitors can be configured in parallel to meet specification.

L1 specified 1.58, available is 1.5
L2 specified 5.27, available is 5.0
L3 specified 1.05, available is 1.0

 

[adason]

Well, if you are using two small woofers on the table, you can cross higher. Its totally up to you. If you cross higher, you can have lower order slopes, even just one cap for monsoons, utilizing more from woofers.
The whole point of steep crossover at lower frequencies was for sub not to be localized too much (which should still be much lower that 250/300, at least 150).
If you run two woofers higher, you save a lot on crossover. First, select what woofers are you going to use, then decide on crossover.
You can put inductors in series to obtain desired value, btw.

 

[bfb1963]

Well, if you are using two small woofers on the table, you can cross higher. Its totally up to you. If you cross higher, you can have lower order slopes, even just one cap for monsoons, utilizing more from woofers.
The whole point of steep crossover at lower frequencies was for sub not to be localized too much (which should still be much lower that 250/300, at least 150).
If you run two woofers higher, you save a lot on crossover. First, select what woofers are you going to use, then decide on crossover.
You can put inductors in series to obtain desired value, btw.

That was super informative. Like a light bulb moment. So, I have my woofers picked out, and just need a crossover point recommendation. Where would you like these planars to take over? And what slope would you recommend?

 

[adason]

Post measurements of the woofers. On axis and off axis.

 

[bfb1963]

That will be a bit. I reached out to the designer, mattp at TechTalk, maybe he has them. Otherwise, I will just have to build the module (one driver and two radiators) and then measure them.

 

[ChrisABC]

some ideas- The Kairos and Continuum Three-Way.pdf

https://app.box.com/s/a4bqr447s7ox7v9kt7r9tjui0h7yqkrv

page 7

 

[bfb1963]

Read that with interest, but this is a small form factor desktop project. Thank you.

 

[bfb1963]

Post measurements of the woofers. On axis and off axis.

This is the data for the raw driver, not the enclosure. The enclosure includes a single driver and two passive radiators.

 

[adason]

That looks very good. You can cross it anywhere below 2-3kHz. But i would avoid crossing in this part of spectrum, as ear is most sensitive.
My suggestion would be to cross at 900Hz. I would use 2nd order for midbass, and just a cap for monsoon.

 

[bfb1963]

This is the crossover result, but I do not understand how to design it with your suggestion of "just a cap for monsoon."

 

[adason]

Just do not use L1, experiment with C1 value. It will depent how you like the sound.