Second BFM Build: Otop12 with alternative drivers

[Martijn]

Hello Everybody,

Today is my first official build day of my second set of BFM Speakers. My first build is not finished yet, but
the state of our PA system demands this build.

I will build 2 OTop12 Speakers with a Compression driver/Horn crossed at 1,2 Khz.

As Low Frequency Driver i will use the Beyma SM-112/N http://profesional.beyma.com/pdf/SM-112%20NE.pdf
And for the High Frequencies i will use the Monacor MRD-180 http://monacor.co.uk/products/speakerbu ... nr/104380/

I am starting the build by first making this topic (and 1 for questions about the driver choice) and then i will
start by drawing everything on the wood.

Greetings,
Martijn

[AntonZ]

Martijn, I'm in the Netherlands and have my OT12's for sale (4 single 12 cabs). Might be useful if you are in a hurry. They are the older design and have straight piezo arrays. Contact me if you are interested.

[Martijn]

Hi AntonZ,

Sorry but i am not interested.
I want to build them myself..
And i already have the drivers sitting on my desk.

[gdougherty]

Hello Everybody,

Today is my first official build day of my second set of BFM Speakers. My first build is not finished yet, but
the state of our PA system demands this build.

I will build 2 OTop12 Speakers with a Compression driver/Horn crossed at 1,2 Khz.

As Low Frequency Driver i will use the Beyma SM-112/N http://profesional.beyma.com/pdf/SM-112%20NE.pdf
And for the High Frequencies i will use the Monacor MRD-180 http://monacor.co.uk/products/speakerbu ... nr/104380/

I am starting the build by first making this topic (and 1 for questions about the driver choice) and then i will
start by drawing everything on the wood.

Greetings,
Martijn

That's not the hf driver you want if you want a 1.2k crossover. Check the recommended rather than the range for that. 1.2 on a 1.8 driver is probably asking for a dead driver, bad sound quality or both.

[Martijn]

What am i missing? The Fs is 800Hz, recomended max xo is 1800.
The nsd 2005 has a max recomended of 1500??

[gdougherty]

What am i missing? The Fs is 800Hz, recomended max xo is 1800.
The nsd 2005 has a max recomended of 1500??

Not sure, just know I doubt a manufacturer would recommend a driver for a crossover point that high if it can pleasantly run down lower. I'm no expert, but I'd trust a 1.5k at 1.2k before I would a 1.8k. I think it has more to do with power handling. It may be an 80w driver at 1.8k, but only a 20w driver used down to 1.2k.
Check the beyma cd10fe. It's what I ended up with and I can say it sounds really good and isn't ridiculous in price. Leland also recommends the hf107 from Faital or the hf10ak if you've got the money.

I really like the cd10fe as its high power handling, lower useable range and the weight of a neo driver. The magnet isn't as large or strong as a result but it still sounds good.

[Martijn]

I will cross it at 2K then. to be safe

[Bruce Weldy]

I will cross it at 2K then. to be safe

That is probably a smart move.

[Bill Fitzmaurice]

What am i missing? The Fs is 800Hz, recomended max xo is 1800.

That's with a 12dB crossover. The plans is 18dB. I see no issue with it.

[AntonZ]

Hi AntonZ,

Sorry but i am not interested.
I want to build them myself..
And i already have the drivers sitting on my desk.

Fair enough, using your own home built cabs is great fun

[gdougherty]

I will cross it at 2K then. to be safe

If you're doing an ot12, I'd go for the lower crossover point drivers at 1.2k or 1.3k. I'd think the beyma or Faital drivers could be sourced over there easily since both are European companies.