Author Topic: BMS 4594nd coaxial's  (Read 3748 times)

Offline nzlowie

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BMS 4594nd coaxial's
« on: January 06, 2017, 10:54:57 PM »
Hi all

I've been searching the web for crossover info for my BMS coaxial compression drivers which has lead me here, just started to look around and it looks like a very good place to explore.

On another site I found a post for a 16 ohm version of the BMS crossover but need info on the 8 ohm version.
The 16 ohm schematic is attached, I did find a photo which I think is the 8 ohm version, instead 0f 2.2uf and 4.4uf caps it had 3.3uf and 5.6uf.
Would these cap changes be about right if the coil was the same for both versions?

If anyone has any further thoughts on crossovers for these drivers I'd love to hear about them.

Many thanks 

Offline richidoo

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Re: BMS 4594nd coaxial's
« Reply #1 on: January 07, 2017, 08:46:56 AM »
That is a series crossover, because the coil is shared with both voice coils. Most crossovers are parallel where each driver has separate discreet crossover filter. Series is said to have some sonic advantage, ymmv, idk
http://sound.whsites.net/parallel-series.htm

In a parallel crossover, the coil size would also change with load impedance, but here you're suggesting it does not. dunno

For standard textbook parallel filter, if the load impedance is halved, the size of the caps doubles and the coil is halved. There is no online calculator for series crossovers, but filter theory still applies. It seems you are correct to assume it could be the 8 ohm crossover.

Try it and see. You should be able to build this simple design in stereo for about $40 shipped.

It is a very simple design, you might find that some additional parts could smooth out the frequency response.

Good luck, and thanks for posting on AudioNervosa.com!
Rich

Offline richidoo

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Re: BMS 4594nd coaxial's
« Reply #2 on: January 07, 2017, 08:55:39 AM »
According to the avsforum thread from which you linked the schematic, an 8 ohm version of that series crossover is available from the distributor.




Offline nzlowie

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Re: Re: BMS 4594nd coaxial's
« Reply #3 on: January 07, 2017, 01:25:53 PM »
According to the avsforum thread from which you linked the schematic, an 8 ohm version of that series crossover is available from the distributor.
Thanks, I emailed them but they haven't gotten back.....
This the reason I thought I'd build my own.

Cheers

Sent from my Moto G (4) using Tapatalk

Offline richidoo

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Re: BMS 4594nd coaxial's
« Reply #4 on: January 07, 2017, 05:15:09 PM »
Cool! Glad you stopped by.

Offline nzlowie

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Re:
« Reply #5 on: January 16, 2017, 11:40:55 PM »
Hi guys, as I can't get a reply from the xover suppliers I'll build my own. From web search's I've found the capacitor values for the 8 ohm version but I'm unsure of the coil size, the 16 ohm version is .15mh. can anyone help with size for the 8 ohm one?

Many thanks.

Sent from my Moto G (4) using Tapatalk

Offline richidoo

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Re: BMS 4594nd coaxial's
« Reply #6 on: January 17, 2017, 08:27:50 AM »
From distributor website:

"Crossover

A passive (6.5khz) crossover is available for the coaxial drivers. Note the screws for mounting directly to holes on the back of the 4590. Crossovers are $25ea and work with the coaxial versions of the 4590 4594, 4595 & 4592."

and

"Contact us to order, demo, or for more information.
assistanceaudio@earthlink.net
801.486.2655 office
801.898.6023 mobile"

Why don't you just call them? There is no e-commerce function on their website, so all customers have to call to place an order anyway.

$25 to buy the BMS-made crossover will be cheaper than experimenting and guessing and trusting internet sources.