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audio4him 27th April 2013 02:06 AM

didn't get it right
 
1 Attachment(s)
We have an old Focal 6.5 6V3211B at 8 ohms to match with a Vifa XT19TD00-04 at 4 ohms (but both are an 89 SPL.) Anyone here able to design the crossover and what would the cost be to build the pair?
Vifa XT19TD00-04 3/4" Dual Radiator Tweeter

The Vifa XT19TD00-04 features a patented dual concentric diaphragm and a unique waveguide center plug that provide an excellent on-and off-axis response. This tweeter is acclaimed for its very natural sound with an extremely smooth frequency response extending well beyond the human hearing range. The dual chamber design and absence of ferrofluid results in a low resonance frequency.
Specifications: Power handling: 90 watts RMS/140 watts max VCdia: 3/4" Impedance: 4 ohms Re: 2.9 ohms Frequency response: 1,500-40,000 Hz Fs: 681.9 Hz SPL: 89 dB 2.83V/1m Dimensions: Overall diameter: 3.70", Cutout diameter: 2.70", Depth: 1.08".
and the Focal..Attachment 345079
Thanks in advance

picowallspeaker 27th April 2013 03:19 AM

Hi, pick any assembled crossover for car audio - They're for 4Ω speakers
You'll have to increase the inductance for the woofer, thou...

Edit: I don't know that tweeter, but reading 'No ferrofluid' means that a minimum
power conservative cut above 2 KHz with a 2nd order slope should be chosen

balerit 27th April 2013 05:19 AM

You cannot mix 4 ohm with 8 ohm speakers.

pkitt 27th April 2013 11:16 PM

Really????
 
Don't know where you've been living for the last several decades but you certainly can use drivers with different impedances as the crossover design takes that completely into account.
Paul

Quote:

Originally Posted by balerit (Post 3469865)
You cannot mix 4 ohm with 8 ohm speakers.


audio4him 28th April 2013 05:43 AM

thanks pkitt; maybe he is thinking of something else in South Africa or doesn't realize his mistake, oh well....

I'll post a pic of the Vifa part of the crossover tomorrow, but the Focal I'm having trouble with as I try to match these up....thinking Bessel

system7 28th April 2013 08:43 AM

1 Attachment(s)
Quote:

Originally Posted by audio4him (Post 3470857)
....thinking Bessel

I'm thinking butterworth, as below but I've really no idea what the levels will be. 15 litre closed box for sure though and you'll need to deal with fibreglass cone breakup....:D

Troels has done a few designs for the similar XT25 tweeter.
Peerless projects

He puts a resistor in series and uses third order to protect the undamped tweeter Fs. :cool:

pkitt 28th April 2013 01:24 PM

I forgot to mention that I've used the XT19 in two designs and it's a great tweeter, performing above its pay grade, actually.
Paul

Quote:

Originally Posted by audio4him (Post 3470857)
thanks pkitt; maybe he is thinking of something else in South Africa or doesn't realize his mistake, oh well....

I'll post a pic of the Vifa part of the crossover tomorrow, but the Focal I'm having trouble with as I try to match these up....thinking Bessel


balerit 28th April 2013 08:47 PM

Quote:

Originally Posted by pkitt (Post 3470709)
Don't know where you've been living for the last several decades but you certainly can use drivers with different impedances as the crossover design takes that completely into account.
Paul

I have been designing crossovers and writing books on the subject for 20 years, show me one source that says you can.

pkitt 28th April 2013 09:13 PM

Every single speaker manufacturer has successfully designed and produced speaker systems for years that use drivers having different impedances. In fact, its almost impossible not to do so, especially when paralleling drivers, like for the midwoofers in an MTM or when using a pair of woofers in a 3-way. Also, many, many tweeters are inherently 6-ohm drivers, while midranges and woofers are either 4-ohm or 8-ohm, or somewhere in between. Really, you're either fooling yourself if you believe what you're saying, or you must think the rest of the world is very gullible to give any credence to what you say, no matter how many years you've been doing that. Or, you're just a troll.
Paul

Quote:

Originally Posted by balerit (Post 3471554)
I have been designing crossovers and writing books on the subject for 20 years, show me one source that says you can.


Shaun 28th April 2013 11:04 PM

Quote:

Originally Posted by balerit (Post 3469865)
You cannot mix 4 ohm with 8 ohm speakers.

What is your reasoning?


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