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Multi-Way Conventional loudspeakers with crossovers

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Old 25th October 2007, 03:15 PM   #11
tinitus is offline tinitus  Europe
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A simple 2way series xo may work ok ... I have never tried it ... but a simple 3way wont ever work just like that

You need paralel filter ... but it dont stop by just converting to paralel

Xo needs adjustment

Woofer really needs to be 2.order ... ad a paralel cap

Tweeter needs a paralel inductor ... attenuation may need adjustment

Midrange needs an RC ... and inverted polarity

With this you will achieve a 2.order acoustic rolloff ... with some luck ... but at least you may learn something

A hybrid may be possible ... but I dont know how
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Old 25th October 2007, 10:26 PM   #12
Andy G is offline Andy G  Australia
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sorry, but there is no way the 3-way linked will work effectively with the P13WH and XT25 tweeter.
Can you swap out the tweeter for a Seas or something, and lower the x-o points to say 250 and 2500, you may just have a chance then, although your woofer also seems to be of margina usefullness.
This type of crossover can work, but ONLY with the right driver choices, and a woofer with big breakup is always going to be problematic with a low order crossover.
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Old 25th October 2007, 10:56 PM   #13
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Without measurement and simulation, you are really shooting in the dark.

If there is no measurement, at least simulation can help. I would use a number of FRD tools. First to create the FRD and ZMA files from manufacturer's datasheets. Then use BSD to simulate the baffle. Then plot them with SpeakerWorkshop. Then design your XO... You can get very good result.
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Old 25th October 2007, 11:07 PM   #14
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I'm not trying to stir this can of worms, but series and parallel crossovers can indeed both be satisfactory. The big however, and it is big, is that series is much much more difficult to design, not least because the values are inter-dependent.

So definitely you should start with parallel; that way a value change experimentally will affect only one driver.

It would help a lot if you had minimal test equipment, a meter and an oscillator.

I would suggest paying close attention to some of the other replies, including Pete McK. Some real nuggets there.

I'd add to that advice; use a zobel on the woofer, a conjugate and a zobel on the mid, and a conjugate on the tweeter. These will provide for a much more constant driver impedance, so that the effects of the crossover components will be more predictable.

I'd also say that you should go for the trap on the woofer. One way to tell if it is effective is to just listen to the woofer with full range music, preferably classical with massed violins with the other drivers disconnected. (Another advantage of parallel design.) You should hear harshness without the trap, and an effective trap would kill the harshness.
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Old 25th October 2007, 11:08 PM   #15
Andy G is offline Andy G  Australia
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Quote:
Originally posted by HiFiNutNut
Without measurement and simulation, you are really shooting in the dark.
You are welcome to visit anytime, hear what working blind can do, given time and patience. I'm just up in Newcastle.
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Old 26th October 2007, 04:15 AM   #16
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Andy,

I am happy to take your offer. Given your enormous contributions to the DIY community and posted such vast information about speaker building especially about series crossovers in your website, my hat is off to you. I read all the information you have on your website a couple of years ago and actually tried a series XO before. I am very curious about your results. I went to Newcastle twice in the past two months for my new speaker cabinets and missed the chance. But when I get less busy (doing house renovation at the moment) I will be happy to drive up there to visit you. I will have my NaO speakers in new cabinets very soon and will have my new MTMWWSubSub OB speakers (cabinets received this Monday) designed and built in the next a few months and you will be more than welcome to be my guest in Sydney. I live in a northwestern suburb and is only 1.5 hour away from Newcastle.

Regards,
Bill
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Old 26th October 2007, 09:03 AM   #17
Andy G is offline Andy G  Australia
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Quote:
Originally posted by Curmudgeon

So definitely you should start with parallel; that way a value change experimentally will affect only one driver.
or work with 2-way series for several speaker designs first., before attempting a 3-way linked

And for the 3-way linked you have to be VERY finicky about driver choice.
mid and tweeter about the same spl rating, woofer extra 3-4dB to allow for bsc, or you will be padding the ... out of the mid and tweeter !

ALL drivers need to be very well behaved for some distance either side of the operation band. etc etc etc
You are combining, NOT controlling the drivers.

Just my thoughts, be they wrong or right, only the ears can be the final judgement
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Old 26th October 2007, 09:14 AM   #18
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Ok just for starters & fun I'll try Pete's suggestion.
PARALLEL Xover
*************

Tweeter 12dB 7.4uF with 0.33mH , with 1ohm/8ohm pad.

Mid 0.4mH and 68uF (re-use components)


Bass 12dB 4mH and somevalue C on ???.
(May need to add notch later)

( I'm not sure how to re-calculate the C value so that I can re-use the 4mH inductor ???? )


and my other question is :
Do I need to reverse the polarity on the tweeter only or both tweeter and mid ?
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Old 26th October 2007, 10:45 PM   #19
tinitus is offline tinitus  Europe
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Impossible to give exact values without measurements

Use your 6.8uf on tweeter

Woofer paralel C ... anything from 47uf to 100uf

I normally invert polarity on midrange driver

There are other things that can be done, but you better get this working first
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Old 7th November 2007, 09:27 AM   #20
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Thanks for the help gents.
Sounding a lot better now.

Went for 6.8uF / 0.33mH on Tweeter plus pad. Rev Polarity.
0.42mH / 66.8uF on Mid.
4mH / 70uF on bass.




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