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Multi-Way Conventional loudspeakers with crossovers

Advice on building a MTM 3 way speaker
Advice on building a MTM 3 way speaker
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Old 23rd February 2014, 01:17 PM   #1
sumotan is offline sumotan  Indonesia
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Default Advice on building a MTM 3 way speaker

Hi Guys,

Need advice on crossover design. Years back bought a pair of NHT 1259's & 2 pairs of Vifa p13w-00-008 woofers for a plan diy project. Well like most
of us with work commitments never got around doing it. Now the time has arrive & am looking into building a pair of speakers using these drivers. For tweeter I'm looking at using the Monacor DT300 with waveguide.
Would like to install the NHT in the same enclosure la side firing like the
NHT 3.3. Would appreciate if you guys can advice on crossover frequency,
how to implement crossover design, which type etc. I'm aware that it's not
easy to design a good crossover hence would appreciate all the advice that I can get. Diy a pair of two ways before read the cook book by Vance.
That's all the experience I've got.

Thanks in advance
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Old 23rd February 2014, 02:54 PM   #2
Greebster is offline Greebster  United States
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This would be no harder to implement than a 2way MTM + sub. If using a waveguide keep in mind for proper integration the spacing between MT or TM is 1/4 wavelength at crossover point. The use of a wave guide spaces this out a bit to far in most cases and can be problematic. Use Edge to simulate driver placement on baffle.
The sub section shouldn't be hard, opposing woofers with their magnets bonded together helps to a large degree reduce enclosure vibrations.
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Old 23rd February 2014, 04:38 PM   #3
fpitas is offline fpitas  United States
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Quote:
Originally Posted by Greebster View Post
If using a waveguide keep in mind for proper integration the spacing between MT or TM is 1/4 wavelength at crossover point.
I think you meant 1/2 wavelength. For example, take a "typical" MTM with 6.5" woofers and a dome tweeter, crossed at 1.8kHz. 1/4 wavelength of 1.8kHz is about 2". Obviously, that center-center spacing is highly unlikely.
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Old 23rd February 2014, 05:20 PM   #4
Greebster is offline Greebster  United States
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Quote:
Originally Posted by fpitas View Post
I think you meant 1/2 wavelength. For example, take a "typical" MTM with 6.5" woofers and a dome tweeter, crossed at 1.8kHz. 1/4 wavelength of 1.8kHz is about 2". Obviously, that center-center spacing is highly unlikely.
That is the problem, To get the spacing required is normally done at lower frequencies. As crossover frequency increases this distance becomes impossibly small thus increasing issue with frequency. Spacing distance is correct for proper phase coherency at the crossover point. If unachievable compromise ensues (don't you just love it) and distance is increased to 1 wave length, creating yet another (lobing) issue but less than if at an odd distance. Model with Edge and see for yourself
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Old 23rd February 2014, 05:33 PM   #5
Greebster is offline Greebster  United States
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Quote:
Originally Posted by fpitas View Post
I think you meant 1/2 wavelength. For example, take a "typical" MTM with 6.5" woofers and a dome tweeter, crossed at 1.8kHz. 1/4 wavelength of 1.8kHz is about 2". Obviously, that center-center spacing is highly unlikely.
Typical MT or MTM 6.5" + tweeter is around 2.2kHz and is based on the midbass drivers power response. In a typical system this would be determined by the -6dB @ 60 off axis frequency when measured on baffle as the upper frequency range/breakup region and filter network type and slope plays into this decision also.
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Old 23rd February 2014, 05:42 PM   #6
tinitus is offline tinitus  Europe
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Quote:
Originally Posted by Jaffrie View Post
I'm aware that it's not
easy to design a good crossover hence would appreciate all the advice that I can get. Diy a pair of two ways before read the cook book by Vance.
That's all the experience I've got.

Thanks in advance
close to impossible

imo ... maybe you will have a chance with a simpler MMT 2.5way with active sub
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Old 23rd February 2014, 11:08 PM   #7
Moondog55 is offline Moondog55  Australia
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Active will be cheaper in the long run and most probably better too.
I'd be using a classic Vifa tweeter with the P-13s something like the D27TG 45-06 silk dome at the cheaper end or clone the ME2s by Lynn Olsen at the top end
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Old 24th February 2014, 02:08 AM   #8
sumotan is offline sumotan  Indonesia
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Hi guys,

Thanks for the advice.
Going active would mean tri amp or ???????
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Old 24th February 2014, 03:36 AM   #9
Moondog55 is offline Moondog55  Australia
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Bi-amp is cheaper and there are lots of ways to do it.I am only familiar with using a pre-amp and the analogue Behringer unit but when crossing low I can't hear any problems with it. Use a passive OX on the mid/ tweeter even good components won't cost the earth there
So pre-amp plus 2 power amps plus XO unit, but save money and use S/H stuff to start with
What is your current amp set-up?
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Old 24th February 2014, 07:15 AM   #10
tinitus is offline tinitus  Europe
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MTM should be crossed lowish, and steep (4th order/24db)
and for that fully active would be a good choice

but be aware that you might still be struggling with wrong slopes and resulting peaks and dips
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