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Old 16th January 2004, 08:02 AM   #1
EyalR is offline EyalR  Israel
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Default 2-ways + sub OR 3-ways

Hi all,
I'm going to build an active speaker. I have a 5.5" scan speak revelator (4ohms) mids and thetweeters will be the morel supreme. The room is a small 3X4 meters room.

I was wondering if I should add a sub like the adire audio shiva or parhaps get two 10" or 8" woofers. The woofers will be from morel Israel as well.

Which of the setups do you think would work better and also how much power do you recommend giving each driver (solid state amps).

Thanks
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Old 16th January 2004, 10:52 AM   #2
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I've alway liked stereo subs. It has a big effect on the stereo image. I don't know what the power handling capacity is of the Scan-Speaks, but 100Watts for the mid-bass and up would probably work. For the subs, as much clean power as you can afford and that the speakers can take. Of course, all this depends on how efficient the speakers are, how loud you play your music, and how much power the speakers can handle. As you said, it's a relatively small room.
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Old 16th January 2004, 11:30 AM   #3
EyalR is offline EyalR  Israel
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Thanks for your reply!

Well as I've said it's either one adire audio shiva or two of morel's woffers:
http://www.madisound.com/morel.html

I'll probebly will have to stick with 8" as the 10" requires alot of volume.

I mainly listen to rock music.

Lets say that if I give the tweeters 70W (will probebly lower the gain), the scan's 150W (they can take up to 300W) what wattage would you give to each woofer?

The scan's are about 87DB, and the woofers depends on which one I'll choose, you can see it on the link I gave (can you recommend any of them?)
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Old 16th January 2004, 12:01 PM   #4
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The tweeters, I'm sure you'll have to attenuate a little so 70Watts (odd number, I assume you have something in mind) should be ok. The woofers look to have simular efficiencies so 150Watts should work fine there (more is ok to). Now the

Relevator is a different story. From the Madisound site, the 5.5" relevators are very inefficient. Yet they can't take a lot of power (60Watts according to Madisound). This is the worst of both worlds. On top of that, they're not cheap.

You can run them at their limits and hope they live. I would keep the x-over up in the 100Hz range, but the subs will need to be near the "satellites". This will get some of the power handling back and allow you to use that 150Watt amp. From there you'll just have to be very careful with your volume control.
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Old 16th January 2004, 12:14 PM   #5
EyalR is offline EyalR  Israel
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The Watt ratings on the SS are tested with a sine wave, I know for a fact that people has been giving them 300W with no probelm so yes, they CAN take alot of power.

So with thae fact that the SS can take lots of power, how would you run the whole setup?

Also any perticular woofer looks good?

Thanks!
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Old 16th January 2004, 08:12 PM   #6
sreten is offline sreten  United Kingdom
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Your suggested amplifier ratings are way beyond what is
needed in a small room.
Small and high quality will be much better.

Note that when you go active you are effectively using the
amplifiers in series, That is a 150w bass amp, 75W midrange
and 50w treble amplifier can produce total voltage swings
into the three drivers that would require an 800W amplifier.
(But you can't have this voltage swing through one driver)

[ 150 x (1+1/root2+1/root3)squared ]

IMO 100w+50W+30w is more than adequate.

sreten.
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Old 16th January 2004, 08:19 PM   #7
EyalR is offline EyalR  Israel
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Do you also think that two 8" woofers will be better than one 12" sub?

It'll have to be by morel as I can get them for great prices, anyone from the link I gave looks better than the rest?

Also most of the morel woofers are about 3DB more efficient than the scan speak, do you still think they should be getting twice the power than than the SS?

Thanks
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Old 17th January 2004, 08:26 AM   #8
sreten is offline sreten  United Kingdom
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You are correct that the relative efficiencies of the drivers
needs to be considered when allocating amplifier power.

The tweeter amplifier can be a surprisingly small
class A design with a decent efficiency tweeter.

Depending on your low crossover frequency you should
also note subwoofers are usually excursion limited in the
low bass region, extra amplifier power does nothing.

Also the allocation of power depends on the low crossover
point, the lower it is the less bass and more midrange power
is required.

Also note you need to factor in 6dB of baffle step diffraction
compensation for the Scanspeak, at the low end of its range.
And also note a drivers midrange sensitivity is not its
bass sensistivity, the later is 6dB lower (due to BSD).

Twin subs with careful placement do give better in room bass.

With 8" bass units I'd be tempted to build an active 2.5 way,
with a sealed section for the SS (used without BSDC) and
reflex for the 8" bass, Morel MW267's ?
Possibly seperate cabinets like the Watt/Puppy or Revel's.

sreten.
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Old 17th January 2004, 09:37 AM   #9
amo is offline amo  United States
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If you are building active speakers, and need to calculate the power requriements, you owe it to your self to study Mr. Linkwitz's website at www.linkwitzlab.com (?). He gives formulas for calculating these things, and it was a real eye opener for me. I believe the page you want is on the subwoofer design. If you have questions with some of the formulas, let me know since I have already strugled through them. Shalom.
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Old 18th January 2004, 12:02 AM   #10
EyalR is offline EyalR  Israel
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Thanks for the link

From reading it a little and browsing through this forum I understand that a lot of you prefer open baffle designs.

As I said the drivers I'll be using are:
1. Morel supreme 110 tweeters LINK

2. Scan speak revelator 5.5" LINK

And as for woofers I'm really not sure. It's a small room (about 3X4M) so I don't have room for monster enclousers. I even thaught on maybe using some car woffers which needs less volume.
I want to use morel's woofers as I can get them for a good price. They can be found on this wensite LINK

I would like you guys if you can, to help me plan the best active set using these drivers. Firstly which woffers would you go with and then what enclousers and parhaps recommended xover points and slopes.
As I said this will be an active set and I'll be using the behringer DCX2496 for it.

sreten, I'm not really sure what you mean by a 2.5 way set. I come from the car audio world and this is my first time in building home speakers but I wouldn't mind that it'll be my last (i.e. getting a great result on the first time )

Thanks for any help you can offer
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