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In Reply to: RE: Emotiva 3 Channel Amp posted by hahax@verizon.net on November 02, 2014 at 20:42:10
Seems like you're making a three way speaker the hard way. I really don't want to be the one to tell you this, but the mechanics of getting a three way speaker to work and sound right are VERYYYYY difficult. Even seasoned DIYers get it wrong most of the time. Either look for a good three way speaker or Kit. Just trying to save you from wasted (expensive) efforts.
If you go that route then you are going to need a crossover network for that already inefficient woofer. To get it right you will end up squishing the life out of that woofer. And having to over drive your amp to have the mids and tweeters to keep up.
Just been there. Either make a good traditional three way. Or just go with a good subwoofer and monitor setup.
Follow Ups:
By far the most difficult part to design of a 3way is the crossover. An active line-level crossover simplifies this dramatically. In fact if done actively a 3way is in some ways easier to get right than a 2way.
You can't get to 32 Hz with a 2 way. And a good 3 way makes cleaner upper bass and lower mid range. Plus I don't trust subs. Most are meant to add bass so they're not as well damped as I prefer. A Q of 0.707 is the starting point as far as I'm concerned and a lower Q is better. Plus I have friends who have designed successful speakers to help. The SEAS Froy 3 is a best friend's design among many others. And I am intruiged by the idea of a powered speaker. Not having to drive a crossover is obviously a good thing.
The UK was big on powered speakers at one time. They seemed to really like them.
charles
All things being equal(they never are)powered is better than passive. It's better to just be driving a voice coil rather than a coil and complex crossover components. But a good passive will be better than a so so active.
you can't get to 32 Hz with a 2 way
that statement, but I agree a two way must necessarily compromise something. :) In the case of the Advent, I find top end response got the short end of the stick.
As a coherency fanatic, I'm with AT on the mini monitor plus subs (yes plural) approach. With my HT, I use two and a half way Polks with dual 5" woofers that blend very well with the tweeter. Powered subs offload the heavy lifting below 50 hz and provide independence of placement. The ideal location for the mains is not always ideal for bass which provides more control over room modes. Any potential clipping on low end heavy content never affects the upper eight+ octaves since they are bi-amped.
I will amend the 32 Hz statement to mean with almost all today's 2 ways with at most 6 1/2" drivers. I don't know any that size that go down that far. The Advents were bigger drivers in bigger boxes. But I suspect their in box resonance was still only about 40 Hz which means they are more than 3 DB down at 32 Hz. The woofer I'm looking at has an in box resonance and 3 DB down point of 32 Hz in 1 1/4 cubic feet.
Being an old fart raised on honking sized three way speakers blasting Led Zepplin, I held out changing my speakers for - lets just say a decade or two. I eventually had to switch over to a sub/monitor setup because basically, three ways were too big and bulking. And in truth, the technology of speakers really has passed them by.
I did try it a number of times to setup a subwoofer speaker setup. And failed over and over again. Sounded like crap!
However I was making the same classical mistake ALL us, lets just say "vintage" ears make. I tried making my subwoofer the "woofer"of a three way speaker. Ahhhh, it isn't engineered that way!
Stop trying to use your sub as a WOOFER. Use it as a SUBWOOFER.
Long LONG story short. I ended up with a pair of Zaph Audio SR71 speakers that go cleanly down to around 50Hz. All the subwoofer does is fill in below 50hz and gently bolster up the bottom end. NO MORE NO LESS. A subwoofer should almost not be heard or noticed in a system. But it should be noticed if it's off or on.
Your problem is learning HOW to setup a sub. Try posting over in the speaker forum and learn how to "tune" your subwoofer properly.
Also some tips I've learned over the years.
Get a good plate amp, like a Kreager from Madisound. You don't need a big ass sub box.
Stop trying to get your monitors to go down to 30Hz - they NEVER will. That's what the sub is for.
If you want email me.
charles
Your way works but it can be done with a higher crossover if it's custom designed for it using a computer with good soft ware. I've seen it done. My own system crosses an 18 " woofer passively at 85 HZ and works beautifully. But I'd like to down size so I can move the boxes by my self.
4th order xovers are exactly what I mean by squishing the life out of a speaker.
And once you start mixing crossover orders - now you get into phase shifting, and I don't mean that really cool Star Trek stuff. Slope and impedance matchings that even a seasoned DIYer would have trouble with.
Those xover calculator programs are just basic formula programs. Not an answer to how to really do it. And you will need some testing equipment to boot.
Here is a link to how it's done.
GO with a nice monitor and sub.
charles
Done correctly a 4th order Linkwitz/Reilly crossover is quite dynamic and does not take the life out of a speaker even if used foe a sub woofer. A 4th order LR xover is probably not electrically 4th order. You want it to be acoustically 4th order and that is often only 3rd order or even 2nd order electrically.
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