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A few comments:

I'd pick a different mid -- the RS180 doesn't go high enough imo. I'd pick something that had a published range extending on the high end to 3000hz or 3500hz at least. That should give you some good overlap with the tweeter. I'd look for something in the 5-5" range. The RS150 already mentioned seems to be where I'd look.

The amps you've listed are a great price/performance model. If you can find something that's less expensive that puts out ~35-50watts, you could do that. Obviously, the tweets don't need the same power that a woofer does.

I'd probably stick with 2 woofers -- it does seem like it would make the speaker prohibitively big. What you could do to get the same dynamics you're looking for is to go with a bigger more efficient woofer. For example, if you went with just one of these, you would probably get a better response than with two of the Dayton woofers you're looking for. It would be a little more expensive, but I think you'd like the results better.

The active crossover you've picked is exactly the one that I will use whenever I finally build my all out acive 3 way system.

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I know that for the tweeters (and also for the midrange) I don't need all the power from one A500, but I thought that would be better to use only one amplifier model. But maybe a could use a diferent one that matches the drivers specifications better. Do you have some sugestions? Please, only amplifiers with passive cooling.
I've got nothing off the top of my head -- mostly, just making a point about not needing the same power as you may need for the woofers. You probably won't be able to find anything cheaper unless you find something used -- which might not be a bad idea if you're on a budget. I was able to get a Rotel 75watt stereo amp for ~$150US that I'd argue is going to be better than A500.

Now the driver that JCD recommended. In fact I don't know that driver. But as I'm living in Portugal bying from USA means that I must pay customs. For my TC2000 I had payed nearly as much for customs as I did for TC Sounds Inc. The Dayton drivers I'm buying from bmm-electronics.com
Ahh, that does make a slight difference. I'm not sure what's available in the EU. What online stores are there that are based in the EU?

Also, using a 12" driver means that the enclouser front baffle must be very large, WAF comes into play again.
It still might be better than 2 10" drivers.. it would just depend on the TS parameters of the specific drivers. I'd still keep it in mind when you're looking at alternatives for the low end.

Good luck, and let us know what you've come up with or are thinking about.

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Disadvantages of biamping.

1). Requires a complex electronic crossover that has to be designed to the drivers just like a passive one. So advantages of biamping are only truly realized with a design done from the ground up with active crossovers.

2). One amplifier with twice the power versus two amps of half the power biamped is less likely to clip. The reason is that program is variable. Say we have one 200 watt amp versus two one hundred watt amps biamped at 400 Hz. If the program calls for 150 watts below 400 Hz, then the HF amp sits idly by while the LF amp clips. The 200 watt amp might well not have clipped.

3). If different amps are used there is great opportunity to introduce serious phase problems at crossover, unless the amps phase responses are known and corrected.

4). Generally costs will be increased as well as complexity.

I will not claim to be an expert regardless of whatever "mod" status I may have, but I have some followup questions/comments

  1. Isn't this satisfied by buying a commercial product like the Behringer unit Zeverin mentioned? I would agree that building from scratch would be a LOT more difficult, but something like the Behringer with it's variable crossover point takes most of the complexity out of the equation.
  2. I have some potential problems with that one as well. My understanding is that you gain ~3dB's by going active. If you go from a 100 watt amp to a 50 watt amp, you loose ~3dB's. That's pretty much a wash. And if we're talking about a tweeter, you're still going to never use 50 watts unless you want ear-damaging loudness.
  3. The potential phase issue can be "fixed" by physically moving either driver forward or backwards a little. Also, the Behringer unit has the ability to adjust the phase of the drivers independently, so you should be able to get the drivers in phase with a little bit of testing -- , you can maybe even get the drivers not just in phase, but perfectly time-aligned. With a passive crossover, you're much more limited in adjusting the phase of the drivers. Granted, whatever phase issues that come from the amp are negated, but there are still going to be some phase issues that you will have less ability to deal with at the electronic level.
  4. I do agree -- it will cost more to go active. However, as you can see from the above comments, I think it simplifies the process, assuming you buy a unit like the Behringer DCX2496.

Again, just my semi-informed opinion.

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This is getting interesting.
I want to think the sugestions already made.

lsiberian in fact I have readed those informations about bi-amping. But sometimes I miss some points.

I'm just going to discuss the disavantages.
1- If I go the bi-amp way, I would save money from one amplifier (aprox. 200 €). Great. But, I will need to spend on the passive crossovers. Maybe 80 € for both. That saves me 120 €. Also I will be loosing 2 outputs on the DCX, right?
I agree that 120€ is a considerable amount of money, with that I can almost build the rear speakers for a 5.1 system. But also look at this, I'm young, and certanly I will want to do more teaking and some upgrades in the future, going tri-amp (or 3 way fully active) I'm not going to loose the money spent on the passive crossovers. But I'm still considering any reasonable option.
That is actually something I hadn't really thought about, but adds to my pro active approach. And depending on the parts you get, and how complicated the crossover scheme is, 80€ for the crossover parts may be on the low side.

2 - I completly agree that "one amplifier with twice the power versus two amps of half the power biamped is less likely to clip"
I posed this question to someone I know that has the technical backround to address this point -- his contention is that a 200 watt with a full range signal is more likely to clip than two 100 watt amps with an active crossover between them. There is a thread someplace on the web that this arguement has been addressed -- if I can find it, I'll post a link. I think lsiberian addresses the issues in most real world examples by actively crossing the <250hz signals, but I really don't think this is going to be an issue if you've got ~50 watts for the tweet and ~80 watts for the mid. , the tweet probably can't even handle a sustained 50watts.. but I digress.

JCD by your comments I assume that you encourage the 3 way full acive, right?
Absolutely. There are dozens more advantages to active systems that we haven't fully discussed, such as the ability to perfectly time align the drivers using a well designed crossover, the ability to accomplish perfect phase and impulse response without much effort and without the terrible side effects of passive components attempting to pull it off, improved power response, elimination of microphonics, the ability to create the absolute most ideal filter with virtually no tolerance, the elimation of shift in tolerance related to input voltages. the elimination of back-current artifacts in the crossover, increase in realized damping factor, and many more. (note, this paragraph is shamelessly copied from another thread on another forum)

This doesn't even take into account the ability to subsequently tweak the system using different types of crossovers (e.g., Bessel or LR or Butterworth) or different orders (6dB, 12dB, 18dB, 24dB, etc).

I don't want to completely oversell an active system -- it will still take time, skill, testing, etc to create a good system, but I do think it's simpler to do and offers a lot of tangible benefits over a passive system. And I will put my money where my mouth is -- when I finally build my "all out system", I'm going fully active in a 3 way system and I'm going to use that same crossover you've picked.

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1. Not sure how you are getting that a passive crossover is going to cost you 80 euros. Most can be assembled for far less.

2.You can still manipulate the entire sound of your system with the DCX. You'd be giving yourself the ability to hook up your subs to the DCX. Meaning you could have a 4-way setup with the subs fully eqed.

3. Fully active is just as time consuming as making a 2-way upper module filter. I"m not talking about passive between your bottom driver and the top. Only between the tweeter and the midrange.

4. Don't forget that XLR cables aren't cheap either.

Ultimately the choice is yours.

But I would encourage to at least give the passive crossover a go. If anything it will be a valuable learning experience.

If this is your first project I still suggest you start with a simple 2-way build before you undertake this beast. I don't think stepping into this as your first project is wise. There is a lot to learn that you will want to get before you build your longtime main speakers.

Either way make sure you treat your cabinets with fiber or rockwool and that you brace the out of them.

1. Totally agree.. but I think you can also argue it could be a lot more depending on quality/expense of the various parts. I've designed a passive crossover that had a three inductors, 4 caps and a couple of resistors. The part cost for that ran ~$55/speaker or $110 for a pair. Granted this crossover did have a notch filter and a zobel network in addition to the 2nd order LR crossover, but I wasn't going crazy with my cap selection
3. My opinion is a little different. It's not a ton faster, but some. Not having to deal with how the impedance curve of the different drivers might effect the crossover I think is a time saver. Also, if you want to try a different crossover point, you don't have to redesign, reassemble, etc the passive crossover.

I think lsiberian makes some good arguments, and I certainly don't want you to ignore his advice/suggestions or think that I'm trying to portray him in any way negative -- these kind of point/counterpoint arguments can come across that way online.

And I do agree with lsiberian on his other points:
  • designing a passive crossover is a great experience and you will learn a lot. I've done one now and enjoyed the process a lot. If you're going to continue this hobby going forward, then this is an invaluable exercises.
  • if this is your first project, I think building a simple 2-way would be a great idea
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