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Old 24th February 2011, 09:16 PM   #31
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Phasing may play a role, but you missthe point. Generic XOs are made for theoretical drivers that don't exist. A proper XO is made for the specific drivers being used, and take into account their characteristics.

dave
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Old 24th February 2011, 10:34 PM   #32
Variac is offline Variac  United States
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Originally Posted by nulesus View Post
OK, what would you recommend? I chose the 2 tweeters to match the four woofers. Because I had to give it a lot EQ. This sounded more balanced. I already built a cabinet with a single tweeter(different one) and this same woofer.
Well, to give a break to those that know more than me:

If a driver is large in diameter related to the wavelength it is reproducing, the output "Beams" ie it goes straight like a flashlight. So maybe the sound is OK but if you move your head just a little the sound can change radically. And if you are at an angle, say because you are sitting between two loudspeakers pointing ahead, , you are going to lose a lot of output.

That is the main reason that tweeter domes are smaller than woofers or midranges. Not directly because of weight or other considerations which also are relevent.

If you put two drivers close together and the are producing a low enough frequency for their size then they act as one driver, this work fine with many midrange drivers and most woofers, BUT the mounting plates and magnets of tweeters keep you from putting them very close together, (and with the high frequencies that they handle the moving parts have to be RIGHT next to each other. So instead they act like two separate drivers, that can be out of phase and "comb filter" each other in certain locations so certan frequencies will be canceled out...

Assuming that they did work without interfering with each other you have created in effect a tweeter 1" wide and about 6" tall, SO the beaminess in the vertical direction is going to be like a 6" driver trying to reproduce tweeter frequencies. So as long as you don't slouch at all, and your friends are the same height as you, maybe it would be OK, but most of us are human so have big problems with this.


If others disagree with this please correct me..


Perhaps others can recommend some books on designing speakers, or you could find some books available books and we could tell you which are good ones..


Mark

Last edited by Variac; 24th February 2011 at 10:47 PM.
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Old 1st March 2011, 12:09 AM   #33
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Dave I have 2 questions:
1) Unless there is a single speaker, or single wave-form generator in any physical system there will be phasing. Throw one rock in a pool and then another, watch the ripples. Correct?
2) How can anyone actually make a perfect crossover for s particular speaker? The crossover really only has to do with filtering noises (often referred to as music) out of a voltage carrier line. Unless you have an atomic clock monitoring all of the frequencies, and adjusting in real time to every Khz at whatever bit depth the system you designed could handle, there is no way to really ever do anything more than match the quality of the parts to the quality of the speaker. You can wrap gold foil around a brick of carbon nano tunes to create the ultimate filter, but it is still tuned based on the number of turns, and cannot affect the speaker the is in the future, since we are talking atomic clocks and enstein here...

But really - I would like to hear why this is so important to you. Unless you test with electronic gear, or have a listening reference to that which you prefer, the only bad things about off-the-rack crossovers is that they are passive and they use cheap parts.
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Old 1st March 2011, 12:25 AM   #34
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Originally Posted by silverprl1 View Post
the only bad things about off-the-rack crossovers is that they are passive and they use cheap parts.
There is quite a bit more to than that.
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Old 1st March 2011, 03:31 AM   #35
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Quote:
Originally Posted by silverprl1 View Post
Dave I have 2 questions:
1) Unless there is a single speaker, or single wave-form generator in any physical system there will be phasing. Throw one rock in a pool and then another, watch the ripples. Correct?
2) How can anyone actually make a perfect crossover for s particular speaker?
1/ true
2/ you can't, you can only minimize their problems.

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Old 2nd March 2011, 08:47 AM   #36
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Originally Posted by planet10 View Post
1/ true
2/ you can't, you can only minimize their problems.

dave
Dave -

I am sorry to have been so sarcastic. I do note that you like to push the single speaker format, but also that you are quite talented at it, and share your ideas for free, which is amazing. The problem I see in this is that most people cannot get the dB level they are seeking in that world, so my crappy comment earlier really stems from the fact that I wish you would step back back from that model, and apply the knowledge necessary to do what you do with a single speaker, to helping people conquer their multi-speaker goals in a less technical, more "you can do it" way.

You are seeking the perfection you go for in single speaker, in a way that is unachievable with multiple speakers without spending a ton of money.

If you don't see that I am complimenting you - please note that I am. If you could be a bit more open-minded about things like crossovers, speaker selection, budgets and skill level - I know there is a ton I could learn from you. I decided early on after being evangelized to about "the only way" and being witness to sound companies arguing internally about setting at our shows, that I knew one thing about sound - A huge percentage of people know the only way to do things, a couple a few ways, and I chose to be a minority - If you can accomplish great sound doing it your only way, great. Same for the next guy. I might choose to do it another, but I learn each other person only way as they argue their methods. So now I know a lot of ways to get from a-z, while those I mentioned still know one way, their only way. Competence and genius lie all around, the path to Z does not matter to me, as long as Z is achieved on time and on budget.

I like to use the dishwasher and my wife in this example. We each load the dishwasher in different ways. The dishes come out clean regardless of who loads the dishwasher. She has to do it her way - or "the only way," and gets upset if I do it my way and tosses me out of the kitchen. So now, if we are doing it together, I do it her way, and if I do the entire load myself, I do it the way most natural for me. In the end - the dishes are cleaned - and no one has to argue the merits of one method over the other.
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Old 2nd March 2011, 09:57 AM   #37
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No problems.

Given how poor speakers are at doing what they are supposed to do it is totally possible to have 2 loudspeakers that equally valid and sound very different. The important thing is that the system (a loudspeaker & its amp(s) can't be considered separately) connects you emotionally to the music. I have strong opinions based on a lot of experience. It isn't the only way, but it is a good one.

Buying an off the shelf XO is a recipe for distaster. They really need to be one with the drivers (and amp -- some XOs will drive all but the hardiest arc-welders to sound like crap, and those amps give up a lot to do that) used. You can build a better system with weak drivers & a really good crossover, than really good speakers & a crappy crossover (the off-the-shelf XO is a good candidate for that). A favorite phrase i use is that the "crossovers are evil". This is borrowed from Earl Geddes (his systems have 1 passive XO, and 1 active). In a multiway the XO is the single most important part of the speaker. For an example of well-thot out XOs have a look at Joe Rasmussen's latest.

Early on in my 45 years of making loudspeakers i realized that using a wide range mid made a big difference (it gets the XO points pushed out where the ear is not as sensitive). Until 10 years ago that mid (mid/tweeter) was an electrostat. But they are big, expensive, and the amps you need to drive them are not capable of the finese of smaller amps. After spending the last decade into pushing what FRs do, i am now more actively exploring FAST, which adds helper woofers to a good FR as mid/tweeter (or even down into the upper bass) -- improving the mid/top, pushing the XO to where it does the least harm, getting bass in quantity & extension as deep as you are willing to put dollars out to pay for. Realistically this doubles, triples (or more) the cost of the amp/speaker system. I'm still a Frugal-phile (tm) at heart, as well as feel that if you can't get connected to the music listening to just the "midrange" it is not worth pursuing (at least for me).

I have a vested interest in every new diyer making a successful 1st project (no matter how they do it), as that encourages them to go further... as the saying goes, "i bet you can't stop at one cookie". Pointing out bad moves or things that just don't work helps keep them out of the ditch.

As to dishwashers, my wife wants one, but i can't abide them (so i end up washing most of the dishes)

dave
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