Andy Graddon said:
That's how we form our own preference/opinion ... from our limited experience. You had such experience, and other people say they had different experience.
This fact, in this case, tells me that your not-so-good experience with dome midranges may not be merely due to the crossover point, but due to other factors you may not have been aware of.
Anyway, as you said it's my turn to form my own opinion and have fun!
Sticking to the original topic about making a 3 way with 1st order XO.
It seems that it's impossible to make a 3way speaker with real 6db/ octve response with phase and time coherence. Due to the response behavior of the drivers outside the passband, when combined with the XO. Unless you are Thiel audio , vandersteen and etc.
What About make it a 5 way in a sloping or stepped baffle then, T,HM, LM,MB,W. Consisting of 1" dome , 2 or 3" dome for high mid , 4" cone mid, 8" midbass and a 12 or 2x10" woofer. Without regards to whether the XO freq is at the critical midrange or not, And considering that the drivers will be operating in a narrow bandwidth, That the acoustical slopes could become real 6db per octave. It seems that it is easier for a DIYer to make a real 6db/octave acoustical speaker system, Doing a 5way rather than a 3way.
.... Or is it?
It seems that it's impossible to make a 3way speaker with real 6db/ octve response with phase and time coherence. Due to the response behavior of the drivers outside the passband, when combined with the XO. Unless you are Thiel audio , vandersteen and etc.
What About make it a 5 way in a sloping or stepped baffle then, T,HM, LM,MB,W. Consisting of 1" dome , 2 or 3" dome for high mid , 4" cone mid, 8" midbass and a 12 or 2x10" woofer. Without regards to whether the XO freq is at the critical midrange or not, And considering that the drivers will be operating in a narrow bandwidth, That the acoustical slopes could become real 6db per octave. It seems that it is easier for a DIYer to make a real 6db/octave acoustical speaker system, Doing a 5way rather than a 3way.
.... Or is it?
Each new driver adds cost due to the driver and the crossover.
Certainly a 1st order 5-way would cost more to build than a 1st order 2-way. And you'd need to find 5 drivers whose response pairs well.
Why not a wide band 5 1/2" mid-woof, 4" full range, and low Fs tweeter in a 3-way if you wanted to do that?
Is the main idea with 1st order electrical filters that are looking for a 2nd order result?
Or, what about using a full range 4" driver like Fostex, Lowther, or Tang Band with a tweeter and woofer at their extremes.
Or another idea... use a high efficiency 12" Pro style woofer and 500hz+ horn ???
Does a 1st order electrical crossover call attention to the crossover point? Or does the wider range of blending blur it?
Certainly a 1st order 5-way would cost more to build than a 1st order 2-way. And you'd need to find 5 drivers whose response pairs well.
Why not a wide band 5 1/2" mid-woof, 4" full range, and low Fs tweeter in a 3-way if you wanted to do that?
Is the main idea with 1st order electrical filters that are looking for a 2nd order result?
Or, what about using a full range 4" driver like Fostex, Lowther, or Tang Band with a tweeter and woofer at their extremes.
Or another idea... use a high efficiency 12" Pro style woofer and 500hz+ horn ???
Does a 1st order electrical crossover call attention to the crossover point? Or does the wider range of blending blur it?
"Each new driver adds cost due to the driver and the crossover."
I should have added "regardless of cost", becaus I think It seems money is easier to find than designing a real 6db acoustic rollloff 3 way speaker system.
"Is the main idea with 1st order electrical filters that are looking for a 2nd order result?"
Usually, Yes, But the goal of the design is to produce real 6db/octve rolloff, To produce time and phase coherence in the listening position.
Otherwise, if the acoustical rolloff is 12db/octave, The speaker wont produce a time and phase coherent sound waves.
I should have added "regardless of cost", becaus I think It seems money is easier to find than designing a real 6db acoustic rollloff 3 way speaker system.
"Is the main idea with 1st order electrical filters that are looking for a 2nd order result?"
Usually, Yes, But the goal of the design is to produce real 6db/octve rolloff, To produce time and phase coherence in the listening position.
Otherwise, if the acoustical rolloff is 12db/octave, The speaker wont produce a time and phase coherent sound waves.
Daveis said:
1. I have done a 4-way 1st order electrical, but it was more becasue I was using old drivers and the old 1.5" Kef plastic dome really didn't do the top end at all well , so I added a cheapish ribbon at around 9k. One day I may even finish the cabinet !
http://members.optusnet.com.au/~gradds55/ARGOS/manhattan.html
3. Not necessarly. I would generally be looking to combine the drivers with minimal cross-over components, so that aural tweaking is easier. It just so happens that because of driver choices, I generally will end up with something like 2nd order roll-offs. ie the roll-off is a side effect.
4. This what the "single driver" guys do !! ;-))
And because they have no idea what a real x-o is, they let the mid run full range, use a single cap on the tweeter, and use an active powered sub for the bass.
5. You mean a PA speaker ;-))
6. With a 1st order series x-o it is very difficult to pick where one driver stops and the other starts. This is one reason I prefer low order x-os. I like the "togetherness" of the drivers.
One point I should make about crossing to a 2" dome was that I thought I could audibly hear a vertical position change when the vocal register changed from the high to low (or vici).
I think if one does use a 2" dome, the bass driver should be kept as close as possible. using a 800Hz x-o point also may mean that using say a 10" or 12" bass may become an issue due to directionality. (beaming)
marchel said:
Define acceptable phase and time coherence?
Given a woofer has rolloff down low as well as a tweeter rolling off up high you will never get perfectly flat phase response no mater how well the crossover is implemented.
Using 1st order acoustic crossovers you can get low phase rotation between say 200Hz to 10kHz to +- 15 degrees phase. That will give you a system that will have good step and impuse response. I have observed that a driver has to have enough bandwidth to maintain a BW1 slope after Fc for at least 1 1/2 to 2 octaves. Less may be acceptable but I havn't tried. Obviously this is very difficult with a 2-way.
Vanderstien can acomplish this with with fairly inexpensive Vifa drivers on some of their models so it's not rocket science.
http://tkhifi.homepage.dk/duelund-filter.pdf
Can someone summarize the above?
Is this talking about steep filters with filler mid drivers?
Can someone summarize the above?
Is this talking about steep filters with filler mid drivers?
Not sure anyone mention this. Another good read will be pi speaker crossover document. Inside he show how he came to use the pseudo first-order filter for JBL 15" 2226 woofer and third order for horn tweeter.
http://www.pispeakers.com/contents.html
Have fun
http://www.pispeakers.com/contents.html
Have fun
Its a simulated phase coherent filter with ideal non existent drivers
With all those components you would expect a steep filter, but its obviously not, looking at the slopes, they are quite shallow...its origin is most likely a filler driver design
Components are only there to maintain a specific controlled behaviour outside the passband
Take a look at the components, how "far apart" they are, ranging from very big to very small at the same slope
In real life, dealing with realistic drivers, many of the components probably wont be there, values will be totally different, and additional components, not shown in schematic, might be needed...such as notch filters, attenuation and ressonanse control curcuits
To obtain those slopes in real life wont be easy, but it might be worth a try
With all those components you would expect a steep filter, but its obviously not, looking at the slopes, they are quite shallow...its origin is most likely a filler driver design
Components are only there to maintain a specific controlled behaviour outside the passband
Take a look at the components, how "far apart" they are, ranging from very big to very small at the same slope
In real life, dealing with realistic drivers, many of the components probably wont be there, values will be totally different, and additional components, not shown in schematic, might be needed...such as notch filters, attenuation and ressonanse control curcuits
To obtain those slopes in real life wont be easy, but it might be worth a try
It seems to me unless the drivers are coincident they can only be perfectly in phase and "in time" at one given direction. All other directions, toward teh walls, ceiling, etc, are no different than any other competently designed conventional speaker. Unless you maintain very tight directivity this seems to render the charm of the first order, time perfect design kind of useless.
There are many more important factors that effect sound quality that should be considered. People think this time perfect stuff is the holy grail that will finally allow them to achieve audio nirvana. It's not.
There are many more important factors that effect sound quality that should be considered. People think this time perfect stuff is the holy grail that will finally allow them to achieve audio nirvana. It's not.
tinitus said:Its a simulated phase coherent filter with ideal non existent drivers
With all those components you would expect a steep filter, but its obviously not, looking at the slopes, they are quite shallow...its origin is most likely a filler driver design
It's hard to tell with the shallow knee in the rolloff but it looks like 2nd and 3rd order to me.
Daveis said:
Duelund 3-way is a theoretical generalization of LR type all-pass 2-way crossover to 3-way. People usually use LR, BW, Bessel, etc to define/describe a 3-way crossover simply by combining two individual 2-way xovers. But in fact, more precisely, these types of theoretical crossovers were derived under the assumption that there's no cause of phase shift near the xover point other than the intended rolloffs. So, they are, strictly speaking, only 2-way crossovers, not 3-way.
But in a real 3-way, a 2-way xover occurs near another 2-way xover, resulting in a phase error in band pass acoustic rolloffs. For this reason, if you implement one of the above 2-way xovers in a 3-way, especially when two Fc's are close to each other, the summed response distorts from the intended one. The severity of this distortion depends on how close the Fc's are and how steep the filter's acoustic rolloffs are. The farther the Fc's are and the steeper the rolloffs are, the less severe the distortion is.
This is why LR4, which is quite steep, works almost always as intended in a 3-way. But when LR2 is used with relatively close Fc's in a 3-way, pure LR2 curves do not provide flat summation due to phase errors.
But the Duelund 3-way provides the properties of LR-type xover no matter how close the two Fc's are. That is,
1) All three drivers are in phase (not only woofer-mid and mid-tweet but also woofer-tweet)
2) Flat summation
3) 360 degree total phase wrap just like LR4 2-way
4) When Fc's are getting closer and closer, the 3-way is reduced to simply a LR4 2-way as the need for a midrange is gone.
5) When Fc's are sufficiently far apart, the 3-way becomes more like a simple combination of two LR2 2-ways (Thus, what we call LR2 3-way is kind of approximation to this).
In this sense, it's a sort of generalization of LR type 2-way to 3-way.
It's not easy to expain all the detail here. Read the article yourself to get a better idea.
augerpro said:
Hey Auger
There are many important factors to consider just to pull off a transient perfect 1st order 3-way. It's hardly what I would call a good beginers project. Is it the holy grail? I don't think so but it is possible to make a perfectly good sounding speaker. So many styles...so little time.
There are a number of well regarded high end manufacturers that have made a good living over the years selling just this type of speaker.
I wont tire you by telling that I have the most perfect 3way speakers trimmed 100% by ear and that my friends think they are truly fantastic...its just beginning to get a bit boring
So what can a man do
I have some drivers collecting dust
15" woofers with heavily modified cone, and a pair of FR125...so I only need a couple of BohlenderGraebender OB "ribbons"
They should do a nice 3way OB...I may even have wood fore the baffles...from an old wardrobe
So what can a man do
I have some drivers collecting dust
15" woofers with heavily modified cone, and a pair of FR125...so I only need a couple of BohlenderGraebender OB "ribbons"
They should do a nice 3way OB...I may even have wood fore the baffles...from an old wardrobe
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