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Hi Doug, well, one reason I didn’t build yet is that there are still compromises I wasn’t happy with. A smaller FR for mid-high often means the treble has fewer unwanted peaks; you can see this clearly in the Fostex line where the FF85 is the smoothest. But the smaller drivers also have the lowest sensitivity which means less performance from those low power tube amps that similarly interest me. Consequently, a larger FR might be preferred and after buying the AN 15” my needs have been more or less satisfied, save for the itch of trying new (new to me) things.
I’ve had an interest in trying a Lowther and that will need a woofer, maybe also a tweeter
I’ve had an interest in trying a Lowther and that will need a woofer, maybe also a tweeter
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I just ran across this thread - interesting slow-and-steady posting history.
Anyhow, I'm offering the third option since it hasn't come up yet. Which is, crossover - very thoughtfully - in the center of the critical band, using two fullranges so the response overlap is huge.
I place that at about 800Hz. Keep the diameter ratio below 2:1 so the directivities won't mismatch, keep the drivers as close as possible, first order crossover. Most of you know the drill.
You can usually get a 4" fullrange with decent efficiency and better treble than any 8" and you can get an 8" with better bass than any 4" so it's a step up, without choosing between treble or bass.
Anyhow, I'm offering the third option since it hasn't come up yet. Which is, crossover - very thoughtfully - in the center of the critical band, using two fullranges so the response overlap is huge.
I place that at about 800Hz. Keep the diameter ratio below 2:1 so the directivities won't mismatch, keep the drivers as close as possible, first order crossover. Most of you know the drill.
You can usually get a 4" fullrange with decent efficiency and better treble than any 8" and you can get an 8" with better bass than any 4" so it's a step up, without choosing between treble or bass.
Thats not too far off from what I am planning with the peerless tc6. Basically it will cross to a dayton rs150p around 500hz, first order. Both are very wide band paper drivers. I want to cross when both are close to omni directional which gives the best integration.
Main issue is that the woofer is about 5db more sensitive so it might create too much baffle step.
But particularly in small rooms a small full range with woofer is a good combination.
Im discovering that putting the speaker near the middle of the room and allowing some mid range to leak out creates better ambience.
Hi Doug, well, one reason I didn’t build yet is that there are still compromises I wasn’t happy with. A smaller FR for mid-high often means the treble has fewer unwanted peaks; you can see this clearly in the Fostex line where the FF85 is the smoothest. But the smaller drivers also have the lowest sensitivity which means less performance from those low power tube amps that similarly interest me. Consequently, a larger FR might be preferred and after buying the AN 15” my needs have been more or less satisfied, save for the itch of trying new (new to me) things.
I’ve had an interest in trying a Lowther and that will need a woofer, maybe also a tweeter
Sensitivity is often a problem for small drivers. I was reading up on lowthers a little while ago. Some people say they have certain special qualities and you have to hear them to appreciate. Their paper cone is patented and is lighter and stiffer than others. Maybe you know all this already. Certainly fun to play around with one.
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I am certainly leaning in that direction, not that I need another project of course!
The oft repeated advice with the Lowther + woofer is the approach demonstrated by several people including Nelson Pass (the idea predates his SLOB) - an open baffle up top and some kind of dipole underneath. I may try it one day, but as my 15” is open backed box I don’t want another dipole so some other kind of box is called for.
The oft repeated advice with the Lowther + woofer is the approach demonstrated by several people including Nelson Pass (the idea predates his SLOB) - an open baffle up top and some kind of dipole underneath. I may try it one day, but as my 15” is open backed box I don’t want another dipole so some other kind of box is called for.
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Hi Paul, good to see you joining in. Interesting idea.
However, in the spirit of the Full Range Forum, the thread title specifically precludes the middle way, but rather the discussion is focused on the traditional extreme cases so as to leave the mid range relatively unmolested in terms of polars and other things
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I was looking at this 8" sbacoustics woofer. Its reponse looks very flat. It would be good choice for the bottom end with a full range. Probably do it in a box and then leave the full range open baffle. Its on sale too.
SB Acoustics SB23NRXS45-4
SB Acoustics SB23NRXS45-4
bigun
I doubt you can get away from 2 x 15", but if you have the 15" reaching up high (600+) and 6db cross between the 2 drivers (nirvana + whatever), that can work and give satisfying bass further into the room than a small driver.
With dsp, bob brines said he had luck making 2 drivers (8" woof plus 3" full range) roll at 6db for time / phase alignment.
But yes, fast is sort of skirting the full range driver mantra, so is waw, so is a coax with its crossover, and so is a full range with a supertweet.
Wideband is seemingly more acceptable here.
I doubt you can get away from 2 x 15", but if you have the 15" reaching up high (600+) and 6db cross between the 2 drivers (nirvana + whatever), that can work and give satisfying bass further into the room than a small driver.
With dsp, bob brines said he had luck making 2 drivers (8" woof plus 3" full range) roll at 6db for time / phase alignment.
But yes, fast is sort of skirting the full range driver mantra, so is waw, so is a coax with its crossover, and so is a full range with a supertweet.
Wideband is seemingly more acceptable here.
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I don't get the point of trying to squeeze low frequencies from an open baffle. You lose a huge amount of energy to phase cancellation. The bass is more directional is the only plus, but also harmonic distortion is much higher.
Its easier to build a box and then put the full range in its own chamber. Then you can leave that open in the back but have the woofer closed. The drivers will integrate well if they omnidirectional at crossover. Series resistors can be used to deal with sensitivity issues. One can simply biamp and use tubes for the full range.
Its easier to build a box and then put the full range in its own chamber. Then you can leave that open in the back but have the woofer closed. The drivers will integrate well if they omnidirectional at crossover. Series resistors can be used to deal with sensitivity issues. One can simply biamp and use tubes for the full range.
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Norman, my 15” is a whizzered full range and it reaches well past 600, more like 15kHz. It’s probably a better candidate for a supporting super tweeter than for a supporting woofer since the bass is far from lacking. But my ears don’t go past 14kHz so the driver is, alone, meeting all my needs except the occasional desire for a change of scene.
33polkhigh, whilst quantity of bass is harder to come by with an open backed box, the quality is very good. In the case of my speaker, based on a single 15”, the particular driver is well suited to the open back box because of it’s large Vas and high-enough Q. In fact, when operating it sealed I get no obvious change and a BR box for this driver would be huge.
Note: I listen in mono, having built only one box as I prefer not to have to arrange my living space like a stereo-triangle listening room.
33polkhigh, whilst quantity of bass is harder to come by with an open backed box, the quality is very good. In the case of my speaker, based on a single 15”, the particular driver is well suited to the open back box because of it’s large Vas and high-enough Q. In fact, when operating it sealed I get no obvious change and a BR box for this driver would be huge.
Note: I listen in mono, having built only one box as I prefer not to have to arrange my living space like a stereo-triangle listening room.
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Hi Paul, good to see you joining in. Interesting idea.
However, in the spirit of the Full Range Forum, the thread title specifically precludes the middle way, but rather the discussion is focused on the traditional extreme cases so as to leave the mid range relatively unmolested in terms of polars and other things
Well, yes, I agree that the most attractive feature of fullrange drivers is the ability to avoid crossover issues in the most critical frequencies. It is widely observed that no single driver will provide high-quality deep bass and high treble at the same time, and it is my contention that the best approach is to balance the bass and treble losses.
However, many "fullrange" drivers are more compromised at one extreme or the other, and this thread is largely about augmenting the more compromised end of the spectrum, accepting the crossover anomalies but pushing them away from the midband where they will do less harm. Having accepted the use of crossovers, I wanted to present the alternative of minimizing the anomalies. To me it's an open question whether a good crossover in a sensitive region is better or worse than a bad crossover in an insensitive region.
A good crossover in this sense would need to have a flat response with no phase shift, which basically means a first-order crossover. This only works well if the drivers have a wide overlap around the crossover and can be mounted close together.
By "wide" I mean two or three octaves on each side, e.g. for an 800Hz crossover the woofer must have flat response to 3200-6400Hz, and the tweeter must be flat down to 100-200Hz. And by "close together" I mean with centers no more than a half-wavelength apart at the crossover frequency which would be about 8 inches at 800Hz.
This is really only possible if both are widerange drivers, which are the subject of this forum, so it seemed an appropriate place to bring up this idea.
Well put.
I see 6db crossed as even better than any whizzer full range.
Better phase, better waterfall, less gargle, better dispersion.
Even 8" crossing to whizzerless 3-4", getting more and more traction lately.
And i am a fan of 8" full range.
But simplicity, 2 drivers cost, a little less point source, cap absorbing detail (moot compared to a paper whizzer ?), etc.
Depends what floats your boat.
I see 6db crossed as even better than any whizzer full range.
Better phase, better waterfall, less gargle, better dispersion.
Even 8" crossing to whizzerless 3-4", getting more and more traction lately.
And i am a fan of 8" full range.
But simplicity, 2 drivers cost, a little less point source, cap absorbing detail (moot compared to a paper whizzer ?), etc.
Depends what floats your boat.
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Fellas, certainly these are all valid options, none of these approaches are wrong and neither am I saying otherwise. I was simply pointing out that I started this thread to explore the pros and cons of the two options traditionally accepted as still being in the spirit of Full Range because the XO is at one extreme or the other, even if the moniker of Full Range may not be acceptable to all who like to debate such things (railway modellers call these folk ‘rivet counters’).
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I thought about it but more from a want of ‘I wonder if...’ than any desire to solve a problem, i.e. there isn’t really any problem, I don’t really want to add a super tweeter but who knows how I’d feel after trying one? And I must admit that after building the 15” single driver full range speaker it was so good that it kinda took away the need to build speakers. The last project I did was a pair of BR boxes that I made partly because I was gifted a pair of A10.3 drivers so I thought why not, could be handy to have something easier to move around and partly because I was gifted a small table saw and was itching to put it to some use. But these BR boxes sit unused, whilst the 15” remains in use. Adding to the 15” is just another excuse to do something.
However. now I have some thoughts to build a new mono speaker, something fairly large based on a full range driver from Lowther. I expect it will need woofer support, it may also benefit from a super tweeter. Is that a Full Range still or a 3-way .... I’m going to view it as an assisted full ranger option if ever I go that far with it.
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Why 300-400 Hz is a popular choice. 300 Hz is about the half-way point of the spectrum and about ehere half the energy is above and half below.
Based on Danley’s work, ¼ wavelength is a more appropriate distance at which the spacing essentially becomes moot.
dave
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