Best size for full-range driver?

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ra7

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You might be quite surprised by EL70eN/CHR70eN/Alpair7eN

dave

While they may be all good sounding drivers, I doubt they can defy the laws of physics. That said, I would like to see off axis measurements and then I will believe you.

Anyway, off axis performance is not as important to me as Toole, et al make it out to be. I will still take a ragged off axis response from a full range driver over a 1" dome tweeter crossed in the sensitive frequency range.
 

ra7

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In my experience, with good dispersion the image forms deeper, behind the speaker. Directional cues are better. Read Linkwitz' website.

Amazingly enough, my B&Ws can reproduce one recording (just one) better than my OBs with full rangers. Simply because of better dispersion. The recording is of a cellist playing the cello in a large hall and the mike picks up all the reflections from the hall. There is a lot of information about the venue in this recording. On my full rangers, the venue is not quite clear and the image of the cello is between the speakers. On the B&Ws, its like you are sitting 5 rows back with the cellist on stage. On an all horn Altec system, which was a pleasure to listen to, you are 20 rows in the back from the cellist and the feeling of being there was really real.

Of course, on everything else the full range OBs leave the B&Ws in the dust. They just sound more real. With full range drivers, you sacrifice on directionality, but you get a lot more in return. At the end of it all, you should still get a huge soundstage and all that good stuff if you sit in the sweet spot. So, don't worry about it too much.
 

ra7

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Cool... that would be nice. I don't have that kinda space at hand. I've tried measuring the ANs, but not too seriously.

You know, its about time we start measuring our FRs. Granted the curves aren't pretty, there is still something we love about them and it needs to be investigated.
 
I'm trying to figure out the best size for a full-range driver for my requirements. I don't need high treble because my hearing only goes to about 11K anyway, but I do like big bass.

I love my vintage Jensens. They have full range 12" drivers. (Jensen calls them extended range.) My hearing only goes up to 12K. I've A/B'd them with multi-driver speakers. If the Jensens are missing any treble, I can't hear it. :D Lots of bass and efficiency. I think younger ears would at least appreciate the low bass and smooth midrange.

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Bobby Dipole
 

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I love my vintage Jensens. They have full range 12" drivers. (Jensen calls them extended range.) My hearing only goes up to 12K. I've A/B'd them with multi-driver speakers. If the Jensens are missing any treble, I can't hear it. :D Lots of bass and efficiency. I think younger ears would at least appreciate the low bass and smooth midrange.

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Bobby Dipole
An extended range 12" is one option I've considered. Do you think your cabinet would benefit from a bass-tuned port? Or does it have one I don't see?
 
I'm afraid not. Mass affects efficiency, but it does not impact on transient response. Transient response is inherently linked to bandwidth covered & the acceleration of the powertrain is proportional only to the amount of current in the voicecoil. The equation B*L*i / Mms clearly demonstrates this, where B = magnetic strength in the Vc gap, L = length of the VC in the VC gap, i = current in the VC, and Mms = moving mass of the powertrain (all in SI units, naturally). Dan Wiggins's did a short writeup on the subject a few years ago: http://www.adireaudio.com/Files/WooferSpeed.pdf
Good ideas don't often scale. That's why we don't have giant insects (anymore) or land animals above the size of an elephant.
A given construction, material strength or capability doesn't scale linearly and that goes very much for speaker cones too. Paper is paper, no matter how thick you make it, or how much power you move it with.
You'll get ever diminishing returns the more resources you pour into the speaker being it power or construction.
Small well constructed FR drivers can do some stuff larger drivers will never be able to do. At lower volumes of course, but that is a given.
 
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Hi motosapien, you definitely need a filter to relieve the fullranger of the bass.

Hey thanks!:) I know it is a good idea in OB to prevent over excursion.
Although I'm very satisfied with my Coniston^2's (they brought me to tears last night in a drunken listening session:eek:), I'm interested in pursuing an OB project with the Alpair 7's similar to this:

http://www.diyaudio.com/forums/full-range/170079-new-alpair-7-small-ob-project.html

I like the idea of sealed woofers because I am a bit space challenged for an H frame like MJK's OB project. Leaning towards the bi amp route too though plate amps are a possibility.

It's time for me to take the plunge and download some speaker design software so I can better understand this hobby. A woofer box that does 40 to 150hz, a high pass and a low pass should not be insurmountable for a neophyte. I did note however that Planet 10 has box designs for CSS's line of woofers so it may not be necessary to re invent the wheel.
 
Hi motosapien, you definitely need a filter to relieve the fullranger of the bass.
I'm interested in the same arrangement (FR on an OB with a separate helper woofer). What is the least obtrusive filter arrangement one could get away with? Is it really necessary to filter for both drivers, or can you just hi-pass for the FR and leave the woofer alone? I'm just trying to minimize the crossover business if that's possible.
 
frugal-phile™
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What is the least obtrusive filter arrangement one could get away with?

If you are willing to into your HF amp, the least obtrusive is to shrink the size of a coulping cap to create the appropriate HP. If not willing, then a single cap on the input that creates an appropriate HP in conjunction with the amp's input impedance.

The LP XO is less audible. A 1st or 2nd order PLLXO can usually be implemented, and typical IC active XOs aren't to bad if well exectuted.

A PLLXO on top and something like SY's Acheron XO on the bottom, would be high on my list.

dave
 
I probably misused the term obtrusive, but I just meant a way that would have the least negative impact on the sound. Passive crossovers have such a bad rap but I've heard a few negatives about active XO as well.

Intuitively, I like the idea of the drivers being driven separately with a crossover device like this one Pyle-Pro PPCX2 2-Way Active Stereo Crossover PPCX2 B&H Photo in between because of the high degree of control you have to experiment with. I'm also thinking about using a couple of Tripath chip amps in this arrangement which would keep the costs down. I don't mind coloring the spectrum with EQ and such if I like the sound better. But, I don't really know the in's and out's enough to know what works and what doesn't.

What do you think about that idea with woofer-augmented FR-on-OB speakers?
 

ra7

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For crossing full range drivers to woofers on OBs, there is nothing better than NP's FirstWatt B5 active crossover. They are available now from Lowther America. They are basically active filters placed between buffer circuits.... superb sounding and way better than any other active solution.

Another option is the MiniDSP. It is really flexible and easy to use.
 
For crossing full range drivers to woofers on OBs, there is nothing better than NP's FirstWatt B5 active crossover. They are available now from Lowther America. They are basically active filters placed between buffer circuits.... superb sounding and way better than any other active solution.

Another option is the MiniDSP. It is really flexible and easy to use.
The final pieces are falling into place. Thanks.

I find it very interesting that people are willing to spend $1500 on a crossover specifically made for OB's. As a newcomer, that tells me that OB is not just about economy and simplicity, but about sound quality as well. Alas, this option is too costly for me but the MiniDSP looks interesting.

Any other active crossover suggestions are welcome.
 
An extended range 12" is one option I've considered. Do you think your cabinet would benefit from a bass-tuned port? Or does it have one I don't see?

I'm a dummy when it comes to speaker design. I don't know the difference between ported and bass reflex, are they similar? Jensen called this cabinet their type "D" bass reflex. It's 31"x28"x13". There is a substantial rectangular opening just below the driver, otherwise the enclosure is sealed. You could easily blow out candles in front of that rectangle!

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Bobby Dipole
 

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I'm a dummy when it comes to speaker design. I don't know the difference between ported and bass reflex, are they similar? Jensen called this cabinet their type "D" bass reflex. It's 31"x28"x13". There is a substantial rectangular opening just below the driver, otherwise the enclosure is sealed. You could easily blow out candles in front of that rectangle!

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Bobby Dipole
Very cool looking. Keep them. The bottom opening looked sealed up on the pics is why I asked. Others here can explain how this cab works better than I.
 
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