Hi Godzilla,
Hey thank you. I have spent far too much time trying to understand BLH's (like many or most people here). And I'm eagerly awaiting Martin's forthcoming work (hoping he will share it as he so generously has in the past).
I love the "open" sound that some BLH's have. The flat-out best BLH I have heard is the Austin A166, but oddly enough, the Harvey also blew me away for different reasons. They are absolutely as different as can be (sonically, and design-wise), so it pays to hear 'em all
Hey thank you. I have spent far too much time trying to understand BLH's (like many or most people here). And I'm eagerly awaiting Martin's forthcoming work (hoping he will share it as he so generously has in the past).
I love the "open" sound that some BLH's have. The flat-out best BLH I have heard is the Austin A166, but oddly enough, the Harvey also blew me away for different reasons. They are absolutely as different as can be (sonically, and design-wise), so it pays to hear 'em all
Depends what you call optimised. The aforementioned Saburo achieves its design goals well enough, but minimising deflection was not one of them. Assuming that's what you're meaning, Ron's A126 & my Valiant cabinet are a couple of examples. Basically, best advice I can give is that you sit down with a piece of paper & a pencil if needed, & spend an hour or so deciding exactly what your priorities are / what you would like to achieve with your next set of speakers (other than greater efficiency of course
).You seem to have decided to move the goals away from my point (which was merely a gentle reminder that just because one cabinet is not designed to significantly reduce deflection, that does not mean none of them are), into absolute territory.
If absolutes are the subject in question, then BW limiting a wideband drive unit (in terms of a high pass) will naturally reduce deflection, no news there. You should be able to achieve ~equal or less total excursion than the same unit in an optimal reactance annulled hyperbolic back horn, depending on the specifics of the design. If maximum dynamic BW is therefore the primary design criteria, about the best practical way to achieve it, short of a 2 - 3 way reactance-annulled FLH setup, is with multiple HE 15in - 18in woofers per channel crossed to compression mid-HF units around 500Hz, give or take.
Since nothing in audio is absolute, this will ever be a question of circumstance. A few points though. It appears to be predicated upon the assumption that distortion is present, when this in practice depends on the drive unit, the noise floor of the listening space, power-handling requirements and the dynamic range of the material of choice (or the desired dynamic range). Excursion does not automatically entail distortion and / or audible distortion. It may, or it may not. Without more specifics, it's all rather academic.
Then we have to consider exactly what is meant by 'the sacrifice of adding a crossover.' Audibility of components? Difficulty of combining different drivers into a frequency & phase accurate system? Added expense? Requires different design techniques? The fact that it will sound very different from, to use the current example for convenience, a single-driver based back-horn? And so on & so forth. Again, what is the best compromise depends on specific circumstances.
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It looks like Ron Clark himself (designer of the A166 and other BLHs) eventually became a believer in OB. http://www.diyaudio.com/forums/full-range/108751-new-mjk-baffle-article-34.html#post1410931
I'm building a pair myself to compare against the A166.
I'm building a pair myself to compare against the A166.
I'm on the fence as to doppler distortion... On one hand it makes sense, on the other it is not something that bothers me. Usually a speaker being pushed far enuff is going non-linear as it is out of its gap & the amp is straining. ie much mre objectionable stuff intrudes 1st.
Also, the athour of the more general of 2 textbooks i am reading on hearing is of the opinion that it is a red herring.
dave
Also, the athour of the more general of 2 textbooks i am reading on hearing is of the opinion that it is a red herring.
dave
I have tried a number of OBs, and althou they can sound very good, and can be very appealing, i find something a bit off with them so keep going back to boxes.
And i find the argument that OBs getting rid of the box making them less boxy a non-starter... one of the boxiest speakers i've heard was the Silver Iris.
They all have their compromises, you have to pick the ones you can live with best.
dave
good to hear he's still kicking - there was some worry when he was off the radar for a while
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as for OBs - I've heard most of the same ones as Dave, plus a few others, and while the more well executed examples can do a lot of things very well, for me they share at least one trait with the whole gamut of large panel dipole (ELS/Magnepan/ribbon), and true full range omni types such as Ohm A/F, German Physics: getting them to work in a non dedicated audio room (IOW in the Real World) can be more problematic / intrusive than a conventional enclosure, whether direct radiating "monkey coffin" or boundary reinforced rear mouth BLH.
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BLHs can sound very good. However to second (or third?) rjb's previous statement, it's hard to beat a large woofer when you really want to rock. The only real draw back to FAST systems is all the added expense of the woofers and crossovers/amps. If you don't mind those...
then put my vote in for a FAST
then put my vote in for a FAST
>>> I'm even wondering now if I'm going to be needing more than 1pr speakers.
You do! lol... i have several and love swapping them out from time to time. Heck, i have three pair in my office... two pairs of bookshelf speakers behind me on the back cabinet and a pair of floorstanders in the corners in front of me... and i swap them in and out with new projects. My shelves are full of raw drivers i hope to get to sometime in the future. Before cutting up the wood for your project, to save money and time, think about cutting for another future project.
Joseph, i bet that speaker sounds excellent. It's a fostex 168 plus what? a dayton 12"... is the woofer powered by another amp? It must throw a great big soundstage. Love it!
You do! lol... i have several and love swapping them out from time to time. Heck, i have three pair in my office... two pairs of bookshelf speakers behind me on the back cabinet and a pair of floorstanders in the corners in front of me... and i swap them in and out with new projects. My shelves are full of raw drivers i hope to get to sometime in the future. Before cutting up the wood for your project, to save money and time, think about cutting for another future project.
Joseph, i bet that speaker sounds excellent. It's a fostex 168 plus what? a dayton 12"... is the woofer powered by another amp? It must throw a great big soundstage. Love it!
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that's a nice looking speaker!
Now that I think about it, a BLH is a FAST - the horn mouth is the woofer and the cabinet is the cross-over and there can be some phase shifts along the way ?
I'm thinking that having two separate drivers offers more flexibility and appears to allow extension to lower frequencies than most house-friendly horns. I don't have a budget limitation per se for this project as I'll likely make everything myself.
PLLXOs are new for me, I don't have much understanding of them - this is both an opportunity and a risk !
PLLXOs...
A capacitor of the correct value in series with the input of an amplifier would act as a 6dB/octave high pass.
A resistor in series with the signal, and a capacitor to ground after that acts as a low pass.
You can play with resistors and capacitors to avoid using op-amps completely. That might be an over-simplification, but I'm pretty sure what I've said is correct.
I used such a thing for flattening the response of my system when the gain of my room made anything <40Hz really overdone. A capacitor in series with the input, and it's all good.
Certainly something to try, but I more recently went with op-amps for a 4th order LR crossover.
Chris
A capacitor of the correct value in series with the input of an amplifier would act as a 6dB/octave high pass.
A resistor in series with the signal, and a capacitor to ground after that acts as a low pass.
You can play with resistors and capacitors to avoid using op-amps completely. That might be an over-simplification, but I'm pretty sure what I've said is correct.
I used such a thing for flattening the response of my system when the gain of my room made anything <40Hz really overdone. A capacitor in series with the input, and it's all good.
Certainly something to try, but I more recently went with op-amps for a 4th order LR crossover.
Chris
I only called adding a crossover a sacrifice because that's what it's usually considered to be in the FR community. The reason we're here is because we wanted to escape from playing with more circuitry than strictly necessary. The audibility of it all is subjective, but a totally optimal cross-over in any form isn't a common occurance, and a sub-optimal crossover won't do the sound any favours.
I hadn't intended for my post to come across as ignorant/arrogant or anything like that, though it would appear it has. Perhaps it was my blanket terminology that potentially covered some of your designs (which I am looking forward to hearing). If that is the problem, I apologise, no offence was intended.
Chris
Actually, a lot don't. OBs and FAST (or what were traditionally called 'two-way' systems before the obsession with reducing size &c. resulted in rocketing XO frequencies) projects are extremely popular here. Granted, there are a lot of 1-way purists as well, as you'd expect. Plenty of room for everyone though.
Not to the best of my knowledge it didn't.
Never occured to me. As noted, the sole point I was raising was that you can't take one example of a cabinet and assume that what applies to it must apply to all other cabinets of it's general type. That's it. No comparisons to other types of loudspeaker. No profound meditations on the infinite improbability drive, toasters, or what nightwear Kylie Minogue favours (although the last is not without interest). Just what it said on the tin.
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dammit Scott, just when I was trying to elevate my contemplations to a higher plane
... with that image in mind, this should only take a few minutes
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Hope you recovered from that Chris !
Well, I'm getting cold feet on putting a cross over in at the 300Hz level. The idea was that this was outside the telephone range and would do 'little harm' but I have been reading around and see a number of opinions on the importance of the 100Hz to 400Hz range for general music. Jeez if flipping snowing outside! anyhow, I'm going to do a bit of reading about the inverse, push the cross-over up high instead of down low.
Well, I'm getting cold feet on putting a cross over in at the 300Hz level. The idea was that this was outside the telephone range and would do 'little harm' but I have been reading around and see a number of opinions on the importance of the 100Hz to 400Hz range for general music. Jeez if flipping snowing outside! anyhow, I'm going to do a bit of reading about the inverse, push the cross-over up high instead of down low.
Series xo first impression
Gotta say my first dip into FR+sub test of parallel vs series x/o, first order, is almost night and day, like going from conical to hypereliptical on a phono cartridge. Same pieces reconfigured, but the result is as if the parallel connection included a bonus scrap of heavy carpet in front of the full range. It lead to a few hours of vinyl spinning. I just sat there, loving the non-graphed detail.
Gotta say my first dip into FR+sub test of parallel vs series x/o, first order, is almost night and day, like going from conical to hypereliptical on a phono cartridge. Same pieces reconfigured, but the result is as if the parallel connection included a bonus scrap of heavy carpet in front of the full range. It lead to a few hours of vinyl spinning. I just sat there, loving the non-graphed detail.
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