Thank you, Stefano. That is an interesting path to a very impressive system; I especially like the woodhorn. You must be most pleased!
As I read more about this I'm getting ever more keen on the compression-driver and horn option, but it does feel like walking along a very slippery slope, which might be inappropriate for me to go down. Mostly because I cannot bank on having very much space and was also intending to use my existing 10" bass drivers. Yet.... given my wish to cross over well below 1khz, I'm already drawn into thinking that around 15" would be best for the waveguides and (for integration and directivity purposes) now also for the bass drivers!
Perhaps I need to look at pro direct radiating midrange drivers for a bit, and get excited about those too/instead.
As I read more about this I'm getting ever more keen on the compression-driver and horn option, but it does feel like walking along a very slippery slope, which might be inappropriate for me to go down. Mostly because I cannot bank on having very much space and was also intending to use my existing 10" bass drivers. Yet.... given my wish to cross over well below 1khz, I'm already drawn into thinking that around 15" would be best for the waveguides and (for integration and directivity purposes) now also for the bass drivers!
Perhaps I need to look at pro direct radiating midrange drivers for a bit, and get excited about those too/instead.
One thing to consider is if you are using a 10" pro driver, you will not need the most expensive high power version for home use as it will never be pushed hard. Something with a light cone, less x-max and smooth / minimal breakup will be good. (I am considering Fane drivers for an upcoming 10" / 1" CD project, but already have 3x 15" drivers to use so am finding it difficult to justify spending out on more drivers.)
Rob.
Rob.
Thanks, Rob. Yes my interest in pro drivers for the mid+high frequencies is mostly about dynamics, rather than particularly high SPL, and in the case of compression drivers the lower SPL would even be useful in using them at lower frequency than normal. Admittedly I want a bit of kick to feel as well as hear, and would be disappointed if that were completely absent, but this is just a modest home scenario with only a few meters to the listening position and neighbors to think about.
My existing 10" bass drivers are just scanspeak hifi types, bought second-hand years ago. So they aren't especially sensitive or high power handling, and so pro midranges or compression-drivers would have no trouble keeping up. In fact these 10"s would likely be the weak link in such a system; both in terms of xmax and potentially power compression. So I have wondered if using them was the best plan.
But the reality is that I don't have the space for really huge speakers, so actually the 10"s might work out quite well in combo with a slightly more modest waveguide/horn size. They only require large, rather then enormous, boxes and will even work best sealed which I like. If I ever do want to get more enthusiastic, then crossing to subwoofers would perhaps be better (for me) than using huge bass drivers; I like the idea of distributed subs for very low bass anyway.
Thanks,
Kev
My existing 10" bass drivers are just scanspeak hifi types, bought second-hand years ago. So they aren't especially sensitive or high power handling, and so pro midranges or compression-drivers would have no trouble keeping up. In fact these 10"s would likely be the weak link in such a system; both in terms of xmax and potentially power compression. So I have wondered if using them was the best plan.
But the reality is that I don't have the space for really huge speakers, so actually the 10"s might work out quite well in combo with a slightly more modest waveguide/horn size. They only require large, rather then enormous, boxes and will even work best sealed which I like. If I ever do want to get more enthusiastic, then crossing to subwoofers would perhaps be better (for me) than using huge bass drivers; I like the idea of distributed subs for very low bass anyway.
Thanks,
Kev
I'll go active in mine at least, and the Scanspeak 26W/8534G00 is 89dB sensitive, and that should be enough to go loud in my space. it's not perfect, but i already got the woofer and used it in other configs with success. It goes more than loud enough in my room. And compression drivers is also about directivity (due to the horn), not only about volume. I would also not do this passive as taking 19dB off (in my case with the HF-201) is a bit ridiculous much amp power that is wasted in heat. Maybe i later upgrade to a higher sensitive woofer, but for the moment it should do.
Compression driver could make a narrow coverage speaker. I'm not sure if dome tweeter could be successfully constrained to narrow coverage, below ~100deg nominal for the whole bandwidth without "issues". Perhaps they could fine enough.
It is then matter of acoustics and listening distance and stuff like that, what kind of a stereo image one is after. Big "diffuse" sound is easy to get but if one likes to have very accurate image with >2m listening distance then I would say narrower coverage would suit be better. If proper room acoustics can be implemented then I'd think it wouldn't matter that much.
It is then matter of acoustics and listening distance and stuff like that, what kind of a stereo image one is after. Big "diffuse" sound is easy to get but if one likes to have very accurate image with >2m listening distance then I would say narrower coverage would suit be better. If proper room acoustics can be implemented then I'd think it wouldn't matter that much.
Hello All,
I use line level active crossovers in my "Big" speakers. Yet I still L-Pad both the 10 inch pro Mid-Range drivers 101 dB's per Watt and Compression Driver tweeters. The L-Pads attenuate amplifier hiss and hum or another way of saying it is that the amplifiers have lower THD+N when they operate a few Watts above minimum. The CD Tweeters also have DC blocking capacitors to protect the drivers.
Thanks DT
I use line level active crossovers in my "Big" speakers. Yet I still L-Pad both the 10 inch pro Mid-Range drivers 101 dB's per Watt and Compression Driver tweeters. The L-Pads attenuate amplifier hiss and hum or another way of saying it is that the amplifiers have lower THD+N when they operate a few Watts above minimum. The CD Tweeters also have DC blocking capacitors to protect the drivers.
Thanks DT
Thanks everyone. Interesting thoughts there. Yes I am going active, but hissing is a concern so padding could be useful to keep in mind. I haven't yet thought about what amps shall be used but when the time comes some headroom and low noise would both seem worthwhile.
It is very true that I don't need the SPL of compression drivers. My interest in them is to use them differently, where their capabilities will be turned into extension at the low end instead of high volumes.
Essentially, I realised that a compression driver can be used much like the full/wide range mid-tweeter in a typical WAW/FAST. Perhaps with a slightly higher crossover. But with better dynamics, less concern over power compression and better directivity. I like the idea of a single driver for upper-midrange and above, but with a conventional wide-range would need to compromise much more on size , dynamics, power etc for preserving dispersion higher up. Though a bigger one with a wizzer cone might also come close, so would be a fair alternative.
Cheers,
Kev
It is very true that I don't need the SPL of compression drivers. My interest in them is to use them differently, where their capabilities will be turned into extension at the low end instead of high volumes.
Essentially, I realised that a compression driver can be used much like the full/wide range mid-tweeter in a typical WAW/FAST. Perhaps with a slightly higher crossover. But with better dynamics, less concern over power compression and better directivity. I like the idea of a single driver for upper-midrange and above, but with a conventional wide-range would need to compromise much more on size , dynamics, power etc for preserving dispersion higher up. Though a bigger one with a wizzer cone might also come close, so would be a fair alternative.
Cheers,
Kev
Well I spent several hours over the last few days, reading threads about the use of compression drivers (I perhaps now know enough to be wrong). I'm still quite keen. In many cases I'd be pushing them a bit at the ends of the frequency range to do what I'd like (crossover low and go right up to the top). However, the low end should be okay at my SPLs, and presumably 1.4" or even 2" Compression Drives won't beam noticeably more than a 3" full/wide-range driver (which was my previous intention), even though their cones are getting quite clever these days.
The main annoyance is that my 10" bass drivers aren't as ideal as I'd like. To optimally match directivity with a 90-degree waveguide I'd have to cross much higher than wished (and higher than I'm confident in the bass drivers performing so well). So to use them I'd ideally need to use a wider angle waveguide and/or one short enough for directiity control to have diminished down by the crossover point. Or get 15" drivers instead, which might then also be a better sensitivity. Though I should also remember that whilst I'm being attracted by directivity (due to it surrounding the use of horns and waveguides) that was not my main aim, so any improvement at all in that respect would essentially be a bonus. Fundamentally, I was mainly looking for a better compromise than a full/wide-range mid-tweeter driver. Directivity is quite appealing though.
The other option is still to use a sensitive midrange and a tweeter. Again I've been reading and have confirmed my opinion that the evils of crossing over at high frequencies are minimal, in spite of the large driver spacing (relative to wavelength) if done above 7kHz or more. Where we lose the ability to distinguish some of the negative effects. Maybe coaxial would also be a different take on that same option, though they have their own compromises. However, currently this is still not as attractive to me as a capable CD used without crossover for both mids and highs.
Cheers,
Kev
The main annoyance is that my 10" bass drivers aren't as ideal as I'd like. To optimally match directivity with a 90-degree waveguide I'd have to cross much higher than wished (and higher than I'm confident in the bass drivers performing so well). So to use them I'd ideally need to use a wider angle waveguide and/or one short enough for directiity control to have diminished down by the crossover point. Or get 15" drivers instead, which might then also be a better sensitivity. Though I should also remember that whilst I'm being attracted by directivity (due to it surrounding the use of horns and waveguides) that was not my main aim, so any improvement at all in that respect would essentially be a bonus. Fundamentally, I was mainly looking for a better compromise than a full/wide-range mid-tweeter driver. Directivity is quite appealing though.
The other option is still to use a sensitive midrange and a tweeter. Again I've been reading and have confirmed my opinion that the evils of crossing over at high frequencies are minimal, in spite of the large driver spacing (relative to wavelength) if done above 7kHz or more. Where we lose the ability to distinguish some of the negative effects. Maybe coaxial would also be a different take on that same option, though they have their own compromises. However, currently this is still not as attractive to me as a capable CD used without crossover for both mids and highs.
Cheers,
Kev
A 1" compression driver should easily cross at 700Hz. I've used one to 500Hz with a first order crossover without taking it too loud, although it would.
Therefore 2" is only going to compromise your highs, but again, it shouldn't. At least not the same as a direct radiator, only because the 2" phase plugs available are not necessarily made for 20kHz. It's not the same thing as a 2" direct radiator when you have a plane wavefront and matched waveguide. DRs have varying lobing patterns up past breakup.
Thank you Allen, that is good to hear. If 1" drivers will do the job then likely there'd be no need for me to use bigger formats then; the 1" size looks in general to be cheaper and offer a good choice of both drivers and horns. Probably just comes down to what is available here and how they measure, more than size and power for my purposes. I found Earl Geddes favouring 1" compression drivers in some older comments; he didn't say that bigger formats couldn't work, but at the time had simply not found any that he felt were comparable at the top end.
I believe some of that was related to his preferred choice of Oblate Spheroid horn/waveguide being a bit less efficient (than some other designs) at higher frequencies. I've made no decisions on what type of waveguide to go for myself, all that is still to come, I may even attempt a DIY one unless any of the standard offerings happen to suit my slightly different use-case.
Thanks again,
Kev
I believe some of that was related to his preferred choice of Oblate Spheroid horn/waveguide being a bit less efficient (than some other designs) at higher frequencies. I've made no decisions on what type of waveguide to go for myself, all that is still to come, I may even attempt a DIY one unless any of the standard offerings happen to suit my slightly different use-case.
Thanks again,
Kev
I've spent more time looking at this and have not been put off by what I've found. As I see it now, the main disadvantage of a compression driver used like this is probably size of the waveguide/horn, both for its intrusive nature and for driver spacing (unlikely to reach <1/4 wavelength, as Planet10 frequently cites for his small cone wide-ranges). But I could probably find some way to make it visually acceptable, and for driver spacing I could at least compromise on a somewhat flatter (rectangular or elliptical) waveguide, and attempt to place the vertical nulls appropriately.
In return for that sacrifice I think I'd get a single driver+waveguide that'll play reasonably low with great conviction, and so marry nicely with the dynamics of a capable woofer below it, and yet still act more like a largish tweeter when it comes to high frequency beaming. In a world of compromises, really quite an appealing combination. And of course there is directivity control, which wasn't my starting point but seems a definite bonus - again in matching the woofer below it (this time in dispersion), as well as helping to choose/manage the degree of room reflection. Maybe also sidestep some diffraction and/or early reflections from whatever enclosure is used.
I was temporarily 'very' excited to find that coaxial compression drivers exist, and could do even more of what I wanted; the crossover is out of the critical hearing range and no problem with driver spacing. Then... I saw the price, and also worked out how big a waveguide should be if you stretch down the lower frequencies for a home/hi-fi setting (as I'd no doubt want to do). Plus, in order to not waste the potential for directivity control I'd probably need an enormous woofer, or two side by side. This is a dangerously slippery slope to be walking across the top of!
In return for that sacrifice I think I'd get a single driver+waveguide that'll play reasonably low with great conviction, and so marry nicely with the dynamics of a capable woofer below it, and yet still act more like a largish tweeter when it comes to high frequency beaming. In a world of compromises, really quite an appealing combination. And of course there is directivity control, which wasn't my starting point but seems a definite bonus - again in matching the woofer below it (this time in dispersion), as well as helping to choose/manage the degree of room reflection. Maybe also sidestep some diffraction and/or early reflections from whatever enclosure is used.
I was temporarily 'very' excited to find that coaxial compression drivers exist, and could do even more of what I wanted; the crossover is out of the critical hearing range and no problem with driver spacing. Then... I saw the price, and also worked out how big a waveguide should be if you stretch down the lower frequencies for a home/hi-fi setting (as I'd no doubt want to do). Plus, in order to not waste the potential for directivity control I'd probably need an enormous woofer, or two side by side. This is a dangerously slippery slope to be walking across the top of!
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Thanks; it is reassuring to know that, whatever I make of this, at least it is a good track to take.
Well, yeah of course you should do what feels right and seems reasonable to you 🙂 better sound means different things for people, circumstances vary and so on.
Big speakers are a lot of fun in general and yes there is possibility for better sound just because physical size allows directivity control to lower frequency, also narrower directivity on high frequencies, increased maximum SPL, things you already wonder about. But, it comes with practical issues you've also wondered so its not free lunch. Issues like resonances drop lower in frequency as physical size increases, which makes somewhat harder to deal with them. Building the speakers is more expensive and laborous and so on, space requirement. But, did I mention its much fun listen to big speaker system?😀 Yeah its fun, I'm not downsizing any time soon 🙂 Build it modular so its not too tough a task.
Big speakers are a lot of fun in general and yes there is possibility for better sound just because physical size allows directivity control to lower frequency, also narrower directivity on high frequencies, increased maximum SPL, things you already wonder about. But, it comes with practical issues you've also wondered so its not free lunch. Issues like resonances drop lower in frequency as physical size increases, which makes somewhat harder to deal with them. Building the speakers is more expensive and laborous and so on, space requirement. But, did I mention its much fun listen to big speaker system?😀 Yeah its fun, I'm not downsizing any time soon 🙂 Build it modular so its not too tough a task.
You're right about placing nulls and other things which allow wide spacing to work, but it is a challenge to balance them. The narrow directivity alters the requirements a little and can be an advantage. I wouldn't compromise the waveguide too much to cater for other things.
https://www.diyaudio.com/community/threads/is-it-best-to-use-a-non-axisymmetric-waveguide.375799/
Thank you, Allen; I've read a few of your posts on this subject and all have been very helpful. It is also useful to see where and why you might choose to draw some of the compromises, since weighing competing requirements is quite difficult from my position of far less knowledge and experience. Of course I'm learning the basics, and enjoying doing so, but there is a long way to go at this stage.
I recall reading that Earl Geddes also preferred axisymmetric guides over closer centre-to-centre spacing, as of course is demonstrated by his speakers. It does make sense to me. I suppose reasons for quite so many people choosing flatter guides would often be more practical in nature (size, availability etc); I haven't yet seen a great deal that explains their reasoning reasoning in making the choice. Though there was a PDF article from Pi speakers in which (somewhere around the tenth page) the increased loading of flatter horns is additionally mentioned. If I understood it correctly, anyway. I don't think I'd personally need that in my home setting though, or could choose a driver that was more comfortable with less loading at my modest SPLs.
Thanks again,
Kev
I recall reading that Earl Geddes also preferred axisymmetric guides over closer centre-to-centre spacing, as of course is demonstrated by his speakers. It does make sense to me. I suppose reasons for quite so many people choosing flatter guides would often be more practical in nature (size, availability etc); I haven't yet seen a great deal that explains their reasoning reasoning in making the choice. Though there was a PDF article from Pi speakers in which (somewhere around the tenth page) the increased loading of flatter horns is additionally mentioned. If I understood it correctly, anyway. I don't think I'd personally need that in my home setting though, or could choose a driver that was more comfortable with less loading at my modest SPLs.
Thanks again,
Kev
Thank you for this, also.
Yes I am quite interested in bigger speakers, I've noticed in the past that they seem to have something about them that I like. In my younger days most were quite a bit bigger than we tend to see in hifi now. Though my preference is potentially as much tied up with dynamics and sensitivity than size alone; I haven't really nailed it down. But in any case I'm interested to try something more sizeable, not least to make a worthwhile contrast to the small pair I'm currently building (specifically for quiet near-field listening).
EDIT: I'm not currently sure if this will mean the entire speakers must be big, or just that they'll involve bigger drivers (or horns). I don't have masses of space, and also get frequent inspections from the letting agent, so can't go for anything too outrageous. Though I'm now keen on directivity control, so it seems unlikely they'll be particularly small. In the past I've had some success making cabinets look like innocent cupboards and also in reducing box size with linkwitz transforms, so both may be options.
Cheers,
Kev
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I've done a few speakers using pro compression drivers and horns. The main things I've found are that A: not all pro drivers are created equal. I've found drivers with titanium diaphragms to be rather harsh sounding- I suspect the reasons are that they are designed to be loud and durable. I much prefer phenolic diaphragms for mids and mylar for tweeters. B: Pro drivers are extremely efficient. To match them, you'll either want a very efficient woofer, or heavily attenuate the mid driver in your crossover with either an autoformer or an L-Pad or both. It's my opinion that too much driver attenuation may be sub optimal. Another issue with highly efficient woofers is that efficiency comes at the expense of bass response. my current test mules use a 99db efficient Eminence Delta Pro 12A woofer that has an FS of 51Hz. with a 5 cf cabinet and a 15" passive radiator, it will extend to 38Hz, which is not nearly as low as a smaller, more power hungry woofer may go. the next cabinets I build will use a 15" woofer and displace 8-10 cubic feet, in hopes of digging down to 32Hz; I currently have to use a DSP crossover, parametric EQ and bi-amping to extend that low.
the pros of using compression drivers and horns are that they produce very little distortion, require little power and have tremendous dynamic range. The sound can be incredibly natural and lifelike, if properly voiced. Directivity, which is a valid and common complaint can be mitigated by using plasticine "mumps" in the corners of the horns, a la the recent Klipsch Heritage horns.
the pros of using compression drivers and horns are that they produce very little distortion, require little power and have tremendous dynamic range. The sound can be incredibly natural and lifelike, if properly voiced. Directivity, which is a valid and common complaint can be mitigated by using plasticine "mumps" in the corners of the horns, a la the recent Klipsch Heritage horns.