In my experience, the "xray" thing is a Unity horn thing. Here's an example of what I mean:
This is a frequency analysis of the melody that I referenced from the song "Little Secrets" by Passion Pit. In my review, I noted that there's a modulation of the melody that I'd never noticed before - and I'd heard the track at least a hundred times, over a dozen systems.
A look at the frequency analysis is a bit baffling, because normally basslines have a fundamental and a series of harmonics. If you did a frequency analysis of a 50hz note from a bass guitar, you would see a strong fundamental at 50hz, 2nd harmonic at 100hz, third at 150hz.
But this melody from the Passion Pit song stretches across the entire spectrum, with fundamentals all the way up to 20khz. I think the reason it looks like this is that there's some type of effect thats create gobs of harmonic distortion AND it's also shifting the pitch!
It's quite a torture test, really, because real instruments just don't produce this bizarre combination of pitch and harmonics!
But it also illustrates why the xray quality of a Synergy horn is well suited to extract detail like this. A conventional two-way speaker with a high order crossover is going to alter the phase in the midrange, and that will mask the harmonics in the octave where the crossover is. A wide bandwidth front loaded horn like a TAD TD2001 on a 300hz horn can't go low enough to get close to the fundamental of the melody, which is way down at 48hz. Admittedly my Synergy horn won't get down to 48hz either. But 48hz is over seven meters long! So it's not difficult to integrate two drivers at 48hz, due to the very long wavelengths. But integrating two drivers at 1500hz is tricky, because 1500hz is just 23 centimeters long. To get them to look like a single driver requires some tight spacing, perhaps as little as 6-8cm.
Probably the one type of speaker that can get the closest to doing was a Synergy horn can do, as far as the xray thing goes, is a full range driver. But details in a mix don't pop out on a full range the way they do on a Synergy. My guess is that the low frequencies reproduced in a full range modulate the cone in a way that makes it impossible to reproduce the upper frequency harmonics. For example, in the sample from "Little Secrets", the fundamental is at 48hz, with harmonics out to 20khz. To reproduce both 48hz *and* 10khz means that the cone has to move at both 48 cycles per second *and* 10,000 cycles per second. Obviously, somethings gotta give. In the Synergy horn, the drivers are split, so low frequency modulation of the high frequencies isn't as big of a problem, and hence, the extra detail.
I hope that paragraph made sense. Basically the "xray" quality of the synergy is noticeable on sounds that are wide bandwidth. Male voice is another example of a sound that crosses that octave where compression drivers are running out of steam, from 500-1000hz. (And note that male voices can almost get into subwoofer territory, as low as 80hz.)
One thing that might be interesting to investigate would be to figure out where we reach a point of diminishing returns. Do we want the horn to go down to 500hz? 250hz? 50hz?
I'm not sure. But let's do a bit of a though experiment, ok?
Going back to this melody that was particularly revealing, we see that there's information from 48hz to 20khz, or about 8.5 octaves.
The information above 10khz is fading fast, so I think it's safe to say that there isn't much to hear in this melody above 10khz. So let's throw that out.
Now we have 7.5 octaves.
48hz is over seven meters long. Due to the very long length, it's trivially easy to get two speakers to 'blend' at 48hz. So let's adjust the bandwidth to compensate for that. For instance, if we lop off the bottom two octaves, we can still get our midbass and our midrange very close. Even with a cutoff of 200hz, if we get our midbass within half a meter of our midrange they're going to blend pretty seamlessly.
By doing some aggressive reduction, we've whittled down the most important bandwidth to about 200hz to 10khz. That's five and a half octaves of music, but I think those octaves would probably cover both the fundamental and the harmonics of most voices and musical instruments. And if it didn't 'catch' the fundamental, it's trivial to get a woofer within one quarter wavelength at 200hz.
Unfortunately, I am not aware of any compression drivers that will go down to 200hz.
I think that leaves a couple options if xray speakers are your thing:
1) A speaker like the Dunlavy SC-IV, where the midrange is tasked with covering close to five octaves
or
2) A Synergy horn, where you split the bandwidth right down the middle. Take that frequency range and chop it right in the center, about 1200hz.
My primary opposition to 1.4" drivers is simply the law of diminishing returns. There's a lot of music fundamentals in the octave of 250-500hz, and a 1.4" compression driver just can't get that low. A really clean direct radiator midrange can do 250hz-5khz, and that might be the most compelling alternative to a Synergy horn.
If the xray like detail is from time aligned, phase coherent, single point source from 200hz to 12khz, 3 to 4 inch full range drivers excel in this range and is perhaps why full range speakers are so engaging. Many can cover 200 hz to 20khz well it is the lack of high spl that makes them not able to compete with unity or synergy horns. For home listening (with circa 90 db efficiency) maybe a good 3 in full range driver can be used as the tweeter and mid in a synergy with some woofers helping on the bass injection ports? Has anyone tried a synergy without a CD as the main tweeter? As you say the CD struggles below 1 khz, standard territory for a full ranger.
I'm using a Dayton Audio PA130-8 5" Full Range PA Driver from 150hz to 3K. It sounds great for $17. It has some good xray qualities in its range.
Now I'm thinking in my design would have been better to use one of the 3 or 4 inchers from FaitalPRO instead. And have them go from 150 to 5K or above with correction of the peaks.
3, 4, 5 inch drivers
Makingmoney,
Thanks for the tip on the Faitalpro new full range offerings on PE. The 3FE25 3 in sounds very interesting - the spec of 91 dB and 100 Hz to 20 kHz range for $19 is worth trying out. A 3 in class 90 dB full range drivers from Fostex will cost a whole lot more. For the Synergy, you really don't need expensive high Bl, low Qts motors.
Reagrds,
X
Thanks for the tip on the Faitalpro new full range offerings on PE. The 3FE25 3 in sounds very interesting - the spec of 91 dB and 100 Hz to 20 kHz range for $19 is worth trying out. A 3 in class 90 dB full range drivers from Fostex will cost a whole lot more. For the Synergy, you really don't need expensive high Bl, low Qts motors.
Reagrds,
X
Quite correct. I have seen so many bad implementations of OS. Many people don't get that you just can't make changes or modifications without serious implications.
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I've tried the 3FE20, Dayton ND91 and Fostex FF85WK.
If full range is what you're after, the Fostex is the one to get.
I opted for the ND91 for my current horn because I wasn't planning on using it past 1500hz, and the ND91 has much more undistorted output than anything else in it's size.
To me the 3FE20 is in a weird spot. Not as "full range" as the Fostex and can't generate as much output as the Dayton.
I'm mostly using small drivers because of the wall angle.
Wider walls allow for larger drivers.
If I used 5" drivers the compression would be too high.
As it is I'm nervous about 3" drivers, and hoping that they sound alright with such a high compression ratio.
I think that leaves a couple options if xray speakers are your thing:
1) A speaker like the Dunlavy SC-IV, where the midrange is tasked with covering close to five octaves
I've heard these loudspeakers in a number of locations with varying equipment and music.
Spatially they were good as long as you were listening within a very narrow vertical window relative to the distance from the speakers. Depth of field was very good, width only good. They were pretty bad (poor linearity and "phasey") once you moved out of that vertical window or got closer to the speakers. Part of the real problem here was that "integration window" that required you to be well away from them - at that point the room becomes a greater contributor and "shuts-down" the perceived expansion beyond room boundaries (..recording variable).
What they didn't have however was clarity, either as an overall general quality or specifically with respect to transients/dynamics. They always sounded somewhat dull and even a bit "plodding".
When I think of "x-ray" it's usually in relation to "see-through" character or general extreme clarity (and usually artificial sounding). ie. plasma, electrostats, planars/ribbons, accutons, and cheaper/smaller compression drivers. In other words low mass drivers vs. sd OR higher mass extremely rigid diaphragm drivers with a very high propagation velocity and a low or relatively lower internal loss.
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This morning it occurred to me that I'm using an extremely minimalist crossover - a single resistor!
And once I have four midranges on the horn, that will bring the efficiency to a point where I could probably ditch the resistor.
That would be a very odd beast - a two-way loudspeaker with no crossover.
I'm not a big believer in minimalist electronics, but some might wonder if the transparency and lack of crossover components are related.
As far as the mass of the drivers go, yes, I am using one of the smallest compression drivers in the world. (Celestion CDX1-1425.)
That may be a factor too.
Yes, it's probably down to the CDX1-1425 being driven so low - not unlike the "ring"-based BMS drivers in sound when the Celestion is utilized below 3 kHz. Lot's of treble detail, but usually lacking depth in that range (..though the mid drivers may counter-balance this to some degree).
You can do it, and even lower order harmonic distortion is still good (at more home-levels), but it usually doesn't sound "right".
A bit smaller driver than the Celestion:
http://www.bcspeakers.com/products/hf-driver-neo/0-5/de5
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Things like approximating the throat as a circle, or changing the shape to elliptical or square. These things are compromised which degrade the performance. I prefer the ideal with its pristine performance.
This evening I've been updating my YT channel, and noticed there was a fairly nice video of the Gedlee Summas in action:
Bateman gets married
This video is from my wedding, they did a splendid job of rocking the crowd in a space that was quite large. The Summas are high fidelity, but they also get LOUD.
Bateman gets married
This video is from my wedding, they did a splendid job of rocking the crowd in a space that was quite large. The Summas are high fidelity, but they also get LOUD.
Very impressive these speakers for recreating live rock concerts would be effortless. Will plug the headphones in and listen again Samsung Tablet not the best for judging sound quality. Zero chance of finding a pair of these for sale in Australia
I had purchased the NA12 used (by one owner) and then took it to another level from a finishing standpoint. The NA12 was the replacment for the Abbey, and is very close in performance (judging by the directivity curves and other measurements) to the all active NS15.
I have listened to the original Summa, Abbey (in its various iterations), Nathan and Harper (I own 4 of them) and find that the NA12 supersedes the original Summa in performance which makes sense objectively as well.
Here are some details of my rebuild, if any of you are curious:
This GedLee NA12 visited the boutique!
A colleague of mine is very pleased with the Buchardt S400's. Something to consider, but not DIY though. He owns JBL M2's, just for a token of comparison.
Best,
Anand.
I have listened to the original Summa, Abbey (in its various iterations), Nathan and Harper (I own 4 of them) and find that the NA12 supersedes the original Summa in performance which makes sense objectively as well.
Here are some details of my rebuild, if any of you are curious:
This GedLee NA12 visited the boutique!
A colleague of mine is very pleased with the Buchardt S400's. Something to consider, but not DIY though. He owns JBL M2's, just for a token of comparison.
Best,
Anand.
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