Beyond the Ariel

And to tie this to Dr. Geddes's approach--
while the strength and diffusiveness of reflections could be addressed to some extent with room treatments, the timing can't. The hallmark of room size is the ITDG (Initial time delay gap- the period before any room effect information is received) followed by the density and direction of first reflections (which also tells us the character of the room).

Earl's answer of [high directivity + speaker orientation + live walls] to intentionally generate (relatively) later reflections while reducing the earliest reflections is the only passive 2-channel solution that mostly 'works' to virtually enlarge a room. Get the the brain to identify the later, denser, more diffuse package of reflections as if they are the first reflections, and voila, bigger room.

WOW!!! Somebody gets it! Very very good!
 
I use a similar approach, but I tend to like the effect of diffusion better than absorption. A room does need both, for sure. I wonder if judicious use of diffusion would imitate the sound field of a larger room? Back to the text books!

I loath absorption in small rooms, except in one place - behind the speakers. Elsewhere, it just kills the acoustics IMO. But diffusion is never perfect, if it were then it would be ideal. The sound should hit the listener, then a long gap followed by as much acoustic energy as possible. This is key to all room acoustics. You need that gap for the ear to process the sound.
 
Diffusion can't really simulate a larger room, just make one less obviously small, if that makes sense. There is a ton of confusion in the application of the terms diffuse (a condition), diffusion (an action), and diffusor (a device).

Although rarely stated so clearly (thank you, Marketing), The true purpose of diffusion in small rooms is simply to reduce the small room 'signature' without excessive absorption.

Ironically, The best way to simulate larger room is with some later Temporally Preserved "TPR" Reflections. These are ones that still have phase information for the original signal - planar reflections.

Read that twice, because nobody ever says it!

By design, Diffusion devices actually destroy phase information. I'm not saying this is bad, but the simple fact is that planar reflections are only beneficial if they are many and adequately delayed. As you pointed out above, this is the opposite of what occurs in small rooms: discrete and spaced early reflections.

--Mark

Thanks Mark, this is really right on the Mark (pun intended). The TPR idea sounds very much like Greisinger's ideas about perception, which I completely agree with (although they can be a little hard to translate into goals in a small room.)
 
Both the change when using a finite baffle compared to an infinite one, and what the radiated field looks like for different cylindrical modes would both be very interesting. Should be fairly easy to implement.



Just send me a PM if you can't find it.



Right. Well, I'm not sure. Simulating the driver using the standart lumped parameter model is too simple for such a comparison, I think. And if the acoustic paths in the driver were to be simulated in BEM, it would be difficult to get all dimensions right. In addition comes the fact that viscous losses would not be included, and the mechanical part, with breakups etc could not be simulated.

If it was possible to measure the pressure near the throat surface, that could be used as a reference that all measurements could be normalized to. For instance, the pressure could be measured at the waveguide wall, and the pressure at the same point could be computed in the simulation. The measured pressure in this point could be used to normalize the measurements, and the simulated pressure to normalize the simulations.

Alternatively, Makarski shows how to measure the T-matrix of the driver, but that may be to big a job if you are only interested in the behaviour of the waveguide.

Regards,
Bjørn

I don't think that measuring the T-matrix of the driver is too tough, certainly not with a plane wave. I have gotten good models by just doing three tests. 1) the driver radiating from its open throat;
2) the same test with an open back and;
3) the driver with the throat blocked.
By fitting the impedance curve to these three different conditions - with appropriate models - and using know dimensions it is possible to generate a very good T-matrix model. Maybe not exact, but I have found it good enough. A lot depends on the detail one is looking for.

We should take this discussion to another thread. I'll set that up when I get a chance. Its a holiday here and we are having 17 people over (plus us three), so I am kind of busy.

I still cannot get on your web site. IE just refuses to load it and I don't have any other browsers.
 
Hi Lynn,
This may not be unique to Ariel. No two amplifiers, SS or tubes, sounded the same on my setup, with both my previous speakers and present one.

Possibly, the Ariels are more revealing than other speakers, I haven’t heard them.

I never intended the Ariels to be "revealing" in the audiophile sense, but that's how they turned out. They do better than many audiophile speakers in the objective sense: flatter response, quick time decay with good freedom from resonance in the decay interval, and low diffraction. They're aimed at people who like the sound of electrostats but want more dynamic range and better imaging.

The impedance curve falls between 3.5 and 10 ohms, with low reactivity. There are some transistor amps that are so badly designed they cannot deliver even 20 watts into 3 ohms without triggering the protection circuits, although I've never had this happen with any visiting amp (or HT receiver).

Modern home-theater receivers seem to be especially bad with reactive loads ... just plain cost-cutting and carelessness from I what I can see. All of those little stickers on the front panel means many royalties were paid to Hollywood IP companies (HDMI, Dolby, THX, DTS, etc.) for the algorithms inside the digital do-it-all chip, and less was available for physical things like transistors, heat sinks, and power transformers. Most of these receivers are now made in China: the labor costs are small, so my guess the royalty payments must be a significant part of the final retail price. It's basically the Nike business model; almost nothing for labor and parts cost, and the rest goes to marketing and IP royalties.

The high-end business isn't exempt from these kinds of marketing monkeyshines: check out the nearby thread on the latest from Wilson Audio. The fact that Wilson has received nothing but glowing reviews from the mainstream magazines (and websites) for the last thirty years tells you a lot about the state of reviewing in the industry.
 
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I never intended the Ariels to be "revealing" in the audiophile sense, but that's how they turned out. They do better than many audiophile speakers in the objective sense: flatter response, quick time decay with good freedom from resonance in the decay interval, and low diffraction. They're aimed at people who like the sound of electrostats but want more dynamic range and better imaging.

The impedance curve falls between 3.5 and 10 ohms, with low reactivity. There are some transistor amps that are so badly designed they cannot deliver even 20 watts into 3 ohms without triggering the protection circuits, although I've never had this happen with any visiting amp (or HT receiver).

Modern home-theater receivers seem to be especially bad with reactive loads ... just plain cost-cutting and carelessness from I what I can see. All of those little stickers on the front panel means many royalties were paid to Hollywood IP companies (HDMI, Dolby, THX, DTS, etc.) for the algorithms inside the digital do-it-all chip, and less was available for physical things like transistors, heat sinks, and power transformers. Most of these receivers are now made in China: the labor costs are small, so my guess the royalty payments must be a significant part of the final retail price. It's basically the Nike business model; almost nothing for labor and parts cost, and the rest goes to marketing and IP royalties.

The high-end business isn't exempt from these kinds of marketing monkeyshines: check out the nearby thread on the latest from Wilson Audio. The fact that Wilson has received nothing but glowing reviews from the mainstream magazines (and websites) for the last thirty years tells you a lot about the state of reviewing in the industry.

Respectedly good comments. On the aim for a replacement for electrostatic loudspeaker, I would expect that Ariel already probably does these two things, on range and imaging. My direct driver system does so. I have to remind people I ran a revised ELS57 and AE1 system for 37 years with valve and class A SS You learn something, and yet new
things pop up from time to time.

Your appertaining to audiophile sound is important in at least one are. I believe it can if done right beat the direct drivers. But the price is now the issue. A few dollars in parts to make a power amp in China contrasts with a premium of $600 for just a beryllium diaphragm. So this price pushes the CD into preofessional only or serious audiophile.

You can be a serious audiophile with very cheap direct drivers, and this will possible preclude those DIY ers who cannot afford the parts , versus the ones that want it both ways. i.e buy realistically priced top of the market devices. That means caps resistors inductors drivers horns and enclosured yeh? Could be $3000 in parts alone for a set of speakers.

Now your project shows it can start small ie al diaphragms with ceramic magnets through to Be and Neo for the true Audiophile.

W'ere on this audiophile horn bandwagon and do not want to get off. Will the Be Neo CD's compete as they get out there and fall to a I'll buy that price. Not at $800 on principle period. I'll wager there are cheaper ways of bettering Be. From an aerospace material coating lab view I can see huge scope for cheaper stiff materials. I am not referring to thin films of VD PD ED applied metals but I may be. Lets hope that PA speaker designers do not get the HIFI bug and start overpricing it Be? Happening already?
 
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WOW!!! Somebody gets it! Very very good!


In typical listening setup 1st reflections remain floor, followed by ceiling for HF content. Sidewalls typically follow, then for many setups rear wall. Two boundary reflections start appearing too; floor and ceiling typically are so close together, and close to direct sound that single fused response is processed.

Auralization of normalized results shows one dimensional distortions as difficult to pick out. Procedure asks one question, which answer becomes small relative to bigger question that it poses: Why do so many people have little difficulty in picking out changes in sound character with changing playback levels?

Some would like to study possible changes in diffraction behavior with changing SPL; this is difficult to do without changing non linear distortion levels, leaving non linear distortion as root mechanism. This could be broken down into non linear temporal effects and non linear frequency response effects, and non linearity as intermodulation effects.

Simple case: what happens with 12" driver used to >1kHz in typical two way design of direct radiator and horn/waveguide? For undistorted signals (or baseline level of some manner), Greatest directional cues are from content >1kHz. Harmonics for signals with fundamentals <1kHz still form primary directional cues for these types of sounds. Below 1kHz 12" driver in typical cabinet is highly omnidirectional, but harmonics radiated from 12" driver above 1kHz are not omnidirectional. These signals form diffraction patterns with signals from horn, further complicating diffraction pattern. The speaker sounds different, the room sounds different, the sound of the speaker in the room sounds different. That this changes in signal dependent fashion, means both speaker and room become unmasked. Auralization techniques as typically used do not capture this well at all.
 
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"Be Neo CD" is often lower quality sound then aluminum, titanium and other materials.

That wasn't my experience. I have owned (and used) Altec 604, 802, 806, 902, 288, 290, 291, GPA 288, Radian 745 ceramic/aluminum, and now the Radian 745NEO/Be. The 745NEO/Be has been the only CD in my system that hasn't had trouble with the sound of upper strings.

I have heard titanium in other people's systems, and don't care for the sound.

I'm not bothered by the cost of the 745NEO/Be. It would have been much cheaper for me had I started with them!

Lynn really liked the 745NEO/aluminum. But enough is enough--I'm done buying compression drivers.

3DHorns, is that your horn system in your avatar? I could never fit a system like that into my listening room, but it looks very interesting and I'd love to hear about it.
 
Hi Barlywater
This is a difficult area to suss out for a couple reasons beyond just trying to associate what “it” sounds like to how its measurements look..
First, the timber of your ears hearing changes with level, a look at equal loudness curves gives an idea just how much your response changes with changing levels.

Your ear has a protection mechanism where it partially shuts down the ear canal causing what they call “temporary threshold shift” imposed on your hearing.

These variables are added to the task of evaluating what you are hearing.
From the large scale sound perspective I would add;

From the faithful reproducer standard, one can say a loudspeakers electromechanical performance consists of two ideals;
First, to convert the electrical signal into a radiated sound pressure waveform equivalent.
Second, to minimize any additional “free sound” generated by the mechanism and electrical conversion and “within reason” preserve the frequency / time relationships present in the input signal.
One could also say that to the degree harmonic distortion is present, it is “new” energy not in the signal that is added to the high side of whatever fundamental frequency it’s tied to and so VERY OFTEN before you reach “ugly distorted loudspeaker” level, it’s bright / brittle sounding.

To this area, it is a case where the non-linear things a loudspeaker does contribute “free sound” at a rate that increases faster than the desired signal with increasing input level. Making even this complicated is the fact that as Earl has observed, IF the distortion is short (like peaks) a surprisingly high level of harmonic distortion can be subjectively inaudible.

So with ones ears being a variable and chasing what one hears making loudspeakers that have to go loud, what to do?

Simple, the outdoors and inverse square law becomes your friend, every time you double the listening distance, you lower the spl reaching you 6dB. To the degree one has a CD sound source like an omni , the frequency response doesn’t change* with distance, only the SPL falls. * at high frequencies there is some hf attenuation via air absorption.

Part of the funny part is we judge “how loud” a sound or loudspeaker is in part by what it “sounds like”. We have all heard painfully loud speakers at concerts and we instinctively know that sound.
When moving to listening at a large distance, if what you hear gets better sounding as you move away, that part was probably your ears / loudness issue. If it sounds worse though, it will more obviously sound like a loudspeaker in distress and now being a lower SPL, the bad stuff is standing out of context of our experience.

It has proven to be difficult to project 500- 1000 feet and still sound like hifi that far out but it can be done even in a football stadium and at low level up close, only sounds better because of the headroom.

One can remove the two ear spatial hearing process and level expectation issues too by listening to a loudspeaker through a measurement microphone and headphones. Maybe get used to the lack of spatial image by listening to house sounds and friends talking etc first.
The mic lets you listen from one point in space and so can also be used to “hear” the radiation pattern if you wave it around the speaker while listening with headphones.
Play pink noise with the mic and headphones and you might be surprised how much you hear moving the mic around. Do that with the speaker at mid room height away from walls and at 1 meter or less, much of what you hear then is the radiation of the loudspeaker itself. If you have a program which allows you to record say 15 seconds and then display that as a 15 second spectrogram, you can fudge a quick polar pattern measurement a way my co-worker Ivan came up with using Smaart and introduced to Synaudcon.
You attach a string to the speaker center and play pink noise, then record holding the mic pointed at the speaker as you carefully walk a 180 degree arc around the front at say 2 meter radius (the string). Play that recoding and look at the spectrogram and you see a graphical radiation pattern, the lobes and nulls etc.
Generation loss recordings with a measurement mic in a semi anechoic space also rapidly reveal a loudspeakers subjective sonic warts.

FEW loudspeakers sound listenable after even 2 or 3 generations and often once you have heard a caricature of “what’s wrong”, you can go back and hear that wart in the loudspeaker live.

We did ours on a tower outside to eliminate the room (during the development process) with the object of hearing what it is that prevents it from being a subjectively “Faithful reproducer” capable of many generations. With some loudspeakers, you could hear “what’s wrong” just listening through headphones and measurement mic live.
I am not sure I have ever seen anything that suggested that the way sound radiated from the loudspeaker (post electrodynamic conversion to sound) other than cone breakup changed significantly depending on level with the exception of the shocking up (aka throat distortion) our old acoustic levitators produced at high intensity (>160dB) .
Best,
Tom Danley
 
That wasn't my experience. I have owned (and used) Altec 604, 802, 806, 902, 288, 290, 291, GPA 288, Radian 745 ceramic/aluminum, and now the Radian 745NEO/Be. The 745NEO/Be has been the only CD in my system that hasn't had trouble with the sound of upper strings.

I have heard titanium in other people's systems, and don't care for the sound.

I'm not bothered by the cost of the 745NEO/Be. It would have been much cheaper for me had I started with them!

Lynn really liked the 745NEO/aluminum. But enough is enough--I'm done buying compression drivers.

3DHorns, is that your horn system in your avatar? I could never fit a system like that into my listening room, but it looks very interesting and I'd love to hear about it.

There is so much confusion sometimes. The ubiquitous SEAS 27TBFCG is an aluminum alloy dome. This has beaten more 1" tweeters in back to back tests, so it is really how you design and engineer the use these materials that decides how the tweeter tweets.

When back to back was done by Zaph of a well know tweeter in aluminum, hard anodised aluminum silk and titanium, CSD results were almost identical. You could possibly pick out dome resonsance above 20kHz which is generally inaudible. The SEAS above rings at 27 KHz. Nobody complains.

The recent posting back a few weeks showed the 745 ceramic against the Be version.The FR traces were almost the same but for the treble where the Be rolled down more smoothly with no nasty jagged peaks. So for most music on paper should not hear a difference. If we roll off the top aadd a super tweeter RAAL or Fountek we can save some money. Now some one may claim the Be is better sounding all the way. If so the series roll off cap on the Al version may recover that. This could save $500 per speaker.

Why do so many good speakers use silk domes in preference to Be. It is not necessarily a cost issue. I am not knocking Be. I am a materials man and accept that it is not all down to Young Modulus etc. If you come away from Be vapour or chemical deposition to alloys and composites these are eventually likely to win the material war and be a lot cheaper.
 
"Be Neo CD" is often lower quality sound then aluminum, titanium and other materials. many times alnico and ceramic magnets easily out perform neodymium. It seems most new people to horns often waste a lot of time and money with this type of thinking. i do not always recommend cheap parts to build the horn system but to start it should begin with the midbass horn and be developed from there rather then the midrange horn and scramble to find a driver to "match". The core of sound is 100 to 1000 so I advise to get that built first in mind then decide on how to match the harmonics.

I have compared almost identical neo and ceramic magnet 1" Beyma compression drivers using a plastic foil diaphragm. The neo version was always a little more detailed, but too intense sounding for my taste.
 
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Going back to the discussion of "moderate-power vacuum-tube amplifiers", I highly recommend this diyAudio thread. The Mullard circuit, in particular, is not hard to build, and is superior to the great majority of amplifiers marketed to audiophiles. Translated into crude dollars, it'll easily hold its own against audiophile amplifiers in the $9,000 to $25,000 price range.

This is a DIY group, but for those not comfortable with high voltage or a soldering iron, Jim Nichols (JWN) builds an excellent PP pentode amp for not much money. The linked PFO review shows a picture of the one he built for me.

Building a high-quality amplifier with direct-heated-triodes is another animal entirely. DHT's require twice the voltage swing of pentodes, the driver must be more linear than the output device, and these designs typically have no overall loop feedback, so attention has to be paid to layout and grounding techniques. Getting these things quiet and low distortion is a bigger job than a traditional Class AB PP pentode-with-feedback circuit.

Transistor amps? There are good ones out there, I just haven't heard many of them. (By "good" I mean audibly better than my thirty-year-old Audionics CC-2 amplifier.)
 
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Your ear has a protection mechanism where it partially shuts down the ear canal causing what they call “temporary threshold shift” imposed on your hearing.
Good audio I find works on this, the ear/brain AGC does an excellent job of keeping the sound balance subjectively 'right', perhaps because this is part of what one learns instinctively as part of growing up.

Quite a number of times over the years I've deliberately done the exercise, when hearing some music completely acoustically produced, is to then approach the source to as close as I can - all the time noting how my hearing is registering what's going on. A classic example is a brass band in full cry, 100 metres down the road - OK, that's the sound 'signature', now walk towards them until I can literally touch one of the band members, and the sound of the instruments completely blocks out the sound of the atomic explosion back where I came from, :D ...

The hearing system can handle this, beautifully, so IMO that is what needs to happen with a home system. The experiment, equivalent to the live brass band thing, is to wind up the SPLs so that at the furtherest reach in the house the sense of live music permeates through, it sounds fully "real". Then, walk towards the audio system until you're directly in front of a speaker, move your head until it's only a few inches from the drivers - not touching the volume the whole time. If at that point you've got the "brass band an arm's length away from you" sensation then the system is doing all right ... :)
 
Going back to the discussion of "moderate-power vacuum-tube amplifiers", I highly recommend this diyAudio thread. The Mullard circuit, in particular, is not hard to build, and is superior to the great majority of amplifiers marketed to audiophiles. Translated into crude dollars, it'll easily hold its own against audiophile amplifiers in the $9,000 to $25,000 price range.

Hi Lynn,
It's first time I hear any review, or opinion, about that amp.
What did modern amps do to screw up the sound?
 
The classic Mullard has been around since the early Fifties. Not many were imported into the USA, but they were all over the Commonwealth countries in the Fifties and early Sixties. I remember seeing them, along with the Quad II, at Radio People in Hong Kong, so they were around, usually with "Tropicalised" plate on the back.

Modern vacuum-tube designs, at least the ones aimed at wealthy audiophiles, go all-out for power and bass "slam", which magazine reviewers are always obsessing about. High-end manufacturers mimic solid-state techniques: regulation, more regulation, very large capacitance in the power supply, multiple feedback loops, and large arrays of output tube running in Class AB.

A conservatively operated PP-pentode amp will give an honest 35 watts RMS per channel. If you want 60 watts from the same output pair, you can back off the bias, decrease the Class A operating region, and increase the Class B region. This increases power at the expense of more low-level distortion. In practice, 60 watts doesn't sound any louder than 35 watts, since overload behavior and recovery dominate the perception of loudness.

The only reason to use more than two output devices is more power; quality goes down, not up, since multiple devices inevitably have slightly different Class AB transition points, which substantially degrades low-level distortion. This applies to pentodes, direct-heated triodes, bipolar transistors, and MOSFETs.

Solid-state rectification has the advantage of cheapness, cooler running, much higher current capability, and much less voltage sag under peak loads. It has the disadvantage of 10x more switch-noise (we're talking about 1000V peaks here), which radiates into the circuit and down the power-line, to contaminate other equipment. Yes, snubbing techniques help, but there's a big difference between a diode that has a rough on/off action spread across 0.7V and a diode that has a very smooth action spread over 12 to 30V.

I could go on. The tube amps that have gotten the glowing reviews from the hifi press over the last thirty years are usually overpowered behemoths that are substantially inferior in sound to pretty ordinary tube amps from the Fifties. Part of the reason that SETs took off in the Nineties was that mainstream high-end amplifiers sounded so nasty ... and rogue audiophiles made the discovery that old junk, barely restored, sounded better than the latest-and-greatest $7000 confection from Audio Research.

This is exactly what happened to me and the intrepid band of Tek guys who were working on our little MOSFET project for three years. We went to one of the first Oregon Triode Society meets back in 1991, and one of the members demoed an especially foul and rusty-looking Dyna Stereo 70. The chrome on the chassis was so badly pitted it looked like it had been dug up from a hole in the ground.

The so-called "mod" was a Triode Conversion, which consists of moving the screen connection of the EL34 from the transformer winding to the plate pin. The fancy version of a Triode Conversion is putting a 100-ohm, 10-watt resistor between the screen pin and the plate pin of the socket. Not exactly rocket science.

The ugly little Stereo 70 cleaned the clock of the top-reviewed Audio Research. Not even close. It sounded better than any amp the dealer was selling, and not by a small amount. It made the other amps sound broken. Not surprisingly, the dealer did not welcome any more OTS meetings. Bad for business. It was a wake-up call to everyone at that meeting: don't trust the reviewers, listen for yourself, and get serious about building your own.

After that meeting, our group of three abandoned the MOSFET project.
 
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