January 2006

Tonian Laboratories TL-R1 Tweeter
Review By Jeff Rabin
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What's it like to be a bat?
-- Thomas Nagel

Damned if I know, ask the bat.

  I was about to start this review with the sentence, ‘Nothing quite arouses such controversy among audiophiles as does the subject of super-tweeters.’ But it occurs to me that I could just as easily use that sentence for subwoofers, SACDs, cables, turntables, cryogenically treated valves, magic chips, and green markers…The sentence means both nothing and everything which is, pretty much by many accounts, the definition of nonsense. But one of the curious features about nonsense is that there is interesting nonsense and boring nonsense and for a select (and sometimes embarrassed) few the debate surrounding the use of super-tweeters is far from boring.

Personally, I think a very good case can be made for the use of super-tweeters from first hi-fi principles. Indeed, I have an argument for the use of super-tweeters that does not even require any listening, critical or otherwise.

If the first principal of hi-fi, the founding axiom as it were, is to reproduce as closely as possible the original acoustic event, and the original acoustic event contains frequency content that only a super-tweeter can reproduce, the use of a super-tweeter is necessarily entailed to reproduce those frequencies so as to recreate the original event as closely as possible. Otherwise, it just ain’t as hi-fi as it could be and is not the point of it all? (Actually, I am not sure it is. The purpose of domestic hi-fi, I think, ought to be enjoyment and education. But that’s another story.)

The Explanation
I can hear some of the more vociferous voices of hi-fi lunacy right now. The human ear, they say, particularly ears with hairs sticking out of them, can not hear frequencies high enough for a super-tweeter to make any difference. Moreover, the good Dr. Nyquist’s theory states that the maximum frequency that can be reproduced digitally with bog standard pulse code modulation is half the sampling frequency. For Redbook CD, that’s 22kHz, tops. What’s more, most CD players use a brick wall filter well below this theoretical maximum leaving, effectively, even less music for dogs and bats. And while, of course, SACD does go higher than 20kHz, a byproduct of Direct Stream Digital is ultra sonic noise that you will not want to hear unless you like Sonic Youth played at 78, which I do.

Such noise has also been known to melt a Krell or three. DVD-Audio of course may not suffer from such problems, but when was the last time you played a DVD-Audio? And how many DVD-Audios do you actually own? And while vinyl, in principal, is able to produce ultrasonic frequencies, such playback will only be available on perhaps the first or second play before normal stylus wear eliminates it. On FM, of course, listeners with super-tweeters may be given the pleasure of listening to the 19kHz pilot tone, but from there on up it is a sonic void. Tape me another matter, but I don’t know anything about it.

But there are also, I would like to add, a number of a posteriori or empirical arguments supporting the use of super-tweeters, aside from the fun of scaring bats, and the dogs and other vermin, none particularly welcome in the listening room. There is, for example, credible evidence that the human brain can sense sonic events of between 10uS to 20uS (equivalent to 100Hz to 50kHz. (Acuity of Laterising Transients Klump and Eady, 1956. See also Yost, 1971). In terms of a listening to a point source this is the same as a listener being able to detect a shift of 1 degree laterally. While this is for steady state sources, it has been reported that for random sources may even be better.

Furthermore, neuron firing in auditory nerves can be detected above 20kHz in healthy humans. This spatial detection is not just dependent on the relative amplitude of sounds, the ear can also detect astonishingly small differences in phase, good transient response over a wide band from the acoustic source will help with transients and with the original sound field being accurately reconstructed. If the same transient signal is fed to two speakers of headphones and one of the signals is made to lead in time the signal leading in time will sound louder and be dominant, this effect can be detected down to 2uS for detecting (Jeffress and Hafter, 1968). In real sound sources, i.e. those not manufactured with the help of a Robert Moog, but rather an Antonio Stradivari, audible beat tones can be generated from ultrasonic energy in the sources. Such beat tones do contribute to the timbre of the music and should, it would seem, be retained if you are to maintain the highest standards of fidelity.

Of course you may say if you record these sources you also record the beat products tones so the super-tweeters are not needed. But most recordings are multi tracked, rarely are all the instruments and vocals recorded at the same time, with over dubs more common than not, that such beat tones rarely if ever exist on the recording. However a wideband audio system is capable of reproducing these. Whether or not this is a good or a bad thing is, as with many things in audio, a matter of taste. And for those of who like to listen to very loud music at very high volumes, at high SPL air inter-modulates (above around 130dB) and to accurately reproducing such inter-modulations could also be an interesting reason for having a supertweeter. Cerwin Vega, who know more than most when it comes to busting ear drums, have done a lot of work on this for their coaxial drivers with ribbon tweeters.

The above empirical arguments I cribbed (to put it politely, plagiarism is probably closer to the truth) with the help of Southern Ontario based audio engineer who has spent a lifetime looking into these and other problems. This, our intrepid designer hastened to add was prefaced on the distinction that such super-tweeters did not begin only begin to work at 50kHz and go on from there. Obviously, then, the Golden Sound Super Tweeter, reviewed very well elsewhere I should add, a super-tweeter that only begins at 1GHz (!!!) need not apply.

So I am bitten. You might even say I am prejudiced. Before even listening to a super-tweeter, I want it to work. I want to know that I have the hearing of a bat and know once for all that the reason I dislike dogs in the park is not the dogs but the owner’s whistles. And so we come to the subject of this review, Tonian Laboratories TLR1 super-tweeters. It’s not every product that’s not snake oil that you’re not even sure if you will hear.

Well packed in Styrofoam, the super-tweeters weighed in about 3 or so kilograms each, and were about 15 centimeters wide, 15 centimeters deep and just over 20 centimeters high. The weight is accounted for not by the ribbon that weighs next to nothing, but the internal transformer. My review samples came in matte black, but for an added charge, they can be finished in other colors. Attractively finished, I thought the tweeters with their silver slits and black box rather looked the biz. My wife, alas, was less than impressed comparing them to Darth Vader, and this from a woman who has so far as I know never seen a Star Wars film that has Darth Vader in it. Looks of course are a matter of taste and are in the eye of the beholder but in this case, my wife is (she doesn’t read this stuff anyway, only edits it) simply wrong.

The Hookup
Installation was quite straightforward except for the fact that each speaker has two positive binding posts and one negative binding post. My confusion was quickly cleared up. If the super tweeter is to be connected directly, without attenuation, you run a pair of wires from the input terminals of the speakers that you wish to mate the amplifier with. If you need to attenuate the super-tweeters, as they are rated as 97dB/W/m efficient, you can place a resistor of your own choosing with a valve of your choosing between the second positive terminal and the real terminal. This seems to me a rather ingenious as attenuation is set and forget and you can insert whatever value resistor you would like to match your main speakers. It is unlikely, I imagine, that you would pair these super-tweeters with speakers of greater than 97dB/W/m, but if you did, other means may be required and as I understand it, Tonian Labs can supply examples with even higher efficiencies.

The manual specifically warns against connecting the super-tweeters directly to an amplifier as doing so may cause your amplifier problems. Bi- and tri-amp’ers ought, therefore, to tread carefully with their interconnects. As an experiment I did connect the super tweeters directly to my Audio Note Kit 1 amplifier but experienced no such problems. I was however watching the amp closely and had my favorite annoys wired in parallel. No nasty smells either, always a bad sign and not just in hi-fi.

The Listening Part 1
I then placed my ear close to the tweeters. I had prepared a test disc to see if my spidey senses, make that my bat-ears, were at all functional. Oddly enough from about 16kHz on up I could hear a faint whine through the left super-tweeter and nothing at all from the right. My thoughts were:

1) One of the speakers was damaged in transport and

2) the functioning one crossed over much lower than advertised.

This review was a little unusual as it is often the case that short hanging up the phone, I can’t get the manufacturers to stop telling me about the underlying theory and practice of their products. Tony, of Tonian Laboratories (geddit), was a little less forthcoming.

Tony,

I wish I can talk more about the technique we use, but we definitely do not want some information to be revealed on the internet or any other magazine. We found out that most of the industry is stealing information from each other and basically copying ideas. An average customer really doesn't care about the crossover point, materials, cables, and etc. All they care about is a good-sounding speaker.

I am not sure I completely agree with this. It is of course true that the customer does want great sound from his stereo, or a great ride from his car, but when it comes to making a substantial purpose for one’s Hi Fi, it’s important to know how the new component is likely to react with the old ones. Does your speaker’s treble roll off slowly or quickly. How high do your existing speakers go? If you are using some form of either digital or analog correction system, how should you configure it? If you are bi-amp’ing or even tri-amp’ing, how is the speaker going to react with the amplifier. It’s no understatement to say that just as all speakers are different, as are most amplifiers as are rooms, ears and tastes: It’s just good to know these things so you can at least place yourself in the right ball park before tweaking the system to audio nirvana. It’s also nice to know what exactly you’re buying.

Just trust us is in these days of audio hyperbole and snake oil is, I believe, insufficient. Having your hard work stolen from you is no fun either, so I suppose a happy medium can be found and it does sound as if Tony was burned in the past and you certainly don’t have to and buy Tony’s excellent super tweeters if you don’t want to.

But Tony did allow the following to appear in print, belying his professed reticence at spilling the beans:

We designed the tweeters after testing lots of dome tweeters and we found out that none of them, even the expensive ones like the Diamond tweeter or the Beryllium tweeter, came close to the ribbon. Hence we thought we could help some customers who already have speakers to have a better transient response by adding the tweeters. The experience varies due to peoples' electronics but once they spend time and match the tweeters to their system, they will be very happy. We highly believe in a resonant cabinet and our speaker-design philosophy is based on that. We like full-range drivers to blend with the ribbon tweeter. We also use crossovers in some of our speakers, which is unusual in the world of high-efficient speakers. Some people like to put a full-range driver directly to the amplifier and think that they are getting the purest sound. As we measured the full-range drivers (we also carry and distribute the highly regarded ones, such as PHY-HP and AER), we came up with the conclusion that it is impossible to produce sound between 20Hz and 20kHz with a single driver. They all have their own flavors, but once the right crossover is used for them, and they are blended with the ribbon, the result is a perfect transient response in the low, mid, and high frequencies.

So That, As They Say, Is That.
But as I said, one of the two super-tweeters out of the box was dumb as a doornail while the other gave off just a very faint, very high frequency, taste of music. Throwing caution to the wind, I decided to crank the amplifier to see how loud I could get them to play. As I was using tubes, I thought that I would be saved frying them with some soft 300B clipping and guess what happened? Rather than smoking them, the quiet one came nicely on song  It has not previously been my experience that over driving a tweeter is the way to repair them, but in this case it was.

Setting up the super-tweeters was simplicity itself. After taking them out of their well packed boxes (after paying the FedEx bastard a ‘customs brokerage’ fee, I placed each tweeter on top of each of my Tannoy D700s, approximating as far as I could to line them up on the same axis as the ‘speakers’ tweeters. Not quite sure how far back to place, I experimented with a number of positions from flush with the front to flush to the back. As my speakers have nothing on their top surface that is at all grippy and as the super-tweeters had nothing grippy on their bottoms, things tended to slip slide away some. I see other people have used such super-tweeters with stands all their own, not a bad idea I think, but I am already pushing it when it comes to gear in my listening room. Instead, I found some ‘puds’ from an old Cambridge Isolation Stand and squashed one between each of the speakers. This gave me a firm foundation that I could set an’ forget and hopefully isolate somewhat the tweeters from cabinet vibrations.

The system at the time was bi-amplified. A Nad Silverline provided bottom. Top end was delivered by a bog standard Audio Note Kit 1 with TJ Mesh Output Tubes. Sources ranged from a Sony SACD player, a Garrard 301 turntable with Rega Arm, Goldring Cartridge and EAR Phono Preamp. Preamp was also a Nad Silverline. Power conditioning was by Monster. And there was a variety of cables employed — nothing coherent about this cable loom. Standout cables were prototype Masonics of Masonic Cables, Datchet. A monster of a subwoofer, subject of a forthcoming review, provided extreme bass duty. Couch by Ikea.

The Listening Part 2
Hoping to actually hear these super-tweeters I played mostly SACDs. Serendipity would also have it that my local HMV was blowing out Mercury Living Presence and RCA Living Stereo’s, two for $20. I think I must have bought all of them all, which may have been a mistake as there not all good. Of course these being older recordings, it was not clear that there was much high frequency content available on them, but what the heck. I also unsealed a few junk store classical music finds that still had the cello tape to see if there was any truth to there being super-tweeter friendly content on them. I also, as always, listened to a great deal of radio, my one and only awful sounding DVD-Audio. (What was Led Zeppelin thinking.) I also played a variety of more modern SACDs such as Eden Atwood (the song Boy from Impamema still makes me feel odd), Diana Krall’s The Girl In the Other Room and some regular music DVDs such as Clapton’s Sessions for Robert J. I also played Pink Floyd’s SACD of Dark Side of Moon.

What were my impressions? I’d say that on first listen I found the super-tweeters indispensable and immediately sent a check off to Tonian Labs to keep the review pair. Truth be told, initially, unless I had my ears pressed right to them (and they definitely crossed quite a bit lower than claimed) I couldn’t actually hear them, good or bad, at all.

But then went on Dark Side of the Moon, CD and SACD. This was my first clue that the tweeters were really working. I could immediately hear that they were doing something quite different to the extreme treble. They made the treble sound distorted and harsh. I later learned from the very self-same audio engineer previously cited that it was not the tweeters that were wrong, but the recording. This was definitely a good sign.

Extended listening led me to notice all the things a super-tweeter is supposed to do, but everything they did do was enormously subtle and while I think I could tell you on a regular basis whether or not they were switched into the system, I would not want to do an A/B test in front of my mother. Midrange was perhaps a little more fulsome. There was a certain addition of ‘air’ to the high frequency and imaging was mildly improved. Diana Krall’s SACD The Girl in The Other Room sounded absolutely fabulous and I don’t even like Diana Krall. While the Living Stereo SACDs were definitely a good purchase, I couldn’t tell whether or not the Ribbons were connected or not with them but I think this owes more to these elderly recordings than it does to these super-tweeters. While I had the super-tweeters in my possession I fell into one of my regular cello binges. Weirdly, while digging out my Rostropovich (no yo yo for me me), Du Pre and even Ofra Harnoy, I could have sworn cello was richer and more extended.

I would say that if your system is already enormously resolving, you listen to a lot of modern high-resolution recordings and you just need to make that next step, the Tonian super-tweeters could just be the ticket for you.

Specifications
Type: Supertweeter

Tweeter 2.5-inch ribbon tweeter

Frequency Response: 15kHz to 40kHz

Nominal Impedance: 8 ohm, DCR 0.02 ohm

Sensitivity (Variable): 85 to 95 dB/W/m

Power Handling: 17W nominal, 40W max

Dimensions: 8.0 x 4.75 x 6.5 (HxWxD in inches)

Price: TL-R1 as reviewed $950, larger TL-R2 $1,250 

Company Information
Tonian Laboratories
700 South 6th Street
Unit 107
Burbank, CA 91501

Voice: (818) 848-9881
Fax: (818) 848-9090
E-mail: info@tonianlabs.com
Website: www.tonianlabs.com