Around a decade or so ago I used super tweeters on a stacked Oris 150 horn system with good results. The speaker system came to me with the Fostex T900A tweeters already installed, so I had nothing to do other than enjoy the benefits of their extended HF output.
Over the years I’ve gone through many different speakers and several times I’ve considered experimenting with super tweeters to try to add more air, and ambiance and ultimately retrieve more detail from the speakers. But it isn’t always so straightforward. First, you need to think about a crossover. Then, you need to make sure there’ll be sufficient output from the super tweeters such that you can actually hear them! For this, you’ll need to consider the sensitivity/efficiency of your main speakers and the efficiency of the tweeters to make sure they’re compatible. And that will only give you a rough starting point, you’ll probably want some form of attenuator so you can dial in the level/output of the super tweeters for a seamless blend with the mains. Then you’ll need to think about the mechanical side of attaching them to the main speaker, and lastly, cabling and the optimum way of making the connection.
Fortunately for those of us who are less inclined towards taking on tricky DIY projects, Aperion Audio has come up with a solution.
Aperion Audio’s Dual Firing AMT Ribbon Super Tweeter
Aperion Audio’s top-of-the-line super tweeter is the Dual Firing AMT Ribbon. At a penny under $1000 it’s hardly an inexpensive proposition, but when you look closely at what’s included, it starts to make a lot of sense.
Firstly, it’s a dipole design, outputting sound both from the front and back, and its design is such that it can be matched with any speaker whose sensitivity is between 87-98 dB. That makes it compatible with a pretty good percentage of speaker systems in home audio applications.
It’s a self-contained standalone unit that can sit atop your main speakers without the need for any mechanical brackets. Next, it has a dial for adjusting the output where it can be cut in one decibel increments to a maximum of -5db. Clever or what! And if you want the extended highs but you’re concerned about the super tweeters’ ability to seamlessly blend with your mains, don’t be. The AMT Ribbon Super Tweeter also has a 5-Point Crossover setting, along with a position for ‘OFF’, where you can drop the tweeters out of the circuit without having to disconnect anything.
The 6 dB/octave 5-Point crossover can be set for 8, 10, 12, 14, and 16 kHz, with the lowest setting providing the most overlap and the highest setting, the least.
On the more technical side, the AMT Ribbon Super Tweeter is a dual-layered driver made from a Kapton/Aluminum sandwich, is 3.19 x 1.34 inches (81mm x 34mm) with 12.5 μm thick Kapton and 20 μm aluminum, for a total thickness of a mere 44 μm. For more detailed specs you can visit the manufacturer’s website here.
Connecting the AMTs to your main speakers is a very simple task, just connect them to the main speaker binding posts and you’re all set. Or, you can run them back to the amp terminals, if there’s no easy way to piggyback from the speaker posts.
How Do They Sound?
I’ve tried the Dual Firing AMT Ribbon Super Tweeter on a range of speakers and each time the results have been positive, but with varying degrees of positive. My initial project was with a pair of Altec Lansing Valencia 846b vintage speakers. The Valencias have a warm tonal balance and are quite midrange-centric in a way typical of classic designs from yesteryear. I embarked on a project to modernize the Valencia’s sound while retaining its classic speaker virtues. I would describe their main virtue as being a speaker that one can listen to and enjoy music through for many hours without developing listener fatigue. And in this sense, their virtue is also their Achilles’ heel. Being rolled off in the upper treble makes for a warm and ‘comfortable’ sound at the expense of musical information, or detail. So the first task was to try to extend the upper frequencies, capture more of the detail in modern recordings, and without upsetting the speaker’s tonal balance. Enter the Aperion Audio AMT Ribbon Super Tweeter.
Now while researching the pairing of the AMT Ribbon Super Tweeter with the Valencia, it was obvious that the AMT’s efficiency spec placed them just on the edge of being a useable match with the Valencia’s 97 dB efficiency. (The AMT Ribbon Super Tweeter is for pairing with speakers in the 87-98 dB range). After some experimentation, I finally arrived at settings on the AMTs that made an obvious, in fact, quite startling improvement. Cymbals sounded more crisp and airy, plucked acoustic guitar strings were rendered with more vibrant energy, a greater sense of dynamic realism, and more of a sense of the attack, sustain, and decay of individual notes. But what surprised me the most was the way in which the midrange opened up – the same quality and midrange warmth but a more spotlit presentation that seemed to make the whole soundscape larger and more spacious – everything in the soundstage was rendered with more space, more air, and separation.
After spending several hours listening to the Valencias with the Aperion Audio Dual Firing AMT Ribbon super tweeters in the circuit I sensed no additional listener fatigue and the level of engagement was far higher than it had been before. The old audiophile cliche of hearing hitherto unheard details on recordings was true in the sense that I hadn’t heard some things previously on the Valencias, and now I was hearing them clearly – hearing what I knew should be there but wasn’t apparent without the AMT ribbon super tweeters. Great stuff!
To prove that you can’t just use these super tweeters on any speaker regardless of sensitivity, I later removed the passive crossovers on the Valencias and drove them using the digital XO in a Lyngdorf TDAi 2170 and with active bi-amping. Removing the passive XO components raised the efficiency/sensitivity of the Valencias at which point the AMT super tweeters ceased to have any noticeable impact on the sound. I would estimate the sensitivity of the Valencias without the passive crossovers to be somewhere in the range of 100+ dB, so the AMT super tweeters just weren’t able to contribute enough to make them readily audible.
Using the Aperion Audio AMT Ribbon super tweeters with my main reference speaker, the Piega C40, brought about some interesting results. The Piega C40 has a dual AMT ribbon driver which is essentially a larger midrange ribbon with a smaller HF ribbon etched on top. A similar design/technology to the Aperion Audio though configured as a monopole and not a dipole. With the Aperion Audio AMT Ribbon super tweeters set at 12 kHz and -2db, they blended seamlessly with the large Piegas, and once again their most noticeable contribution and enhancements were through the midrange, where they blessed the Piegas with a slightly enhanced sense of air and separation. Brass instruments benefited noticeably with an enhanced sense of air and presence but never tipping over into something harsh and bright. I’ve heard similar shifts in presentation from cables costing multiple $1000s, so in my experience, the Aperion Audio AMTs represent excellent value for what they contribute.
If you have speakers in the range of 87-98 dB and you find them a little too warm, a little too rolled-off on the top end, or you’re just missing some detail that you know should be there, then the Aperion Audio AMT Ribbon super tweeters may be exactly what you’re looking for. They don’t appear to change the overall sonic character of the mains, they just seem to provide a little more of everything from the very top, all the way down into the lower midrange. And their real attractiveness is in just how easy they are to install. No complicated brackets and stands, and no need for additional capacitors, L-Pads, or resistors, just basically set them on top of your main speakers, spend a while getting them dialed in, and enjoy.