Pyramid Sequerra T1 Ribbon Tweeters Extremely Rare Set Of 2

• From the Pyramid Loudspeaker Corporation promotion info October 1978 :

The Pyramid model T-1 Ribbon Tweeter

FOR THE FIRST TIME; A SPEAKER THAT REACHES 40 KHZ AND BEYOND, WITH NEGLIGIBLE DISTORTION AND NO COLORATION.

Do you know what "uncolored" high frequencies really sound like? The answer is "no" if you have heard only the conventional cone tweeters used in most speaker systems today.

Add the Pyramid Model T-1 Ribbon Tweeter to any high-quality loudspeaker system and you will hear detail you have never heard before.

Frequencies response from 3 KHz, the lower limit of the ribbon speaker, to 50 KHz are reproduced with low intermodulation and frequency modulation distortion.

Peakless, resonance free response over the whole range, so the Model T-1 adds no color of its own to the sound, but simply extends the high-speed range of the system.

The leading edge or "ictus" of musical sounds is clearly reproduced because the speaker can respond at extremely high speed;

Highs dispersed perfectly over a full 160 degrees in the horizontal plane, for the firmest stereo imaging;

High efficiency, allowing the Model T-1 to hold its own in any direct radiator speaker system, with a built-in adjustable attenuator to match lower efficiencies.

How does the Pyramid Model T-1 perform in this revolutionary way?

The remarkable performance of this new tweeter springs from the inherent advantages of the ribbon transducer, here put to use in a speaker fully, with no design compromises. Basically the ribbon transducer is simple. A thin ribbon of metal is suspended in a powerful transverse magnetic field. The signal current passes through the aluminum ribbon, forcing it to vibrate through the interaction of the current and the magnetic field.

The ribbon is the voice coil and diaphragm both.

The sound is projected by the ribbon itself; the ribbon is both voice coil and diaphragm. Every part of the ribbon is driven directly and simultaneously. There is no mechanical coupling separating voice coil and diaphragm, the source of so much distortion and coloration in conventional cone tweeters.

The vertical ribbon, 3.75 inches long and .75 inches wide, has an extremely wide sound dispersion pattern that is broad horizontally and compressed vertically. The horizontal dispersion of 160 degrees is complemented by a vertical dispersion angle of 90 degrees.

Earlier ribbon speakers compromised quality for Price.

The ribbon loudspeaker is an old idea. The ribbon microphone is essentially the same device used in reverse, has of course been in use for decades for extremely high quality recording and broadcasting. But attempts to make a successful ribbon speaker in the 1930's and 1940's failed for two main reasons. First, there were no high-strength magnet materials like those available today. Second, faced with the high cost of high-quality design, the builders of earlier speakers made money-saving compromises that robbed the system of much of its inherent superiority.

The Pyramid Model T-1 was aimed for the absolute "best".

In the Pyramid ribbon tweeter, Richard Sequerra has sought to realize the ultimate quality of the design. No penny-pinching has derailed any of the design objectives. The 4.5 Ib magnet produces a field of 3100 gauss across the ribbon. The ribbon is only 0.7 mil thick and has extremely small mass, roughly equivalent to a wavelength of air at 19 KHz. The powerful field and the low mass of the ribbon give the electro-magnetic forces complete control of ribbon motion, for the negligible distortion and extremely fast response of the speaker.

The fundamental resonance has been put far below the crossover point, at around 100 Hz. An ingenious magnetic circuit reduces standing waves that might develop when internal vibration modes of the ribbon are reflected back from its ends. Such "internal" standing waves are very common sources of peaks and coloration in cone speakers.

When added to a high-quality speaker system, the Model T-1 has the ability to "clean up" not only the extreme highs but the middle tones without distortion. Assess these results for yourself: put a Model T-1 on one speaker of a stereo system, turn the mode switch to "mono", and A-B the two channels. You will be amazed!