I was slowly looking for a compression driver that would go in my Fundamental Chanel down to 200Hz. The YL Acoustic 550N attracted my attention. Then I realized that it is the narrow throat type of the drivers, aka WE555, not exactly that I would like to use for Fundamental Chanel. However, what I was looking information about 550N I came across a Japanese site with interesting read:
It looks like it has a history of those “exotic in US Japanese drivers” and I am quoting it below. I do not know how accurate the information from user JJK, treat it as anything else coming from internet. Since the folks who sell that stuff do absolutely nothing to publicize the information about those expensive driver then it is what it is. I have to warn that I do not agree with some of the motives that JJK injects into his story about those compressions drivers but it is not my text and I just reprint it:
By JJK From : 2009-2-8 23:43 ****************************************************************************
In the beginning was the Western Electric 555, still today sought after and going for high prices on the market. In 1926, lets remember us, it makes 82 Years by now, that E.C. Wente and A.L.Thuras projected it at Bell Labs.
It was unifying innovative and revolutionary solutions, still in use today !
They were rated 30 watts RMS, and a frequency response from 60hz to 8000hz. Of course the motor was not alnico, but a very strong field coil. At the gap , it developed 20000 gauss, which was extraordinary for it’s time. It was possible because of a mix of cobalt, nickel and other materials. For the first time, a tangential suspension was utilized, still today a reference.
And for the first time as well, edge wound voice coil was used. These techniques were not the invention of the two developers of the 555, but were used after their research. Another “ first time “ was the use of a phase plug. Of course, the one used in the 555 was far from being perfect. Note the different distance of the phase plug to the diaphragm, but bigger on the border. This was due to standing waves. Also , the diaphragm was not used inverted, as today is common. This configuration has a lot of advantages, but a important disvantage, which is higher costs to make them. Also, the diaphragm has a strange fold of the suspension part of the diaphragm. This is where the most rigidity is, since it is also the point with major variation of pressure. This solution helps considerably to lower 3th harmonic distortion. Another note : this driver had a efficiency of 30 – 50 % , which means 110db/wm, using 3 watts at the voice coil. The weak point of the 555 was the phase plug, very simple and not aloud the transmission of high frequencies. In fact already the following model, the 594, was a considerably improved design in this regard. In fact , the goal was to improve the treble capabilities. However, WE modified also other parts of the driver, to be able to produce it at lower cost, and to give easier assistance. The 555 was the starting point for the Japanese high efficiency compression drivers.
The 555 was the starting point of the compression drivers, and the 594 of all drivers commonly used today. At that time back, compression drivers were indispensable because of the low power of the amplifiers, specially for cinema and outdoor usage. However, even at this time, many enthusiasts were using these diffusors at home as well. These drivers had low power handling, and other constructive solutions, which made them suitable for home use. With time, the amplifiers improved power handling, and it was not indispensable anymore to use high-efficiency transducers at home, but only in cinema applications, P.A. etc. At the same time, the progress of technology brought important modifications of speaker design. At this time, horn speakers and compression drivers were used exclusively for cinema and professional use , were high power handling was important. In short, the modifications were important, and we arrive today. Many prejudgments of horn loaded speakers derive of listening to wrong designs and concepts. Modern P.A. drivers and horn loudspeakers are made for opposed needs to domestic use. So, they wont work well. High efficiency horn drivers for home use must be developed specially for this purpose. And this is exactly what the Japanese made. They started with the 555, and made improvements, remembering , that the homes had small rooms, the needed power was small etc. And they remained with the solution of the diaphragm not inverted, but directed to the throat exit and phase plug, because better. They didn’t care about cost, but only about the result. Important advantages of high efficiency is , that the signal information does not get lost, the distortion is infinitely lower, the diaphragms are extremely light, the needed power is ridiculously small. All reasons, that make high efficiency speakers for home use fantastic.
In the beginning were YL ( Yoshimura Laboratory ), and they became very famous. YL started with the 555, and tried to go beyond. Even today, if not produced anymore for many years, YL drivers are very common in Japan, and many used ones are available. YL let a important mark. All contemporary high efficiency speaker designers in Japan had their beginning at YL. Goto was founded 1965 by Seya Goto. Goto san was employee at YL Acoustic, which president and founder was Yoshimura San. In a short time, Goto got responsible for development and construction of compression drivers for home use ( hi-fi). Beside Goto, Endo San , founder of ALE acoustic, and Koizumi San ( founder of Onken ) were also former employees of YL Acoustic. 1965, after some important developments of drivers for domestic usage, YL ( which was not a small company, but rather making products at industrial scale ) decided to work with other products, more compact and easier to produce, directioning to finished speakers with folded horns. Seya Goto however, went the opposite route, developing more complex drivers and systems, with higher performance , without care of cost. In a few words, he wanted to produce new products , wanted to find new limits, go beyond the limits achieved at that time being. YL was not interested to go in this direction, so Goto left, and let Endo San and Koizumi with the development of YL.
Goto had in mind to make products, much more superior to the ones, YL had made in the past, products in fact, that would be the avant-garde of audio products for home use. So he started his independent research , and came to the conclusion, that the horns hat to be spherical, round, and straight. He came to this conclusion through mathematical / theoretic research, and as well through long listening sessions.
Soon after starting his venture, he met Takajo San, a famous guy amongst audiophiles in japan, and expert in master recording. Takajo San was also a passionate of hi-fi, and so, right after they met, he asked Goto to develop better drivers, with the ability to have higher dynamics and better detail . At that time, Takajo had a not very common opinion and philosophy, which today might make us smile : a audio system must be able to reproduce sound in a way, that it is indistinguishable to original sound. Takajo made a vast number of recordings, and compared them with his audio system, improving the results more and more. This influenced Goto remarkably. Takayo registered many times the noise of insects, because they represented to him very specific and particular sound, like a violin. The noise of insects is particular, repetitive, and rispid transients, very difficult to reproduce well. Takajo understood the importance of the transients , more than other parameters commonly used. So, the support of Takajo San was enormous, and permitted Goto to improve the horn profiles, to change the magnets, the diaphragms etc.
After this important and intense period, Goto presented his new products, with the promise of a sound, closer to the original sound, with the slogan : Original, and reproduced sound, must be the same. Since then, Seya Goto never stopped, and improved his products, even at a short looking, it doesn’t appear evident, the big step forward he made in more than 40 Years. Goto had in the beginning only compression drivers in his program, and not woofers. In 1965 the diaphragms of the drivers were of aluminum, like the best American tradition, from which he started. Amongst the first products were the sg17 tweeter , and the sg555 midrange. One of the first improvement were the substitution of the tangential suspension with a FRP film ( probably mylar ) : the improvement was substantial. Afterwards Takajo was fundamental also for the development of the first Goto woofer. At the time, Takajo used woofers special for horn loading, and made for him, from a TAD engineer. When one of the TAD woofers stopped to work , he searched for the TAD engineer, but the men had died , and TAD was not able to repair the woofers. So Takajo asked Goto to repair it. Goto observed intensively that object and understood that the development and production of a good woofer was perfectly in his ability. Goto never repaired that woofer, but developed one with a enormous magnet . The weight was 40kg. It was this way that Goto also started to make woofers, completing this way his offers, to realize a horn system, only using Goto Unit drivers. So the SG38W was born. Goto did find out as well, that horns had to be short, to have low distortion and a correct sound. So , contrary to all others, he choose the hyperbolic profile. This profile has a important characteristic : The impedance is constant almost from the cutoff Fc frequency, contrary to the exponential profile. This was the determinant factor of the choice of Goto, if however not the only one. Don’t let forget us the listening. The model SG370 , and SG16TT, have been produced without any change for 30 years, now. The SG38W is not the same today as in the past. The improvement of the Goto products went through various steps in the last 40 Years. Seya Goto founded his company with this goal in mind, to surpass always the limits, and this is what he does until today. Cost is not a important factor, he is driven by the passion of research, because, reproduced sound must sound the same as the original sound. Some improvement was to use stronger and bigger magnets, and the bettering of critical parts, with the introduction of very expensive but extremely well performing materials, like permendur, and last not least, with the introduction of diaphragms made of beryllium. Unfortunately, these drivers are also much more expensive.
All Goto unit drivers are hand made in Japan, including the diaphragms, with extremely tight tolerances, and exceptional craftsmanship. Really unique objects. The principal characteristics of the creatures of Goto can be mentioned in two points, that do represent the thinking of Goto:
1. low distortion. Normal speakers do have a specific coloration, which makes them sound better with one kind of music, and less good with other kind of music. This coloration depends on the distortion, the harmonics added to the original signal.
2. Transients. The response to the transience is fundamental. Normally a speaker system is projected to have a flat frequency response. However, many are not satisfied with these systems.
This is because the response in time domain has to be considered as well. Goto products do have a extremely low distortion and excellent transient response. Always with these two points in mind, Goto developed his drivers.
The actual catalog has a quit vast selection of drivers. There are drivers for 3, 4 or 5 way horn systems, in a crescendo of prices and performance. The products can be divided in 4 families : tweeter, mid-high, mid-low, and low frequency transducers. A standard Goto system has a woofer, working up to 200hz, a lower midrange covering the 200hz – 1000hz range, a mid – tweeter, covering from 1000 hz up to 5000hz, and finally a tweeter.
How to use them
A minimum configuration is 3 ways. These are not broadband devices. Goto has chosen the highest performance of each driver, but in a restricted frequency range. So the tweeter do not go lower than 5000hz, to reach 20000hz. And the mid-treble do cover from 800hz to 5000hz max. So the lower midrange drivers go down to 200hz, but do not go higher than 3000- 5000hz. So the mid-high frequency drivers can go up to 18khz, but their optimal frequency range goes only up to 6000hz. Since Goto drivers are so expensive, many do buy only one pair of a certain frequency range, and use other brands to cover the other frequencies.
A interesting topology is to use a Altec 416-8A with a Goto SG505 midrange driver, and S150 horn, and SG160 tweeter. Crossover could be 300hz and 5000hz. One important further improvement could be afterwards the utilization of a mid-treble driver, like the SG370, to cover between 2500hz and 8000hz.
A second option would be , woofer the same, Altec 416-8A, with SG370 mid-high driver , ans S600 horn, and tweeter SG160. Crossover could be 800hz and 5000hz. This second system would cost less. The further improvement would consist in using a SG505 and S150 horn. In both cases however, the drivers would be used at the limit of their capabilities.
A 4way system would be better, to be used with Goto drivers. To listen to a Goto horn system, is a worth while experience. A entirely new universe can be discovered. After such a experience, many opinions , held before, vanish. It’s without any doubt a remarkable experience. So last not least, I invite all of you to make the effort, and to go and listen to a Goto horn system .
Here are some correction based on GOTO and my experience for a 3 way system.
The SG505TT with S150 horn should only cover from 200Hz up to 1kHz - that is recommended by Mr. GOTO. To use SG505TT in a 3 way system, one should follw that advice or choose to use different horn. If choose S200 horn, the crossover can be 270Hz to 11000Hz ~1500 Hz. If choose S300 horn, the crossover can be 400Hz to 3000Hz. If user want to cover up to 5000 Hz, the SG570 + S300 horn combo is better. The best of such application is SG5880S + S300 horn to covr 400Hz to 5kHz. This way, the GOTO tweeter can cover 5kHz and up.
Here is another type of application for a 3 way system, same woofer of choose but SG505TT + S200 to cover 270Hz to 1kHz and SG370DX +S600 horn to cover 1kHz and up. The SG370DX can cover up to 18kHz and using it with 1kHz high pass filter. This will give the best low-mid range performance and still have good 1kHz to 5kHz range and also keep the tweeter range(5kHz up) acceptable.
Of course, the best is GOTO SG38WNS(200Hz down) + SG505TT and S150 horn(200Hz to 1kHz) + SG370DX and S600 horn(1kHz up). For space concerned user, S200 or S300 hron can be use by need to up shift the crossover to 270Hz or 400Hz.
"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche