Restored and Improved: Sony SS967 Speakers

Sony SS967 Speakers

We have completed another great project – total overhaul and restoration of the vintage Sony speakers. We never been huge fans of Sony speakers, but when we saw the ribbon twitter installed in this pair we decided to give it a chance.

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SS967 LINE HISTORY

Sony actually have made several attempts  to make a decent speaker line.  The SS series were originally made in Japan in 1978. They come with factory swivel stands and had blue fronts. Some reviewers believe these speakers were made to complement the original Sony Session Systems like ST-636 and TA-636 in late 70’s. And the 967 were probably the biggest in that lineup but not exported to Europe, unlike the systems above. The SS967 have quite interesting sound, surprisingly good build quality, they are a 3-way design, but the ribbon tweeter is by far the best component on them.

RIBBON TWEETERS

Ribbons have a thoroughly deserved reputation for being special. Some of their advantages:

• Low mass
• Ultra-fast transient response
• Able to reproduce frequencies even above 50 kHz

These advantages come with the cost… Nothing is perfect in this world and ribbon tweeters are not exception. Known issues:

• Ribbon tweeter demands unusual manufacturing precision
• They don’t respond particularly well in the middle frequency
• Due to their low impedance, they may require a matching transformer

Sony SS967 Ribbon Tweeter

OVERHAUL AND RESTORATION

The speakers came to our lab were in quite rough condition. The wooden finish was scratched all over the place, blue front panels faded and had some decolorizing spots. We decided to restore it to the “almost new” condition and apply some improvements that affect the sound dramatically. All drivers are working properly now. No static in the controls. Woofers required some cleaning, but they are in great condition now.

Here is the list of repairs and improvements:

• all internal wiring replaced
• spring roll ports at rear panel replaced by premium grade threaded ports
• the inner box was resealed and airproofed
• sound insulation material replaced
• grills repainted and fabric replaced
• cabinets have new veneer finish
• front panel repainted, now it is black
• the biggest upgrade we did is the installation of rear passive radiator

PASSIVE RADIATOR

A passive radiator is a speaker without the magnet, and electronic structure attached to it; it is just the cone, suspension, and frame. A normal speaker can be used as a passive radiator. Passive radiator expands bass area and improves low frequencies reproduction.

We carefully calculated the size, weight and location of the passive radiatorы for these speakers. And the result was marvelous, to say the least.

Sony SS967 Speakers with passive rear radiator installed

THE SOUND

We were actually shocked at the sound from these speakers, as we don’t really ever expect too much from Sony. You would not believe your ears once you experienced their their sound! The speakers themselves are not huge, but the sound is big! Highs are crisp clear thanks to ribbon tweeter and the bass is energetic and punchy!
The verdict: these are fine sounding speakers: well balanced and smooth. Probably best suited for classical and/or jazz.

Although we are very proud of our restoration efforts result – we put these speakers on sale. Simply put it this way – we have several pairs of more superior speakers. So if you are looking for the small or average size room speakers – this is something that will make you and your guests drop their jaws!

Set up for audition. Pick up only in London ON.

MORE ABOUT RIBBON TWEETERS

Ribbon Tweeter Pros

Ribbons have a thoroughly deserved reputation for being special. Their low moving mass and evenly spread drive over their whole surface means they have a potentially ultra-fast transient response, so if detail resolution and delicacy are your main priorities, ribbons could be just what you’re looking for. Ribbons respond to the most subtle waveforms, and to the highest frequencies, including those above 50 kHz that are the special preserve of high resolution formats like DVD-Audio and SACD. They can easily cope with the subtle ultra-high harmonics that lie above the main part of the audio band, and which add some of the air and sense of space you will hear from a really fine recording. Domes on the other hand need a suspension to work, which introduces a hard to control compliant mass to the system, and this inevitably introduces high frequency resonances which under the right circumstances may be audible.

Domes have a significant mass – often around half a gram – and they need a suspension to work, and they may have ferrofluid injected into the voice coil gap, and these things add additional compliant mass to the system, which is not ideal. Ribbons are essentially undamped, and well behaved when controlled by their magnet.

Even the shape of the ribbon influences the sound. The ribbons themselves are generally narrow and tall, which gives them wide lateral dispersion and very limited vertical dispersion (due to cancellation). Narrow vertical dispersion is often beneficial as it reduces muddling ceiling reflections (reflections from the floor are not usually an issue as they will be absorbed by soft floor coverings), while the broad, even horizontal dispersion gives a wide sweet spot which is good for households with multiple listeners. Another plus point with speakers equipped with ribbon tweeters is that they tend to sound predictable and consistent from room to room.

Ribbon Tweeter Cons

The ribbons themselves have characteristically low impedance, which can be hard to couple to the system amplifier. The usual solution is to use a matching transformer, increasing cost and complexity.

The way ribbon tweeters work demands unusual precision in their manufacturer. The coupling transformer for example will have very few secondary windings, in some cases as few as five, so even minor variations in the way they are assembled can have a disproportionate effect on their audio behaviour.

Ribbons don’t lend themselves naturally to production line automation – another reason for their high cost. There are some reasonable low cost ribbon tweeters of Chinese manufacture, but even cheap ribbons are expensive in everyday terms. In addition the overall design of ribbons tends to be complex for the reasons given earlier, and sound quality is not necessarily an improvement over conventional designs – though the best of breed do inject a touch of magic into the sound that is hard to find elsewhere.

Ribbons don’t respond particularly well in the middle frequency region because they don’t usually work well at their lower frequency limits, where dome tweeters are still on song. As a result the majority of speakers with ribbon tweeters are three way systems, meaning that they include a dedicated midrange driver. There are hidden traps for the unwary here too, as the dispersion of midrange drivers near their high frequency limits tend to become very directional and may not work well where they overlap with the ribbon’s output. Very few ribbon tweeters will work down below 2.5 kHz, and one consequence is that crossover designers are forced to use high order filters in their crossover networks which can be problematic.

Scandinavian manufacturer Dali has gone to the extent of designing a novel twin driver tweeter assembly, which includes a moving coil midrange unit combined with a high frequency ribbon sharing a single faceplate. There are some good two-way ribbons, an example of which is the Monitor Audio PL100, but they’re few and far between.

The bottom line here is that ribbons tweeters are no panacea for the limitations of alternative dome based technologies. They offer some real musical benefits, but equally they introduce problems of their own. The ribbons themselves are necessarily very light and as a result this means they tend to be both fragile and very expensive, though it is usually possible to rebuild a ‘blown’ ribbon.

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