Vintage Japanese Drivers

One of the main reasons audio lovers have been apprehensive about getting into single ended micro power amps is the relative scarcity of efficient speakers. There are a few decent commercially available units but they are hard to find and audition. DIYers have discovered Fostex drivers which are not cheap but some of their mid-priced models are affordable and represent good value for the money. Prices asked for vintage WE, Altecs, EVs, Jensens and etc. have soared because of the demand from collectors. Another complicating factor is the size of vintage horn systems. Aficonados have also discovered old German radios and consoles from Telefunken, Saba and Siemens.

Vintage Japanese speaker units are just beginning to be appreciated. Prices at eBay for desireable Pioneer and Coral, full range, coaxial and triaxial units are starting to rise due to collectors and SE amp users realizing their merits. Look for old stereo consoles or table top radios and even early solid state models. The logic behind this is, power was at a premium in those days and for mass market consumption, manufacturers used efficient drivers to fill the living room with sound from amps with less than 10wpc. Likewise some of the speakers [plywood cabinets usually indicate good drivers inside] that were sold along with compact stereo systems are good candidates for SE amp use.

In my opinion, some units like the SK98, is on par or better than some of their Altec or Jensen counterparts. The others are good alternatives to mid-priced Fostex drivers which can be acquired cheaply at thrift stores.

The following drivers are no longer easy to find especially the alnico models, but the ceramic versions sound good too. These still come up at thrift stores or maybe sitting in the basement or attic of an older relative. This list is notcomprehensive, it is just a guide for those of you who like rummaging through yard sales, flea markets and thrift stores. Enjoy!

6" Full Range

Pioneer PIM16 OEM for Lafayette as found in SK124 bass reflex cabinets. This is the predecessor of the PE16M re-issue.Mechanical "2-way", perhaps a Japanese interpretation of the Altec "Bi-Flex"? MJ issue no. 2/2001 listed the following specs for this unit: 3W nominal, 70-16Khz frequency response, 11,000 gauss 850 gram Alnico magnet, 90db/1W/1M sensitivity and Fs = 70-85hz. Introduced in 1959.

Found inside a pair of Sony speakers originally sold with a compact system at department stores.

Same story as the Sony above, but these came from Panasonic branded boxes.

Another Panasonic but bigger magnet, 16 ohm voice coil and a whizzer cone.

Sonic Impressions - The PIM16 is probably the best of this bunch, it has slightly less bass response than a DiatonePM610B but the midrange is more 3 dimensional and has a smoother top end. The Panasonic RAS16PO2 above is also pretty good, although one can hear a slightly grainier midrange and top end, perhaps due to the ceramic magnet. The Sony and other Panasonic are decent too but not in the same league as the latter two.

I use these drivers in a recycled Coral cabinet - 14.5"H x 10.5"W x 8.75"D approximate outer dimensions and built with 3/4" plywood. 

I modified this into a bass reflex by replacing the front baffle and back cover with a 1.5" x 4" rectangular port with light poly-fill damping. 

I use them as rear surrounds but they are also ideal SE friendly mini-monitors for those who live in small apartments or dormitories. I have tried them also in open baffles, but given the foot print of the baffles and the frequency range of a 6" driver, I don't deem it practical since a decent 8" can give better bass extension.

8" Full Range

Lafayette SK98, the 1961 catalog list the following specs: freq. response = 40-16,000 cycles, Fs = 55-70 cycles, 99.5dB/watt sensitivity, 10,500 gauss/56,000 maxwells alnico magnet and 8 ohm voice coil. Notice the similarity of cone construction to the above Pioneer PIM16 and PIM8L below. I'm almost sure these were Pioneer OEM units.

This Pioneer PIM8L is very similar to the SK98 with economy cosmetics - bare metal frame and no magnet cover. Voice coil impedance is 16 ohms. These 8" drivers are pretty damn good sounding, Perhaps these are Japan's answer to the Altec 755. I rate them as the equal of a 755C or 755E with a slightly lightweight presentation. If I'll draw a car analogy, it is rather like a Honda Civic Si, smooth and high revving but light on torque as opposed to a torquey VW Golf GTi [755C or E].

12" co-axial

Lafayette SK58 12" driver with a co-ax mounted 3" cone tweeter. I modified the crossover slightly to get rid of the slight upper midrange harshness by adding another 4uf cap in series with the stock 4uf paper in oil can type. This shifts the crossover an octave higher and sounds smoother, very efficient not quite the snap in the midsas the SK98/PIM8L and the 3" tweeter not quite extended but still very satisfying.

Tweeters

Pioneer PT-3K horn tweeters came with the PIM8L above. This tweeter is in between the size of an Altec 3000 and Jensen RP103 with a 1 5/8"H x 4"W horn mouth. 16 ohm voice coil and 2.8khz recommended crossover. I use it as a super tweeter [x'over above 7khz] and this unit sounds sweet, silky and extended highs. Better than the Fostex FT17H in my opinion. Not quite as good as an Altec 3000 but quite close.

Trio/Kenwood horn tweeter Jensen RP103 clone[?], same horn dimensions. Can't remove the magnet cover but my gut feel is that this uses a ceramic magnet, the diaphragm is probably mylar. Not quite as articulate as an RP103 but slightly more extended in the top end.

Sonics AS-304A, 70s Japanese 4-way speaker with a 12" woofer, 5" midrange, 2" cone tweeter and horn loaded super tweeter. I guesstimate efficiency to be in the lower 90s but plays loud with an SE2A3 amp. It can be used "as-is", but for best sound I probably will pull out the drivers and mount the purest sounding combination of woofer + high frequency driver in an open baffle. 

Have fun and happy listening!

Open Baffle

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After building my first SE 300B amp in the mid 90s, I embarked on a search for more efficient speakers to replace my Spendor LS3/5A. I had just purchased a pair of Altec 755Cs at an Audiomart Show and was looking for a suitable enclosure for the unit. Fortunately I came across an open baffle article in Stereo Sound "Tube Kingdom", Volume 3, 1996. I don't read Japanese but these magazines (like MJ) have detailed pictures where I get a lot of ideas for projects. The article was a "shootout" of 8" full range and coaxial drivers - Altec/WE755A, Altec 755C and 755E, Altec 409B and 409-8E, JBL LE8T-H, EV Pro-8A, as well as 15" coaxials- Altec 604-8K and JBL 2155H.

The Stereo Sound plan was in metric and used a material similar to a butcher block around 3/4" thick. It was designed to take adapter plates so that an 8" or 15" driver can be mounted on the same baffle. Knowing that such material will cost a lot of money and hard to procure, I decided that the easiest way to build my baffle was to convert the dimensions to inches and make a quick trip to the lumber yard for 3/4" baltic birch plywood pieces cut to size so that I can start listening. Here is my version of the Open Baffle. 

This open baffle was part of my Home Brewer Article published in Sound Practices Issue 17.

Around the same time I embarked on this project, my friend Ding acquired a pair of Altec 604-8G and was also looking for a suitable cabinet. I immediately faxed the plan to his office and that same weekend he called stating that it was a success. He still uses the same configuration after trying a couple of bass reflex cabinets through the ensuing years. Likewise a few of my SETUP friends have so far found no reason to experiment further with enclosures.

Ding's Altec 604-8G

I later found the June 1996 Hi-Fi News and record reviews, "Classic Hifi Supplement" issue which reprinted a November 1956 review of the Wharfedale SFB/3 designed by G.A Briggs. 

Wharfedale SFB3

This baffle has almost exactly the same dimensions as the Stereo Sound version, which also shared the proportion of the original Quad ESL57, another favorite speaker from my PP amp days. 

G. A. Briggs prototype

Brigg's approach was to use thinner sheets of plywood "sand-filled" in between for the baffle and utilized a 3-way configuration using 12" and 10" drivers with a 3" cone tweeter mounted on the rear top plate firing upwards. 

There must be something behind the dimensions [golden mean, perhaps?] that make it work. Of course one cannot expect ultimate bass extension with an open baffle but the lack of cabinet colorations gives purity to the sound that many will find very appealing. It won't cost much and not too difficult to build so give it a try with your favorite driver.

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FAQs about the OB plan

"Form follows function"

1. Materials [acrylic, plexiglass, MDF and etc.] - visitors to this site are already familiar with my adversity towards "dead sounding" synthetic components. Solid wood or edge glue butcher block type material will probably give the best sonic quality. I endorse 3/4" plywood because that is the material I use and very satisfied with the sonic results. Besides it is cheap and if you like what you hear and decide to experiment with your own exotic materials later not much is lost with the initial investment.

2. Driver off set - I have read in various reference materials on audio that off setting the mounting position [slightly off center] of the driver can further reduce cancellation. I have not tried this because in the real world unless your cutting tool is aided by computer and laser devices, it is almost impossible to perfectly cut exactly at center. So I do not worry about it.

Free field response graph

3. Driver mounting too low - common sense dictates that the reason why the baffle was tilted 80 degrees and mounted closer to the floor is to aid bass response. I tried lifting the OB a few inches off the floor and lost a substantial amount of weight in the lower frequency (see more below). Logically if one is to sit 1 meter away from the speakers the apparent soundstage would be a bit low. My listening position is almost 3 meters away and was never bothered by a "low soundstage". A good super tweeter can aid in giving more height if your driver has limited high frequency extension.

how not to...

4. Tall and narrow baffle vs. wide and squat - the table above shows that 35.5" will give a low frequency response sharply falling by 90hz but this is free field - floor mounting provides an additional barrier to the nominal 35.5" width which significantly helps the low frequencies. Turn it around so that it becomes slimmer (35.5" tall x 31.5" width) and hear how bass extension suffers.....keep this in mind before designing a modern looking Magnepan style OB (see above). G.A. Briggs was a fine engineer with good ears that's why he designed his OB to mimic Quad ESL 57 proportions, or was it Peter Walker? I think they were acquainted and exchanged notes on their research and development. 

OB built using Philippine Tanguile wood flooring planks 

mounting hole is for an Altec 605B Duplex

5. What's the purpose of the 6" x 8" top plate? This may look like an after thought but omit this from the design and you lose overall definition from the bass to the midrange. It serves as a deflector and focuses the sound. The back legs and this top plate serve to further delay or disperse rear sound waves from reaching the front too soon which can result in bass cancellation.

WE/Altec 755 Part 1

From Western Electric to Altec

The original Western Electric 8" 755A driver along with the 10" 756A and 12" 728B and 754A were marketed a couple of years after World War II. According to Walt Bender, former publisher of Audiomart and a leading authority and expert on vintage American audio components, the transition from WECO [Western Electric Corporation] towards Altec [All Technical Services division of WECO/AT&T] was not completed until the early 1950s. This was due to a 1930s anti-trust lawsuit filed against the giant telephone company whose business ventures, amongst other interests, included providing sound systems for movie theatres during the booming Hollywood film industry of the pre-WWII era.

Below is an email I received from Steve Schell, manufacturer of Cogent True-to Life Loundspeakers and whose research on vintage American classic speaker components I truly respect. This is probably the most comprehensive and easily grasped explanation of the transition from WE to Altec as well as establishing the [James B.] Lansing connection. Many thanks to Steve for allowing me to upload this information!

May 26, 2006

Hello Joseph,

I just read your 755 pages, after following a link from the Audio Asylum High Efficiency Speakers forum. I recall running across your site several years ago, as well as reading your fine contributions to my well worn and valued copies of the Angela Instruments print catalogs.

There is a little history I can add to the story of the 755. What follows is not authoritative, but based on the reading I have done. Altec Lansing was formed in 1941, after All Technical Services bought Jim Lansing's struggling Lansing Manufacturing Company in Los Angeles. All Technical had been the theatre service branch of Western Electric, which maintained service contracts with several thousand theatres that were equipped with Western Electric sound systems. When the U.S. Government forced W.E. to divest itself of its U.S. theatre sound operations in September 1937, the All Technical branch was purchased for a token amount by several of its managers. They continued to maintain the theatre contracts, though they began running low on replacement parts. Part of the reason for their purchase of Lansing's company was to give them facilities to manufacture the needed parts. They also acquired the designs and production capability of Lansing's theatre systems, regarded by many as being the best at the time. The Lansing product line continued in production, and formed the basis of many of Altec's later sound products.

Western Electric continued to manufacture sound products for numerous applications, but not for domestic motion picture theatre use due to the 1937 consent decree. In about 1940 they began making the 750A, which looks to me like the ancestor of the 755A. It was a 10" driver with an aluminum cone and 4" edgewound aluminum voice coil- please see attached pictures. The 750A is very scarce, and sells for $5000 or more in Japan.

After WWII they introduced their postwar line of speakers, including the 755A, 756A, 728B, 754A, and several phenolic cone variants. W.E. made a huge effort to design the best speakers possible, and to market them effectively through Graybar. In 1949 the U.S. Government intruded on them again and insisted that they cease manufacture of these products. W.E. signed another consent decree at this time. In late 1949 a full page ad in Audio Engineering magazine announced that W.E. was discontinuing manufacture of several of their speaker and microphone models, and that these products would be henceforth be manufactured by Altec Lansing. W.E. had apparently made a deal with their former associates at Altec to manufacture these products and provide W.E. with a portion of them as an OEM. This apparently satisfied the gov't. and allowed W.E. to continue to offer products such as their monitor systems, which contained the Altec-produced components, now labeled with "KS" numbers.

One funny story... I have seen at least two Altec hi fi speaker cabinets from about 1950-1952 on ebay that used shiny perforated metal discs to hold their fiberglass lining in place. Looking closely, I realized that these discs were identical to the metal rear plates on a W.E. 756A. Altec must have received a box of these along with all the other stuff from W.E. and found a use for them.

Altec continued to produce several of the W.E. drivers, horns and microphones through the 1950s. Most of them eventually left the catalog, but a few W.E. designs like the 755 continued to be produced through the 1970s and 1980s.

Apparently the government had good reason to go after W.E. in the 1930s, as they held a majority of market share in the theatre sound business and often acted as a tyrannical monopoly. I'm not sure why they hounded W.E. in 1949, except possibly to try and contain W.E's endeavors to the communications industry for national defense purposes. I have often wondered, though, if the awful performance of most current consumer loudspeakers would have been better if the government hadn't repeatedly driven W.E. out of the business. I suppose we'll never know the answer, but at least we can enjoy some of the surviving W.E. products. I got to hear a pair of 753C monitors recently and they were really something.

Best regards,

Steve Schell

Long Beach, CA

Co-founder, Lansing Heritage web site www.audioheritage.org

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Altec 755C, Altec 755A and Altec 755E [left to right]

This 8" full range driver has achieved "cult status" amongst audio aficionados. The most desirable version are the ones branded with the Western Electric logo with the frame in smooth silver or textured charcoal greyish brown finish. The mounting gasket always had 5 - 8 quality control stamps showing the tight tolerance procedures excercised in their manufacture. The later Altec branded 755As only had 1 or 2 stamps but essentially looked the same and came finished in either textured charcoal greyish brown or silver hammertone. A lot of silver Altec 755As served as the midrange/tweeter unit in Edgar Vilchur's AR-1 speaker.

Aside from those quality control procedures and alnico magnet, what sets the 755A apart from the later 755C and 755E is the chemistry of the cone material. The procedure was very intensive according to Walt Bender, involving a "vacuum formed" process to produce a cone that contained silk and cotton components. This cone material is also found in original examples of WE/Altec 756A, 754A and 728B. Perhaps this contributes to that beguiling and lifelike midrange quality of a 755A that eludes the later "pancake" versions.

I have seen 755As without the WE or Altec logo but with a KS14703 decal. KS = Kearny Specification, a New Jersey subsidiary which supplied replacement parts for WE. These units may have been represented the final transition period from WECO to Altec. But take note that there are ferrite magnet "pancake type" with KS14703 logos finished in Altec green. These units are really 755Cs and should be identified as such.

Altec 755A

early to mid 50s

[alnico magnet]

Frequency Response: 70-13,000

Sensitivity: 81.5dB/8W/9M

SPL graph courtesy of Steve Schell

Nominal impedance 4 ohms

Impedance graph courtesy of Steve Schell

Typical prices asked for a mint matched pair of WE755s are in the stratosphere, about $3,000/pr. while the Altec 755A go for about 50% less. I never owned a pair of WE nor heard them in the context of my system. But I have heard them in familiar systems and honestly cannot hear much difference between the WE and Altec. Although my impression might change if I start splitting hairs....but I do not want to get into that, through the years I learned that if I can't afford it, I would not think about it.

Altec 755C

Introduced ca. 1961

[ferrite magnet]

Frequency Response: 40-15,000, Impedance: 8 ohms, Sensitivity: 95.5dB/1W/1.2M

In 1961, the "Altec green finish" 755C "pancake" was introduced and the alnico magnet was replaced by ceramic/ferrite. Although the cone looked familiar, the material is diferrent, indicating a move towards 'cost effectiveness'. An additional roll or two was also added to the suspension surround [more compliant] to extend bass response.

This unit was later replaced around 1969 by the slightly less efficient but still SE amp friendly 755E, also with ferrite magnet but the frame is now finished in white and blueish grey combination. The 755C usually came with the surrounds heavily doped, even running and staining the cone itself, whereas the 755E is typically doped sparingly.

Altec 755E

Replaced the 755C around 1969

[ferrite magnet]

Frequency Response: 40-15,000, Impedance: 8 ohms, Sensitivity: 92dB/1W/1.2M

These later versions should not be overlooked because they sound good. Supply is drying up but nice clean units with intact cones show up ocassionally at eBay - 755Cs normally trading from $700-$900/pr. and the 755Es for $500/pr.

I have not come across a modern 8" full range driver that sonically comes close, so they are still worth it in my opinion. Amongst the classics, the only 8" FR drivers I've heard that compare favorably are the rare and hard to find Japanese Pioneer PIM8L OEM for the Lafayette SK98.

The most important consideration when purchasing any of these drivers is to make sure that the drivers are matched! Since they were used in various applications, they may have been electrically damaged or physically abused. Typical problems include partially damaged voice coils. This usually shows up when tested with a DVM, for example the DC resistance reading on my Altec 755A is 2.2 and 2.3 ohms and 6.8 ohms for both 755Cs and 755Es.

At a reasonable price, slight cracks or splits in the cone material can easily be repaired with careful application of Elmers glue and will not significantly impair the sound, if the voice coil is intact. Unfortunately I am not aware of NOS replacement cones for the 755A. There may still be replacement cones available for the "C" and "E" but the availability of original voice coils for these models is also unconfirmed, I have a pair of 755Cs with damaged cones waiting for this procedure.

Here are some 755 sonic impressions from esteemed hobbyists collected from Sound Practices list archive:

Joe Roberts: "Well the 'C' is pretty good. A little bit less high frequency energy than the 755A but good nontheless. More tilted towards the lower mids and a little less crisp than the 'A'.

jc morrison: "by the way, i would also like to add that the later 755s are, in my not always respected opinion, much better than the early ones, which are too peaky for my taste [especially joe's favorite, the really dry cones...] i have heard a lot of 755s. i like the c's and e's crossed over to a tweeter (yegads) in a tapered pipe. these are some of the nicest direct radiating midrange speakers of all times. make a nice pipe drea with a 755C or E, add a focal titanium tweeter: nice, in my book anyway...."

Koji's [of EIFL] translation of Stereo Sound "Tube Kingdom" No. 3 comparison:

Altec 755A - "...reproduces musical sources as it is. The presence of musical instruments is excellent..."

755C - ".....sounds modest but sonic qualities very amplifier dependent. Very good for monitoring the sonic characteristics of amplifiers."

755E - "....also sounds modest, calm, thick and beautiful. Very good for a real audiophile."

WE 755A - "....you feel as if you were embraced with music. Sounds open and brilliant."

Sources and references:

• Stereo Sound Special Issue Volume 1 featuring vintage American speakers.
• Stereo Sound "Tube Kingdom", No. 3 and No. 26
• Walt Bender's "Ask Walt" essays in Audiomart and article on "Olden Goldies" published by The Absolute Sound in the '80s

Go to Part 2 (2 cf box)

Visit Joe Robert's Junkyard Jukebox for great WE 755A information!

Another site I just discovered with good information on WE/Altec 755s.