After this project ended, and successfully if I may add, it was decided to further check the drivers, especially the S-104 and the S-105 units. The negligible difference between the S-104 and the S-105 units leads one to wonder if the change was purely for marketing. In any case, these little fellas sounded exceptionally nice despite their age and despite the not so favourable test results. This brings to mind the following, copied from one of my much earlier web pages.

I once read an article in a loudspeaker journal about a Japanese company's attempt at designing a loudspeaker system. They had all the latest technology at their disposal and a team of top notch engineers. After all the equations were digested by their computer, the computer designed the system. It was built and tested and passed with flying colours. Unfortunately, it didn't sound too good. After several more trips back to the drawing boards the newer designs didn't sound much better either. Consultation was sought of a noteworthy foreign loudspeaker guru, an American in San Francisco, and this individual pointed out the flaws in their design. It seems the Japanese designers relied on pure theory, but one thing they didn't consider was that their computer and test equipment didn't have ears.

There was also a company's amplifiers that were tested by a well known audio lab sometime in the late eighties. The folks testing the amps stated that had they relied solely on the test results, the amps would have been considered unworthy. However, they decided to give the amps an audition. The results were nothing less than astounding. Their test equipment didn't have ears either.

Q.E.D.

All the figures are linked to a larger image

S-105, left and S-104, right. The brown colour cones is original, not due to age.

The other sides with the plastic cups removed.

Self explanatory

Responses at 1w1m

RED: S104 ORANGE THD

GREEN: S105 BLUE THD, around 1%

Both drivers in original plastic cups

Responses at 1w1m

RED: S104 ORANGE THD

GREEN: S105 BLUE THD

THD around 1%

Both drivers in 160in^3 closed box wool stuffed

This is the S-133, a slightly larger version of the S-105. The so called cup, or isolation chamber is a very tight woven or compressed material fixed to the inside of the basket. This gives a very small back chamber resulting it its having to be used above about 500hz.

To avoid possible damage to the speaker, this material was not removed as it would have had to be cut. The close proximity of the cone to this material made this a risky venture which was abandoned

1w1m response of the S133 (red) and THD (grey)

THD around 0.6% above 900hz and around 1.7% below 900hz

CONE TWEETER

The only Sansui cone tweeters I have. These response curves are the last of a few run because the response looked too good to be true; flat within 5dB from about 1400hz to about 18khz. THD above 3khz is remarkably low around 0.6%. Keep in mind that these two little guys are over 50 years old as are all the speakers described in this page.

HORNS - Midrange and Tweeters

The S-106 and no plastic horn here; it's aluminum. It doesn't ring when bolted to a baffle.

1w1m S-106      BLACK-no lens GREY-THD     GREEN-lens BLUE-THD

THD somewhat high around 3.2% above 2khz.

The green and blue curves are the lower curves in each pair.

PHOTO 6

FIGURE 5

Another remarkable vintage unit. Response is flat within 5dB from 2khz and beyond. THD may be considered high between 4khz and 5khz, hovering around 2%. However, in the SP-3500, it's high pass filtered around 6.5khz where THD drops to under 1%.

PHOTO 9  

WOOFERS

W-200

It should be noted that these drivers have had new annuli installed around 2010.

T-S parameters are given as well as data on two vented enclosures of 2 ft^3 and 3ft^3.  A slightly larger enclosure will provide a little lower bass but that comes at the cost of compromising diaphragm excursion. Figures 11 and 12 show this. If a cabinet of 4ft^3 is used, diaphragm excursion is exceeded between 47hz and 70hz. This can be brought down into spec by limiting the power to 41 watts. Without a frequency insensitive wattmeter, one has no way to know how much power is being applied. However, the ear is sometimes the better judge of that.

Orange is 2ft^3 and red is 3ft^3

Orange is 2ft^3 and red is 3ft^3

Red is 3 ft^3, blue is 4ft^3

Increasing the volume to 4ft^3 seems to have gone beyond the point of diminishing returns, the price of which is shown in fig.12

Red is 3 ft^3, blue is 4ft^3

W-114

Around April, 2024, a private conversation with an AudioKarma member began regarding his Sansui SP3500 speaker systems. This went on for a few months until we resolved the issues he described which resulted in fine tuning the system to suit his preference. Initially, the woofer had to be repaired by removing much of the sealant in the annulus which had hardened over some 50 years, raising the resonant frequency, fs of the woofer to about 54hz. We managed to get that down to just under 40hz. Not knowing its original fs, it was considered to be under 40hz due to its being in vented enclosure of about 1.5 ft^3.

I bought the speaker components on ebay in order to duplicate his system. Photos of the original crossover were sent which enabled my duplicating it. The crossover is a second order 4-way network consisting of an all pass woofer and three high pass sections for each of the high frequency units. Usually, such a crossover comprises a low pass section for the woofer, a band pass section for the midrange and a high pass section for the tweeter. In this case there are two midrange sections, both of which are high pass. Again, the woofer operates full range.

The original crossover used three position switched pads for adjusting the levels of the high frequency units. These were replaced with variable L-pads in my model as the rotary switches are unobtanium.

As for softening the annulus, fs can be lowered to about 40hz using pure acetone but caution is paramount so as not to compromise the annulus's attachment to the cone, which can be fixed. Also, several washes will be required as the under side of the annulus is not readily accessible. A method of measuring fs is highly recommended otherwise one is guessing which can give unreliable results.

It has been mentioned by several on AK that this W114 was designed by JBL, who also have a 14" speaker which, if memory serves me well, has a white diaphragm and is the LE14A.  Simply speakers has an annulus for the LE14A but it's questionable if it will fit the Sansui W114 without some creative modifications.

It should be noted that the annulus of the W114 is fine woven cloth, which means it's insensitive to acetone. Even with the most rigorous washes, all the sealant won't be removed which many think will allow the annulus to breathe. This may be a legitimate concern if the speaker were used in a sealed enclosure but doesn't appear to be a serious concern with a vented enclosure.

After being stored for several weeks, the W114 was tested again and fs was found to be 39.461hz. This was measured a day after playing half a dozen songs through the speaker. This would have lowered fs a little below it's value after being idle for several weeks which would have been between 40hz and 41hz.

Corrected Cabinet Volume

Internal dimensions, wood to wood 23.4375"H by 15.875"W by 7.5"D

Internal volume 1.6ft^3

Volume displaced by cone = 59in^3

Volume displaced by magnet assembly = 49in^3

Volume displaced by 2 vents = 32in^3

Volume displaced by 2 cone mids = 58in^3

Volume displaced by horns = 30in^3 (approximated)

Volume displaced by recessed mids' and tweeters' baffle = 105in^3 (approximated)

Total internal volume displaced = 333in^3 (0.19ft^3)

Effective internal volume = 1.41ft^3

There seems to have been model SP3500A with crossover frequencies of 1000hz, 5000hz, 8000hz. This info was found on a reliable website of which I have been a member for 16 years. The posting seems to have come from Germany.

The model SP3500 has crossover frequencies of 700hz, 2000hz and 6500hz

Here's the Sansui Owner's manual for the SP3500

Performance Simulations Using Bass Box Pro, ver6

The following is some data from BBP. Fig.2 shows the TS parameters derived during three annulus washes using pure acetone. For clarification, they are as follows.

RED: prior to treatment, f_s was 54hz. This was subsequently brought down to 43hz(yellow), then 40hz(blue) and still lower to 38hz(orange).  After several hours, the 38hz settled in around 41hz due to evaporation of the acetone.

It should be noted that the sequence seen in fig 2 has nothing to do with the washing sequence; it is the result of picking the data from BBP files. The washing sequence can be determined by the f_s parameter. Red, yellow, green orange.

From the data shown, it's a good possibility that the original data is that of design 2, orange. This is because when BBP calculated vent dimensions, it resulted in the same vent dimensions as the SP3500.  The vent dimensions in the other three designs were manually inserted.  It also makes sense that the lowest possible fs be desirable due to the small enclosure volume.

Design 4(blue) is considered to be the expected result after restoration. This is due to the annulus drying after washing and becoming stiffer after about a day and holding for several days later. After playing for about an hour, fs was found to lower and rise after sitting idle for a few hours. Based on that, the simulations of designs 2 and 4 are what are considered to be what is the norm.

Actually, looking at fig.3, the difference seems negligible. The orange does do better at lower frequencies below 100hz and the bump between 100hz and 300hz is smoothed. It should be stated that the audible difference with music is much more pronounced. The extended range below 100hz is more noticeable than the smoothness between 100hz and 300hz, although the latter of these may be preferred with some music. 

Figure 3

Amplitude response, normalized to 0dB. Sometimes referred to as frequency response. 

Figure 4

Diaphragm excursion vs frequency with 40 watts input. All of these designs will stay within 5mm excursion to 35hz with 40 watts to the woofer.

Figure 5

The delay between the input signal and the speaker's acoustical output, the latter lagging behind the former.  The acoustical difference, if any, is unknown to me. However, consider a single speaker. Now, connect this speaker to an amplifier through a DPDT switch which, when toggled, will reverse the connection of the speaker to the amplifier. If you can hear a difference, you're a better man than I am, Gunga Din. (Rudyard Kipling, 1890)

Figure 6

Ahh, group delay, which is phase response expressed in time. For one thing, the more linear the graph, the better the transient response.  At low frequencies, this may be perceived as a tighter bass.  It will usually go unnoticed unless the delay is long or the listener doesn't care. However, if the speaker system is being used with video, this can become quite noticeable. With a camera zoomed close to a bass guitarist, the note will be heard after the string is plucked. This I've seen to be quite noticeable with classical music and the camera zoomed to the kettle drums. The drumstick hits the drum and the note is heard when the drumstick is elevated back up.  This is quite noticeable with a single strike to the drum. A glass dropped to the floor will shatter before the sound is heard. With a person talking in a low register, the lips will appear out of sync with the sound.

In the following figures, the blue is the same as the blue trace shown in figs 2 through fig 6 above.  The pink is that same speaker in an enclosure of corrected volume of 2.9ft^3. The white trace is that same speaker in an optimum enclosure according to BBP of volume 4.1ft^3. The same vents can be used which may restrict diaphragm excursion. However, to allow for maximum excursion, BBP suggests two vents of diameter=2.7" and length=6.9". Given the cramped front baffle space, it's questionable if these larger vents will fit. Also, such a vent diameter isn't readily available, the closest being a diameter of 3" which will increase the length to 9"

Comparing the response between the white and pink in fig.9, this hardly seems worth the effort.

This shows the cabinet specs for 1.4ft^3 and 2.9ft^3. the original vents were used due to possible limited baffle space for larger ones. This is covered later.

Increasing the cabinet volume to 3ft^3 may or may not be worth the effort. It does improve the bass output but at the cost of diaphragm excursion and low frequency power handling, both of which can be controlled by avoiding attempts to obtain rock concert levels. The white trace is that of optimum enclosure volume which has its price as will be shown later.  In short, there is no free lunch.

As can be seen in the pink trace, maximum power handling is compromised with an enclosure of 2.9ft^3 to 30 watts in the bass region around 50hz (caveat 1).  This could be a problem with rock music. It gets worse with an enclosure volume of 4ft^3, (white trace). This may be one reason why Sansui used such a small enclosure (blue trace). Another possible reason may have been to keep the enclosure small enough to pass the WAF (Wife Acceptance Factor).

The other caveat is diaphragm excursion. As can be seen by the blue trace, excursion is highly controlled. As the enclosure volume increases, more excursion is allowed but less power is required to obtain it as is seen in fig.12. Admittedly, the bass output will increase in volume due to larger diaphragm excursion but this increases the risk of damage. Common sense can keep one out of trouble.

No significant change here

Not much change here either above about 40hz.