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Sansui TA-500 Tuner / Amplifier
Professional Restoration with Audiophile Modifications
SN 019060018
Circa 1979 MSRP $465
Cost adjusted for inflation (2024) $2020
$1077
SOLD
FMI HiFiHealthCare@Gmail.com
Old School Sansui has a significant following for good reason, quality!
The TA-500 is a very handsome Tuner Amplifier combination with distinct stylistic appearance in line with the very popular x17 series such as the TU-717 and AU-717. Here in one package you get the aesthetics of one of the most popular Sansui series ever made at significantly less cost than buying separate’s. The creamy white dials on classic matte black has a character that is undeniably Sansui.
In 1979 the TA-500 was Sansui’s top dog in their “Tuner Amplifier” line…from Sansui’s promotional literature they describe the TA line as follows…
” SANSUI'S NEW TA-300 AND TA-500 : MORE THAN JUST RECEIVERS... We indeed prefer to call them both integrated tuner/amplifier instead of just receiver. Their performances - from the tuner as well as from the amp section - excel most other conventional receivers' performances. They indeed feature impressive static and dynamic characteristics. A complete new look in receivers.”
As with all of our restorations, we take a cost no object approach (within reason) to component replacement especially as it relates to recapping a unit in order to see how much potential can be realized by maxing out a stock unit with high performance upgrades and modifications.
A manufacture is somewhat bound to the bean counters to produce a product that is competitive as well as desired. As part of the compromise, often it is the capacitor choices that lead to a significant part of cost savings, not to mention the advancements in capacitor technology that has transpired in the last 50 years bringing better options for less money with higher reliability as a bonus.
Having the freedom to choose the best capacitors for the particular circuit allows us to make the engineers proud, knowing full well that their design intent was the strong point but often compromised by the realities of staying economically competitive.
In this restoration we used the Gold line “Audio” from Nichicon for the main Power Supply, Pre-Amp and Amplifier stage and their highest end audio grade “MUSE” series where BiPolar is required.
In most ‘recaps’ you see, the main power capacitors are rarely replaced!...Why is that?...tech’s say “They tested fine so I didn’t replace”. I could go into a lot of dissertation on this but suffice it to say, they are the most expensive components in the receiver, other than the main drivers… AND, testing large value caps isn’t very effective with most capacitance testers due to the limitations of the frequency of the testing.
Only when testing these caps over the broadness of the audio spectrum do you reveal the whole picture of how that device is behaving at say 30hz vs 1khz. Long story short, we always upgrade these caps, even though it’s expensive because our intent is to have the piece still be working in 50 years and we feel the expense is worth it for the amount of overall labor in the restoration.
All problematic fusible resistors were upgraded with modern metal film equivalent’s.
The main Power supply was also modified with Stacked Metal Film Poly capacitors in parallel with the 6800Uf caps to provide lower ESR and improvements for higher frequency filtering ability improving the soundstage potential of the amplifier.
In the phono pre-amp we stepped things up even a notch higher by selecting the highest grade Audio Capacitors from Nichicons UKA series and Highest Audio Quality Metalized Stacked Film Poly caps for the complete audio path from the cartridge input to the phono output to the Pre-amp stage.
The phono input stage was modified with KSA992 transistors to replace the original 2SA906’s that were pretty good in 1979 but are now substandard when compared to the 992’s.
This improved the noise floor of the phono section by a noticeable margin, (2.1db)…it’s the last 10% of improvement that is the hardest to achieve but the most rewarding as well.
The one thing that kills old amps more-so than anything else is the failure of heatsink compound over time. This leads to avalanche effect when the power transistors are not able to transfer their heat away to the heatsink effectively, causing them to give up the white smoke.
As part of our restoration, we completely remove the heatsinks and all output transistors in order to clean the surfaces of the old dried heatsink compound and upgrade the outputs with SilPads that will last the life of the amplifier providing better heat conduction than the original design.
All Power Supply Regulators and associated heatsinks were stripped down of old dried heatsink compound and new long life synthetic heat grease was applied.
The Pre-Driver on this design is an application specific high performance AN7070.
The AN7070 audio driver offered very impressive linear performance but unfortunately was a limited run primarily used in the Sansui TA series.
The 7070 is key to much of the performance characteristic of the TA-500’s amplifier performance and as such, a key role in the restoration is insuring the longevity of the device.
With that in mind, an improvement to the original design was incorporated by means of adding additional heat dissipating performance to the 7070 by means of integrating external heat sink which was not part of the original design.
In testing this brought the mean operating temperature from 160 degrees Fahrenheit to less than 110 degrees under ambient conditions of 72 degrees F after 30 minutes at 50% rated load.
Contacts on the output relay can become damaged over the years, especially when the amp is turned on inadvertently with the volume up high.
We always remove the relay and inspect the contacts and refresh them when needed.
This unit was obviously ‘adult owned’ as no arcing was apparent on the contacts, non the less the contacts were removed and cleaned with contact cleaner and synthetic rubber pad.
Every audiophile would like the ability to use 5 way binding posts for speaker interconnection and as such we have modified the “A” speaker outputs to high quality Gold Plated binding posts!
Although the tuner was not recapped, a complete tuner alignment on the FM band was performed.
To our surprise the sensitivity of this 2 ganger exceeded our expectations and in Mono (DX) we were able to get a cleaner reception of a hard to reach station in the area, better than our Fanfare high end tuner in fact!
The analog tuning is mechanically smooth and fluid with a nice counterbalance system helping to sweep through the band with ease and finesse.
The wire routing out of the factory on the Sansui’s is so much better than many of it’s competition such as Pioneer and NAD and although well thought out we still found some room for improvement by separating all signal paths from power lines and cleaning up excess wiring by shortening paths where applicable.
24hr burn in of new components and final adjustment of Amplifier DC offset and Bias were performed. Bias was adjusted exactly to the manufacturers specification of 20mv across emitter resistors.
DC offset was adjusted to less than +-5mv!
Amplifier performance evaluation was performed with 1khz reference sinewave into
8 ohms = 66 Watts < 0.05%THD.
4 ohms = 92 Watts < 0.1%THD
If you want a centerpiece for that nostalgic Sansui look that REALLY performs, you won’t find a better piece than this one to fit the bill.
FMI HiFiHealthCare@Gmail.com
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