This Pioneer SM-B201 Stereophonic Amplifier was built in the early 1960’s. It has FM and AM tuners and produces 14 watts per channel.
In the pre-MPX days of AM-FM simulcast stereo one channel was on AM and the other on FM. Two broadcast towers were required for stereo. In other words, FM was broadcast on one tower and AM on another. The user of the SM-B201 would have to tune both dials to the correct frequencies to get stereo. Of course, not many stations wanted to build two towers to broadcast in stereo so the design was short lived. The Fisher 800 was another example of simulcast stereo.
The Pioneer SM-B201 has a strange symmetric front because of its dual tuning dials and “magic eye” tubes.
The controls include separate Bass and Treble as well as a Whistle and Loudness switch.
On the back panel there are outputs for 4, 8 and 16 Ohm speakers. There are phono inputs for both ceramic and magnetic cartridges of 3mV or more. There’s also a Tape In and Out, Aux in and FM/MPX out.
The SM-B201 has 19 tubes including the two 6E5 eye tubes. 12AX7’s are in each channel driving a pair of 6BM8 (ECL82) output tubes. There is also a 5AR4 rectifier tube.
The early Pioneers were built like tanks but age takes a toll on them. The magic eye tubes in the SM-B201 are usually dead and the gray capacitors are usually leaking. With a little servicing you can have a nice amp and a great conversation piece.
These early receivers are somewhat rare but not impossible to find. They are not as popular as the later 1970’s Pioneers. A nice SM-B201 will run anywhere from $200 to $400 depending upon condition.
Sansui made a number of iconic receivers during their run as one of the top audio producers in the world. One of those is the classic Sansui 1000A. The 1000A is a tube receiver is known for its big and powerful sound. The A revision added bias adjustment for the 7591A output tubes. The receiver pushes out 40 watts of clean power per channel.
The phono section does use transistors but the two top level inputs and the tuner are all tube. Unfortunately the phono section uses old germanium transistors which are somewhat difficult to replace since there aren’t really modern equivalents. It can be done however. I know that some people will utilize a small outboard phono preamp and use the tape monitor loop instead.
Speaking of old parts the 1000A’s also have old oil filled capacitors in them which when powered up for the first time after many years can have explosive effects. Best case would probably be to replace them all but you could also bring the receiver up to power very slowly with a variac. Still, I think most would agree that replacement is the best course of action.
An interesting feature of the 1000A is that the low frequency filter works on the aux and tuner. Usually it is only used on the phono circuit to remove record rumble. It also has both Presence and Loudness switches which seems a little redundant.
Some of you may already know this, but the real secret behind the 1000A and many other Sansui audio products is their use of Hashimoto transformers. Hashimoto Electric was started in 1958 and has built high quality transformers practically ever since. Sansui was one of their main customers so many of their products have Hashimoto iron in them.
The Sansui 1000a came with a metal case but many user removed it due to the large amount of heat that the unit generates.
The 1000 version is much harder to find than the 1000A and there are actually a few different versions of the 1000A as well. The 1000 was only made for a year before revisions were made and the 1000A came out.
Some feel that the Sansui 1000A is the best sounding tube receiver ever made. That’s saying a lot when comparing it to the popular Fisher 500C or 800C. Nonetheless, it definitely performs to high standards which means it is also in high demand. Run of the mill working units sell for around $500 while fully restored units can sell for $1200 or more.