From that slightly awkward time that lies between the fully analog and fully digital eras come the Pioneer SX-3700. It was 1980 and digital displays were just catching on and Pioneer sought to capitalize on the movement with its Fluroscan technology. The SX-3700 produces 45 watts per channel and incorporates a direct coupled amplifier design.
There is a variant of the SX-3700 labelled the SX-820. Apparently it is a European version but has a black dial face and white Fluroscan. A couple other SX-3000 series receivers also had European variants in the SX-620, SX-720.
The Fluroscan display shows the tuning for the AM or FM bands depending upon AM or FM selector button is pushed. The analog dial shows both FM and AM tuning as well. The power output meter is also a Fluroscan display. Pioneer utilized a 3 gang FM tuning capacitor and quartz servo lock technology to create a very good FM tuner section. The Fluroscan FM display is backed up by a quartz crystal oscillator that provides a stable time base so that the correct numbers will always be displayed for a given frequency selection. The display is also 5 digits as opposed to many other manufacturers that used only four digits. Pioneer referred to all of this as their P.D.Q. or Pioneer Digital/Quartz tuning technology.
The SX-3700 was a mid range receiver and had bigger brothers in the SX-3800 and the SX-3900. But, those receivers had more complicated designs and are more difficult to work on than the SX-3700.
If you like the Fluroscan display then the Sx-3700 (or SX-3800, SX-3900 depending upon your budget) might be the way to go. They do look very nice in the dark and are a good representation of the technological shift from analog to digital. They are also very good performers and can be found for a price that is within most budgets. A fully serviced unit will sell for around $300 while the average working unit will sell for $150 to $200.
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This is the Pioneer SX-3900 which was Pioneer’s top of the line Fluoroscan receiver. It’s the big brother to the SX-3800 and was introduced in 1980 at a retail price of about $800.00. It represents Pioneer’s transition from analog receivers to the more contemporary digital receivers. In fact, the SX3900 basically has both analog and digital features. As you can see it has an old school analog tuning dial, the mechanism is mechanical, as well as a five digit digital tuning display. The displays use fluorescent bulbs hence the nick name fluoroscan.
The blue fluorescent display is beautiful and one of the more iconic displays in vintage audio. Still, the FM Quartz Locked SX-3900 was not all looks. It pumps out 120 watts per channel with less than 0.005% total harmonic distortion and is built with quality engineering. It also incorporates a non-switching amplifier.
You can see from the pictures that the SX-3900 has illuminated push buttons for certain functions as well. Some other features are:
- 2 high pass filters
- Tone turn-over controls for bass and treble
- Adapter loop switch
- FM de-emphasis
- Tape duplicate
- 2 phono inputs
Measuring in at 20.7 x 6.9 x 17.8 inches the SX-3900 is pretty big and weighs roughly 46 pounds. It is similar inside to the Pioneer SX-D7000 which, oddly, was on the market at the same time. The SX-D7000 moved even more toward the digital side and had all push button and slider controls and no analog dial.
It’s a little hard to see in the picture but the SX-3900 has a large toroidal transformer that is tucked in on the left side and sits sideways like a tire as opposed to flat like most transformers. I suppose they had to economize on space given the number of features the unit has. You can also see the large heat sink in the middle. These units generate a lot of heat so it’s not a good idea to stack anything on top of them.
The Pioneer SX-3900 represents the end of the analog era and the beginning of the digital era. And, being from one of the pre eminent audio companies of the time in Pioneer, they are popular. However, I would say that, given the features, performance, and iconic nature of this receiver, they tend to be under valued. A good working unit will sell for $300.00 to $400.00 which is quite a bit under what other comparable receivers sell for. Of course, I did see one SX-3900 that was nearly mint and had been completely restored that sold for $1400.00. But, it had been fully recapped and had a LED lamp conversion as well. It was a VERY nice receiver.
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