Pioneer SX-3700

Pioneer SX-3700 Front

 

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.

 

Pioneer SX-3700 Meter

 

 

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.

 

Pioneer SX-3700 Knob

 

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.

 

Pioneer SX-3700 Inside

 

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.

 

Pioneer SX-3700 Inputs

 

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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Yamaha CR-840

Yamaha CR-840

 

This ebony classic is the Yamaha CR-840 receiver. It was produced from 1979 to around 1981 and retailed for about $500. It was a mid range receiver in Yamaha's CR-XX40 lineup. It puts out 60 watts per channel into 8 ohms.

 

Yamaha CR-840 Left

 

The CR-840 has the big flat toggle switches as do many of the other Yamaha models. Overall it has a very nice sleek hi-tech look to it, though some think the Yamaha models look somewhat sterile.

 

Yamaha CR-840 Right

 

The CR-840 has a built-in AUTO-DX circuit that monitors the signal strength and amount of interference present.  If needed it will automatically switch to the DX Mode IF Stage to increase the selectivity to 83dB.

 

Yamaha CR-840 Meters

 

It also has continuously variable loudness control which means that the frequency balance and volume are adjusted simultaneously to compensate for the ear's insensitivity to high and low frequencies at low volume settings. So, a natural-sounding balance is maintained regardless of volume level. It weighs about 30 pounds and measures 20" x 6-9/16" x 15-1/4".

 

Yamaha CR-840 Inside

 

One problem with the Yamaha CR-840 is that it uses output modules rather than discrete output transistors. These modules have a tendency to overheat and die. Unfortunately, original replacements are difficult to find and newly made versions tend to be out of spec and perform erratically. It has been speculated that the Yamaha IG 02970 output module was in fact a rebadged Sanyo STK 0060-II or STK-0080-II. The STK-0080-II is fairly easy to find which would make repairing these units far easier.

 

Yamaha CR-840 Back

 

The Yamaha receivers have never garnered as much attention as the Pioneer and Marantz receivers but perform just as well.  They do emphasize a "Natural Sound" so they tend to have a more accurate representation of sound which some find to be a little harsh. Prices are rising for these receivers though - especially the higher end models. You can find a nice working version of the CR-840 for about $150 to $200.

 

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