In 1972, there was a big shift in high-end home stereo systems from the separate components that dominated the 1960s to new component types, and Yamaha released the first generation of component stereo, the 700 Series integrated amplifiers. They featured a rich assortment of input/output channels including separate MM-only and MC-only phono inputs, tape deck input/output, two channels of aux input/output, and a stereo microphone input on the front panel with mixing volume adjustment, making them suitable for a wide range of applications including home audio, audio-visual education, in-store, and other semi-pro uses. The power amplifier circuit was an orthodox ±2 power supply all-stage full-direct semi-complementary OCL type, and the tone control was one that would continue to be used in many later models as the "Yamaha method" tone control, the original NF type. The external design was a conservative style with not even a hint of the appearance of the CA-1000 that would be introduced the next year, and the circuitry was not the latest pure complementary type, but the engineers may have been avoiding an adventurous approach for their first foray into the component stereo field. The 400mm wide cabinet was slightly smaller than modern models, and the Brazilian rosewood veneer was luxurious by present-day standards. It didn’t have outstanding specs or appearance that would make it appeal to audio fanatics, but it was a fine, Yamaha-like piece of workmanship. The series included an inexpensive amplifier version, the CA-500, the CT-700 tuner, YP-700/500 players, and the TB-700 cassette deck.
History of Integrated Amplifier
Yamaha Integrated Amplifier History (Since 1972)
From the CA-1000 that whipped up a whirlwind and brought Yamaha recognition in the audio world, to the AX-2000A that after groping around with digital technology managed a comeback to pure analog. Here we use each year’s flagship model to explain Yamaha’s continuing search for low noise and low distortion.
Handles a wide variety of uses with its rich assortment of input and output terminals. Yamaha’s integrated Amplifier debut model.
A true audiophile amplifier including a Class A/B operation selector, all enclosed in a beautiful form.
Yamaha released the CA-700/500 and entered the component stereo market in 1972, and the next year began a completely different integrated amplifier lineup. This was the birth of the CA-1000, a classic representative Yamaha HiFi component that is still talked about today. The seamlessly connected single-sheet aluminum front panel and a white wood cabinet (open-pore-finished prickly castor oil tree wood) modern style was created by the GK Design Group and its beauty was distinct from both the heavy wood grain style and the mechanical component style. Of course the CA-1000 had more appeal than just its exterior. With features, performance, functions and high cost-performance, it overflowed with charm to steal the audiophiles heart: a power amp section with the world’s first Class A/B switchover that had a convenient switch that changed from low-distortion, priority-on-sound-quality class A operation to high-power class B operation, two huge 18,000 μF block aluminum electrolytic capacitors that blew away the competition, a phono equalizer boasting accuracy to within±0.2dB of the RIAA standard and a permissible MM input of 310mV, and a unique continuous loudness control. With its audiophile insides and clean form, it would not be too much to say that this new Yamaha design swept over the industry overnight. The power amp’s output in class B operation was 70W + 70W (20Hz—20kHz, 0.1% THD, both channels driven) and in class A operation was 15W + 15W (same conditions). Only CA-1000 owners could enjoy both the delicate sound variations revealed by the operation mode change and the high heat radiation of class A operation (which they liked).
Polishing the control amp’s precision to pursue an S/N ratio approaching that of separate amps.
The first CA-1000 received wide acclaim, and in 1974 it was updated to the CA-1000 II, then again in 1976 to the CA-1000 III. The first update was an improved version of the CA-1000, while the second was actually a full model change, and at that time a higher end model, the CA-2000, was added. From 1974 through 1976, Yamaha had released the super high end B-1/C-1 and B-2/C-2 separate amps, already establishing an admirable position as an audio maker, and with the CA-2000, Yamaha began feeding back the functionality of the separate amps into the integrated amps, such as the phono equalizer, MC head amp, and a tone control amp substantially the same as the one in the C-2. The CA-2000 had S/N improvement as its main theme, and Yamaha developed a super low noise dual FET and a super low noise IC in house and used them. The internal layout was completely redesigned with a 4-gang potentiometer that controlled volume both before and after the tone control to minimize residual noise at low volumes and an input selector using universal joints to minimize signal path lengths by directly connecting the circuit board and rear panel. Naturally the power amp featured Class A/B switching. In class B, the power output was 120W + 120W (20Hz—20kHz, 0.03% THD, both channels driven), and in class A 30W + 30W, double the power of the first CA-1000. In those times, using tape for live recording and recording from FM were popular, so a Rec Out Selector (allowing recording of a different source than the one being listened to) and a peak meter with selectable Speaker Out/Record Out monitoring were provided for the first time. The meter was added to increase the unit’s appeal as a product, but it didn’t necessarily match with Yamaha’s design concept of simplicity. Even so, it didn’t break the link with the image of the CA-1000, and the look of precision of the C-1 control amp that had the same meter was added. Note that the external appearance was the same as the CA-1000 III, but the lettering around the volume and tone controls was changed from simple numbers to a decibel reading, and this assertion of control amp performance was the only identification other than the model number.
After deeply considering the meaning of DC amps, Yamaha brought out the prioritized-for-disc "straight DC configuration."
After the middle of the 1970s, the "DC amp boom" occurred, which resulted in the removal of capacitors from signal paths and negative feedback loops, providing 0Hz (DC) playback performance. At first it was only the main amp that was DC, and integrated amps with a DC main amp section were common in 1977, but the DC amp that Yamaha announced was the revolutionary A-1 all-DC integrated amp that achieved the original aim of simplifying signal paths to the limit. Both the phono equalizer and the main amp were DC, and the use of a high-gain power amp allowed the intermediate amp stage to be eliminated, so the phono equalizer output or Aux line level signal simply passed through the volume control before entering the power amp, a "straight DC" configuration. Up until then, the number of input channels was considered an indication of the "rank" of an amplifier, but the A-1 eliminated most of them (leaving one each of Tape and Aux) as well as the A/B speaker selector. To symbolize that, the majority of the input selectors and other controls were hidden in a sealing panel, achieving a minimalistic design. The front panel had only the volume knob, and "Disc", "Speakers", and "Power" lighted buttons. Pressing the Disc button caused the input selector and Tape Monitor switches to be ignored, giving priority to the Phono input, while the Speakers button allowed the smart feature of disabling the speakers while raising and lowering the phono cartridge to prevent noise. The whole design was optimized for analog disc playback: setting the gain to 0dB defeat would turn on a fixed 10Hz, 12dB/octave high-pass filter, while setting the tone control to flat would make it function as a subsonic filter. The power supply section was somewhat unusual, featuring two power transformers, and a pair of block aluminum electrolytic capacitors, but the idea was that the leakage flux from the two transformers connected in parallel would cancel. If you actually try using the A-1 you find that to choose a source other than Disc it is necessary to open and close the sealing panel (or more likely, just leave it open), so you notice a gap between the ideal and the actual, but it goes without saying that the concept of Disc Priority influenced later features such as the Pure Direct switch and the CD Direct Amp.
Pursuing quality over quantity, and realizing easy operation. this popular-priced model gave owners a sense of Yamaha refinement and conscientiousness.
Among the numerous lower-priced integrated amps available, one of the ones that made you sense Yamaha refinement and conscientiousness was the A-5, released in 1979. Briefly stated, it emphasized quality over quantity, and its design combined high performance and easy operation. It followed in the footsteps of the A-1 with its simple, calm panel face, and among the other amps of same class that competed to be larger and more magnificent, this model had a unique attraction. Its power output was a restrained 40W + 40W, but its input stage used a low-noise transistor differential amplifier, and the output stage used a full-fledged single-ended push-pull design. The first stage of the phono equalizer also used a luxurious current mirror differential amplifier built with fully discrete components. The phono input signal-to-noise ratio was 86dB (MM) and the RIAA deviation was within ±0.2dB over 20Hz—20kHz, an excellent specification. The MC cartridge compatibility was unusual for its price range, and was achieved through a gain switchover. MC/MM selection and input selection were handled by switches mounted directly on the circuit board and controlled remotely from the front panel, and careful attention was given to optimum layout and short signal paths. The input selector had a recently added TV setting, which was probably intended to handle the new multiplexed audio on TV broadcasts that began that year. The aluminum panel had a restrained gloss and a silky feel and the handsome knob layout gave careful attention to the spacing, while meticulous care was also given to the colors and illumination level of the self-illuminated buttons, resulting in a high-class, natural design that appealed not only to audiophiles but to many customers that had a sensitivity to product design. The ad campaign was unusual in stating "We won’t change the design for three years," and the product enjoyed a long popularity.
Yamaha’s flagship amplifier of the 1980s that brought the creativity of Yamaha electronics technology to flower.
The A-9 was introduced in 1979 to replace the CA-2000 as the new generation flagship integrated amplifier. It continued the tradition that began with the CA-1000 of providing Class A/B switchover but the whole configuration was completely redone, and with the exception of the volume control knob all the controls were either square pushbuttons or straight-line sliders giving a strong impression of a design for the 1980s. During this period, there were many amps that were advertised to be high efficiency (pseudo) Class A amps with the sound quality of Class A and the efficiency of Class B, but the principle of changing the bias current depending on the signal level was controversial, and Yamaha stayed away from this approach. The A-9’s answer to pseudo Class A was the New Linear Transfer Circuit that kept a fixed bias current but reduced switching noise and crossover distortion, and unique Pure Current Servo Amp technology that maintained constant current in the power supply and ground lines, eliminating their effect on the audio signal. With the addition of the New Linear Transfer Circuit, the A-9’s Class B could actually be called a "high-efficiency Class A" amp, but since there was a switch to select pure Class A that was not necessary, Yamaha deliberately called it Class B. Internally the A-9 used more material resources than the CA-2000, with five huge toroidal transformers, one for each of the left and right power output stages, the power driver stage, the preamp stage, and the MC head amp stage, and original plastic-cased aluminum electrolytic capacitors (15,000 μF×4) took up positions in the center of the chassis. In addition, it featured Output Impedance (Ro) Control, which took control of the connected speakers’ Q and the cables’ DC resistance from the amp side to improve damping characteristics under actual use conditions, a big change from the relatively orthodox configuration of models up to the CA-2000 and showing another face of Yamaha: bold, advanced, and creative.
Audio-like appearance and huge material resources. The Yamaha No. 2000 returned with a new style of Class A.
The Yamaha No. 2000 that gave up its status as flagship to the A-9 with its near-modern look (released in 1979), was clearly back in 1983 as the A-2000 new-generation model with its audio-like appearance and huge material resources. The traditional Class A/B switchover feature was finally abolished, and in its place what could be said to be Yamaha’s final answer to the high efficiency Class A competition of the past few years, the "Dual Amp Class A" with ZDR 150W + 150W (6Ω rated output, 0.003% THD) high efficiency Class A amp was used. A Class A amp and a Class A/B amp were operated in parallel and both were connected to the load (speakers), with negative feedback from the load applied to the Class A amp only, so that the Class A amp completely controlled the load current and the Class A/B amp handled all the power dissipation with high efficiency. It was the realization of the audio amp dream of using pure Class A operation in all operating regions and was a great advance. Two huge EI power transformers (the larger one for the Class A amp and the smaller one for the Class A/B) were employed, and the block aluminum electrolytic capacitors had a capacity of 55,000 μF×2 for each channel, a total of 220,000 μF. The view after removing the top cover was just that of a separate amp, and the unit massed a big 26kg. Also, a new feature that stood out was the Richness loudness-like equalizer circuit that expanded the speakers’ frequency response by an octave at the low end and had a three-position selector for the Yamaha representative speaker models NS-2000 and NS-1000M, and a third generic position. The front panel had a lineup of flat pushbuttons and a sealing panel, and the walnut cabinet with polyurethane finish was the same as that used by Yamaha’s high end grand pianos and was a good fit for the popular conservative trend. The A-2000 did not have the bold looks of the CA-1000 and A-9, but on the other hand Yamaha was no longer playing catch up, but was in front, and the marketplace itself was reaching maturity, so these factors were no doubt reflected in the design.
A super-high end integrated amp that used the HCA power amp that was the pride of the 10000 Series, and held fast to analog amplification in the digital age.
With the growth of CD, DAT and audio-visual, the amps of the second half of the 1980s were groping towards a fusion with digital and video sources. After the A-2000 came out in 1983 and went through a minor model change to the A-2000a in 1985, the AX-2000 came out in 1987 with high resolution D/A converters and video inputs. In 1990, in a dizzying about face, the D/A converters and video inputs/outputs were removed on the audio-only AX-2000A. There was not yet an A/V amp category, and the various manufacturers differed on whether digital audio or video inputs should be included, but as far as Yamaha was concerned, based on its experience with the AX-2000, it was decided to pursue A/V amp development, but for audio amps it was decided to insist on analog audio inputs, and this policy was visible in the AX-2000A. The old AX-2000 applied technology developed for the Yamaha 100-year anniversary monumental product "10000 Series". The power amp circuit was the HCA (Hyperbolic Conversion Class A operation) and greatly surpassed the previous A-2000 that had Dual Amp Class A and a ZDR power amp circuit. However it mainly received attention for its D/A converters and video inputs, which gave the impression that it was somehow lacking on the audio side. To correct this, it was decided to remove all the D/A converters and video inputs, and to further evolve the Active Volume Control from the old AX-2000 to increase the signal-to-noise ratio by 22dB in actual listening conditions (dubbed MEGA-SN, or Most Effective Gain Arrangement for Signal to Noise ratio). In addition, in order to get the best audio quality from digital sources such as CD and DAT, the Mega Direct In circuit was employed. Finally with the AX-2000 Series it was possible to change the input selector or adjust the volume by remote control, and the selector circuit used a discrete FET electrical switch to prevent sound degradation. The chassis was completely separated into preamp and power amp sections with completely symmetrical two-box construction, the chassis and frame were completely copper plated, and the power amp circuit board was located so as to be in contact with the non-metallic wood panel on both sides to reduce mutual interference and electromagnetic distortion. This model was a compilation of Yamaha integrated amp technology in the 1970s and 1980s, and at the same time was a model that showed unshakeable belief in pure audio even after the baptism into the digital and A/V age.