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HIFIREVIEW The TA-N77ES stereo power amplifier: beautifully finished, superlative performance. Sony enters the big po"7er stakes Sony don't make a separate stereo preamplifier and high power amplifier do they? They never have. Well now they do. Just released, the new Sony ES-series preamplifier and power amplifier set new standards for audio quality. Reviewed by LEO SIMPSON Sony has long been at the forefront of audio but it is a long time since they have brought out something really new in the category of amplifiers. Sony were one of the first manufacturers to pioneer the use of high power Mosfets in their amplifiers and it was quite long time ago too; around 15 years or so. Now Sony have released this interesting duo, the TA-E77ES stereo control amplifier and the TA-N77ES 30 SILICON CHIP stereo power amplifier. Sony's designation of the former unit is a little odd; it has no power amplifiers as such although it does have an inbuilt stereo headphone amplifier. Conventionally, the TA-E77ES would be described as a stereo control preamplifier but no doubt Sony feel justified in calling it a control amplifier because of particular features of its construction. We are inclined to agree with their thinking, as you will see later. For the moment though, the Sony control amplifier looks like a very well specified control preamplifier. It can handle the full range of audio program sources plus three video program sources. The latter may be two video recorders, hifi or otherwise, and perhaps a videodisc player, or it could be one of the soon-to-be-released CD video players. The unit has circuitry to switch both the video and audio signals. Moving magnet or moving coil cartridges may be selected for the phono player and the moving coil cartridge may be selected as either a low or medium impedance unit. Apart from phono, five high level sources may be selected: CD (compact disc), tape 1, tape 2, tuner and auxiliary (such as DAT). All told then, a total of nine program sources may be selected, when the video sources are included. Each program source is selected by means of a microswitch button which controls a relay. And each button has very discrete red illumination to show it has been selected. Very suave. The signals from these sources may be routed through the tone controls, stereo/mono switch and balance control in the usual way, or via an Adaptor which would usually be a graphic equaliser. Alternatively, the user can select Direct. The Direct mode connects the selected source direct to the output, bypassing all other controls. This feature is becoming more common on upmarket amplifiers although it usually only applies to CD. It is intended to give the minimum possible deterioration of the compact disc signal. In making the Direct mode available for all sources, Sony has taken note of the marketplace and is acknowledging that in every category - CD, hifi VCR, DAT or FM tuner - there are program sources which challenge the best amplifiers and control units currently available. It therefore makes sense to give lovers of high fidelity sound two options: the absolute minimum signal processing or tone controls and filters when they are needed. Since it features the Direct mode, the Sony control amplifier does not feature tone control cancel buttons. Instead there are two buttons to change the turnover frequencies : 200Hz or 400Hz for the Bass con- Specifications TA-N77ES Stereo Power Amplifier Continuous power output per channel (both channels driven) Dynamic power Rated harmonic distortion Damping factor Slew rate Frequency response Input sensitivity Signal-to-noise ratio 270W into 40; 200W into 80 520W into 40; 300W into 80 .006% into 40; .004% into80 100 (at 1 kHz) into 80 150V/µ,sec 1Hz to 300kHz (-3d8) 1V, 30k0 -1 20dB (A-weighted) TA-E77ES Stereo Control Amplifier Rated harmonic distortion Frequency response Phono equalisation Signal-to-noise ratio phono MC phono MM CD, Tuner, etc trol and 3kHz and 6kHz for the Treble control. These are handy if you wish to carefully tailor the amount of Bass or Treble boost applied to your speakers. Remote control An interesting feature of the Sony control amplifier is the companion RM-177 infrared remote control. This includes the following functions: power on/off, volume adjust, program switching, and Direct and Adaptor switching. The remote volume control facility is very nice. Push the button and the volume control on the amplifier .001% 3Hz to 300kHz (-3dB) RIAA curve ±0.2dB -83dB (A-weighted) -95dB (A-weighted) - 1 05d8 (A-weighted) rotates smoothly and quietly for as long as you hold the button down. An illuminated red cursor on the knob shows the volume setting in unambiguous fashion. A small motor .on the rear of the control provides the drive. Another interesting feature is that when you first turn the amplifier on it is muted for several seconds. So that you don't rashly turn up the volume setting in your impatience to hear the sounds of your choice, the LED on the volume knob flashes a clear warning that it " ain't ready yet" . The headphone socket with its The TA-E77ES stereo control amplifier can handle the full range of audio signals plus three video program sources. Both moving magnet (MM) and moving coil (MC) cartridges are catered for. FEBR UA RY1988 31 Inside the stereo control amplifier. Special attention has been paid to circuit shielding. The chassis is a heavy glass reinforced epoxy casting. own inbuilt amplifier is a good idea. It lets you leave the power amplifier off if you are only going to listen to headphones. Inside the case, the Sony control amplifier is unlike any preamplifier/control unit we have seen to date. It has two power transformers, one small and the other a large toroidal unit which is larger than the transformer in many medium power stereo amplifiers. The main filter capacitors are large too, especially for a preamplifier unit. They comprise two 4700µF 63VW electrolytics. The small power transformer is powered up permanently and it keeps the remote control section of the circuitry awake. This means that you can turn on the whole system with the remote control. Neat. The most unusual feature is the chassis. This is Sony's "Gibraltar" chassis, a very heavy and rigid glass reinforced epoxy casting. Sony claims that it is much less resonant than any metal chassis and so less likely to rattle, buzz or otherwise make a contibution to the program signal. We agree; it is as dead as a door nail. Sony have gone to similar trouble with the top lid of the case. It is a 32 SILICON CHIP substantial piece of sheet steel, 2mm thick. It alone weighs 1.9kg. The whole unit weighs 12.1kg. Overall dimensions are 470 x 128 x 365mm, including knobs and rear projections. Other features inside the chassis are the three flat Bowden cables for the various rotary selectors on the front panel, the many miniature relays for switching and the special care taken with shielding. At various places on top of the printed circuit boards are long strips of copper to act as shields for vital parts of the circuit. switch selects either one or both pairs of loudspeakers, via relays. On the righthand side of the front panel are three knobs. One is a two position rotary switch to select either the variable or fixed inputs while the other two are independent level controls for the variable inputs. Sony have provided this facility so that the power amplifier can be used directly with a high quality program source such as a compact disc player. This truly would be an ultimate quality hifi set up since the amplifier has a weighted signal-tonoise ratio of 120dB with respect to full power. Thus, unlike most integrated stereo amplifiers presently available, the Sony power amplifier is a lot quieter than any compact disc player. It would have made more sense though, to make the level control a dual ganged potentiometer; two controls are a bit clumsy. On the rear panel are two pairs of RCA sockets for the inputs just referred to and eight massive shrouded binding posts for the two pairs of loudspeaker outputs. Removing the heavy perforated The power amplifier But if the Sony control amplifier is impressive, the stereo power amplifier is truly something to behold. It is built like a battleship. Immediately obvious are the two large power meters on the front of the amplifier, calibrated to read up to 600 watts into 80 loads. The meters can be switched on or off and when in use are illuminated in red which is easy on the eye but eye-catching as well. On the lefthand side of the front panel are two rotary switches and a large pushbutton which is the power switch. One rotary switch turns the meters on and off, as already mentioned. The other The companion IR remote control provides volume adjust and signal switching facilities. steel lid reveals the more or less standard features of today's high power amplifiers. There is a big power transformer with a copper strap around the laminations to eliminate flux leakage, a bank of electrolytic filter capacitors, a large chimney-style heatsink for the power transistors and so on. What really had us stumped was the large rectangular unit which took up the full depth and height of the chassis. Sony labelled this an "audio capacitor". What's an audio capacitor? It wasn't until we carefully examined the circuit digram that we realised that this "audio capacitor" was in fact a dual 22,000µ,F B0VW electrolytic capacitor which feeds the output stages of both power amplifiers. What we had thought was the main capacitor bank was in fact the electrolytics (4 x 4700µ,F B0VW) which supply the driver stages of both power amplifiers. So Sony have really done some work on the power supply of this brute. Sony haven't told us the concept of this "audio capacitor" but we can say that it is very large, even considering that it does contain 44,000µ,F of capacitance rated at 80 volts. We can only assume that it has a very high current rating. This is important if an amplifier is to deliver a very high current output. The rectangular case raises some interesting questions too. Presumably it is made of some plastic or epoxy material. How is it sealed and does it have safety venting? The seal of the can on a conventional electrolytic is quite critical. It must be absolutely moisture and air-tight otherwise the capacitor will deteriorate over time. But it must also have a safety vent which can blow and safely exhaust the copious volume of gas produced if an electrolytic fails and then seriously overheats. Again, this amplifier employs the Gibraltar-style cast chassis and the whole unit is laid out with the same detailed attention to shielding as in the control amplifier. Testing Testing the performance claims of such amplifiers challenges the test equipment of any organisation. Inside the stereo power amplifier. The "audio capacitor" is actually a dual 22,000µF 80VW electrolytic capacitor that feeds the output stages of the power amplifiers. Note the large chimney-style heatsink. Consider that the Sony power amplifier is continuously rated at 200 watts per channel into 80 loads and 270 watts per channel into 40 loads. We made up some large water cooled loads for our tests but we had to stop periodically because the water kept boiling. Measuring harmonic distortion was a problem. The control preamplifier has a rated harmonic distortion of .001 % while the power amplifier has a rated distortion of less than .004 % from 2 50 milliwatts up to 200 watts per channel into 80 loads. We can measure distortion down to less than .0007 % but there were times when our distortion measurements merely reflected the residual distortion of our equipment. Signal-to-noise ratio was another problem measurement. The control amplifier is rated at better than 105dB A-weighted for the high level inputs and better than 95dB Aweighted for the moving magnet phono input. These are the best figures we have seen to date for any stereo preamplifier. Even better is the power amplifier. As already mentioned, it has a signal-to-noise ratio of better than 120dB A-weighted with respect to full power. To measure such figures reliably you need an audio millivoltmeter set-up which will reliably measure down to less than 30 microvolts . Well, we were able to confirm the figure but not without difficulty. Indeed, as far as we could determine, all of Sony's performance specifications are met by both the control amplifier and the power amplifier. What more can we say? This Sony gear is too good for us to presently sonically test. They must be among the highest performing audio amplifiers available, regardless of price. Price of the control amplifier together with its remote control is $1799 while the power amplifier is priced at $2399. For further information, contact your Sony dealer or Sony (Australia) Pty Ltd, 33-39 Talavera Road, North Ryde, NSW 2113. Phone (02) 887 6666. it FEBRUARY1988 33