Sony TA-N77ES. enlarge.
Rear, Sony TA-N77ES. enlarge. This free website's biggest source of support is when you use these links, especially this link directly to them at eBay (see How to Win at eBay), when you get anything, regardless of the country in which you live. Thanks! Ken.
The actual sample reviewed here is for sale (see How to Win at eBay if you want to win). Buy it and you'll get the only Sony amp for sale today that's been through a battery of serious laboratory certification! These are nearly impossible to find at any price, especially with meter lights that actually work, because they were so insanely expensive when new that few people could afford to buy them. (Note: my photos here have been cleaned-up and are not in any way part of the listing.)
The Sony TA-N77ES is Japan's greatest power amplifier of all time. It's a 55-pound behemoth with huge meters that sounds and measures extremely well.
The TA-N77ES was Sony's last effort at pushing the envelope of serious power amplifiers at the end of Hi-Fi's glory days.
As VCRs and big-screen TVs forever replaced music as people's primary form of recorded entertainment in the mid 1980s, Sony's next amplifier, the TA-N80ES, was the same thing without the meters, and Sony's next amplifier after that was the TA-N90ES, which was a half-power version of the meterless TA-N80ES. This N77ES was Sony's biggest and best of all time; Japan's last stand before before audio was left to the weirdos and everyone normal preferred to watch their VCR on the big screen.
No one will admit to this and I can't tell you it either, but Sony cleverly sold the design to Accuphase in 1989, who still sells it today in their model P-4100. The Accuphase P-4100 uses the same isolated power supply for the drivers ("Spontaneous Twin Drive"), the same triple-parallel bipolar output stage, the same idle-power draw, and even the same speaker, meter, input and attenuator controls — and of course the same wonderful huge meters. Accuphase reduced the P-4100's output power for economic reasons to only 90 WPC, and of course raised the price by ten times over what Sony asked for this landmark TA-N77ES. Such is niche marketing, but remember, I can't tell you any of this.
This Sony amp sounds great, and its high-frequency THD measures better in the lab than any other amp I've had in; even better than the newer 200 WPC ADCOM GFA-555 II.
This Sony has the advantage of silent running. There are no fans, and its power transformer makes no buzzing. It draws so much inrush current that it usually tripped my UPS when turned-on; it dropped the line voltage enough that my UPS kicked-in to correct the dip.
The big gotcha with this huge 55-pound Sony is that, in Japanese tradition, it only barely meets its claimed power output. While both this Sony the ADCOM GFA-555 II are rated at the same 200 watts per channel into 8Ω, the ADCOM easily puts 260 W continuous and 370 W on tone bursts into 8Ω, while this Sony only puts out 180W maximum into 8Ω, period. I suspect this Sony I bought was defective to some extent either as a sample or in design; it has a screwy self-protection circuit in addition to its speaker protection circuitry which kept clicking a relay, and I suspect kept switching supply-rail voltages as I tried to test it.
I purchased this unit personally, but when I discovered slightly low power output and something potentially fishy in the protection circuits (I have no idea if the circuits were defective just designed this way since day one (scroll down for green text)), I returned it, so my time with this sample was limited. As a family man today, I no longer have time to try to fix or analyze problems with items I've bought — I simply returned it to the fantastic dealer from whom I purchased it.
For all I know, the actual output power of this sample is perfectly normal for the USA model — just that no one had the equipment to measure this back in 1986. Since I had paid for a "200 WPC" amp, I sent it back. Consider this as a 125W to 175W rated amplifier, and it way outperforms those ratings.
In any case, the difference between 180W and 200W is completely inaudible, less then half a decibel.
This TZ-N77ES is a real analog amplifier with a real power switch and turn-on delay relays. When it's off, it's disconnected from the power, and the speaker relays ensure there are never any turn-on or turn-off thumps, even when used with other sloppy components.
Its circuit boards are the usual green and brown paper.
At 55 pounds, you really want two men to lift this around. I had a sore back for days muscling it all over between shipping, lab and listening room for this review.
It's built on a gypsum-like base, the same plasti-crete-like stuff ADS used at the same time for speaker cabinets. Sony marketed this stuff as G-fiber or "granite" or some other baloney, while in fact it's stuff that leaves white powder behind if it gets scratched. It's painted black and used for the bottom of the amplifier. The fake granite material (which feels more like the gypsum inside wallboard) is used to hold the power transformer. A nice touch is molded ridges on the bottom to aid picking it up.
The sides are pure chipboard with plastiwood veneer (no metal sides if you remove the plastiwood), and the top and bottom covers are the usual perforated steel. The bottom cover only covers half the base, below the circuit board.
The heatsink stack is internal. No fins are on the outside; the amp is cooled by vertical convection.
While it's a big, tough-looking amp, all the knobs and switches are plastic.
There are two inputs, one variable, making this power amp act as if you've got a free preamp.
The FIXED and VARIABLE inputs are great; it effectively gives you two selectable inputs or an input mute. The VARIABLE inputs are great for desktop use, allowing one to lower the gain to render preamp noise inaudible. The input level controls, while marked in nice deciBels, have no detents, although they track surprisingly well to their marked attenuations.
The meters are the main reason anyone buys this amplifier today. They are big, beautiful and peak-reading, and easily catch even 100µS peaks (one-cycle of 10 kc). They read peak voltage directly off the internal signal output rail, calibrated in equivalent watts into 8Ω.
They move as if they have VU ballistics, but are driven with a peak-reading circuit and have lots of overshoot.
Sadly, there is no useful distortion or clip indicator. A single CLIP, IOC or OVER LED would be far more useful than the big meters.
Driving the Focal Little Bird speakers on a desktop, I find that typical readings are:
Below the meters are some sort of plastic cut or made prismatic in such a way that they appear in different colors of the rainbow depending on the angle at which you view them.
Besides the questionable output power, which makes no real audible defect except a fraction of a dB in peak level which no owner of this amp is likely ever to notice unless they have proper modern lab equipment, this amp's weakest point is defective design of the meter bulb power supply.
While every American electronics engineer knows never to connect incandescent bulbs in series, Sony did exactly this: connecting three 12V 100mA bulbs in series, connected to 36V DC. This sounds fine in theory, but is never done in practice because any variation between bulbs will divide the voltage unequally, so one or more bulbs will be fed with more than 12V, greatly shortening their life. Worse, as soon as the first bulb goes, all the bulbs for that meter go dark at the same time. Sony also made the mistake of running 12V bulbs at 12V, not a lower voltage which would have let them run much longer.
Luckily the sample I bought for review had its meter bulbs still working; its original owner probably left the meter switch OFF most of the time, which turns off both the bulbs and the meters. The bulbs are inexpensive enough, (the original Sony part is part number 1-518-527-51, but priced to include most of the labor at Sony service depots.) You'll need a technician to install them; NEVER open an amp unless you hold a valid licence to do so; too many people read how to "fix" things on the internet, and wind up blowing out and otherwise screwing-up classic equipment forever.
The power plug is polarized.
The power cord is a 6-foot, nicely-flexible 8mm-diameter captive cord.
The speaker output connectors are non-standard. They look big and tough, but feel flimsy, with the big plastic handles just being knobs for screwing-down some sort of bare-wire grabber.
There are two sets of speaker outputs, controlled by relays. These relays have numerous advantages. First, they are there for speaker protection and to prevent power on and off thumps. Since they there as part of the design, there is nothing to lose by providing two sets; the relays are controlled electronically by both the protection circuitry and the front panel selector. One application is if you'd like to compare speaker wire; just connect both, and you can literally A-B them with the switch. They are also a handy MUTE control.
As covered above, don't ever attempt to modify an amplifier if you don't have at least a BSEE degree and years of analog design experience, and don't even think of shorting-out the speaker relays. They are part of the protection circuits.
There are two separate sets of protection circuits, each based on an NEC µPA1237HA overload protector triggering relays.
The Speaker Protection Circuit triggers the front-panel red LED and mutes the speakers for 9 seconds at power ON and instantly at power OFF, and in case of too much DC offset.
The second separate Amplifier Overload Protection Circuit in the USA model selects between two voltage taps on the power transformer secondary. It starts the amp at the lower voltage for the first 45 seconds, then switches taps to the supply usual ±74 V DC rails. If it detects any output above about 66-2/3 watts driving 8Ω, it swaps to the lower voltage taps without telling anyone about it. Weird, but true. It won't trigger open-circuit.
The users manual doesn't explain any of this. The users manual is in several languages, offering only a page of two of very basic hook-up information and specifications.
Use as a Headphone Amplifier
Strange but true, but if you wire either speaker output directly to a headphone jack (again, this is not a project for online experts), the TA-N77ES is so quiet that it works great with 600Ω Beyer DT880s, and the front-panel gain controls are very handy.
If you plug an iPod directly into this amp's variable input, I find setting the gain to about -9 to -16 dB is about optimum. The TA-N77ES is so clean that it's easy to hear the almost silent noise of the iPod itself, and to hear that noise mute after being in pause for several seconds. Since the iPod's idle noise varies with the iPod's level setting, feel free to leave the TA-N77ES' gain full-up if you're that crazy.
To my taste, the power meters usually read about 0.01 ~ 0.1 watts with my DT880s.
With my DT880, I get impressively smooth, deep, revealing and detailed bass, and smooth detailed sound overall.
The MONO switch controls relays to invert the polarity of the left input and feed it to the right input.
This is much better than most amplifiers which use the rear-panel switch to switch the audio directly.
30k Ω, 1 Volt.
Two pairs of gold-colored RCA jacks.
1V for unspecified output.
Rated Power Output
200 watts per channel into 8 Ω from 20 - 20,000 Hz at less than 0.004% THD, both channels driven, from 250mW output to 200W.
230 watts per channel into 6 Ω from 20 - 20,000 Hz at less than 0.005% THD, both channels driven, from 250mW output to 200W.
270 watts per channel into 4 Ω from 20 - 20,000 Hz at less than 0.006% THD, both channels driven, from 250mW output to 200W.
300 W at 8 Ω.
370 W at 6 Ω.
520 W at 4 Ω.
800 W at 2 Ω.
660 W at 1 Ω.
Power Bandwidth (IHF)
10 ~ 100,000 Hz, 8 Ω or 4 Ω at 0.02% THD.
Dynamic Headroom (IHF 1978)
1.8 dB at 8 Ω.
2.8 dB at 4 Ω.
THD at 10 Watts
0.0018% at 8 Ω.
0.003% at 6 Ω.
0.004% at 4 Ω.
SMPTE IMD at Rated Output
0.004% at 8 Ω.
0.005% at 6 Ω.
0.006% at 4 Ω.
Damping Factor (8 Ω, 1 kHz)
0.004% at 8 Ω.
0.005% at 6 Ω.
0.006% at 4 Ω.
(300 V/µS inside before the signal hits the output series inductors.)
< 35 µV, A-weighted.
SNR (IHF 1978)
120 dB, A-weighted.
1 ~ 200,000 Hz, +0, -3 dB.
Power Input & Consumption
Varies by market.
Oddly rated 380 watts consumption for USA, even though rated to produce more than 400 watts continuous output.
It draws zero power when turned off because it has a real power switch. It's not like modern equipment that never really turns off and consumes power and remains a fire hazard any time its plugged in. The TA-N77ES is completely disconnected when switched off.
When switched-on, there is a 9.0 second mute during which it draws 30 watts. Even if ON, the meters are dark for those first 9 seconds.
The meter bulbs are rated a total of 7.2W (1.2W x 6 bulbs).
Actual measured power drain is:
1 W output, both channels
10 W Output, both channels
180 W output, both channels
Warm Idle, if power supply rails at full voltage:
Overall: 7-3/8 x 18-5/8 x 17-3/8 inches HWD.
If you take off the fake wood side panels, what's left is standard 17" wide, but with nothing covering the sides! Unlike other Sony items with fake wood side panels, there is no metal case underneath on the sides.
55.125 pounds (25 kg).
Made in Japan.
All measured with the Rohde & Schwarz UPL, 8Ω load at 1 watt RMS and 1 kHz unless otherwise noted.
The traces are color coded for the Left Channel and for the Right Channel. When they don't lie on top of each other (colored blue), it's because of channel imbalance.
Measured at 1 kHz, 1 watt output into an 8 Ω load:
* Gain varies a tenth of a dB up and down with time; the difference between FIXED and VARAIBLE inputs is because I measured them at different times, not because they have different gains.
This calculates out to 42.462x gain.
2 mV in is 1 mW out into 8 Ω.
6.3 mV in is 10 mW out into 8 Ω.
20 mV in is 100 mW out into 8 Ω.
63 mV in is 1 W out into 8 Ω.
200 mV in is 10 W out into 8 Ω.
630 mV in is 100 W out into 8 Ω.
890 mV in would be 200 W out into 8 Ω.
The meters read peak voltage internally from the feed to the speakers, before the series RL network and speaker relays. They have no idea of the actual load impedance.
The meters are just for show and as a general guide to how loud you're playing it; they are not reading the actual power output.
The service manual says the meters should be calibrated with a sine-wave at 10 W driving 8 Ω, and as you'll see, that's the only reading which is particularly accurate.
Measured at 1 kHz:
*Really only 180W.
10 mS Bursts
The meter ballistics have a lot of overshoot. These are the peak deflections with 10mS tone bursts. With music, they will indicate well over 200W:
* Really only 180W.
Bursts at 1 Watt, 1 Hz PRF
The meter drivers are decent peak-indicating circuits:
Meter Frequency Response
The meters ignore low frequencies, which is too bad. This was done to make them ignore record-player warp and rumble, which would have given phantom meter readings between tracks. In this amp's heyday, most home listeners still listened to some records (not me!).
10% power at 5 Hz
60% power at 15 Hz
80% power at 25 Hz
< 95% power 50 Hz ~ 20 kHz
80% power at 50 kHz
70 % power at 110 kHz
Sony TA-N77ES Output noise spectrum, fed from 5 Ω source impedance.
Unweighted noise, AC coupled:
Measured into 8 Ω when fed from a 5 Ω source impedance:
Sony TA-N77ES Frequency Response, ±5 dB scale.
Sony TA-N77ES Frequency Response, ±1 dB scale.
Sony TA-N77ES Frequency Response, ±0.2 dB scale.
Sony TA-N77ES Frequency Response to 110 kHz, ±5 dB scale.
Sony TA-N77ES Frequency Response to 110 kHz, ±1 dB scale.
Not bad; down only 0.3 dB at 110 kc.
Sony TA-N77ES infrasonic Frequency Response.
Wow, down only 0.3 dB at 1 Hz and 3 dB at 0.4 Hz.
This gives a fantastic measured frequency response of 1 ~ 110,000 Hz +0, -0.3 dB!
Maximum Output at 1 kHz into an 8 Ω load: 180W
I measure only 180 W output at 0.1% THD at 0.859 V in, 115.6V and 597 Watts from wall.
I measure only ±53V peak with the output unloaded, or 36.25 V RMS at 0.1% THD.
This is significantly short from the 200 W rating. I suspect my sample was defective, or for all I know, maybe it's a design defect in all USA version. No one will ever hear this, and meters will cheerfully indicate well over 200W anyway on music.
The USA version I purchased uses a screwy protection circuit which might be defective by design, or just the sample I bought. I don't know.
Sony TA-N77ES THD at 1 milliwatt.
Sony TA-N77ES THD at 10 milliwatts.
Sony TA-N77ES THD at 100 milliwatts.
Sony TA-N77ES THD at 1 watt.
Sony TA-N77ES THD at 10 watts.
Sony TA-N77ES THD at 100 watts, protection activated (low supply rails).
Sony TA-N77ES THD at 1 Watt, protection activated (low supply rails).
Not bad; < 0.01% THD up to 20 kc from 10 mW through 100 W!
Sony TA-N77ES Distortion Components at 1 Watt.
19+20 kHz Difference-Frequency Distortion
per DIN IEC 268-3 or 118:
Sony TA-N77ES DFD at 100 milliwatts RMS.
Sony TA-N77ES DFD at 1 watt RMS.
Sony TA-N77ES DFD at 10 watts RMS.
Sony TA-N77ES DFD at 50 Watts RMS.
When I tried to plot this at 100 W, my lab's power limiter popped, telling me that this amplifier attempted to draw 29.34 amps! Therefore, I stopped this test at 50 watts.
This DFD performance is as good as I've seen.
Damping Factors and Output Impedances
Since the N77ES uses non-standard output connectors, my standard test procedure would have included the resistance of the adapters I need to connect to the N77ES' oddball outputs. This gave poor readings, since the adaptors were infringing the readings, giving output source impedances about five time worse than measured next.
Instead, since the TA-N77ES has two sets of speaker relays connected to the same rails, I got clever and measured the dip at the unloaded A outputs when an 8Ω load was switched-in at the A+B speaker position. This way I measured the damping factor effectively before the speaker relays.
The real damping factor will be somewhat worse than shown here, and better than the values about five times this when I had to measure through cable adapters.
Damping Factors at 8Ω
Method and raw data
Voltage drop when applying an 8 Ω load:
R source = (R load/attenuation ratio) - R load.
The Sony TA-N77ES amplifier is clean, quiet, well-built and sounds smooth, quiet and detailed. Its power-on and power-off relays make it especially well-mannered in any system, and its dual inputs and outputs make it very handy, saving you the need for a preamplifier.
Don't worry that it only puts out 180 watts, or about the same maximum output as a 100 watt American amplifier like an ADCOM GFA-545 II. As I told everyone back in the 1970s when normal people shopped for stereo equipment with the same fervor they expend on big screen TVs today, the audible significance of 180 W versus 200W or 300 W is insignificant. The differences between twice as much or half as much power is only one or two volume-control clicks, but amp makers never wanted you to know that. The only audible difference would be if you just happen to be at the one click where 100 W isn't enough and 200 W is, in which case you'd get a lot of distortion with the lesser amplifier. Lower it a click and the lesser amp will sound great, and raise it a click and both will distort.
As the N77ES' meters will show you, you very rarely use more than a watt unless you're trying to impress visitors or annoy the neighbors.
If you've found my efforts in attempting to buy and then document this classic equipment helpful, this free website's biggest source of support is when you use these links, especially this link directly to them at eBay, where they sell for about $900 (see How to Win at eBay). It helps me keep reviewing these oldies when you get yours through these links, thanks! Ken.
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