Review and Measurements of vintage Yamaha AX-396 integrated amplifier
This review shows measurements of Yamaha AX-396 integrated amplifier, ser. no. Y399871TV, made in Malaysia.
I bought this amplifier in the year 2002 and have been using it shortly. Then it was sleeping in my stock and 5 years ago I gave it to my son, who has been using it till nowadays.
Description
AX-396 is a 2-channel, integrated amplifier. It has 5 linear inputs (150mV/47k) and 1 phono RIAA input (2.5mV/47k). It has 2 link level outputs (150mV/1.6k) (tape and MD). It has headphone output. It has 2 pairs of speaker outputs A, B. And it has 3 switched AC outlets to connect 3 audio units with total power consumption 100W max.
Front view of the Yamaha AX-396
Rear view of the Yamaha AX-396
It is a class II unit with rated power consumption of 150W/230V.
There is an impedance selector switch on the rear panel to select minimum speaker impedance at A or B output terminals, it has 2 positions – 4 ohm minimum and 6 ohm minimum. I have moved the switch to 4 ohm position, as my tests will be performed with 4 ohm load.
The amplifier has tone controls and loudness control, both may be bypassed by pushing “CD/DVD direct” button at the front panel and using the CD/DVD input at the rear panel. The “direct” path has considerably lower noise and better S/N, about 15dB, as will be shown later. That's the reason why it was used for measurements.
The amplifier is working and is in quite a good shape, the only serious issue is that the rotary input selector works very badly and one has to turn it many times round and round before it is willing to jump to the next input. As I was measuring in the direct mode, I left the selector just at the CD/DVD position.
Measurements (direct mode, if not stated otherwise)
THD and THD+N at 1kHz, 5W/4ohm
Yamaha AX-396 distortion 1kHz/5W/4ohm. THD = 0.005%, SINAD(A) = 83.9dB. We can see quite a lot of higher order harmonics and PSU mains lines are about -90dB below base frequency, which is not excellent, however it is acceptable. Maybe new PSU filter capacitors might improve this.
THD vs. output voltage at 100Hz, 1kHz and 15kHz, 4ohm load
Yamaha AX-396 THD vs. output voltage. We can see that maximum output voltage below clipping is about 20V in all 3 cases, which makes 100W/4ohm output power and it is more than specified by the manufacturer, regardless the age of the unit. Very good. Rated power, according to the user manual, is 95W/4ohm/0.7% THD as DIN specs, so the test result is better. I would only appreciate if THD was going a bit lower between 1W and 5W, we have a forest of higher order harmonics even at low power like 1-2W. This gets better if the impedance selector is switched to 6 ohm position, however I did not want to risk damage of the unit.
THD vs. frequency at 5W/4ohm
Yamaha AX-396 THD vs. frequency at 5W/4ohm. Distortion is quite flat with frequency and I appreciate it.
19+20kHz CCIF IMD measurement
Yamaha AX-396 CCIF 19+20kHz IMD at 11.2Wpeak/4ohm. IMD = 0.0047% and this is really not bad at all.
Multitone distortion
This is good!
Output noise in direct mode
Yamaha AX-396 output noise A weighted. It is -81.6dBV(A) and this is very good, the only pain is the PSU ripple throughput. S/N to full power (100W) is 107.6dB(A).
Output noise of complete amplifier, direct mode switched off
Yamaha AX-396 output noise A weighted, direct off. It is -65.9dBV(A) and this is much much worse than in the direct mode. S/N to full power (100W) is 91.9dB(A), nothing to call home about. My recommendation is to use direct mode only.
Maximum input voltage in CD direct mode
Maximum input voltage is 2.6Vrms. Above this level, internal clipping + distortion occurs. Most players would be OK, but never forget about this limit.
Maximum power at 20 kHz
AX-396 keeps its ability to yield 100W/4ohm even at 20 kHz. This is very good.
Square wave response, 4Vp-p output, 4 ohm
Response to 10 kHz square is aperiodic, with rise time of 3.20 us. This makes -3dB frequency roll off at 109 kHz, so bandwidth is sufficient.
Measurement to complex load, 4ohm//(33uF+0.44ohm)
An attempt was made to measure distortion vs. frequency at 4.6Vrms output voltage, which would be 5W at 50Hz, to the complex load described in this thread
https://www.audiosciencereview.com/...ad-for-power-amplifier-torture-testing.10298/
The attempt was not successful and the amplifier protection triggered the unit off at 3.4kHz frequency, where the load impedance is 1.275 ohm and -53°, which indicates to mostly capacitive impedance. The amplifier has only one output pair of 2SA1695/2SC4468 devices,
https://www.semicon.sanken-ele.co.jp/sk_content/2sa1695_ds_en.pdf
which is insufficient for 100W/4ohm amplifier loaded with a complex load like the one used. It is just at the edge for the purely resistive load, however that's how consumer electronics has always been designed. On the other hand, the protection circuit worked well and saved the amplifier. For the same reason, I surrendered to perform a square wave test into the complex load.
Conclusion
The Yamaha AX-396 made a respectable test-bench result, regarding its age and the fact it was a consumer electronics product, priced about $400. I would appreciate if it had lower distortion in 1 – 5W range and less high order harmonics in the spectrum even at low power. It was able to work well with 4ohm resistive load, however it failed to drive my “torture” complex load, triggering the unit of at 4.6Vrms output voltage and 3400 Hz frequency, where the impedance was rather capacitive, 1.275ohm/-53°. Still, for usual use, this amplifier might still be considered, taking into account its output power and low noise in the “direct” mode. I would not use it with direct mode switched off, dynamic range falls of -15dB.
I have this unit here now, so in case you are interested in some kind of a meaningful measurement that I did not do, please let me know.
I will do some listening now.
====================================================================================
New measurement set September 23-24, 2021
As I have some improvement in my measuring system, I am attaching THD and THD+N vs. power plots measured into 4ohm and 8ohm load impedances.
This review shows measurements of Yamaha AX-396 integrated amplifier, ser. no. Y399871TV, made in Malaysia.
I bought this amplifier in the year 2002 and have been using it shortly. Then it was sleeping in my stock and 5 years ago I gave it to my son, who has been using it till nowadays.
Description
AX-396 is a 2-channel, integrated amplifier. It has 5 linear inputs (150mV/47k) and 1 phono RIAA input (2.5mV/47k). It has 2 link level outputs (150mV/1.6k) (tape and MD). It has headphone output. It has 2 pairs of speaker outputs A, B. And it has 3 switched AC outlets to connect 3 audio units with total power consumption 100W max.
Front view of the Yamaha AX-396
Rear view of the Yamaha AX-396
It is a class II unit with rated power consumption of 150W/230V.
There is an impedance selector switch on the rear panel to select minimum speaker impedance at A or B output terminals, it has 2 positions – 4 ohm minimum and 6 ohm minimum. I have moved the switch to 4 ohm position, as my tests will be performed with 4 ohm load.
The amplifier has tone controls and loudness control, both may be bypassed by pushing “CD/DVD direct” button at the front panel and using the CD/DVD input at the rear panel. The “direct” path has considerably lower noise and better S/N, about 15dB, as will be shown later. That's the reason why it was used for measurements.
The amplifier is working and is in quite a good shape, the only serious issue is that the rotary input selector works very badly and one has to turn it many times round and round before it is willing to jump to the next input. As I was measuring in the direct mode, I left the selector just at the CD/DVD position.
Measurements (direct mode, if not stated otherwise)
THD and THD+N at 1kHz, 5W/4ohm
Yamaha AX-396 distortion 1kHz/5W/4ohm. THD = 0.005%, SINAD(A) = 83.9dB. We can see quite a lot of higher order harmonics and PSU mains lines are about -90dB below base frequency, which is not excellent, however it is acceptable. Maybe new PSU filter capacitors might improve this.
THD vs. output voltage at 100Hz, 1kHz and 15kHz, 4ohm load
Yamaha AX-396 THD vs. output voltage. We can see that maximum output voltage below clipping is about 20V in all 3 cases, which makes 100W/4ohm output power and it is more than specified by the manufacturer, regardless the age of the unit. Very good. Rated power, according to the user manual, is 95W/4ohm/0.7% THD as DIN specs, so the test result is better. I would only appreciate if THD was going a bit lower between 1W and 5W, we have a forest of higher order harmonics even at low power like 1-2W. This gets better if the impedance selector is switched to 6 ohm position, however I did not want to risk damage of the unit.
THD vs. frequency at 5W/4ohm
Yamaha AX-396 THD vs. frequency at 5W/4ohm. Distortion is quite flat with frequency and I appreciate it.
19+20kHz CCIF IMD measurement
Yamaha AX-396 CCIF 19+20kHz IMD at 11.2Wpeak/4ohm. IMD = 0.0047% and this is really not bad at all.
Multitone distortion
This is good!
Output noise in direct mode
Yamaha AX-396 output noise A weighted. It is -81.6dBV(A) and this is very good, the only pain is the PSU ripple throughput. S/N to full power (100W) is 107.6dB(A).
Output noise of complete amplifier, direct mode switched off
Yamaha AX-396 output noise A weighted, direct off. It is -65.9dBV(A) and this is much much worse than in the direct mode. S/N to full power (100W) is 91.9dB(A), nothing to call home about. My recommendation is to use direct mode only.
Maximum input voltage in CD direct mode
Maximum input voltage is 2.6Vrms. Above this level, internal clipping + distortion occurs. Most players would be OK, but never forget about this limit.
Maximum power at 20 kHz
AX-396 keeps its ability to yield 100W/4ohm even at 20 kHz. This is very good.
Square wave response, 4Vp-p output, 4 ohm
Response to 10 kHz square is aperiodic, with rise time of 3.20 us. This makes -3dB frequency roll off at 109 kHz, so bandwidth is sufficient.
Measurement to complex load, 4ohm//(33uF+0.44ohm)
An attempt was made to measure distortion vs. frequency at 4.6Vrms output voltage, which would be 5W at 50Hz, to the complex load described in this thread
https://www.audiosciencereview.com/...ad-for-power-amplifier-torture-testing.10298/
The attempt was not successful and the amplifier protection triggered the unit off at 3.4kHz frequency, where the load impedance is 1.275 ohm and -53°, which indicates to mostly capacitive impedance. The amplifier has only one output pair of 2SA1695/2SC4468 devices,
https://www.semicon.sanken-ele.co.jp/sk_content/2sa1695_ds_en.pdf
which is insufficient for 100W/4ohm amplifier loaded with a complex load like the one used. It is just at the edge for the purely resistive load, however that's how consumer electronics has always been designed. On the other hand, the protection circuit worked well and saved the amplifier. For the same reason, I surrendered to perform a square wave test into the complex load.
Conclusion
The Yamaha AX-396 made a respectable test-bench result, regarding its age and the fact it was a consumer electronics product, priced about $400. I would appreciate if it had lower distortion in 1 – 5W range and less high order harmonics in the spectrum even at low power. It was able to work well with 4ohm resistive load, however it failed to drive my “torture” complex load, triggering the unit of at 4.6Vrms output voltage and 3400 Hz frequency, where the impedance was rather capacitive, 1.275ohm/-53°. Still, for usual use, this amplifier might still be considered, taking into account its output power and low noise in the “direct” mode. I would not use it with direct mode switched off, dynamic range falls of -15dB.
I have this unit here now, so in case you are interested in some kind of a meaningful measurement that I did not do, please let me know.
I will do some listening now.
====================================================================================
New measurement set September 23-24, 2021
As I have some improvement in my measuring system, I am attaching THD and THD+N vs. power plots measured into 4ohm and 8ohm load impedances.
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