MAB
Major Contributor
Today I test an Aiwa A22 micro integrated amplifier from 1979.
It features three inputs including MM Phono, plus a tape loop. Bass and treble controls, plus loudness. I bought this used in the '80s. I had to service it 6 or 7 years ago, replacing three capacitors and cleaning the controls. It has the rack handle options, which gives it a badass look.
It's been in occasional use for most of it's life. 10 years in our kitchen for example. Other than the capacitors, it has been very reliable.
Power Amp
It doesn't have preamp outs, so I will test the unit as an integrated amp. It's spec'ed to drive 8-16Ω speakers.
Here is the 5 Watt, 1 kHz, 8Ω dashboard:
This is decent, 78 to 80 dB SINAD into 8 Ohms.
Let's see the 4Ω dashboard, even if the amp isn't rated below 8Ω:
Still not bad, 71 dB and 74dB SINAD for Left and Right channel, lands it in the fair category at ASR. It certainly performs better into 8Ω.
Note that the Left and Right channels are closely matched, the volume knob tracks to within +-0.2 dB across the entire range. That is really good, this unit has been used quite a bit over the last 45 years, I expected to see deviations over 1 dB.
Here is the frequency response in 4Ω resistive load, which is good but not quite matched left to right above 10kHz.
Not a huge deviation, good flatness and extension.
Here is THD and THD+N vs. power into 8Ω:
Aiwa claims 0.05% THD at 1 kHz, 9W both channels driven. It beats that meeting 0.01% at 9 Watts on my QA403, but I imagine Aiwa had test hardware in 1979 that limited their measurement. The amp clips at just over 18 Watts, meeting Awia's spec for peak power.
And here is the same into 4Ω:
It's starting to show some strain into 4Ω, but not horrible and still meeting 18 Watts at clipping. The case is small, it gets warm if driven hard. I've never tried it with a difficult speaker load.
Tone Controls and Loudness
Here is the loudness contour:
Loudness boosts the bass and treble at 100 Hz and 10 kHz respectively. Aiwa claim +6 dB at 100 Hz, and +5 dB at 10 kHz, the frequencies are accurate but the boost is 2 dB more than Aiwa's spec.
The Bass and Treble tone controls have the same corner frequencies, with 5 detents of positive boost, 5 detents of attenuation. Here are the responses at +-2 detents, and +-5 detents:
More attenuation than Aiwa claims (+-9 dB of bass, +-8 dB of treble). The controls are too abrupt, not as useful as I would like. Even the first detent (not shown) drops the bass by 6 dB.
The right channel closely matches the left, so they got that right:
Headphone
A pretty useful feature on a small device. Here is the power into 300Ω and 32Ω resistive loads:
Just over 30mW into a 300Ω load. Not much.
Phono
The phono has mains hum:
I played with all sorts of grounding schemes, plugged it into a laboratory AC line conditioner, used a galvanic isolator on the analyzer. The hum remains, despite the good distortion performance. Maybe playing records with no hum isn't this unit's strong suit.
It does have some overload margin, about 150mV:
RIAA Equalization is within 0.2dB from 20Hz to 20kHz:
Left and right channels are mismatched by 0.1 to 0.2 dB from 30Hz to 2kHz.
Conclusion
For 8Ω speakers in a background/lifestyle setting, this little integrated amp works great. I'm not surprised it struggles slightly driving low impedance loads, I'll continue to avoid those. I never recall hooking up a turntable, now I know what to expect.
All in all, it has a good feel and has been reliable, and sounds good while looking great.
Edit: Added the RIAA equalization graph to the Phono section, which I neglected to include.
It features three inputs including MM Phono, plus a tape loop. Bass and treble controls, plus loudness. I bought this used in the '80s. I had to service it 6 or 7 years ago, replacing three capacitors and cleaning the controls. It has the rack handle options, which gives it a badass look.
It's been in occasional use for most of it's life. 10 years in our kitchen for example. Other than the capacitors, it has been very reliable.Power Amp
It doesn't have preamp outs, so I will test the unit as an integrated amp. It's spec'ed to drive 8-16Ω speakers.
Here is the 5 Watt, 1 kHz, 8Ω dashboard:
This is decent, 78 to 80 dB SINAD into 8 Ohms.
Let's see the 4Ω dashboard, even if the amp isn't rated below 8Ω:
Still not bad, 71 dB and 74dB SINAD for Left and Right channel, lands it in the fair category at ASR. It certainly performs better into 8Ω.
Note that the Left and Right channels are closely matched, the volume knob tracks to within +-0.2 dB across the entire range. That is really good, this unit has been used quite a bit over the last 45 years, I expected to see deviations over 1 dB.
Here is the frequency response in 4Ω resistive load, which is good but not quite matched left to right above 10kHz.
Not a huge deviation, good flatness and extension.
Here is THD and THD+N vs. power into 8Ω:
Aiwa claims 0.05% THD at 1 kHz, 9W both channels driven. It beats that meeting 0.01% at 9 Watts on my QA403, but I imagine Aiwa had test hardware in 1979 that limited their measurement. The amp clips at just over 18 Watts, meeting Awia's spec for peak power.
And here is the same into 4Ω:
It's starting to show some strain into 4Ω, but not horrible and still meeting 18 Watts at clipping. The case is small, it gets warm if driven hard. I've never tried it with a difficult speaker load.
Tone Controls and Loudness
Here is the loudness contour:
Loudness boosts the bass and treble at 100 Hz and 10 kHz respectively. Aiwa claim +6 dB at 100 Hz, and +5 dB at 10 kHz, the frequencies are accurate but the boost is 2 dB more than Aiwa's spec.
The Bass and Treble tone controls have the same corner frequencies, with 5 detents of positive boost, 5 detents of attenuation. Here are the responses at +-2 detents, and +-5 detents:
More attenuation than Aiwa claims (+-9 dB of bass, +-8 dB of treble). The controls are too abrupt, not as useful as I would like. Even the first detent (not shown) drops the bass by 6 dB.
The right channel closely matches the left, so they got that right:Headphone
A pretty useful feature on a small device. Here is the power into 300Ω and 32Ω resistive loads:
Just over 30mW into a 300Ω load. Not much.
Phono
The phono has mains hum:
I played with all sorts of grounding schemes, plugged it into a laboratory AC line conditioner, used a galvanic isolator on the analyzer. The hum remains, despite the good distortion performance. Maybe playing records with no hum isn't this unit's strong suit.
It does have some overload margin, about 150mV:
RIAA Equalization is within 0.2dB from 20Hz to 20kHz:
Left and right channels are mismatched by 0.1 to 0.2 dB from 30Hz to 2kHz.
Conclusion
For 8Ω speakers in a background/lifestyle setting, this little integrated amp works great. I'm not surprised it struggles slightly driving low impedance loads, I'll continue to avoid those. I never recall hooking up a turntable, now I know what to expect.
All in all, it has a good feel and has been reliable, and sounds good while looking great.Edit: Added the RIAA equalization graph to the Phono section, which I neglected to include.
Attachments
Last edited:
and a digital timer:
Promoted to home page.
(V1 though, maybe not the V2).
