This is a review and detailed measurements of the Yaqin MC-84L Stereo Tube amplifier. It is on kind loan from a member and costs US $600 on Amazon.
The picture doesn't do justice to the nice design of this amplifier. The transformer case in the back nicely contrasts with the chrome parts. The latter does make the labels hard to read though when looking from above:
One set of binding posts is available for 4 ohm and the other, 8 ohm. Seeing how speakers don't have constant impedance, nor are advertised correctly as such, I feel bad for people trying to figure out which posts to use (common criticism for all such amplifiers). Let's see how it performs.
There is a headphone jack in the back which I did not test.
Yaqin MC-84L Stereo Tube Amplifier Measurements
For all but 8 ohm power test, I used the 4 ohm tap. Let's start with our dashboard:
We have the high harmonic distortion which we kind of expect. But a lot of mains noise comes along for the ride, causing intermodulation with our main 1 kHz, making for a mess. SINAD which is the sum of all unwanted "stuff," lands the amplifier at the bottom of our rankings:
Noise is a step above but still nothing remotely to be proud of:
Frequency response is flat enough if we ignore varying performance between channels:
Crosstalk is one step above mediocre:
You get a better feel for distortion when we use 32 tones to simulate "music:"
Not pretty. Same story for 19+20 kHz tones:
The amplifier is fairly rated at 12 watts, assuming you don't care about distortion:
One channel is having trouble above 2 watts which we also saw in the dashboard. So maybe it is a bad tube or something. Best of luck to a customer figuring that out without this type of measurement.
If we "only" allow 1% distortion and noise, available power shrinks to a trickle:
Yes, that is only 2 watts!
Using 8 ohm tap, we get similar results:
Sweeping frequencies we see the typical rise in distortion with frequency. But also increase in distortion at low frequencies (transformer saturation?):
I am showing both channels. Dashed line is the "good" channel.
Our power on/off test shows instability on top of noise at these events:
Fortunately if you wait a minute or so, everything stabilizes:
Conclusions
The Yaqin MC-84L made a very positive impression on me with its modest size and super nice industrial design. And reasonable price for such tube products. Performance though, set a new record with respect to how bad it is, taking over the slot for the worst measured amplifier to date. The amp has 42 reviews on Amazon with average of 4.5 stars. Folks must be very tolerant of noise and distortion out there!
I do like the company honesty when it comes to power rating and even SNR.
Needless to say, I can't recommend the Yaqin MC-84L valve amplifier.
------------
As always, questions, comments, recommendations, etc. are welcome.
Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
The picture doesn't do justice to the nice design of this amplifier. The transformer case in the back nicely contrasts with the chrome parts. The latter does make the labels hard to read though when looking from above:
One set of binding posts is available for 4 ohm and the other, 8 ohm. Seeing how speakers don't have constant impedance, nor are advertised correctly as such, I feel bad for people trying to figure out which posts to use (common criticism for all such amplifiers). Let's see how it performs.
There is a headphone jack in the back which I did not test.
Yaqin MC-84L Stereo Tube Amplifier Measurements
For all but 8 ohm power test, I used the 4 ohm tap. Let's start with our dashboard:
We have the high harmonic distortion which we kind of expect. But a lot of mains noise comes along for the ride, causing intermodulation with our main 1 kHz, making for a mess. SINAD which is the sum of all unwanted "stuff," lands the amplifier at the bottom of our rankings:
Noise is a step above but still nothing remotely to be proud of:
Frequency response is flat enough if we ignore varying performance between channels:
Crosstalk is one step above mediocre:
You get a better feel for distortion when we use 32 tones to simulate "music:"
Not pretty. Same story for 19+20 kHz tones:
The amplifier is fairly rated at 12 watts, assuming you don't care about distortion:
One channel is having trouble above 2 watts which we also saw in the dashboard. So maybe it is a bad tube or something. Best of luck to a customer figuring that out without this type of measurement.
If we "only" allow 1% distortion and noise, available power shrinks to a trickle:
Yes, that is only 2 watts!
Using 8 ohm tap, we get similar results:
Sweeping frequencies we see the typical rise in distortion with frequency. But also increase in distortion at low frequencies (transformer saturation?):
I am showing both channels. Dashed line is the "good" channel.
Our power on/off test shows instability on top of noise at these events:
Fortunately if you wait a minute or so, everything stabilizes:
Conclusions
The Yaqin MC-84L made a very positive impression on me with its modest size and super nice industrial design. And reasonable price for such tube products. Performance though, set a new record with respect to how bad it is, taking over the slot for the worst measured amplifier to date. The amp has 42 reviews on Amazon with average of 4.5 stars. Folks must be very tolerant of noise and distortion out there!
I do like the company honesty when it comes to power rating and even SNR.
Needless to say, I can't recommend the Yaqin MC-84L valve amplifier.
------------
As always, questions, comments, recommendations, etc. are welcome.
Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
