Yaqin MC-84L Tube Stereo Amplifier Review

[beagleman]

@amirm

"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 am NOT saying this equals high fidelity as it is far from it in some regards, but I own a Home Made old Tube amp from the 1950s that is all of about 5-6 watts and noisy as hell, and typical old tube amp sound, but when using it on occasion, I truly "Enjoy" its old sound.

So, guessing fidelity is not the utmost thing to some people was my point.

 

[Fleuch]

The review just confirms the belief that the paying public should be protected from dinosaur technology, especially when many excellent solid state amplifiers are available at a fraction of the cost. In the same way preference goes to music in digital form as vinyl is prone to the annoying introduction of such extraneous noise as static, dust, warped vinyl, rumble, scratches, vinyl wear and other forms of noise from the playback equipment. Currently maligned CDs and solid state amplifiers do a great job, as ASR reviews demonstrate, at reproducing the sound that has been recorded sans the clicks, plops and other imperfections. Long live the 'Red Book' !!

 

[Wesseling Audio Lab]

"paying public should be protected"

Are we certain at this time that Class D amps with switching PSU's are "not" disposable items?

Bloody energy star refrigerators with lower quality compressors than the old ones - sorry

 

[DanielT]

Thanks for the review Amir!

______

Some amps give you nothing extra, this one gives you more.

It is one of those classic tube amps where there is more there... there. Certainly more there than just the input signal.

Isn't a lot of distortion what tube dude lovers nowadays want? Then Yaqin MC-84L can be an alternative. For the rest of us who want a clean and uncolored sound we avoid this amp like the plague.

But okay, it's just a hobby. People can do what they want.

1930’s design level.

I know you know this. I mention it to others.
As far back as the mid-1940s with the same power as the Yaqin MC-84L, there were tube amps that were better.

I am thinking of this:

Does anyone have a Williamson tube amplifier?

Or have had, listened to a Williamson tube amplifier? Impression? Are they available? What can one, in reasonable condition, cost? I could really imagine having one. Mostly for its HiFi history. :) Not as a main amp but in some nice secondary system. Then together with a subwoofer + LP/HP...

audiosciencereview.com

If I interpret the technical data correctly, the old Williamson amplifier is better than a Yaqin MC-84L.
Yaqin MC-84L, which is from 2024! It's crazy.

 

[oceansize]

We need an option below "Poor".

Laughable?

My apologies to the kind member that bought this and submitted it for testing.

 

[Bob from Florida]

Don't let the topology fool you - it's not an SRPP.

My mistake for regurgitating marketing. Current source?

 

[Aperiodic]

Is there really a need to test classes of products which always suck?

 

[SIY]

My mistake for regurgitating marketing. Current source?

Not even that. Just some stacked triodes, which are a cut and paste regular feature in cheap Chinese amplifiers.

 

[Multicore]

This appears to throw a little cold water over some of the claims in the recent "Are tubes more musical?" thread about tube amps sounding unremarkable if they operate in the linear zone.

I say "appears" because I get that this review of this amp doesn't show that tube amps can't operate approximately linearly.

Actually the comment on the 32-tone IMD graph made me think of those bit-crusher distortion effects.

 

[Old_School_Brad]

And the blobs of solder. And this poor cap.

 

[DSJR]

One channel does look like there's a suspect valve in there, bearing in mind the general symmetry of construction underneath?

If you look at some of the mid to late 80s 'Choice Amplifier books on the worldradiohistory site's UK page, you'll see many US made and very expensive amps with exalted high end status and with not much better performance Martin Colloms had by this time, gone over to the dark side, eulogising on the wonderful wide and deep soundstages with good 'pace and rhythm' yet diabolical measurements. Most of the good measuring stuff in these books lacked 'depth, aid and space' and simpl,y didn't 'flow' well. Look 'em up if you don't believe me

 

[Multicore]

Laughable?

Made me smile, not quite LOL.

My apologies to the kind member that bought this and submitted it for testing.

I suspect that kind member had a pretty good idea what it would test like.

 

[AndreaT]

It is horrific to think how, for $ 2 less, I could buy two Topping B100 amplifiers, more powerful and w SOTA SINAD compared to this horrible one.

 

[AudioSceptic]

We need an option below "Poor".

Appalling? Unacceptable? Totally ****ed? P*** poor?

 

[totti1965]

32-tone Intermodulation Distortion: Topping B100 vs this sweety: 20 dB vs 120 dB. This is factor 100,000!!!!!
Price is $ 600 for each of them!
Wer da die Wahl hat, hat KEINE Qual! (Those who have the choice are NOT spoiled for choice!)

 

[AudioSceptic]

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.
View attachment 400615
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:
View attachment 400616
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:
View attachment 400617

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:
View attachment 400618

View attachment 400619

Noise is a step above but still nothing remotely to be proud of:
View attachment 400620

Frequency response is flat enough if we ignore varying performance between channels:
View attachment 400621

Crosstalk is one step above mediocre:
View attachment 400622

You get a better feel for distortion when we use 32 tones to simulate "music:"
View attachment 400623
Not pretty. Same story for 19+20 kHz tones:
View attachment 400624

The amplifier is fairly rated at 12 watts, assuming you don't care about distortion:
View attachment 400625
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:
View attachment 400626
Yes, that is only 2 watts!

Using 8 ohm tap, we get similar results:

View attachment 400627

Sweeping frequencies we see the typical rise in distortion with frequency. But also increase in distortion at low frequencies (transformer saturation?):
View attachment 400628
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:

View attachment 400629

Fortunately if you wait a minute or so, everything stabilizes:
View attachment 400630

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.

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As always, questions, comments, recommendations, etc. are welcome.

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Serious question: would the amp in a small portable radio ("tranny") be any worse than this?

 

[davmol]

Appalling? Unacceptable? Totally ****ed? P*** poor?

What about "Musical".

 

[Cogito]

Absolute junk, just like the vast majority of "low-cost" tube amps IMHO. Then again, if you love distortion and poor reliability, tube amps are a dream!

 

[Ruhled]

I wish someday we can test some competent tube equipment. I simply don't understand how these companies build such trash?

I have amps fully opened on boards with crappy proto board front ends (read: no shielding at all, anywhere) with over twice the sinad as this!

 

[Postlan]

The topology itself, at a glance, seems to be a cost-effective SRPP circuit that inverts through a transistor and forms a push-pull configuration, and it doesn't appear to have any major issues. I'm not surprised at these measurement values, but it could get a little better if more money were spent, though.

By the way, it seems there are a lot of people on this site who act 'knowledgeable' despite not even being able to read schematics, but is there anyone who can actually point out any problems with this circuit?