PJ Miaolai A7

Review: PJ Miaolai A7

If you are a regular reader and just casually glimpse at the large pic above, you shall be excused for mistaking this article to be a continuation of our Douk U4/PJ Miaolai A4 reports, but blink and stare again at the speaker binding posts! Yes, in the same tiny chassis, this is a complete amp!!!!

Let's see some Official Spec's:

A7 Parameters:

Audio input terminal: 3.5AUX stereo input, Bluetooth input

Voltage input: 12V

Rated output power: 8Ω 2*30W; 4Ω 2*50W

Headphone Amp Parameters:

Rated power output: 150MW+150MW, impedance 16-300 ohms

Distortion: THD+N: 0.004% (RL>10 kΩ)

Distortion: THD+N: 0.020% (RL=32 Ω)

Signal to noise ratio: >99 dB

Dynamic range: >99 dB

TPA3116 is a class D power amplifier IC, which can reach a modulation frequency of up to 1.2MHz. It has the characteristics of low power consumption, high efficiency, low distortion, and strong reducibility.

-The Bluetooth 5.0 module uses the QCC3008 chip, supports APT-X, APTX-LL. The decoding line uses the classic 1543 chip, and the external high-gain detachable antenna makes the sound quality low-latency high-fidelity lossless transmission.

-The headphone amp part uses the classic MAX9722 audio decoder chip.

-Adopt 6N3 tube, Bluetooth QCC3008 chip + 1543 decoder chip.

The now-forgotten A7 is definitely a cousin of the same company's older version A4. In fact, the relationship probably stemmed from really early on, when the TDA1543 chip had not yet run out. As we have emphasized in the Douk U4/PJ Miaolai A4 (U4/A4) threads quoted above, their current products do not sport the classic chip. And so we came to why I bought this amp - in the hope that its obscurity (nothing on the internet, and deadwood) means that I can get a TDA1543 product. Result? Well, I'm not sure at all! Read on...

I bought it for a very tiny sum during TB 618 (less than a bowl of wonton noodles in HK). The first thing I did when I received it was of course to open it up (hence the pic above). It's construction is very much like the U4/A4, with a daughter board housing the tube. Unfortunately, it's also seems to be hard-soldered to the main board via many pins. Again, this precluded my taking a good look as to whether there is a TDA1543 chip around. It's also amazing that the very limited space there can house an amp. Kudos to digital amp!

Facilities are very limited for this tiny amp. You have BT and 3.5 Aux in, that's all.

Earphone I didn't test it out, but I expect it to be exactly the same as the U4/A4, which is very good.

Bluetooth It shows up as PJ Miaolai (no, not A7, nor A4 etc), and seems to be very similar to its sibling A4 (Douk U4). Connectivity seems the same, that is with hiccups sometimes (follow the previous threads) but I'm OK with my old Samsung cell. I wish Shawn P and his App are around to tell me what this BT is, SBC? I'm pretty sure it is. Apt X support? Doubtful. But then, how good is the BT sound? Supported by a TB BT antenna, sound is as good as U4/A4, perhaps even better. The A7 is now permanent in my setup with the Sansui. It's good enough to have shifted my playback habits to more reliance on BT. When the sonic qualities are not so far away, BT can be very attractive.

Aux 3.5 works perfectly well and sounds very good, of course. I could have tested this input more but I didn't.

Power With only a 12V supply, the claimed output is likely way too optimistic. BUT, matched with my efficient Sansui speakers, sound was beyond reproach! With such limited real estate and minimal components, I'd think twice about increasing the voltage of the PS. It survived my 24V (very brief) but I'd not vouch for it. This 12V (rated at 4A) seems to be fairly powerful. But then my loudspeakers are efficient. It also drives my Beydas well enough.

Sound This is the million dollar question! I'm glad to report that it is very very good, provided you make a few adjustments: 1) I did not even use the stock Russian 6N3 and went straight to the JAN GE 5670 (see our U4/A4 threads); 2) it needs a bit of run in to smooth out some roughness; 3) it needs forgiving loudspeaker cables, like that provided by my "Belden 1309A" 

So? How good is that? I'm not sure how to say it. It's good enough to be a Reference here. In fact the A7's arrival significantly changed my setup here in SZ. It is now a permanent fixture for my Sansui loudspeakers. It made me use BT. It does not have the tonal generosity of my all tubed amplification but it makes up for it in its crisp and incisive delivery. THAT is a good few watts!

I'd reckon I'm hearing some of the TDA1543 qualities (supreme rhythm, at the expense of a little grain overall) but, since I cannot get to the part of the main board under the daughter board, I cannot vouch for it. If you do, let me know.

What I do know is that, this is a great little achiever! If your loudspeakers are efficient and the very limited input suits, think of trying it out. I haven't compared directly, but I'm pretty sure I prefer it to the Aiyima T9.