Neohipo DA300 Amplifier Review. A Bluetooth Version of the Aiyima A07?

[JackWilson275]

I came across this mini amplifier on Aliexpress that looks almost identical to my Aiyima A07, which I purchased a year ago but is now spoilt. The specs shown online are also very similar, so I bought one for around $75 and put it to the test.

First Impressions
The amplifier comes packaged with a 32V 5A switching power supply. When I received it, I had a hard time telling it apart from the Aiyima A07, except for the logo. They are identical in the front, with the only difference being the rear panel. The DA300 supports Bluetooth connectivity, which the A07 does not, so there is an antenna post on the back. From the appearance, it's clear that the DA300 and A07 are both made by the same manufacturer.

Internal Components
The internal layout is almost identical to the A07, with the only difference being that the DA300 has a Bluetooth module. A TI TPA3255 is concealed under the gold-colored heatsink, and two replaceable NE3255 op-amp chips are socketed. There is another integrated NE5532 op-chip in the Bluetooth module.

Measurements
I measured the amplifier with 5 watts into 4 ohms.

FFT Spectrum and Scope

RMS Level, THD+N Ratio, Gain, and Frequency

Signal-to-Noise Ratio at 5 Watts. It's quite similar to the A07.

Frequency Response is very nice.

Crosstalk is good.

Conclusion
With similar appearance, chipsets integrated, and measurements results, the Neohipo DA300 is definitely a newer version of the Aiyima A07. I think it's more appropriate to call it the A07 Pro rather than the one that Aiyima released a few months ago. I know that many amplifiers from China are white-label products produced by one company and rebranded and sold by another company without any changes to the original product. This DA300 is definitely from the same manufacturer as the Aiyima A07. Anyway, if you love the sound of the A07 like I do and just want to add Bluetooth connectivity, the DA300 is an excellent choice.

 

[Wheely]

The internals on this "deluxe" tpa3255 board almost seem better than the A07. (providing it has authentic components) other than there is no big copper wound inductors etc.

Im thinking of pairing this amp board with this 3 band preamp that has 2 replaceable op amps. & then possibly adding the 5.0 bluetooth board. any thoughts on this pairing?

 

[salahspore]

Apparently from the same factory. Aiyima doesn't seem to have their own R&D team or factory, but often rebrand white-label amps.

 

[Biagiod]

Nice review with nice pictures and graphs. Congrats for a job well done and for sharing info on A07 Pro....

 

[Jacob8275]

Apparently from the same factory. Aiyima doesn't seem to have their own R&D team or factory, but often rebrand white-label amps.

Seems right, The Aiyima T9 are very similar to Douk Audio ST-01, maybe they are from same factory.

 

[grogi.giant]

Does it have the Bt operated over switch, or automatically activated?

 

[JackWilson275]

The Bt is automatically activated. It takes priority to the RCA line-in.

Does it have the Bt operated over switch, or automatically activated?

 

[grogi.giant]

The Bt is automatically activated. It takes priority to the RCA line-in.

Typical Chi-fi design - if one listens too laud, the neighbor downstairs will simply take the amp hostage

 

[RogersCompactMonitorFan]

Hello all,

My first post here after lurking a bit, so hello.

Based on this review I took the plunge and ordered one of these. I ordered this on 27th Feb and it arrived today so pleased at the quick shipping to the UK.

I've had an Aiyima A07 for a few months, which I use with a pair of Focal Aria 906 speakers, a Raspberry Pi Zero (running mpd and M.A.L.P mobile app) via Apple USB headphone adapter. I've been very pleased with this setup. But I've always thought Bluetooth would be handy for listening to podcasts etc. So I was interested to read this post, and despite planning to not buy any more gadgets.....well I'm sure some of you know this problem.

I was using an 1980 vintage A&R Cambridge A60 amplifier before, but this now distorts so is on my shelf awaiting repair. But I'd say the A07 is the same as, or improved sound-wise than the A60. Certainly much better than the Marantz NR1512 AV amplifier which I found quite distorted.

(I've been powering it from a 20v battery. This lets me have a solar powered HiFi which is pretty cool, but probably a story for a different post).

I had a few more points I thought might be interesting.

- After some brief listening I'd say it does sound identical to my ears to the Aiyima A07.
- But I get a reasonably loud "crack" through the speakers when I switch off using the power switch on the front, which the A07 doesn't. But if I unplug from the power connector directly there's no crack.
- There's a bit of Digital noise when Bluetooth is selected but not playing. I can't hear it from normal listening position but can when near the speaker. So I suspect Signal to Noise Ratio from the Bluetooth input is likely much lower than from analogue in.
- It has a slightly annoying blue flashing LED when not playing from Bluetooth. This goes solid when Bluetooth is connected.
- The analogue inputs are disabled when Bluetooth is connected. So after using my phone I have to unpair on the phone/turn off Bluetooth to use the audio inputs.
- The device is always pairable when not connected (There's no 'pair' button). So this could be annoying and allows for hijacking by someone within range when using the analogue inputs.
- There's a bit of an audible thump when Bluetooth is first played.

It has the same annoying linear volume control as the A07 rather than a logarithmic one.

So I'd say the main concern is the 'crack' as I don't think it's kind to tweeters. It's also not perfect with Bluetooth. But still usable for "mainly analogue but the odd Bluetooth" input.

Hope these additional thoughts are useful - Thanks to @JackWilson275 for the original post! I'm interested to know if anyone else has the 'crack' problem too.

 

[grogi.giant]

So I'd say the main concern is the 'crack' as I don't think it's kind to tweeters. It's also not perfect with Bluetooth. But still usable for "mainly analogue but the odd Bluetooth" input.

The PCB does seem to miss some elements around the power switch. Don't know from where, but I was always under the impression this was designed to eliminate that crack.

Below is the part of A07 PCB.

 

[isaac507]

I saw a video on Youtube that reviewed the A07 recently. Aiyima seems to have replaced some internals, especially the capacitors. No more Nichicon capacitors but unknown ones that seem much cheaper.

 

[grogi.giant]

It is not "recently". There is no consistency of the capacitors. I came accross the following before:

• 1500μF / 50V (from Samyoung) - below
• 1200uF / 63V
• 1000uF / 50V (Nichicons)
• 2000uF / 50V

 

[isaac507]

It is not "recently". There is no consistency of the capacitors. I came accross the following before:

• 1500μF / 50V (from Samyoung) - below
• 1200uF / 63V
• 1000uF / 50V (Nichicons)
• 2000uF / 50V

They seem to change internals frequently.

 

[RogersCompactMonitorFan]

So I I think grogi.giant is correct.

I opened up the two devices to compare them:

A07 - with extra parts


DA300 - no parts


The A07 appears to have a CJT1117 3.3v regulator and an unknown 8-pin chip. I found This page (I needed to translate it) which suggests it is a small microcontroller.

Additional power supplies on the DA300 - 5v and 3.3v regulators



From what I can tell:

I'm feeding the amplifier a 20v input.
The XL7015 regulator generates a 16v output.
This is fed to the 7812 regulator, which outputs 12v which is fed to the op-amps (and I assume the TPA3255)
This 12v is fed to the 78M05 (DA300 only) which outputs 5v.
This 5v is fed to the CJT117B (DA300 only) which outputs 3.3v which I assume is for the Bluetooth module.

The XL7015 looks to be a switching regulator - I assume it does the rough step-down from the up to 48v input to a voltage the 7812 can handle, and then the linear 7812 reduces switching noise, given it powers the op-amps.

On the DA300 (With the pop) the 16v output is switched on and off with the switch.
On the A07 (Without the pop) the 16v output is continually on, regardless of the on/off switch.

This explains the difference in power consumption. At 20v supply the DA300 uses 0.5w of power, but the A07 uses 1.4w of power.

I'm wondering if I can add a switch to power off the Bluetooth module. The flashing is annoying, and it also adds noise to the output when the analogue input is selected. I'm hoping I can just add a switch to the 78M05 regulator. Maybe even powering it from the XL7015 rather than the 12v output would reduce noise.

The module is marked as BTM344 - perhaps this https://www.tianjiarun.com/zb_users/upload/2020/11/SJR-BTM344-v1.1.pdf

Update: Looking at the TPA3255 data sheet there is a reset pin on the amplifier chip. So perhaps the "anti-pop" circuit uses the amplifier reset to switch it off, but keeps the analogue circuitry powered up all the time.

 

[RogersCompactMonitorFan]

OK, so a follow up...

The power switch controls the enable pin of the XL7015 regulator. This explains the 'pop' - the analogue circuits are just switched off, but power is still applied to the TPA3255 main rails (I think).

The TI TPA3255 EVM schematic in https://www.ti.com/lit/ug/slou441/slou441.pdf shows a TPS3802 chip used to stop pops; this Neohipo amplifier doesn't seem to have this. The Aiyima A07 has a circuit performing a similar function.

The bluetooth module is powered from the 78M05 regulator, which is powered from the 12v analogue supply. This explains the digital noise I could hear. I did an experimental modification to power this from the XL7015 16v output, and it removes the digital noise - a significant improvement.

I'm curious to learn the origin of this board. The Aiyima A07 has a surface mount power LED and NE5532 op-amps in holders - as does this. Yet this has a through-hole bluetooth LED, yet a surface mount NE5532 op-amp in the bluetooth circuit (visible in the photo above to the right of the white relay). This suggests that the bluetooth addition has been performed by someone other than the original designer.

 

[Sri K P]

The internals on this "deluxe" tpa3255 board almost seem better than the A07. (providing it has authentic components) other than there is no big copper wound inductors etc.

Im thinking of pairing this amp board with this 3 band preamp that has 2 replaceable op amps. & then possibly adding the 5.0 bluetooth board. any thoughts on this pairing?

Makes sense! This thing needs a good input signal (5v +) for optimal thump!

 

[mlieber507]

I came across this mini amplifier on Aliexpress that looks almost identical to my Aiyima A07, which I purchased a year ago but is now spoilt. The specs shown online are also very similar, so I bought one for around $75 and put it to the test.

First Impressions
The amplifier comes packaged with a 32V 5A switching power supply. When I received it, I had a hard time telling it apart from the Aiyima A07, except for the logo. They are identical in the front, with the only difference being the rear panel. The DA300 supports Bluetooth connectivity, which the A07 does not, so there is an antenna post on the back. From the appearance, it's clear that the DA300 and A07 are both made by the same manufacturer.
View attachment 266211
View attachment 266212

Internal Components
The internal layout is almost identical to the A07, with the only difference being that the DA300 has a Bluetooth module. A TI TPA3255 is concealed under the gold-colored heatsink, and two replaceable NE3255 op-amp chips are socketed. There is another integrated NE5532 op-chip in the Bluetooth module.
View attachment 266213
View attachment 266214
View attachment 266215


Measurements
I measured the amplifier with 5 watts into 4 ohms.

FFT Spectrum and Scope
View attachment 266216


RMS Level, THD+N Ratio, Gain, and Frequency
View attachment 266217


Signal-to-Noise Ratio at 5 Watts. It's quite similar to the A07.
View attachment 266218


Frequency Response is very nice.
View attachment 266219


Crosstalk is good.
View attachment 266220


Conclusion
With similar appearance, chipsets integrated, and measurements results, the Neohipo DA300 is definitely a newer version of the Aiyima A07. I think it's more appropriate to call it the A07 Pro rather than the one that Aiyima released a few months ago. I know that many amplifiers from China are white-label products produced by one company and rebranded and sold by another company without any changes to the original product. This DA300 is definitely from the same manufacturer as the Aiyima A07. Anyway, if you love the sound of the A07 like I do and just want to add Bluetooth connectivity, the DA300 is an excellent choice.

Nice find. One question, do you know if you leave the amplifier switch on and turn the unit off with another switch will the pop still be suppressed like it is on the A07. I recently did the same test on a Fosi TB10D and I got pops in my speakers. This is a concern to me because I use a cell phone to control my system.

 

[RogersCompactMonitorFan]

Nice find. One question, do you know if you leave the amplifier switch on and turn the unit off with another switch will the pop still be suppressed like it is on the A07. I recently did the same test on a Fosi TB10D and I got pops in my speakers. This is a concern to me because I use a cell phone to control my system.

I've been using the amplifier powered at 20v from a USB-C power adapter. I switch it on and off at the power adapter end, and it's pretty much OK.

There's a very slight audible click, but nothing concerning. Probably similar to the click of the A07 or pretty much any other amplifier I'd think.

Hope this helps..

 

[AIYIMA]

This is a model we customized for some customers.