Douk A5 Budget Stereo Amplifier Review

[Hart]

Seems like the major manufacturers are churning a lot of the same old thing, while these small companies are showing a lot of innovation.

 

[Bleib]

It's powerful enough not to be used just for desktop, so should ideally come with a remote

 

[ripmixburn]

Agreed, great option for 2.1/2.2 setups. Solid engineering and quite a value in the right situations.

Does this mean that you could chain together 3 or amps to drive 3 pairs of speakers?

 

[Jmudrick]

I recently paid more just for a high pass filter. This is great. Bought one

 

[Pariah Zero]

It's powerful enough not to be used just for desktop, so should ideally come with a remote

Having a remote - as well as the ability to just link two amps to auto-match the volume - would be killer features.

I mention being able to have multiple amps auto-match the volume for some of us who are a bit more DIY-motivated: I can take a speaker, put one channel of the amp to the woofer, one channel to the tweeter, and then just use a DSP as the crossover instead of passive components.

... and, you know, do the EQ thing as well.

I know there are some amp boards (Like Dayton Audio's) which kinda have the amp+dsp built-in, but Dayton's kit hasn't tested well in the past, and I _really_ doubt it'd be that different. On the other hand, I'll probably see if Amir is interested in testing one of the amp+dsp boards before I start the project after next...

 

[SlowJim]

$62 shipped for one of these on Aliex without a power supply. Very tempting

 

[DearSX]

I miss old subjective reviews that mentioned how warm yet uncolored and "insert hyperbole" $4000 AMP X is such a bargain for its price, and is 83% as good $8000 AMP Y.

These objective measurements of $99 amps are making my expensive amp sound like a scam.

Thanks @amirm

 

[Symphoniac]

According to specs, this can put out 250w at 4ohms with the 48v power supply. How likely is this to be true?

 

[Power Pop 23]

According to specs, this can put out 250w at 4ohms with the 48v power supply. How likely is this to be true?

That is with a 48 volt power supply unit drawing up to 10 amperes. I think it may be 'true' depending on what THD is specified at that output power.

 

[theREALdotnet]

The 48V version is available for $110 with free US shipping on their website.

I would advise caution with using the 48V supply, it may affect the lifespan of the amp.

I have a Nobsound G2 Pro mono amp (using the same amp chip) which also came with the 32V/5A power supply and which also supports up to 48V. I ordered the 48V supply to see whether it makes a measurable difference for my particular use case, which is driving a 12" 6 ohm subwoofer. It does not, but the amp gets hot to the touch with the 48V supply, even when idle. Enough to make me worry about the longevity of the caps in the amp. I've reverted back to the 32V supply with which the amp stays cool in operation.

 

[gvl]

Is distortion in high frequencies of any consequence? I can’t hear above 14khz or so and cannot be bothered by harmonics of >7khz fundamental. I guess there’s IMD whose byproducts may end up lower than 14khz, but given high frequency content is low energy it will likely be inaudible.

 

[wwenze]

Seems like the major manufacturers are churning a lot of the same old thing, while these small companies are showing a lot of innovation.

Good when products are already at practical perfection e.g. amps and DACs, some functionality of smartphones

Difficult when products are still hard to get right e.g. speakers, some functionality of smartphones (cameras)

Big companies will do one formula that works and stick with it. Apple has, like, 4 iPhone models? While Oppo and Xiaomi has over 9000.

 

[phoenixdogfan]

What a nice little amp! As someone here mentioned Ali Express sells it for l.t. $70 without the power supply. If you do that, you can get a 48v 10 amp supply and almost certainly get it to push a few more watts out.

Thanks for the fine review, Amir.

 

[capslock]

I voted not terrible. Why?

Well, the price is nice, as is the adjustable low pass filter*, but in terms of performance, the good old Ayima A07 without PFFB beats it for even less $$, and for slightly more ($99 including shipping and EU VAT of 19+%), the O-Noorus offers much better performance and a 36 V power brick.

I would argue that it deserves the crown of worst PFFB implementation. It is even worse than the Fosi V3 Mono or the recent PFFB offerings from Aiyima.

* filter response dose have about 0.5 dB peaking when set to 30 Hz (at about 8min30 in the video)

 

[amirm]

Well, the price is nice, as is the adjustable low pass filter*, but in terms of performance, the good old Ayima A07 without PFFB beats it for even less $$, and for slightly more ($99 including shipping and EU VAT of 19+%), the O-Noorus offers much better performance and a 36 V power brick.

You can't compare non-PFFB amps with this one. Those companies charge more for their PFFB offerings.

 

[capslock]

To prove my point, here are a few of Amirs graphs side by side (unfortunately, the old A07 review did not have multitone and two-tone):

The Douk is cleaner for all harmonics except HD3 at -92 dB which is not terrible but poor for PFFB. In fact, the A07 is better at about -94 dB.

We have a clear winner in the A07 for high frequency THD+N in the A07. Look at how even at 15 kHz, it stays below - 70 dB even out to 30 W. This rivals the champions of TPA325x PFFB amps, the PA5(II) and 3e A5!

Those 32 V power supplies are rare compared to the more common 36 or 38 V (I realize even 48 V are availeable but might lead to unhealthy idle heating). But it is interesting how the A07 squeezes out more power from the same voltage (77 vs. 59 W at 4R, 48 W vs. 33 w at 8R). Note how the Douk A5 significantly underperforms it own power specs at 8 and 4 R, while it admirably handles 2 R which is not even specified.

I wonder why it is behaving so poorly. Clearly, it is not a high resistance output coil or we would not have the near perfect load invariance (that is actually better then most PFFB amps). It can't be magnetic binding posts (I just received mine and checked).

And for good measure, here are some results by member UAN:

O-Noorus D1 [TPA3255 PFFB] Stereo Amplifier - User Impressions | Owner's Thread

Wonder if there's a signal sensing auto-on/off function when used as a power amp (BP mode). There is no auto-ON/Off signal sensing feature for the amplifier, auto-ON/OFF is there only for screen display

www.audiosciencereview.com

O-Noorus D1 [TPA3255 PFFB] Stereo Amplifier - User Impressions | Owner's Thread

Wonder if there's a signal sensing auto-on/off function when used as a power amp (BP mode). There is no auto-ON/Off signal sensing feature for the amplifier, auto-ON/OFF is there only for screen display

www.audiosciencereview.com

This is at 5 W (presumably 4 R) and seems to be in PA5 territory!

 

[MCH]

Thanks for the review.
At 75eur shipped vat included (no PSU) this is a bargain + the evidence that pffb and adjustable high pass can be done without doubling the price. I whish them success.

 

[F1Fan72]

Rolling Opamps also

 

[capslock]

You can't compare non-PFFB amps with this one. Those companies charge more for their PFFB offerings.

True, but what is the value of PFFB (other than load invariance at the very top end) if it does not perform? The A07 beats it in HF THD and power on the same supply voltage, so this is what I'd prefer in terms of performance.

And the O-Noorus D1 with PFFB at the same price point (or maybe $10-20 more if you consider frequent and escalating discounts on the Douk) promises to have the Douk for breakfast in terms of power and performance if UAN's measurements are any indication.

I am not saying the Douk is poor value. I like the HP filter, and the case is really well made. I'd just rather they not discount it and spend that money on figuring out what is causing the prominent HD3 and poor HF performance. Some of that will be engineering, some may be using slighly more expensive components.

 

[Rusk Reeder]

The only weakness in this amplifier and the way you have measured it and others is that at 15khz, it is reaching 1% THD at about 5 watts. That's not a lot of power,
and that's not great performance. The new power amplifier measurement standard adopted in October of 2024 by the FTC, wants the power stated as power delivered
from 20 to 20khs at 1% THD. You can read more about this in the October issue of Stereophile, in a short industry update by John Atkinson.

What he has chosen to do in the future is measure maximum power at 20hz and 20khz as well as 1khz. Most amplifiers from the 70s, 80s, and 90s, could meet this.
And the better ones of today, even a two-channel Sony receiver or other brand can meet this. The A/V receivers don't meet it very often. It just costs too much to
do it. A few expensive ones do.

But a lot of the equipment in Stereophile does not do very well either because it's just overpriced glitz that make some people belive they are hearing wonderful sound.

Can you measure a swept tone from 20 to 20khz with your Audio Precision equipment? Also try measuring square waves at 50 and 10khz. I believe you will see some
big differences.

Sincerely,

Rusk Reeder