Douk A5 Budget Stereo Amplifier Review

[theREALdotnet]

And I note the real, minimum bass impedance. That number almost never, ever matches the specs manufacturers publish.

I think everybody here understands that the actual impedance of a speaker can both dip below and far exceed its nominal impedance. However, a 4-ohm speaker is one with a nominal, rather than minimum, impedance of 4 ohms. I don't think the vast majority of speakers have a nominal impedance of 4 ohms.

How useful is the specified nominal impedance? Probably not very, much like the claimed power output of amplifiers

 

[GWolfman]

Too bad for the high frequency distortion! If that was in check I would’ve voted golfing panther. I like the variable high pass filter and sub-out + volume control! Give me a little more juice and I’m sold!

 

[Schlippwhip68]

Thanks Amir.

 

[sonitus mirus]

Too bad for the high frequency distortion! If that was in check I would’ve voted golfing panther. I like the variable high pass filter and sub-out + volume control! Give me a little more juice and I’m sold!

It does appear that the "golfing" panther swung and missed the ball completely and the golf club is broken.

 

[Schlippwhip68]

As an amp it's meh. As an amp for $99 it's outstanding.

An example: I'd like to see much better IMD and high-frequency distortion performance, but at this price point its low noise, very good channel separation, and ability to drive low impedance loads is IMHO more important to have achieved than ultra-low distortion at every frequency.

It's hard to see how anyone could rate this poorly given the price.

Out of interest how and when is one most likely to notice the high frequency distortion?

 

[SuicideSquid]

Out of interest how and when is one most likely to notice the high frequency distortion?

Our ears aren't particularly sensitive in this octave (10-20kHz is a single octave) and you'll struggle to detect tones (rather than noise, hiss, or "air") over 10kHz, so I don't think you're likely to notice distortion that's 60dB below the signal in the top octave.

For fun, put a low-pass filter on a song and roll everything off above 12-13kHz. You'll be amazed at how little difference it makes.

 

[Talisman]

A note of caution regarding the implementation in the high pass filter.
I took this measurement from a video review that tested the response at different positions of the knob.
Green response flat with the filter off.
Red response with the filter at minimum, blue response with the knob at 12 o'clock, so half the adjustment has almost no effect on the filtering, then at three o'clock we notice a slightly inclined roll off starting from about 200hz, and finally at the end of the travel the roll off starts slowly but already from 1khz.
The best way to integrate it will be to try it, measure, try again, measure again etc etc

 

[Talisman]

For those who ask, here are the power values with a 48V 5A power supply

 

[Deleted member 72219]

Mine was delivered on March 6th.
Sadly, left channel started to "die" on March 21st with a channel imbalance issue. Which means, volume randomly oscillanting from normal (=equal to right ch) ...down to zero...and up again after few seconds or so.
Now on March22nd left channel remains dead silent.
Used with 32 volts of power supply and NE5532 opamps in place. Never overstressed. Source was checked of course: no imbalance issues.
(A5 board layout indicating "V2" 2025/01/08)

Try swapping the two op-amps around. If suddenly the right channel is dead, you’ve found your problem.

-Ed

 

[ahofer]

This would make an interesting candidate for blind test challenges.

 

[fulgura91]

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.

The same thing happened to me with the Aiyima A07 and the 48V power supply. Heat with the amp off. I've also gone back to the original 32V.

 

[zachary80]

Well look at that, just as I finished connecting my Fosi V3 w/ 48v...

 

[zachary80]

The same thing happened to me with the Aiyima A07 and the 48V power supply. Heat with the amp off. I've also gone back to the original 32V.

No issue on the one shipped with the Fosi V3 from Amazon that I have observed, amp seems cool even when being pushed. PSU looks like an old laptop power brick (not sure what the basic 32 model looks like). Mine is labeled FJ Power Supply FJ-GN224048005000, output 48v/5A, Huizhou Fujia Appliance Tech Co LTD

 

[fulgura91]

No issue on the one shipped with the Fosi V3 from Amazon that I have observed, amp seems cool even when being pushed. PSU looks like an old laptop power brick (not sure what the basic 32 model looks like). Mine is labeled FJ Power Supply FJ-GN224048005000, output 48v/5A, Huizhou Fujia Appliance Tech Co LTD

Okay. Your power supply is the GAN model. Mine is the standard 48V. Perhaps my mistake was buying the Fosi V3 power supply to use with the Aiyima 07 (great deal). In any case, the voltage and current are the same for both models, so they should work correctly, but..
I'll have to get a Fosi V3 now LOL.

 

[Foxxy]

This would make an interesting candidate for blind test challenges.

Yes, this vs Aiyima 07 max. The Aiyima sound more transparent than the Doug.
And the test components are inexpensive.
I'd rate the Doug a bit above the 125ASX but below the A07 max. The Icepower sounds downright wooly next to the A07.
There are no other differences, just more transparent, even on the Elac DBR62 it's audible.

 

[Talisman]

Yes, this vs Aiyima 07 max. The Aiyima sound more transparent than the Doug.
And the test components are inexpensive.
I'd rate the Doug a bit above the 125ASX but below the A07 max. The Icepower sounds downright wooly next to the A07.
There are no other differences, just more transparent, even on the Elac DBR62 it's audible.

I'm in a way they would sound "more transparent"?
I find it unlikely there would be any audible difference with such similar measurements

 

[unmutual]

Can this amp be bridged to double the power?

 

[Foxxy]

Well, the Aiyima is on average 15dB down in distorition vs the Douk. Amazing coming from the same chip. Voices are clearer, details sound finer, bass is tighter. Which makes the least sense to me when I look at bass distortion speaker vs amp. And both have very low output impedance.
We should ask Bruno Putzey for his input on this

 

[Roland68]

Can this amp be bridged to double the power?

No, this is the wrong amplifier and not intended for that purpose.
There are various TPA3255 amplifiers that can be bridged for more power, such as the Aiyima A07 Max or the Fosi Audio ZA3. However, the power doesn't double at 4 ohms, but rather increases by a factor of approximately 1.2 to 1.4. The power only doubles at 2 ohms.

If you're looking for a good price-performance ratio in bridged amplifiers, then take a look at the SMSL A300 or the Sabaj A20a '2022, for example. They achieve approximately 400 watts at 4 ohms for €/$150-200.

 

[btkli]

Thanks for the review!