Douk A5 Budget Stereo Amplifier Review

[Foxxy]

Is it only me or is this very lackluster implementation of the 3255? Like, compared to something like the Aiyima A07 max at the same price point, it's usually over 10dB worse. The pffb is nice and the highpass is a very enticing feature for making at true small 2.1 system but the measurements... maybe I am just used at looking at way too good graphs from here and the difference would be inaudible.

 

[uwotm8]

Comparing the Douk in terms of thd, power and load delivery it appears to be a direct competitor to your average $10k Class A monoblock.

Sure, expect a lot of Pass Labs owners upgrade to Douk (might happen they're already on Aiyima or Fosi tho)

 

[prerich]

I have one condition on my great rating....you must use the 48v power supply.

 

[VientoB]

So is anyone claiming that when these low cost, well-measuring amps have enough power to drive the speakers they are connected to, they will sound the same as a much more expensive amp that measures similarly?

It depends how loud you listen as gain matters, If you listen at low to medium volumes these amps are fine.

 

[Mojo Warrior]

That Douk A5 THD should give those overpriced tube amplifiers a "run for their money"

 

[levimax]

....you must use the 48v power supply.

For most uses the 32V supply is going to be fine. You need to keep in mind 2 things about higher voltage in a power amp. Increasing the voltage increases the heat generated exponentially and adding power only increases SPL output logarithmically. Going from 32 to 48 volts will double the heat for about ~3 dB more output. For an inexpensive amp like this you will radically reduce it's reliability for a small gain in SPL. If you really need more power it would be better to look for an amp that can comfortably deliver it rather than pushing a economy amp to or past it's limits.

 

[Herbert Shooler]

Great review,looking forward to a sub $500 amp by Douk called the "CHORDCRUSHER"...lol

 

[TonyJZX]

Is it only me or is this very lackluster implementation of the 3255? Like, compared to something like the Aiyima A07 max at the same price point, it's usually over 10dB worse. The pffb is nice and the highpass is a very enticing feature for making at true small 2.1 system but the measurements... maybe I am just used at looking at way too good graphs from here and the difference would be inaudible.

i'd agree with you somewhat

35w isnt that great and maybe you can extraopolate 60w at 8 ohm w/ 48v 5a

but look at the price.... $100 ready to go w/ psu?

the only competition at this price is the Onoorus D1 thing which has a remote and probably a lot more power... and its also pffb

 

[DanielT]

£110 or so on UK Amazon. I'm sorely tempted to get one to play with in the second rig (it might even work as a power amp in the main one at the levels I play at now), although I'm overwhelmed with ancient electronics currently, all of which works just fine and the power amps 'measure' at least as well, especially at hf....

Sell some of your ancient electronics stuff and buy a Douk A5 for that money. Plus add or buy (if you don't have a suitable one now) a subwoofer to go with it. Sub, I think it goes well with the Douk A5 given its HP- filter.

 

[DanielT]

That Douk A5 THD should give those overpriced tube amplifiers a "run for their money"

Also, if you watch the video in #35 from JohnAudioTech you'll see that you can change the colors of the lights that light up from inside the amp.
Are those lights as cool, cosy or nice as vaccum tube glow? What do I know and tastes differ and so on but in any case the Douk A5 gives the color changing light option.
There may also be those who find that type of light silly, but then the option to turn them off is also given.

 

[bolo_nz]

I've been enjoying this amp paired with a SMSL PS200 DAC for the past few weeks but I've enjoyed taking back my desk space even more!

It sounds at least as good as my beloved Onkyo A-9150 and replaced it as my daily driver PC audio set up. Crazy that the A5 including the power brick costs less than the DAC

HPF works well with sub integration but it does get very hot at 48V like others have said!

 

[trevor_bartram]

I'm intrigued by these 3255 based amps. I convinced myself I should buy one in case my main NAD amp failed (wot no music?) & fear of the ensuing repair or replacement time. I settled on the Fosi V3 stereo (32V) because:
1. It was the first to use quality components throughout & measured well at ASR.
2. The impedance of my speakers is low at high frequencies, so no need for PFFB.
3. It has a volume control so a preamp is unnecessary.
3. 32V operation is more reliable than 48V & cooler too.
4. On Black Friday it was on sale at Fosi for $72.
It arrived, I tried it out, it sounded fine & I put it back in its box! I wonder how many other of these amps are sitting in boxes waiting to be used?

 

[capslock]

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

Thanks for giving me the idea to compare FR of PFFB and non-PFFB FRs.

The PFFB pack have < 0.05 dB difference between 4 and 8 R at 10 kHz, with the Douk being slightly worse with about 0.25 dB at 10 kHz. Interestingly, the champions are also very flat out to 30 kHz, the Douk is also pretty flat but the Fosi and the Wiim Pro have a pronouned peak at 30 - 40 kHz, much like the maligned resonance of metal dome tweeters.

The non-pro Wiim and the Stereo Fosi, both without PFFB, have about 0.45 dB at 10 kHz. You'd have to have a really strange compression driver to have impedance swings that high up in order to get audible coloration, IMHO.

 

[uwotm8]

$100 ready to go w/ psu?

AIYIMA A07 MAX
FOSI AUDIO V3
FOSI AUDIO BT20A PRO (Bluetooth)
and Infineon-based
SMSL A50 PRO (has USB in, sub amp for passive sub and HP/LP filters)
SMSL DA-6

 

[capslock]

Let's also look at distortion for the newly added WiiM amps and the Stereo Fosi, which happens to run at 32 V same as the Douk and the A07 I compared earlier.

HD at 1 kHz, the regular Wiim without PFFB has the same - 92 dB HD3 the Douk has with PFFB, but the Douk is about 5 dB lower on the higher harmonics. The Pro Wiim cleans both HD3 and the higher HDs up with PFFB and is clearly a better performer than the Douk. The big surprise is the Fosi which is a lot better than the A07 we looked at earlier. It surpasses the Douk on HD3 (-99 dB) but is about 7 dB worse on higher HDs.

Going on to IMD, the Wiims and the Fosi all are about 15 dB lower in grass at 10 kHz than the Douk. The Pro dips a little lower in the mids but is a little higher at the top end (PFFB with limited bandwitdh noise shapes the harmonics into that range).

On two tone, for the lowest order, the Douk is at -60, the Wiim at -78, the Wiim Pro at 68 and the Fosi at -76. So again, the Douk is the worst performer, and we again see the HF penalty of not enough PFFB in the Wiim Pro.

I am going to spare you the power graphs. The Fosi on 32 V goes 3 W higher than the Douk at 4 R, so it is more similar to the Douk than the A07 in this respect.

For THD+N at 15 kHz, all four are pretty close. Again, the non-PFFB are ahead, the Wiim Pro next and the Douk behind, but we only have 7 dB spread at 15 kHz / 30 W.

I would really pick the Fosi Stereo among this pack. It seems to reach good distortion performance across the band and the lowest degradation to HF, likely through the use of good passive components and PCB design. It might also be a good testbed for diy experiments with PFFB or composite designs.

At $71 with 32 V and $94 with 48 V PSU (shipped from Germany and including 19% VAT), it is also cheaper than the Douk, alas without the HP filter.

 

[elshaddai]

and Infineon-based
SMSL A50 PRO (has USB in, sub amp for passive sub and HP/LP filters)
SMSL DA-6

You should add the RSL iA255.1 to the $100 Infineon-based lineup (USB/BT/RCA in, volume-controlled aux out for subs, 90Hz HPF switch)

 

[bolo_nz]

I would really pick the Fosi Stereo among this pack. It seems to reach good distortion performance across the band and the lowest degradation to HF, likely through the use of good passive components and PCB design. It might also be a good testbed for diy experiments with PFFB or composite designs.

At $71 with 32 V and $94 with 48 V PSU (shipped from Germany and including 19% VAT), it is also cheaper than the Douk, alas without the HP filter.

If the person reading this thread is looking for the best measurements then sure the Fosi would be the way to go but I think I can speak for the majority of the people in this thread are here for PFFB with HPF as the key features. The A5 with these features is what pushed me to get my first class D amp.

The A5 is literally in its OWN category at this point (for now) while offering those features and also measuring more than "good enough" at this price point.

All the other manufactures have got to be scrambling to come with something to compete with the A5 as we speak!

 

[TonyJZX]

AIYIMA A07 MAX
FOSI AUDIO V3
FOSI AUDIO BT20A PRO (Bluetooth)
and Infineon-based
SMSL A50 PRO (has USB in, sub amp for passive sub and HP/LP filters)
SMSL DA-6

none of these are PFFB

except the mono fosi v3s

 

[perdido34]

I'm guessing that you have been spending time in non-evidence requiring audiophile communities where all kinds of silly nonsense is talked about and treated like evidence.

Without a shadow of a doubt, in level matched, multiple trial, blind listening tests, an inexpensive but well designed amp, with enough power for the load will sound identical to a more expensive piece of gear. As long as the amp can contribute to the chain in an audibly transparent fashion, that is all the hearing brain can ever use.

Do you find that so hard to accept?

No, I did not take a position. I am asking what other people are claiming. I have training in developing and evaluating behavioral research, and I just haven't seen any data. I'm open to having no opinion on the issue at hand without relevant data.

Now, concerning your assertion about "level matched, multiple trial, blind listening tests" comparing cheapo vs. expensive amps with similar measurements, has anyone done such tests, and with a sufficient number of listeners who are experienced and hearing music they are familiar with in excerpts of reasonable length? I would love to see a weblink from you that included the results and methodology of such an experiment.

 

[capslock]

If the person reading this thread is looking for the best measurements then sure the Fosi would be the way to go but I think I can speak for the majority of the people in this thread are here for PFFB with HPF as the key features. The A5 with these features is what pushed me to get my first class D amp.

The A5 is literally in its OWN category at this point (for now) while offering those features and also measuring more than "good enough" at this price point.

All the other manufactures have got to be scrambling to come with something to compete with the A5 as we speak!

PFFB is not a panacea. The FR examples in post #93 show that the variation of 10 kHz output with 4 vs. 8 R is minimal even without PFFB, so what are you hoping to gain from PFFB in your application?

Bruno Putzeys' (of Hypex UcD and ncore and Purifi fame) whitepaper about the F-word explains the issues at stake quite well. PFFB will lower output impedance and hence load sensitivity. Feedback will act as a noise shaper, so it will lower low order harmonics at the expense of higher orders which are usually more unpleasant. If PFFB is simply used to obtain passable distortion performance from questionable passive components such as the output coils, it is no good. If you can live with the load sensitivity, i.e. if your tweeter is crossed over below 3 kHz and has no impedance peaks above, I simply do not see why you should go for a half-baked PFFB.

TPA chip based PFFB should really be done only with excellent passive components and sufficient loop gain and bandwidth. The loop gain around the TPA chip is limited, so either excellent output filter performance can be improved upon or a poor output filter can be camouflaged to measure better on some popular metrics but really you just end up shifting the junk to higher harmonic orders where it might be more audible.

I am not sure if the champions (Topping, 3e) use only a PFFB wrapped around the TPA chip and some clever gain structure upstream or more likely have some kind of composite approach where a separate and fully analog op amp is part of the feedback loop around the TPA chip and the filter.

As for the HP filter (and I quite like the idea of not asking your mains/satellites to play LF), if that is what you are after, there are many ready-to-run line level modules availeable on Aliexpress, or you could roll your own with the help of ESP projects in Oz.