Douk A5 Budget Stereo Amplifier Review

[Waxx]

Better than i remember that brand, but not good enough for a class D for me. But it's not a disaster. For non critical listening this is fit for the purpose and the price is ok for what you get. But i would not use this for my main system of for my office (where i listen the most). It's more a kitchen amp or workshop amp.

 

[effj]

Here is my take on the value proposition of Douk’s A5. Let’s first get out of the way that it’s not for everyone.

For the A5’s target audience, what really differentiates it from other amps? First, we can establish that it’s an ultra-low-price, general-purpose stereo amp that can be used on a desktop, in a basic TV setup, or maybe in a listening room. But that’s not enough; as others have said, the market segment fitting that description is increasingly crowded with similar (and potentially better) options.

It’s the 2.1 enhancement (i.e high-pass filter and preamp output) that distinguishes Douk’s A5 from similar amps, and I don’t think that should be overlooked in comparisons. I have a collection of stereo amps sitting on my bookshelf, and what they all have in common is (a) a layer of dust and (b) they lack an HPF and/or volume-controlled subwoofer output.

 

[surroundman]

The criticism that this gem is getting seems to either fully or at least partially omit the existence of (the combination of) two features (HPF and aux-out that is controlled by the volume knob) that this amp offers, unlike none of the competition's offerings. The amp is being compared by some purely as a 2.0 device, with no use of subwoofer at all. This, if anything, seems like comparing apples to oranges. I have two subwoofers, and they were used with Fosi V3's line aux-out. No HPF, no volume matching. It was an abysmal experience. Words cannot describe the difference I am seeing now - subwoofers no longer blasting during low (speaker) volume, and lesser speaker distortion with the HPF. Sorry for the horrible example, I am not good at that stuff, but one does not buy a vanilla-chocolate-strawberry combo ice cream just because he likes only the strawberry - he can find a pure, likely better-quality strawberry one if that one is all he cares about. More likely, he appreciates what the combo offers. Same thing with this amp. The strawberry, or the SINAD, is not all that this amp offers.

 

[elshaddai]

Fully agree with both of points made above. This is a type of device I've looked for over the past two years and would have purchased even a year ago. But now I have a Hypex Ncore power amp and my interest is more in a 2.1 preamp. If this had RCA and XLR outputs instead of the amplification components, I'd be salivating. An adjustable HPF really would be nice - my sub has a 60/80/100 HPF pass through, but my new bookshelf speakers reach down to 50-55. It would be fun to play with that.

 

[bolo_nz]

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?

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.

I probably would still get the A5 if it didn't have PFFB, having HPF isn't new but the fact that Douk listened to feedback and changed the HPF range to something ACTUALLY usable AND could be defeated on top of the volume controlled line out is a big deal.

Put it this way, if the A5 continues to sell well then the features and measurements becomes the BASELINE of all budget amps. Things can only get better from here (maybe)

 

[xhattan]

Great job Douk for sending a unit for testing. This amplifier is a marvel. It has been a few years since a product of such magnitude (understand, "value") dropped. This unit with its features existing makes the majority of the popular competition's offerings obsolete. Not only it has high pass filter, but the aux-out is controlled by the volume knob. This is the budget subwoofer integration solution. With active subwoofer(s), the 32V power supply is enough, and it will run cooler. Best amp purchase I have ever made.

Great job Douk for sending a unit for testing. This amplifier is a marvel. It has been a few years since a product of such magnitude (understand, "value") dropped. This unit with its features existing makes the majority of the popular competition's offerings obsolete. Not only it has high pass filter, but the aux-out is controlled by the volume knob. This is the budget subwoofer integration solution. With active subwoofer(s), the 32V power supply is enough, and it will run cooler. Best amp purchase I have ever made.

Can you elaborate please? How can you use an active sub if it doesn´t have a line or sub out?

 

[JSmith]

Can you elaborate please? How can you use an active sub if it doesn´t have a line or sub out?

JSmith

 

[DSJR]

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.

Can't do the sub thing mate - no room and the house structure is a demon for transmitting low bass to the neighbour. Best have less under 80Hz than a speaker going down to 40Hz or so as I was using until recently - no difference at the listening position but walk outside the room and it was all over the house, this at not high levels (honest ). Yep, the ancient electronics needs to be thinned out. I'm just terrified of selling on the usual auction site.

 

[DanielT]

Can't do the sub thing mate - no room and the house structure is a demon for transmitting low bass to the neighbour. Best have less under 80Hz than a speaker going down to 40Hz or so as I was using until recently - no difference at the listening position but walk outside the room and it was all over the house, this at not high levels (honest ). Yep, the ancient electronics needs to be thinned out. I'm just terrified of selling on the usual auction site.

But isn't it an advantage to be flexible and plug in a subwoofer at appropriate times? Or use subs as much as you can, in relation to the neighbors' patience level? For other listening occasions, disconnect the subwoofer and then use only small speakers that don't produce much and low bass. Compare that to large full-range speakers where this potentially annoying bass for the neighbors is always there.

Then I think that the lowest bass frequency, when it approaches around 20 Hz for neighbors is less annoying than bass between 40 Hz to 80 Hz. Hm, topic for another thread. ..and ..:

Transmitting sound to neighbors, which bass frequency is most audible for these neighbors?

Scenario. Thin walls, sound transmitted between neighbors' apartments. You know how it can be. You have all, those of you who have ever lived in an apartment, experienced this. More or less experienced it depending on the construction of the house of course but it exists as you know. Then the...

audiosciencereview.com

Okay, if you don't think you have room for one or think subwoofers make your listening room look ugly? Then there's not much you can do. You can hardly accuse most subwoofers of being beautiful creations.

 

[Bacchusoo7]

Is that Aux out a full-range preamp out? Can the HPF be used as a cross over to send just the low-end information out the aux?

 

[Deleted member 72219]

Is that Aux out a full-range preamp out? Can the HPF be used as a cross over to send just the low-end information out the aux?

The high-pass filter only affects the speaker level outputs and the Aux out is full-range. Probably only affected by the volume attenuator. You'll need to use an active subwoofer, not some home-jobby.

-Ed

 

[Bacchusoo7]

The high-pass filter only affects the speaker level outputs and the Aux out is full-range. Probably only affected by the volume attenuator. You'll need to use an active subwoofer, not some home-jobby.

-Ed

Thank you.

 

[Hiten]

Shouldn't marking be in steps like, 30, 40, 50 hz so if one has response measured bookshelf (lots of candidate on ASR) one can more or less choose at which frequency the reponse should roll off ? also I dont get the idea behind transparent lid with lights inside. Serves very little purpose. Besides increasing manufacturing cost which can be diverted to something else.
regds.

 

[trevor_bartram]

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.

I assume the additional feedback provided by PFFB reduces the forward gain of the 3255 circuit & that reduction has to be made up in the input-buffer/single-ended-to-diff converter opamp circuit for the overall amplifier gain to remain the same. Those opamps will have to work harder & as a result produce a little more distortion?

 

[Audionaut]

also I dont get the idea behind transparent lid with lights inside. Serves very little purpose

It is a small tribute to design and to people who want to swap OPAMPS.
You can question design, but most of the time it's pointless.

 

[capslock]

It is a small tribute to design and to people who want to swap OPAMPS.
You can question design, but most of the time it's pointless.

View attachment 436021

wow, that's fugly. Steampunk meets Weber barbacue?

 

[effj]

It is a small tribute to design and to people who want to swap OPAMPS.
You can question design, but most of the time it's pointless.

View attachment 436021

Yeah, I don’t get it either but as long as only a fraction of my $70 went to it, no big deal. I’ll take those tradeoffs in an otherwise minimalist product over a pricier Swiss army knife amp any day of the week.

 

[Audionaut]

Steampunk meets Weber barbacue?

Home | Dan Dagostino amplifiers

Dan D'Agostino is a leading figure in high-end audio amplifiers, renowned for pushing the boundaries of sound quality and design. His company manufactures top-tier amplifiers like the Relentless Mono and Progression Integrated, all handcrafted in the USA.

www.dandagostino.com

 

[KL....]

View attachment 435995Shouldn't marking be in steps like, 30, 40, 50 hz so if one has response measured bookshelf (lots of candidate on ASR) one can more or less choose at which frequency the reponse should roll off ? also I dont get the idea behind transparent lid with lights inside. Serves very little purpose. Besides increasing manufacturing cost which can be diverted to something else.
regds.

As an interesting touch, a plexiglass cover is easily removed to change op-amps but also change switches which change the RGB lighting inside!

 

[shuppatsu]

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.

Most people won't hear the coloration or the distortion, IMO. But more likely to hear the coloration.

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.

I'm in that camp, personally. I use the standard non-PFFB Wiim Amp, in part because this is my speakers' impedance graph:

But I think we've all seen speakers with huge impedance spikes, and we have reports of severe coloration with those speakers. Meanwhile we have pretty strong evidence that most people can't tell the difference between amplifiers up to 1% THD. It would need to be much higher than that for HF, since 2nd order distortion for 10Khz is 20Khz! So really we're only concerned about IMD.

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.

Is this a real problem or a theoretical problem? The graphs you quote show a typical spray of higher order harmonics similar or better than the non-PFFB cheap amps you compared them to, at least at 1KHz. While it may be worse at higher frequencies, are we really worried about 5th order harmonics of a 15KHz signal?