Douk A5 Budget Stereo Amplifier Review

[Bruce Morgen]

I'm in a very small and quiet bedroom sitting about 5 feet away from the speakers, it's an apartment building so I doubt I would be turning up the volume too loud in most situations. Thanks for the heads up though, I'll keep doing some more research and maybe I'll make a thread of my own when I have more options in mind.

This is a classic "near field" situation -- which is exactly what most smaller "monitor" speakers are designed to accommodate. Seek out a small-enough monitor with reasonably flat frequency response -- and no red flags in its other measurements -- and I predict you'll be happy listening from such a short baffles-to-ears distance.

 

[JRowland]

I run a pair of Polk ES 50 towers in my garage from the A5 using a 48v 10a power supply. It gets loud, there is no running out of steam. It’s sitting on a copper heat sink the size of the A5 so it only gets warm and it gets used often, loud every weekend. So far so good, but that lack of power comment above should be taken with a grain of salt.

 

[Jankob]

I just bought this and I've got a question about the crosstalk measurements.

Do the measurements mean that if I have the left source RCA unplugged, there should be no sound coming from the right speaker? In my set up with the volume knob about 1/3 of the way on you can still hear a faint, highly distorted sound (and the same if I unplug the right source RCA with the left speaker). Do I have a defective unit? Or is this to be expected?

 

[adamus]

Douk A5 replacement ventilated Lid by adam walker | Download free STL model | Printables.com

ventilated lid for the Douk Audio A5 to help manage the heat (they get hot on 48v). | Download free 3D printable STL models

www.printables.com

If anyone has a 3d printer - i made an stl for a ventilated lid, fits perfectly. You are welcome

 

[truth_soldier]

It sounds OK at lower volumes, but at higher volumes it sounds strained. For nearfield applications, it's fine though. For far field, if you like it loud, look elsewhere.

it of course depends greatly on how sensitive your speakers are. Mine are large 96db open baffle. What's yours?

 

[escape2]

it of course depends greatly on how sensitive your speakers are. Mine are large 96db open baffle. What's yours?

True. Mine are 89 dB.

 

[makruger]

I just replaced an Aiyima A07 Max with one of these Douk A5's. It's driving a set of Polk XT15's and I have also connected an inexpensive Rockville Rock Shaker 6.5 subwoofer to the aux port. This is an apartment set up, so to keep base tight/musical and the neighbors happy, I stuffed the subwoofer's base reflex port with a tightly rolled up microfiber towel. Both the HPF on the Douk and the LPF on the subwoofer are set to 80hz.

When switching over to the Douk, I set the volume on my WiiM Pro to fixed and am now using the Douk A5 to control volume. It sure would be nice if the Douk had a remote, but I can still pause things on the WiiM with the remote. In any case, this is probably the optimal way to feed the Douk and the sub. Using a slightly modified spinorama EQ profile for the polks, I am really quite pleased with the results for both music and movies.

Interestly, the Douk A5 gets kind of warm, even with the lowly 32 volt power supply. It's not 48 volts warm, but warmer than I expected it to be. The Aiyima in contrast, didn't seem to heat up very much on 32 volts, but it surely did on 48 volts.

 

[DanielT]

Edit:
I was just imagining things; see #597 below.

_______

I have to say, Douk A5 it gets really hot with the included 48V, 5A power supply. I happened to find a 20V, 3.25A power supply in a drawer. With that one, the Douk Audio A5 barely gets warm , though the output drops to around 25 watts into 4 ohms (estimated).


Has anyone tried placing an ultra-quiet fan—powered by a USB charger—underneath the amplifier? There are ventilation holes under the amplifier. Blow air in there... somehow.
Something like this, if it's good enough? Enough capacity?

Noise level 19 Decibel
Maximum rotation speed 1500 RPM
Air flow capacity 104 cubic feet per minute

NewHail 1Pack 120mm USB Fan Ultra-Quiet USB Fan 5V with 3 Adjustable Speeds for Router Modem Receiver DVR Playstation TV Box and Other Electronics : Amazon.se: Electronics

NewHail 1Pack 120mm USB Fan Ultra-Quiet USB Fan 5V with 3 Adjustable Speeds for Router Modem Receiver DVR Playstation TV Box and Other Electronics : Amazon.se: Electronics

www.amazon.se

 

[Moks]

I have to say, Douk A5 it gets really hot with the included 48V, 5A power supply. I happened to find a 20V, 3.25A power supply in a drawer. With that one, the Douk Audio A5 barely gets warm , though the output drops to around 25 watts into 4 ohms (estimated).
View attachment 550430View attachment 550431

Has anyone tried placing an ultra-quiet fan—powered by a USB charger—underneath the amplifier? There are ventilation holes under the amplifier. Blow air in there... somehow.
Something like this, if it's good enough? Enough capacity?

Noise level 19 Decibel
Maximum rotation speed 1500 RPM
Air flow capacity 104 cubic feet per minute
View attachment 550432

NewHail 1Pack 120mm USB Fan Ultra-Quiet USB Fan 5V with 3 Adjustable Speeds for Router Modem Receiver DVR Playstation TV Box and Other Electronics : Amazon.se: Electronics

NewHail 1Pack 120mm USB Fan Ultra-Quiet USB Fan 5V with 3 Adjustable Speeds for Router Modem Receiver DVR Playstation TV Box and Other Electronics : Amazon.se: Electronics

www.amazon.se

It may help, also with opened glass or even with removed glass, placed on top of the amplifier

 

[Roland68]

I have to say, Douk A5 it gets really hot with the included 48V, 5A power supply. I happened to find a 20V, 3.25A power supply in a drawer. With that one, the Douk Audio A5 barely gets warm , though the output drops to around 25 watts into 4 ohms (estimated).
View attachment 550430View attachment 550431

Has anyone tried placing an ultra-quiet fan—powered by a USB charger—underneath the amplifier? There are ventilation holes under the amplifier. Blow air in there... somehow.
Something like this, if it's good enough? Enough capacity?

Noise level 19 Decibel
Maximum rotation speed 1500 RPM
Air flow capacity 104 cubic feet per minute
View attachment 550432

NewHail 1Pack 120mm USB Fan Ultra-Quiet USB Fan 5V with 3 Adjustable Speeds for Router Modem Receiver DVR Playstation TV Box and Other Electronics : Amazon.se: Electronics

NewHail 1Pack 120mm USB Fan Ultra-Quiet USB Fan 5V with 3 Adjustable Speeds for Router Modem Receiver DVR Playstation TV Box and Other Electronics : Amazon.se: Electronics

www.amazon.se

From everything I’m reading here, there is something going on in the signal conditioning stage that causes the TPA3255 to heat up—or, far more likely, the 12-volt regulation circuit for the TPA3255 and the op-amps is the actual source of the heat in units using higher-voltage power supplies.

 

[whazzup]

I have to say, Douk A5 it gets really hot with the included 48V, 5A power supply. I happened to find a 20V, 3.25A power supply in a drawer. With that one, the Douk Audio A5 barely gets warm , though the output drops to around 25 watts into 4 ohms (estimated).
View attachment 550430View attachment 550431

Has anyone tried placing an ultra-quiet fan—powered by a USB charger—underneath the amplifier? There are ventilation holes under the amplifier. Blow air in there... somehow.
Something like this, if it's good enough? Enough capacity?

Noise level 19 Decibel
Maximum rotation speed 1500 RPM
Air flow capacity 104 cubic feet per minute
View attachment 550432

NewHail 1Pack 120mm USB Fan Ultra-Quiet USB Fan 5V with 3 Adjustable Speeds for Router Modem Receiver DVR Playstation TV Box and Other Electronics : Amazon.se: Electronics

NewHail 1Pack 120mm USB Fan Ultra-Quiet USB Fan 5V with 3 Adjustable Speeds for Router Modem Receiver DVR Playstation TV Box and Other Electronics : Amazon.se: Electronics

www.amazon.se

I did (not the same model) for the mini 300, drops ~10°C in my case

Topping Mini 300 Amplifier Review

To close the loop (for no one) for my earlier post about the temperature of components in the mini 300: https://www.audiosciencereview.com/forum/index.php?threads/topping-mini-300-amplifier-review.68581/page-28#post-2637934 Texas Instruments does rate the TPA3255 up to 70°C operating range. I'm...

www.audiosciencereview.com

 

[Moks]

I did (not the same model) for the mini 300, drops ~10°C in my case

Topping Mini 300 Amplifier Review

To close the loop (for no one) for my earlier post about the temperature of components in the mini 300: https://www.audiosciencereview.com/forum/index.php?threads/topping-mini-300-amplifier-review.68581/page-28#post-2637934 Texas Instruments does rate the TPA3255 up to 70°C operating range. I'm...

www.audiosciencereview.com

I think it all depends on the amplifier's cooling system. If the amplifier chip is located underneath, with heat dissipated into the case, then it might make sense to blow air over the entire case rather than trying to force air into the vents underneath. In the case of the A5, removing the glass cover and installing a fan on top, directing airflow inward, seems more effective to me, although less aesthetically pleasing. If A5 owner has time and a thermometer, he could try comparing the two options.

 

[whazzup]

I think it all depends on the amplifier's cooling system. If the amplifier chip is located underneath, with heat dissipated into the case, then it might make sense to blow air over the entire case rather than trying to force air into the vents underneath. In the case of the A5, removing the glass cover and installing a fan on top, directing airflow inward, seems more effective to me, although less aesthetically pleasing. If A5 owner has time and a thermometer, he could try comparing the two options.

The mini 300 with side / bottom vents and no top vents demonstrates that even with active cooling underneath (tpa chip is on topside of pcb, under heatsink), it does improve temperatures as shown by my rough measurements. So where you want to locate the fan is down to user preference / asethetics, it'll work as long as airflow is improved.

 

[DanielT]

From everything I’m reading here, there is something going on in the signal conditioning stage that causes the TPA3255 to heat up—or, far more likely, the 12-volt regulation circuit for the TPA3255 and the op-amps is the actual source of the heat in units using higher-voltage power supplies.

Edit:
I was just imagining things; see #597 below.
______
But wait a minute—does that imply a fundamental design flaw?

It’s a real long shot, but since you mentioned op-amps, I might as well ask: could swapping to a different op-amp reduce the heat? I have no idea if or how that would work—I’m no electronics engineer—but there’s no harm in asking.

Damn, I’m so curious now that I’m going to buy a cheap $20 IR thermometer today.

Then I’ll take measurements here and there, with the lid both closed and open. I also have a fan heater that I can set to blow just air (without heat); I’ll position it in various spots and take readings.

I’ll get back to you on this later tonight.

 

[Roland68]

But wait a minute—does that imply a fundamental design flaw?

It’s a real long shot, but since you mentioned op-amps, I might as well ask: could swapping to a different op-amp reduce the heat? I have no idea if or how that would work—I’m no electronics engineer—but there’s no harm in asking.

Damn, I’m so curious now that I’m going to buy a cheap $20 IR thermometer today.
View attachment 550687
Then I’ll take measurements here and there, with the lid both closed and open. I also have a fan heater that I can set to blow just air (without heat); I’ll position it in various spots and take readings.
View attachment 550688
I’ll get back to you on this later tonight.

In principle, I wouldn't immediately assume there is a design flaw.
However, significant input noise or oscillation in the small-signal stage could also cause the amplifier IC to heat up, even without an audio signal.

It is far more likely that the heat comes from the 12-volt supply generated by the power circuit; depending on the type of regulator used, this can generate more heat than the amplifier chip itself—at least at low volumes.

Regardless of that, however, modifying an amplifier's cooling system is pretty pointless unless you are actually measuring the temperature or have genuinely burned your fingers—since only then would the temperature have exceeded 40°C.

 

[Power Pop 23]

It may help, also with opened glass or even with removed glass, placed on top of the amplifier

The paper-backed adhesive affixing the glass panel on my recently-acquired, Douk Audio A5 includes this 'Warm Tip':

3. No high voltage inside but don't open the glass window during working

Until recently, Amazon USA had been noting the variant of the Douk Audio A5 with a 48 volt PSU was a 'frequently returned item' while the variant with the 32 volt PSU did not have this notation.

In choosing to differentiate the A5 with RGB lighting visible through a glass panel top, Douk Audio may have hindered the ability of the enclosure to dissipate heat compared to other enclosure options.

 

[DanielT]

Excuse me. And apologies to @Douk Audio —I take back what I said; I was just being paranoid.I have to say, it's embarrassing.
I don't get how I imagined it was running so hot.

Douk A5 had been on for 20 minutes before I started measuring. I was listening at high volume—or rather, not that loud, considering the speakers only have 81 dB sensitivity. The volume control was turned up to three-quarters of the way to max. Using a 48 V, 5 A PSU.
Initially, I fed Douk A5 a signal that had passed through my subwoofer's 80 Hz high-pass filter.
Measurement on the outside:36 C/ 98F

Measurement on the inside, at the hottest point:53.8 C/126.6 F


Then, with the lid open, a measurement after 15 minutes. No difference. Or at least differences so small they're negligible.

Just the Douk A5, full-range signal to the speakers. Measurement after 20 minutes of listening. Same as the initial measurements.

I listened to these speakers with Douk A5 when I was testing/measuring:

Micca MB42X G2 Budget Speaker Review

This is a review, listening tests and detailed measurements of the Micca MB42X G2 low cost 2-way bookshelf speaker. It is on kind loan from a member and costs US $100 for a pair, shipping included. I expected thin, cheap plywood construction but instead, found a robust composite enclosure that...

www.audiosciencereview.com

Edit:
By the way, it’s not ideal to drive those small Micca speaker with that much power; the bass bottoms out long before that, but that’s another topic.

 

[truth_soldier]

installing a fan on top, directing airflow inward,

That would increase dust buildup and lower the longevity of the amp - the opposite of what you want to do with lowering the operating temperature.

 

[DavidR]

That would increase dust buildup and lower the longevity of the amp - the opposite of what you want to do with lowering the operating temperature.

I have been opening the top only when in use as well, recognizing that dust buildup could/would eventually be an issue. But I've got receivers/amplifiers with grated top sections that have accumulated many years worth of dust that, so far, have not affected them that I'm aware of.

That said, an earlier comment about on-hand power supplies made me look and find two 19.5V multi-amp laptop power supplies in my box. I've replace the 48V 5A Douk supplies with them. This is for wall-mount desk speakers, so high power isn't needed. The amps never get warm to the touch now with the cover closed. But had I kept the 48V ps, I still would open the tops as I suspect that heat (lacking any mods) over time is more detrimental than dust over time.

Edit: One more comment. I a Fosi V3 Mono on my test bench. I purchased a fan to place underneath it. I ran REW distortion measurements with/without the fan and did not like the additional distortion the fan introduced. Now it sits on a copper heat spreader from a fanless PC. The fan sits some distance away to move air through the spreader. Not an attractive setup, but this is for a hardware distortion measurement rig also used for speaker measurements. Point being that these class D amps are fantastic and there's a THD war between and within manufacturers. Adding a fan in close proximity counters that, possible rather signficantly even though I doubt it's audible. But I've seen no discussion of this easily measured influence.

 

[Roland68]

I think it all depends on the amplifier's cooling system. If the amplifier chip is located underneath, with heat dissipated into the case, then it might make sense to blow air over the entire case rather than trying to force air into the vents underneath. In the case of the A5, removing the glass cover and installing a fan on top, directing airflow inward, seems more effective to me, although less aesthetically pleasing. If A5 owner has time and a thermometer, he could try comparing the two options.

That would increase dust buildup and lower the longevity of the amp - the opposite of what you want to do with lowering the operating temperature.

Except in very specific use cases, warm air is generally exhausted from the device being cooled.
Blowing in cooling air is a typical beginner's mistake that can actually lead to heat buildup and overheating in certain areas. Dust and condensation can cause additional problems in such cases.