Douk A5 Budget Stereo Amplifier Review

[unmutual]

no issue with stereo vs. mono ?

I mean: the Douk A5 obviously has a stereo 3.5mm out; the REL "expects" on single RCA both channels;

in good case first the 2 channels of the stereo must be properly (!) unified, like through Single Stereo auf Mono Konverter

I am not convinced what happens if a simple cable on one side with 3.5mm stereo Jack male and on the other side with RCA male connector is used; depends how the connections are done; e.g. bass not only from one channel arrives

In most cases the bass content is the same in both channels. I suppose you could use a stereo to mono RCA adapter to cover the rare exception cases.

 

[regoc]

If the housing gets very hot, the aluminum block that connects the TPA3255 to the housing does not need to be any larger, as it then performs its task perfectly as a heat exchanger.
The actual housing is then too small for heat dissipation and you have to resort to additional means.
Either activated with a fan or passive with a heat sink.
As I don't like active cooling in hi-fi devices, I opted for a massive heat sink for the O-Noorus D1, which is also used in power amplifiers.
There are also cheaper solutions on AE, for example.


View attachment 446850

View attachment 446851

Long story short, you are wrong.
Heat dissipation from TPA3255 follows a series thermal resistance model. The total temperature rise from the junction (chip) to ambient air can be expressed as:



Where:

P = Power dissipation (W)
RθJC = Junction-to-case thermal resistance
RθCB = Case-to-block thermal resistance (includes TIMs)
RθBH = Block-to-housing thermal resistance
RθHA = Housing-to-ambient thermal resistance

In a series system, the largest resistance dominates the temperature rise. If the aluminum block (between case and housing) is too small or has poor thermal conductivity, RθCB or RθBH will increase, and so will the junction temperature—even if the housing can dissipate more heat.

Scientific principle involved: Fourier’s Law of Heat Conduction

Q = -kA \frac {dT} {dx}

Where:


Q = heat flow (W)
k = thermal conductivity (W/m·K),
A = cross-sectional area (m²)
dT/dx = temperature gradient

If the block has a small cross-section or length (i.e., low thermal conductance), Q will be limited regardless of how effective the downstream components are.

I hope this clears it for you and why Douk audio design of the thermal block in v2 is inferior to v1. This goes for all hot running TPA3255 and similar amps.

 

[regoc]

why do you write this definitely false thing ? why do you write if you are not familiar with the REL T2 ?

here on the top the situation of the connectors and below more with question mark: is this the proper solution to use such connectors ?

I agree bro, lukewarm responses shouldn't even be posted here

A5 goes to Low Level RCA. Other RCA and XLR connections are reserved for "REL Theatre Reference". You just need 3.5mm to RCA, mono or stereo it does not matter. In case of 3.5mm to RCA Stereo cable, you are connecting L or R channel, it's the same. Bass frequencies are non-directional, so stereo separation in sub-bass is usually unnecessary.

 

[Audionaut]

Long story short, you are wrong.

Long story short, I don't appreciate it when you pass off an AI's answers as your own.

 

[BlueGuerrilla]

1) About Cooling
I combined and cooled the parts that connect 5V USB power using the leftover computer 120MM fan at home, and now my A5 is completely cool. ^^

2) New OP-amplifier Combination
I launched and installed the new Discrete Style opamp AK05 on Akliam and it looks great with the A5. The personality is close to Burson Opamp and I like it. It also looks great with the A5.

 

[Audionaut]

I ordered the A5 from Aliexpress today for 55 euros.
Absolutely unnecessary , but I'm looking forward to its performance.

 

[unmutual]

I use a DAC + the Douk A5 with 48V PSU to send the audio from my TV to a pair of tower speakers. No problem getting enough volume to fill the room (medium sized, L-shaped living room). The only thing I am missing, is remote control for the volume.

 

[Audionaut]

I ordered the A5 from Aliexpress today for 55 euros.
Absolutely unnecessary , but I'm looking forward to its performance.

There's the little A5.

It really is small, but very solid. It feels like a very solid piece of technology.

The workmanship is very good for the most part, except for a few spots on the inside that I can't quite put my finger on. On the other hand, I would probably never have noticed them if it weren't for this window.

The sound is very powerful and transparent with a 48V 10A power supply.

Green lighting is set on delivery, but there are various LED color options.

I still have the small heat sinks here in stock and have put them on loosely. Let's see if I have to come up with an additional cooling solution, as it runs on 48V and 10 amps.

So far, everything is OK as far as temperatures are concerned.

Operating instructions are understandable and visualized. Not a matter of course.

 

[Audionaut]

Does it actually mean anything if there is no version number printed on the circuit board?
The other photos in this thread show either Ver: V1 or V2
There is nothing on my A5.

 

[regoc]

Does it actually mean anything if there is no version number printed on the circuit board?
The other photos in this thread show either Ver: V1 or V2
There is nothing on my A5.

Yes, there is. You just need to look a little bit better

 

[Audionaut]

Yes, there is. You just need to look a little bit better

Thank you
Version 3
It would of course be interesting to know what distinguishes the individual versions from each other.

What I find very good about the A5 is that there are no on and off clickers, because it is relay-controlled.

You switch it on using the rotary knob and a short time later you hear the relay. Very good.

 

[Audionaut]

Power is fitting with price but more modest than the more expensive competitors (from memory):

Wouldn't it be much more meaningful to compare all these TPA3255 chip-based amplifiers with the same power supply, Amir?
For example, all with 48V 5A or 10A.

It would then be much easier to find out the actual differences.
As it is now, you mainly see the differences that arise due to different power supply units.

Since almost all of them have external power supply connections, it would be very easy and straightforward to create the same test conditions, which would be very useful for the science in the Audio Science Forum.

 

[avl2]

Wouldn't it be much more meaningful to compare all these TPA3255 chip-based amplifiers with the same power supply, Amir?
...

100% agree and support the question

there are opinions about the role of the power supply ...for all amps, and especially for D class chip-based amps

a variation would be: measure 1 amp with different power supplies or swap between 2 - rather different in SINAD - amp their power supply to see if and how big the effect is ~similar to op-amp rolling, how results look like with power supply rolling (~ no effect ? minor effect ? big effect ? -> or can be this answered without measurements ?)

 

[t_im]

Very happy with the A5 - it sounds better than the Arcam FMJ that was driving my desk's kef LS50s; for 1/10th the price the Arcam cost back in the day, and 1/10 less space (and weight) this can't be beaten. More room to pile even more stuff on my desk!
FWIW I'm using the A5 as a power amp - sort of: HF filter off, volume fixed at 75%, with camillaDSP taking care of volume and LF/HF filters (+ loudness when listening at low volume), on an embedded board driving a motu M4.
The A5 is dead silent, unlike the arcam which had a lot of static noise at similar volume (same setup - volume set at 66 on the arcam for a max of 99 ; roughly the same sound pressure as the A5 at 75%).
I was surprised by the mini size of the A5 and initially thought it wouldn't (/couldn't) be better than the arcam, but nope - great stuff. I was used to heavy, not-particularly-cheap A/B amps, it's the first time I try a mini amp (and a class D)- I'm dumbfounded.
Btw I got the 32V power supply and the A5 doesn't run hot.
That thing put a grin on my face - I spent hours listening to music after I switched the amps instead of working lol.
Thanks to ASR/Amir for those great reviews!

 

[BlueGuerrilla]

Why did version 3 come out? Did you reduce the heat sink more? (Just kidding)

 

[Madragon]

Interesting observation on the A5:

Since the amp gets pretty hot with 48V and the turn off pop kinda bothered me, I tried the supplied 32V Nobsound brick and noticed it has ZERO turn off pop and while running barely luke warm!

So if you use the A5 for PC audio where it's on for extended periods I would recommend running it at 32V unless you REALLY need more power, it could also be my generic 48V brick causing the pop but I did see Amir showing ON and OFF pop with the 32V brick in the review whereas I only get the OFF pop with a generic 48V brick and none with the 32V. Weird but I'll take it.

I came to suggest replacing the glass window and using passive heatsinks, but I see some people have already done that.
By the way, do all of you plug your gear directly into the wall, or do you use AVR surge protector?
I recently saw someone complaining about an amp overheating, and once they connected it to a AVR, the issue was resolved.

 

[jmc06]

 

[jmc06]

View attachment 455563

When using a 48v10a power supply, it gets very hot. By using a large heat sink of 10cm*13cm and bonding it with silicone grease, the heat can be perfectly dissipated, and the overall effect is very perfect

 

[Madragon]

When using a 48v10a power supply, it gets very hot. By using a large heat sink of 10cm*13cm and bonding it with silicone grease, the heat can be perfectly dissipated, and the overall effect is very perfect

For those who were complaining that the heatsink was too small hahaha what a crazy mod! I love it. Even aesthetically, it looks great.

 

[jmc06]

red line is HPF OFF
green line is HPF ON（@13:00）
so this device‘s HPF is fake