Douk A5 Budget Stereo Amplifier Review

[Madragon]

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

Do you have more measurements with the HPF control turned up even further? From what I’ve seen, the filter only starts to take effect after turning the knob quite a bit. Although even if it has some effect when turning the control to the maximum, it would still be a rather poor and imprecise filter, I'm just asking out of curiosity.

 

[Audionaut]

so this device‘s HPF is fake

I don't know what you measured, but the HPF on my A5 is definitely not fake, because it works perfectly and is clearly audible.

Based on your "measurements", however, it would be inaudible.

 

[jmc06]

I don't know what you measured, but the HPF on my A5 is definitely not fake, because it works perfectly and is clearly audible.

Based on your "measurements", however, it would be inaudible.

From the measurement data, I don't consider this to be a true HPF, as it lacks the characteristic roll-off and instead demonstrates a very gradual attenuation with a shallow slope. At best, it's a non-functional filter; at worst, it's merely a bass tone control.

 

[Punchy_Power_Cat]

Amir needs to retest version 3 of this amp. Maybe there is even a v4 at the time I am writing this. They changed some lane lenght on the board beside other things (speaker out cable better distance to power in etc).

 

[jmc06]

Amir needs to retest version 3 of this amp. Maybe there is even a v4 at the time I am writing this. They changed some lane lenght on the board beside other things (speaker out cable better distance to power in etc).

My test is based on the third version. The hpf is fake. It starts to drop slowly from around 200hz. It's just a bass knob, not an hpf. Other parts can't be tested for the time being. Besides, I'm a bit suspicious of the moderator. He clearly had the conditions to test. Why did he choose to ignore it at that time

 

[regoc]

My test is based on the third version. The hpf is fake. It starts to drop slowly from around 200hz. It's just a bass knob, not an hpf. Other parts can't be tested for the time being. Besides, I'm a bit suspicious of the moderator. He clearly had the conditions to test. Why did he choose to ignore it at that time

Im suspecting there is a difference between v1,v2 and v3 in the hpf section of the board.
Some pictures of V3 board would be nice to post here.

This is V1/V2. Clearly here's visible that audible roll-off starts at blue line a.k.a 1 o'clock , yellow line is at 3 o'clock and black line is at the max 200hz.
But yeah, it's also visible from the slope at around 200 hz that is not a true HPF.
Still, for my demands of hpf, this is just fine.

 

[jmc06]

Im suspecting there is a difference between v1,v2 and v3 in the hpf section of the board.
Some pictures of V3 board would be nice to post here.

View attachment 455840
This is V1/V2. Clearly here's visible that audible roll-off starts at blue line a.k.a 1 o'clock , yellow line is at 3 o'clock and black line is at the max 200hz.
But yeah, it's also visible from the slope at around 200 hz that is not a true HPF.
Still, for my demands of hpf, this is just fine.

This so-called hpf is completely unable to connect with the frequency of the subwoofer

 

[Punchy_Power_Cat]

This so-called hpf is completely unable to connect with the frequency of the subwoofer

Because subs use a straight and steep 12/24oct slope to down pass and the high pass from the Douk A5 does not match those cuts/slopes due to their "exotic" nature? That means there would always be slight doubling resonances when you try to tune in the sub??

 

[Punchy_Power_Cat]

This is V1/V2. Clearly here's visible that audible roll-off starts at blue line a.k.a 1 o'clock , yellow line is at 3 o'clock and black line is at the max 200hz.

I have recreated the yellow line (Knob@three o' clock) in the Roon-EQ to hear what it would sound like on my KEF LS50 Metas. Fantastic detail and still quite powerful base but much less distortion. This is not a bad filter to enhance some book shelfs. I think I could add a sub to that without too much compromise. The full knob position seems unusable tho, unless they have fixed the curve in a later version. Maybe someone from Douk audio can eloborate on this.

 

[NielsMayer]

View attachment 455563

What is the purpose of the ferrite added to the power cord?

 

[regoc]

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

Pretty confident offensive which is offtopic btw, for someone who can't clarify which version is of Douk A5 from their own pictures.
If that's something that lights your fire, let it be.


Even AI is on my side.

 

[regoc]

What is the purpose of the ferrite added to the power cord?

Ghostbusters thing, you would never understand....

 

[regoc]

I have recreated the yellow line (Knob@three o' clock) in the Roon-EQ to hear what it would sound like on my KEF LS50 Metas. Fantastic detail and still quite powerful base but much less distortion. This is not a bad filter to enhance some book shelfs. I think I could add a sub to that without too much compromise. The full knob position seems unusable tho, unless they have fixed the curve in a later version. Maybe someone from Douk audio can eloborate on this.

It's not a bad filter at all, especially from 12 to 3 o clock.
around 12 dB/oct is good compromise between roll-off and proper performance

 

[jmc06]

What is the purpose of the ferrite added to the power cord?

I just found such a thing at home. It seems to have been taken from some Hitachi ATM. Then I thought it was beneficial and added it. May I ask if this has no effect at all?

 

[jmc06]

It is very useful to add magnetic rings to the DC power line.
This small magnetic ring, often referred to as a ferrite magnetic ring or an anti-interference magnetic ring, mainly functions to suppress high-frequency noise and electromagnetic interference (EMI).
It can be imagined as a filter, specifically targeting high-frequency signals. It allows the direct current we need (with a frequency of 0Hz) to pass through smoothly, but it will "eat up" or "attenuate" those unnecessary high-frequency interference signals. These interferences may come from the power supply itself, other electronic devices around, or electromagnetic waves in the space.

Ghostbusters thing, you would never understand....

gemini tell me

 

[Punchy_Power_Cat]

It is very useful to add magnetic rings to the DC power line.

No, the other way around. Very useful at the AC-IN to clear out the PSU especially when you're dealing with an internal PSU and super especially when this internal PSU is not properly located and shielded from the (op)amp. I have wrapped the AC cable coming into a switching power supply inside a DIY amp multiple times around a hand palm sized blue colored N30 Toroid ring from Epcos/TDK. The result was:

ear directly held to speakers driver cone to measure idle noise

• without N30 Epcos: from around 70% vol noise starting to arise
• with N30 Epcos: from around 97% vol noise starting to arise

It basically made the amp nearly dead silent. For about 9 bucks or something.

 

[jmc06]

No, the other way around. Very useful at the AC-IN to clear out the PSU especially when you're dealing with an internal PSU and super especially when this internal PSU is not properly located and shielded from the (op)amp. I have wrapped the AC cable coming into a switching power supply inside a DIY amp multiple times around a hand palm sized blue colored N90 Toroid ring from Epcos/TDK. The result was:

ear directly held to speakers driver cone to measure idle noise

• without N90 Epcos: from around 70% vol noise starting to arise
• with N90 Epcos: from around 97% vol noise starting to arise

It basically made the amp nearly dead silent. For about 9 bucks or something.

Then why are the ferrite magnetic rings of other devices that I usually see installed on the dc side of the device? For example, the dc input line of the monitor

 

[Punchy_Power_Cat]

Then why are the ferrite magnetic rings of other devices that I usually see installed on the dc side of the device? For example, the dc input line of the monitor

That is to ensure there is no leak-in by EMI from the direct environment where the cable is put. It is not to clean out the DC signal produced by the PSU. Lots of people like to bundle all their cables (printer, display, dac, whatever) behind the desk and create some sort of "spaghetti monster" with their cables. To ensure those spaghetti bundles don't intefere is what these small toroids are for.

This is how the magic happens. At the AC side. This picture is what PS audio and other companys sell as "AC cleaner devices" for thousands of bucks. Their devices usually remove some but add other noise. Those rings do nothing than to remove noise. They literally convert noise/ripple into heat. They cost around 10 bucks that size. They come in different frequency filtering ranges, you would have to experiment to find the perfect one. I was going for "N30" I believe. Here is a list of applications

 

[Blew]

I have recreated the yellow line (Knob@three o' clock) in the Roon-EQ to hear what it would sound like on my KEF LS50 Metas. Fantastic detail and still quite powerful base but much less distortion. This is not a bad filter to enhance some book shelfs. I think I could add a sub to that without too much compromise. The full knob position seems unusable tho, unless they have fixed the curve in a later version. Maybe someone from Douk audio can eloborate on this.

Interesting, thanks. I would love to see what this looks like at 80Hz or 90Hz.

 

[ctakim]

Based on the review I just got one of these to drive a secondary bookshelf system that I put together as a DIY project. Running mostly Roon and Qobuz as my musical source through a Raspberry Pi 4 with a Hifiberry DAC2 Pro HAT. I can't believe how compact a system this is. It is replacing a Loxjie A30 mini-amp/dac.