Douk Audio H7 Amplifier Review

[AdamG]

Pretty sure it doesn't measure actual Volume Units -- and I'll bet it doesn't have the ballistics of a VU meter, either.

VU And PPM Audio Metering

ESP Project Pages - VU and PPM metering. Visit my other pages for more audio projects and articles

sound-au.com

https://mikeriversaudio.files.wordpress.com/2010/12/meter-madness_1-2_revised.pdf

For a Hundred and fifty bucks I think it’s pretty safe to assume the Vu meter is eye candy and just shows if the unit is functioning. Let’s be realistic about what you are getting here. This is not a multi thousand dollar unit.

 

[PeteL]

i apologise I was confused with the figure 2 next to it. Still what would a 1dB difference at 15kHz matter?

It matter to me, 1 dB is audible. It shows load dependency. Combine this with the fact that the amp didn't play nice with the reactive load Power cube test, not a good look.

 

[Deleted member 48726]

Can you explain to me how a layman can roughly estimate from the 4 and 8 ohm measurements of the amplifier, how the frequency response of the amplifier will be affected if, for example, in the 100 Hz range and around 2-3kHz the speaker has 60 ohm impedance?

Is there a way to calculate the frequency response deviation of the amplifier using the speaker impedance, phase and using the 4 to 8 ohm impedance difference of the amplifier?

The only thing these two resistive measurements tell is that the amp is load dependent. -That's it. Nothing about how it behaves with real load.

Is that okay for HiFi?

I think this is a disguised piece of hot disposable garbage sold by its metal enclosure and a nostalgic meter on front..

 

[Dougey_Jones]

Dual volume controls can be really useful. I have an 'L' shaped room that requires a bit of a tweak left, and then some old (vinyl) recordings where you wonder what on earth happened in the recording change to have such an unbalanced result!

This is a crowded market, so it makes sense to differenciate with a product like this. Using a pre-amp for volume, and with these controls on full, or almost on full, gives a bit of room adjustment in many scenarios.

It's just a pity about the bit of harshness / brightness commented on top - and the channel variation regarding noise etc - puts me off.

Or they could've just added a balance control.. One of the main reasons that I basically CAN'T upgrade from my current preamp (not that I have a reason to) is that high end, balanced preamps no longer come with remote controlled balance adjustment. I have some HF hearing loss in my left ear that causes vocals on certain tracks to sound like they were mixed off-center to the right. It drives me crazy. The only way I can consistently enjoy my music is to just keep the remote in my hand and tap the balance control button to center the image when it bothers me.

I have no idea why this feature no longer matters to people, but it's certainly easier to operate than two independent volume pots.

 

[bboris77]

Speaking about balanced connections, it would be interesting to test whether they do a proper job of eliminating ground loop noise. Hopefully they are wired properly and not there just for show.

The likelihood of this unit actually creating a ground loop is fairly low because it does not use a three prong grounded outlet. IMO, they are included for marketing purposes again, to give this unit an appearance of pro-level gear.

 

[PeteL]

Speaking about balanced connections, it would be interesting to test whether they do a proper job of eliminating ground loop noise. Hopefully they are wired properly and not there just for show.

The likelihood of this unit actually creating a ground loop is fairly low because it does not use a three prong grounded outlet. IMO, they are included for marketing purposes again, to give this unit an appearance of pro-level gear.

The TPA3255 is differential in it's architecture.

 

[Trell]

Or they could've just added a balance control.. One of the main reasons that I basically CAN'T upgrade from my current preamp (not that I have a reason to) is that high end, balanced preamps no longer come with remote controlled balance adjustment. I have some HF hearing loss in my left ear that causes vocals on certain tracks to sound like they were mixed off-center to the right. It drives me crazy. The only way I can consistently enjoy my music is to just keep the remote in my hand and tap the balance control button to center the image when it bothers me.

I have no idea why this feature no longer matters to people, but it's certainly easier to operate than two independent volume pots.

Not sure how your setup is but the RME ADI-2 DAC FS has balance control on the remote, and has PEQ per channel you can configure on the device. For one analog input there is the bigger brother RME ADI-2 Pro.

The output is stereo.

 

[bboris77]

@amirm, did this unit pass the torture test that fried the Sony receiver you tested a few years ago?

Sony STR-DH190 Stereo Receiver Reviewed

This is a review and detailed measurements of the STR-DH190 stereo amplifier. I was talked into buying it to review a while back. The STR-DH190 costs an incredibly low US $140 from Amazon including free shipping! The economics of this is impossible to fathom. If I had to sell you its empty...

www.audiosciencereview.com

The reason why I’m asking is because of the fact that these two are very close in price and, save for that failure, you said that you would have recommended the Sony at the time.

 

[PeteL]

@amirm, did this unit pass the torture test that fried the Sony receiver you tested a few years ago?

Sony STR-DH190 Stereo Receiver Reviewed

This is a review and detailed measurements of the STR-DH190 stereo amplifier. I was talked into buying it to review a while back. The STR-DH190 costs an incredibly low US $140 from Amazon including free shipping! The economics of this is impossible to fathom. If I had to sell you its empty...

www.audiosciencereview.com

The reason why I’m asking is because of the fact that these two are very close in price and, save for that failure, you said that you would have recommended the Sony at the time.

I sure would have liked to see how the Douk would have performed at this test:

 

[hansik]

No that is totally untrue. The TPA3255 has a recommended typical power voltage of 51V, with a maximum of 53.5V. 48V is commonly used in practice to allow a very safe margin. See the datasheet at https://www.ti.com/lit/ds/symlink/tpa3255.pdf

I had 3 TPA3255´s dead after using a 48V power supply for months.

 

[antcollinet]

I had 3 TPA3255´s dead after using a 48V power supply for months.

It will depend on if there is sufficient cooling in place for the chip. Maximum PSU voltage will need much better heatsinking and airflow.

Also depends on what died. Other components in the design might also be overstressed by higher voltages and temperatures.

 

[dtaylo1066]

144 clams with XLR in seems a great buy to me.

 

[pseudoid]

It's just a cheap Chinese moving coil meter strapped on the front panel just for fun. Don't take it seriously. After all, the 'amplifier' is just a teenage kid's toy in the first place.

I started with a cheap japanese all-in-one 'stereo system' that had these hard-wired 'speakers', each weighing less than a pair of AirJordans!
I can honestly say that it was a good start, for a punk that paid for it with a newspaper route.

 

[sofrep811]

Amir,

This has likely been addressed before, but in keeping these reviews objective—shouldn’t the review ignore the cost of the item being measured? I would guesstimate that 99% of the ASR readers can decipher and comment the cost vs data in the comments section.

 

[RayDunzl]

I've never understand the fascination with VU meters. I don't think they look good nor are they much useful. Log LED meters are better to me if you have a use for that.

Agree with the modern solution. Instant response.

I guess the VU may still have its place in the recording studio.

That (and a spectrum) is what my DEQ2496 gets used for since a miniDSP has superseded the equalization functions in it, at least for the most part.

It monitors the signal after processing before it hits the DAC.

I get to watch the high stuff I can't hear to at least see what I'm missing.

 

[PeteL]

I started with a cheap japanese all-in-one 'stereo system' that had these hard-wired 'speakers', each weighing less than a pair of AirJordans!
I can honestly say that it was a good start, for a punk that paid for it with a newspaper route.

Many of these older "all in ones" actually sounded quite alright, miles better than what youngsters go for as "all in ones" today, like the common Beer Can sized Bluetooth speaker, that still is going to set you back 200 bucks or so, each, not for the pair.

 

[respice finem]

Many of these older "all in ones" actually sounded quite alright, miles better than what youngsters go for as "all in ones" today, like the common Beer Can sized Bluetooth speaker, that still is going to set you back 200 bucks or so, each, not for the pair.

let alone the "music" that comes out of some of them, esp. the portable ones in the neighborhoods... Yes I know, I'm just too old

 

[pseudoid]

let alone the "music" that comes out of some of them, esp. the portable ones in the neighborhoods... Yes I know, I'm just too old

I consider the current generations growing up with IEMs as if they were committing a dis-honorable act of cranial 切腹 with "music".
But I feel more sorry for the "music"!
Yes I know, I'm just too old

 

[amirm]

Amir,

This has likely been addressed before, but in keeping these reviews objective—shouldn’t the review ignore the cost of the item being measured? I would guesstimate that 99% of the ASR readers can decipher and comment the cost vs data in the comments section.

In general I do disregard the cost. But I can't ignore the category a product is in. Should we crown 1000 watt amplifier with SINAD of 120 at $5,000 the top and everything then gets progressively lower score? Clearly that wouldn't make sense and would garner more complaints. In other categories such as DACs, it doesn't cost a lot to achieve very high performance. But with speakers, and amplifiers, there is direct cost in getting higher and higher overall performance. Getting 20 Hz response in a speaker is not going to happen in a $200 bookshelf speaker.

So what I have done is informally created a category of budget desktop amplifiers. In there, amplifiers like this do very well due to very low noise and distortion. The SINAD here is better than 100+ other amplifiers regardless of price! It beats the median for all amplifiers ever tested. All for $140 including all the other features it brings. If I give poor marks to amplifiers like this, where does that leave amplifiers with SINAD of 55 and lots of noise and other issues?

Members are free to ignore my subjective assessment and vote in the poll. That is there to avoid people complaining about my criteria for evaluation.

 

[amirm]

I sure would have liked to see how the Douk would have performed at this test:

View attachment 278348

I will see if I can run it before I ship it. I got stuck with the loadbox issues which cost me an entire evening to troubleshoot, forgetting to run this test....