5th element
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High H3 in these amplifiers is usually related to poorly chosen output indicators or incorrectly chosen coupling caps. Read non C0G/NPO or electrolytic.
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Douk A5 Budget Stereo Amplifier Review
- Thread starter amirm
- Start date
Voted fine because it's a very well performing amp, with exceptional price-performance ratio. Highpass functionality is very nice and almost unique in this price range.
At the same time it's a good example of why I stay clear of these very cheap offerings. There's always a compromise or two. PFFB is nice but only ever a technical afterthought, and never perfect. External PSU is a hassle, and the device heating up in idle with a 48V one hints at inherent design problems.
Good for a super low budget. But in the meantime I'm gonna stick to the well tested formula of spending a few hundred instead, on a Hypex amp that is a long proven design and has none of these problems, while being cleaner and more powerful. Or any AB amp that measures well, from a reputable company for the same money.
If all you can spare is 100 moneys, this is perfectly fine. If you got a little more, look elsewhere.
At the same time it's a good example of why I stay clear of these very cheap offerings. There's always a compromise or two. PFFB is nice but only ever a technical afterthought, and never perfect. External PSU is a hassle, and the device heating up in idle with a 48V one hints at inherent design problems.
Good for a super low budget. But in the meantime I'm gonna stick to the well tested formula of spending a few hundred instead, on a Hypex amp that is a long proven design and has none of these problems, while being cleaner and more powerful. Or any AB amp that measures well, from a reputable company for the same money.
If all you can spare is 100 moneys, this is perfectly fine. If you got a little more, look elsewhere.
effj
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I trust (whatever that’s worth) that generally speaking, since I bought it from Douk’s store in AliExpress (not a different store there) that the product is legit and not a counterfeit or knockoff. That said, I checked the circuit board of my unit and saw that I have V1 instead of the V2 in Amir’s photos. So there might be some differences.
Not complaining, just sharing thoughts.
ok Glass lid is for opamp rolling. But use will depend on how frequently one changes them. I guess not too often. So instead of sticker holding the lid, slotted metal top cover with screws would have been better. Color changing leds inside will give no indication if amplifier is on or off. More traditional approach of power on light indicator on front plate would not hurt. DIP switches adds cost too. May be they want to be different from other versions and models. Another point is there have been discussions that any external light falling on led will generate noise depending on where leds are placed in circuit design.
ok Glass lid is for opamp rolling. But use will depend on how frequently one changes them. I guess not too often. So instead of sticker holding the lid, slotted metal top cover with screws would have been better. Color changing leds inside will give no indication if amplifier is on or off. More traditional approach of power on light indicator on front plate would not hurt. DIP switches adds cost too. May be they want to be different from other versions and models. Another point is there have been discussions that any external light falling on led will generate noise depending on where leds are placed in circuit design.
At least with class AB amps, it is said that those with copious higher orders sound unpleasant. Let's not forget that you can also have a 100 Hz signal where the higher orders would be very audible.
What I showed was more like a trend and not a clear cut difference. There are so many variables that could be different between these amps (preamp stage, coupling caps, power supply buffering, PCB layout, quality of output coils, PFFB implementation, quality of resistors in the feedback path. Those IMD plots or the THD+N(P) at 15 kHz are really more telling than the 1 kHz HD. And again, in most cases you will have 100 Hz and several kHz intermodulating which can give rise to very audible distortion products.
JSmith
Master Contributor
JSmith
Hey J, you have a V2. Mine is a V1. I wonder what changed?
haskellcurrying
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Not a bad piece of kit! 'Would love to see a balanced input version. The built in high pass is something I've been looking for in an amp; the A5 seems like a real no brainier.
@amirmReserved for @AdamG to kindly post the specs.
Manufacturer Specifications:
View attachment 435591
Link to product details webpage:
Douk Audio A5 TPA3255 Stereo Amp HiFi Audio Class D Amplifier High-pass Filter
Features HiFi Sound with Adjustable High-Pass Filter: This TPA3255 amplifier features an adjustable high-pass filter (HPF) 30-200Hz to refine mid-high frequencies while minimizing low-frequency interference. Perfect for bookshelf or passive speakers, it enhances clarity and creates a dynamic...doukaudio.com
Two questions...
1) In your YT review, you said you didn't recommend rolling the op amps? Why not?
(What does it do to your measurements? )
2) You tested this w 32v/5a and not the larger 48v/5a or 48v/10a. I get that w the larger power brick... more heat will be generated if you push this amp... and I suspect that you could burn it out... That said... I still have to ask... if you got the larger brick... how would that effect your tests?
And of course I just thought of another question...
You mentioned that the amp had some distortion issues... ok... but of the Chinese made class D amps that you've tested... what about its competitors... do they suffer from the same issues?
Thx
Last edited by a moderator:
JSmith
Master Contributor
It's either pointless or potentially detrimental, see this thread for more discussion;
Serious Question: How can Op Amp rolling improve the sound of an already well measuring device? Are that many confused? (Master Thread)
On OP-Amps and Op-amp rolling Another contentious topic. Manufacturers of DACs and Amps often socket op-amps to allow people to swap them with different types, with the aim of improving the sound - or getting a different “sound signature” (Whatever that might mean to you). We get it. It’s...
www.audiosciencereview.com
Further, please don't use that term here, thanks;
Let's Avoid the Term Chi-Fi
I often see the use of the term "Chi Fi" to describe audio products from China. I see the intention and don't think anyone is trying to be racist and what have you. Still, I like us to show the highest respect to products from around the world. As avid readers of this forum know...
www.audiosciencereview.com
JSmith
OP
- Thread Starter
- #131
Higher voltage would increase power for > 5 ohm (e.g. 8). Since vast majority of speakers are 4 ohms or lower, higher voltage won't do you much good, yet it will increase power consumption. Higher current would produce more power for < 5 ohm. So ideally you would stay with 32 volt but higher current. Either way, it will produce more power until thermal shut down occurs, or it gets damaged.
Ok... so how do you classify the low end, cost effective class D amps manufactured in China?It's either pointless or potentially detrimental, see this thread for more discussion;
Changing opamps is not the way to tailor ones sound.Serious Question: How can Op Amp rolling improve the sound of an already well measuring device? Are that many confused? (Master Thread)
On OP-Amps and Op-amp rolling Another contentious topic. Manufacturers of DACs and Amps often socket op-amps to allow people to swap them with different types, with the aim of improving the sound - or getting a different “sound signature” (Whatever that might mean to you). We get it. It’s...
Further, please don't use that term here, thanks;
Let's Avoid the Term Chi-Fi
I often see the use of the term "Chi Fi" to describe audio products from China. I see the intention and don't think anyone is trying to be racist and what have you. Still, I like us to show the highest respect to products from around the world. As avid readers of this forum know...
JSmith
Keep in mind that there's also a set of A, A/B manufacturing of older Amp designs based on more expensive / famous amps?
But more to the point.
I scanned the links you sent.
What sound tracks were used? I mean it seemed that the tests focused on noise or tone generation at specific frequencies?
(He did say that one audiophile could tell when using a piece of music he selected.) Note: It could be that there were listening tests and then measurements.
And then here's another conundrum. ABX testing comparing two sets of op amps.... if you use a single amp... you will have a time delay between listening.
Then there's if you use two different amps... you'll get accused of there being a difference in the amps themselves. (So its a no win situation unless you do a test to show that the amps measure almost the same (indistinguishable) and then you do 2 sets where you run the op-amps in one then the other...
And here's the other kicker. When you listen to the reviewers talk about things like 'presence', 'depth', sound stage, etc ... how do you capture this in measurements?
Or how tubes give more warmth, and color the music over clinical class D that do not 'color' the music?
Its not that I don't believe that there's something wrong w the measurements that were taken but that that there's a disconnect. Are you saying that every person who has talked about sound stage is imaging it?
Note: Bruno Putzi recommended upgrading the op-amp on one of his boards. I can't remember who he told and which board, IIRC it was his Purifi stuff.
Now he wasn't talking about rolling op amps, just upgrading the OPA he used to a Sparkos (which is a specific recommendation.)
And keep in mind that there are cost considerations when designing and building hardware. So a vendor may choose component A because of price, while component B may be a better one.
Gotcha, so then there's no difference in your test results.Higher voltage would increase power for > 5 ohm (e.g. 8). Since vast majority of speakers are 4 ohms or lower, higher voltage won't do you much good, yet it will increase power consumption. Higher current would produce more power for < 5 ohm. So ideally you would stay with 32 volt but higher current. Either way, it will produce more power until thermal shut down occurs, or it gets damaged.
(I didn't see a 32v/10A option.)
I think the price difference is ~$12.00 USD between the 32v/5A and the 48v/10. (Although that may be a different Amp you reviewed... still same power brick options)
As to the amp swapping, I have a set of Burson 5i's and was going to see after burn in of both op-amps... if there was a noticeable difference. If you look at the higher end options, you'll end up spending 2x the cost of the amplifier on op-amps. (A pair of Burson V7s (single) is more than this amp costs. ) This then begs the question of if its actually worth it or just buy a better amp to start?
And that's the thing. Amp ~$75.00. Op-amp upgrade (single v7 pair $110. Duals $170.) So for $250.00 ... can you get a better amp than getting the Douk and upgrading the op-amps? (Assuming you can hear the difference in sound?)
In looking at some of the posts on one of the threads...It's either pointless or potentially detrimental, see this thread for more discussion;
Changing opamps is not the way to tailor ones sound.Serious Question: How can Op Amp rolling improve the sound of an already well measuring device? Are that many confused? (Master Thread)
On OP-Amps and Op-amp rolling Another contentious topic. Manufacturers of DACs and Amps often socket op-amps to allow people to swap them with different types, with the aim of improving the sound - or getting a different “sound signature” (Whatever that might mean to you). We get it. It’s...
JSmith
In this post on the thread, Fran (The poster who did the testing) showed two different op amps and you could see the differences in the graphs.
He even admitted that w different music, the differences could possibly heard.
Again, I haven't tried it. But w so many different people talking about the sonic differences between op-amps... its hard to say if its all imaginary.
Note: I haven't tried it... and I suspect YMMV depending on starting amp. (OPAxxx) and then the upgrade you make. Burson, Sparkos, etc ...
Fosi Audio V3 op-amp rolling, has anyone tried it? Snake oil? Or are there actual differences?
To throw in something here that might muddle the discussion, consider "blind sight" research in neuroscience. There are people who, due to specific damage to the visual cortex, have areas of vision on which they cannot consciously report. Yet they are able to respond to stimuli in those areas...
audiosciencereview.com
theREALdotnet
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You've been saying this quite a lot, and I'm curious about it, since it doesn't mesh with what I'm seeing. I think 8 and 6 ohm speakers are as common, if not more. I don't have any statistics on this, does anyone? ChatGPT thinks that 8 ohm is the most common:
I know that the last three or so AVR models I owned required 6 ohm or above.
There will definitely be a difference with a different power supply. See below from the Douk website. The biggest difference is going to be the amount of heat generated. While the power gains look impressive on paper you need to double power to get 3 dB more SPL. The fact that the company sent in a 32 Volt supply should tell you something. When buying an amp engineered to save every possible penny in general it is not a good idea to push them hard. Use them as designed and enjoy them for what they are.
Sorry, Let me rephrase.
I meant that if Amir ran his tests using the 48v/10A vs the 32v/5A his results should match. (In terms of noise, distortion, etc...)
Obviously more power means more wpc output.
OP
- Thread Starter
- #138
ChatGPT hasn't measured 300 speakers. I have. And I note the real, minimum bass impedance. That number almost never, ever matches the specs manufacturers publish. Their numbers are essentially random is best ignored since no speaker has constant impedance anyway. Here is one of many examples:
Company spec is 8 ohm.
OP
- Thread Starter
- #139
That is also a bogus setting. UL testing has limit on maximum heat generated during a special test. These multi-channel AVRs get too hot with 4 ohm in that test, even though they are fully capable of going down to that impedance. To wit, every AVR I have tested has had no problem producing power at 4 ohm. Indeed that is the main impedance for most of my tests. If there is a setting for 4 ohm, be sure to NEVER set it to that as the AVR will then limit its power output as to not risk failing UL test.
I would definitely try it but if you do make sure to do it right which as you say means you will need 2 amps in order to do fast switching. The most important part is level matching with a sine wave and a volt-meter (not by ear). You also need to set up a way to switch back and forth quickly and an assistant that can do the switching without any "tells" to help you figure out which is which. If you do it like this I am pretty sure your audio life will be changed forever and you will realize most things you read on the internet are not true. It is not that people are liars or imagining thing it is called "bias" and all humans no matter how rational are affected by it. The only way to know for sure is to test blind and level matched.
If you don't want to go to the trouble (again I would highly recommended it as it will save you untold amount of money over your lifetime) then I will share my experience which is swapping op amps is not a cost effective way to improve an amp. Different op-amps have different electrical requirements and just because they fit in the same socket does not mean that they will work optimally. Also there is little if any correlation between cost and audio quality, usually the more expensive op-amps are run in lower quantities for a specific application and some are just overpriced snake oil. If you are going to test I would recommend you try some TL072 which only cost pennies and you may be very surprised.
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