What's causing the sound difference between two class D amps.

[LifeCapsule]

Y

I read the OP differently, PFFB is not likely the culprit.

He describes "shallow sounds in the mids" and later that his tone controls do not impact it because he has no midrange tone control. PFFB, even in worst cases, impacts frequencies from 10kHz (just barely) to 15kHz (perhaps 1dB) to 20kHz (quite a bit, potentially). All of these frequencies are well above not just midrange, but any music fundamentals at all.

If you have great young ears it may show up as a slight increase or decrease in "air". Frankly, I have yet to learn of any blind test that proves you can hear it at all. If course, of you read about how awesome PFFB is, you will hear it. I think something else is going on here.

since my primary language isn't English pardon my mistakes in term of Grammer ...
You know it's pretty simple , I like a warm sound a wide clear bass controlled sound , which according to AI most normal ab class or A class amps can provide without having to pay high prices, basically I call this kind of sound a natural normal sound it's good for listening to music , movies , games , etc...
What I hear in m139 is unnatural
If I got it right the problem is shallow mids like you figured. It sounds like tin can I even flipped polarities and I changed and tested different voltages, speakers , subwoofers and cords even changed input Audio source and different 3.5mm jack with Shields.. Since I don't really know about the terms I describe it like this , as a song playes it sounds like doobs dabs doobs dabs the dabs part is shallow idk if it's called mid or not honestly

 

[Salt]

Perhaps your former sound reproduction system gave you the distortions that you like, and now they are missing ...

 

[solderdude]

I flipped polarities before I saw no difference ... Like you and many other people said it's because the whole thing is crap !

You should only flip the polarity of 1 speaker.
Then sit in the middle of the 2 speakers and hear how the bass sounds compared to how it sounds with both speakers in correct polarity.

When all is O.K. bass should be louder and in the center, when polarity is flipped bass will sound lower and mids have a 'weird' sound.
In case this is the other way around (so bassier and correct imaging) with just 1 speaker polarity flipped then the labeling on the amp is incorrect.

This would be the only reason for bass and mids to sound 'weird'.
The poor choice of inductors should only affect how warm the inductors get, should not affect the sound.

 

[dfuller]

You know it's pretty simple , I like a warm sound a wide clear bass controlled sound , which according to AI most normal ab class or A class amps can provide without having to pay high prices

Found your problem. You're trusting a chatbot.

 

[WerT]

amplification has been solved since hypex and very very solved since purifi

stop wasting time them or dacs and focus on the room and speakers it's much simpler.

 

[dfuller]

amplification has been solved since hypex and very very solved since purifi

stop wasting time them or dacs and focus on the room and speakers it's much simpler.

It's been a non problem since the Bryston 4B, an amp that came out in the early 90s.

 

[Chrispy]

What a strange proposition/assumption. Nonsense it seems.

 

[LifeCapsule]

Perhaps your former sound reproduction system gave you the distortions that you like, and now they are missing ...

Lol maybe ... Idk

 

[LifeCapsule]

You should only flip the polarity of 1 speaker.
Then sit in the middle of the 2 speakers and hear how the bass sounds compared to how it sounds with both speakers in correct polarity.

When all is O.K. bass should be louder and in the center, when polarity is flipped bass will sound lower and mids have a 'weird' sound.
In case this is the other way around (so bassier and correct imaging) with just 1 speaker polarity flipped then the labeling on the amp is incorrect.

This would be the only reason for bass and mids to sound 'weird'.
The poor choice of inductors should only affect how warm the inductors get, should not affect the sound.

Ty I'll try it when I get my next module

 

[LifeCapsule]

Found your problem. You're trusting a chatbot.

Yep I've learned it the hard way ... Never trust AI

 

[LifeCapsule]

I have an amplifier here based on two really cheap TPA3118 boards and they sound more than fine. Sure they are load dependent (which can be fixed with EQ) and don't have tons of power, but I've been using them for years for various applications and I've had no problems with them. For around 5 euro each the bang for buck ratio is really just up the roof!

Hmmm nice but you might wanna try these songs on it

Filebin | s0jpemjqao1om8cb

Convenient file sharing. Registration is not required. Large files are supported.

filebin.net

lemme know what you'll hear IN TERMS OF doobs dabs the dabs part what is it like to your ears ... Does it sounding shallow or warm clean and bassy ? If possible please record the output sound with your phone and upload it to a link just like what I did if you are willing to ofc

My speakers are fine I changed couple of them I had 5 pair completely healthy speakers and 5 subwoofers all of them were fine untill getting connected to the amp board I said here
Please lemme know what you'll hear with these files played on your TPA3118 module , BTW it would be nice if you could send a picture of your board because the IC isn't the main issue I guess like people said here it might be low quality of other components on the board or the board itself

 

[Chrispy]

Hmmm nice but you might wanna try these songs on it

Filebin | s0jpemjqao1om8cb

Convenient file sharing. Registration is not required. Large files are supported.

filebin.net

lemme know what you'll hear IN TERMS OF doobs dabs the dabs part what is it like to your ears ... Does it sounding shallow or warm clean and bassy ? If possible please record the output sound with your phone and upload it to a link just like what I did if you are willing to ofc

My speakers are fine I changed couple of them I had 5 pair completely healthy speakers and 5 subwoofers all of them were fine untill getting connected to the amp board I said here
Please lemme know what you'll hear with these files played on your TPA3118 module , BTW it would be nice if you could send a picture of your board because the IC isn't the main issue I guess like people said here it might be low quality of other components on the board or the board itself

So much frequency response variance seems to point at some incompetence....

 

[LifeCapsule]

So much frequency response variance seems to point at some incompetence....

English is not my primary language...Could you elaborate? You mean my speakers are bad ? That's why I'm hearing sounds like this ? Or the board itself is faulty? Bc same speakers worked just fine with another amp

 

[solderdude]

You probably still have other amplifiers around.
Sounds good on those as you said.

If so connect that good sounding amp... listen... then flip the polarity of 1 of your speakers and listen if the 'effect' is similar to what you got.

What you describe sounds like 1 speaker being flipped in polarity.

Amplifiers, even crappy ones, should (could) not have a 'sound' that you describe.
Feedback regarding the XH-m139 does not show issues with sound quality nor suggest there is a polarity issue though.
This begs the question... did you wire the speakers correctly ?

 

[LifeCapsule]

You probably still have other amplifiers around.
Sounds good on those as you said.

If so connect that good sounding amp... listen... then flip the polarity of 1 of your speakers and listen if the 'effect' is similar to what you got.

What you describe sounds like 1 speaker being flipped in polarity.

Amplifiers, even crappy ones, should (could) not have a 'sound' that you describe.
Feedback regarding the XH-m139 does not show issues with sound quality nor suggest there is a polarity issue though.
This begs the question... did you wire the speakers correctly ?

View attachment 540998

Brother it's not so hard to connect + to + and - to - it's easy ... As you said I flipped polarities. I done that but still the same output appeared , the problem lies in the board itself it has some issues... Listen to this this is before I returned the product ...

Filebin | egdobbf1akx7i4pz

Convenient file sharing. Registration is not required. Large files are supported.

filebin.net

 

[LesterHiggins]

Yes

 

[LesterHiggins]

Wait, sorry, I meant No

 

[LifeCapsule]

Wait, sorry, I meant No

Lol

 

[LesterHiggins]

Yep I've learned it the hard way ... Never trust AI

ChatGPT once advised me to use the underside of my desk as the safety containment for 120V AC terminals on a DC power supply and distribution block - it probably would not have started a fire or killed me, as long as I didn't touch it. Probably.

 

[Multicore]

Brother it's not so hard to connect + to + and - to - it's easy ... As you said I flipped polarities.

According to Murphy's law, if it can be done wrong it will be.

Indeed it happened to me last week. I finally yielded to the pressure and upgraded the old Quadro P400 in my office computer. The new card requires its own power so I went to my collection of ancient power cables and found what I needed. Looked at the manual for the PSU and the new card, plugged in the cable. The PC didn't turn on. Eventually I figured to try the same cable the other way around and it was fine. I've never used such a cable before and the cable directionality wasn't indicated in the docs and I didn't take the hint about the double connector end until after trying it the wrong way first.

Murphy's law isn't like Sod's law, which is simply invoked on occasion of an unlucky outcome to make you feel better about it. Murphy's law is there to remind us engineers to not rely on people to read the instructions, understand them and get it right. Hence the design of connectors and cables that cannot be used the wrong way is rather a good idea.

Thankfully my PSU is protected against such a misuse. But it would have been better to design cables with connectors that don't allow this though. Murphy's law.

Sorry to go OT but I figured a discussion of the engineering implications of Murphy's law is more interesting than yet another do-all-class-d-amps-lack-pace-and-timing contribution.