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

[Perichoresis]

Hello, I've read the forum for awhile but this is my first post. I was hoping to get some help troubleshooting. I believe that there likely shouldn't be large audible difference between the two class D amps. That said, I am hearing a distinct difference between two setups and I'd like help narrowing down what is most likely causing the difference. The two signal paths are below:

Computer > Aiyima t9 via usb > Kef Q150's

Computer > Aiyima T9 via USB > aux out to Douk a5 > Kef Q150.

The first signal path has a clearer high end and sounds more open in general. The second signal path is stronger in the mids but overal sounds a like there's a cloth in front of the speakers. Also the highs seem attenutated. I am assuming it's not the amps themselves casuing the difference in sound since they're both class D and similar enough that I doubt it's casuing a differnece. Is it possible that the 3.5m to RCA cable or the T9's auxiliary out are somehow attenuating the highs? Any thoughts would very helpful. Thank you.

 

[antcollinet]

The t9 has tubes in it (I assume that is for the preamp part)

God knows what they are doing to the sound quality - and we have no idea what signal the aux out is based on. That could also be haveing an impact.

Without measurements it is impossible to say what is causing your perceptions - even if it is based on real sound differences, and not your (humanities) perceptive biases.


PS - welcome to the forum.

 

[kyuu]

That Aiyama is an unknown quantity, but given what it is I would say it's highly likely that its frequency response is load dependent. On the other hand, we know that the Douk A5 is pretty much load independent. That by itself could result in audible differences. Then of course who knows what the hell those tubes are doing to the sound.

My advice would be to get rid of the Aiyama T9 and use something reasonable.

 

[amadeogt]

The Douk A5 has PFFB (post filter feedback), which makes it load-insensitive. It should deliver a flat response.

The Aiyima T9, as far as I know, does not have PFFB - so its frequency response might change (reinforcing the treble, for instance) according to your speakers' impedance curve.

This is a known issue with class D amps. PFFB fixes it.

 

[kemmler3D]

On the other hand, we know that the Douk A5 is pretty much load independent. That by itself could result in audible differences. Then of course who knows what the hell those tubes are doing to the sound.

Yep this, load dependence in these Class D amps can lead to a few dB change in frequency response:

The big impedance peak in the lower treble on the Q150 might correspond to something you're hearing between the two amps.

The tubes might have something to do with it too, but that would tend to be more subtle than load dependence in this case.

Welcome to ASR!

 

[Perichoresis]

Thank you for for the warm welcome and the responses.

The load dependance of the Aiyima in conjunction with the Kef's impedance curve causing the difference makes a lot of sense. I don't know if it's supposed to correlate exatly but the line indicating the magnetiude of the Kef's impedance curve represents almost exactly what I'm hearing with the Aiyima. Pronounced highs, slightly hollow mids, strong low end. Which I'm percieving as being less vieled in relation to the Douk. So there may not be anything problematic that needs to be solved. It may just be that I've gotten use to a bit of a V curve response.

I also see how the T9's pre-amp section with the tubes causes some unknown factors. I don't think the tubes are actually being used as a real tube preamp in the T9. It's more likely they are being used as a buffer. Regardless, I don't really know what's going on in the pre-amp of the T9. I ordered a Topping E30 ii lite to use as a DAC/Pre-amp rather than the T9. I'll be interested to see if that changes anything.

 

[LifeCapsule]

hey guys i had a question .... does all D class amps sound shallow in mids? my speakers and subwoofer are fine .... i tried xh-m139 and it made me wanna go back to ab class amps since it sounds unnatural and robotic like a cold soulless sound i guess ... the ab class amps sound much more natural and warmer .. is there a way to make the output sound more warm with D class amps like xh-m139 ؟ i tried using it but TBH its kinda harsh to my ears .. esp in games like valorant and marvel rivals the sound diff is much more noticeable .. like the ab class is wide and warm the D class is like cold shallow and kinda harsh to hear . what you guys suggest ? is there a way to make them more like ab class amps ? like if i buy this module (((((XY-s100h ))))it would sound like xh-m139 or its better and warmer ? can it be modified to be warmer ?

 

[LifeCapsule]

with my class D amp the sounds are like doobs dabs the dabs part is shallow if you know what i mean by that ... its like its not wide sound its kinda feels like coming from a Tin Can its so flat .. it feels harsh to ears .. i changed speakers couple times i changed +_ to see if that makes a diff but no i found out it might be my board peoblem or maybe its the sound signature on Class D amps i really dont know thats why im asking

 

[melomane13]

"All properly designed amplifiers, operated within their capabilities, show no audible differences."

 

[kemmler3D]

There's probably something wrong with your specific amp module if there's an obvious difference in sound. Check polarity / connections first, bad connections or reversed polarity can make the mids sound thin / hollow.

(For anyone not bothering to Google the xh-m139 is a ~$6 amp module. )

In general a decent class D amp sounds exactly the same as any other decent amp.

Welcome to ASR by the way!

 

[MaxwellsEq]

hey guys i had a question .... does all D class amps sound shallow in mids? my speakers and subwoofer are fine .... i tried xh-m139 and it made me wanna go back to ab class amps since it sounds unnatural and robotic like a cold soulless sound i guess ... the ab class amps sound much more natural and warmer .. is there a way to make the output sound more warm with D class amps like xh-m139 ؟ i tried using it but TBH its kinda harsh to my ears .. esp in games like valorant and marvel rivals the sound diff is much more noticeable .. like the ab class is wide and warm the D class is like cold shallow and kinda harsh to hear . what you guys suggest ? is there a way to make them more like ab class amps ? like if i buy this module (((((XY-s100h ))))it would sound like xh-m139 or its better and warmer ? can it be modified to be warmer ?

Welcome to ASR

Don't expect any $10 amplifier to sound any good driving worthwhile speakers. The point at which you may luck into something worth owning is closer to $100 than it is to $1.

 

[pjug]

This inexpensive amplifier probably does not have post-filter feedback (PFFB). There is a lot on this forum about that, but in Class D without PFFB you can get peaks at high frequencies with some speakers that might cause the tinny sound you describe.

 

[MAB]

That module has tone controls in various configurations. Are they flat? My version doesn't even have detents for the center flat position so hard to get them flat, and they are quite sensitive. For sure they include some other wonky stuff on various versions (I think even have stereo blend control).
Likely you haven't measured the output, but the tone controls can be used to flatten or make the midrange recessed.

To your question, no Class D amps in general don't have a unique sound. Amps in general don't have a sound. Some amps like these cheap ones will have a sound, in this case likely from tone controls, also possibly from the amp's intrinsic performance.

I use one for a DIY boombox, it is a fine-sounding boombox built into a suitcase. The tone controls help, and TBH the amp does a fine job considering how cheap it is. I would test it, but for what I paid not really worth the time.

 

[LifeCapsule]

This inexpensive amplifier probably does not have post-filter feedback (PFFB). There is a lot on this forum about that, but in Class D without PFFB you can get peaks at high frequencies with some speakers that might cause the tinny sound you describe.

yepp thats it

 

[LifeCapsule]

Welcome to ASR

Don't expect any $10 amplifier to sound any good driving worthwhile speakers. The point at which you may luck into something worth owning is closer to $100 than it is to $1.

ty yeah in my country the montly wages are low so even this is expensive lol

 

[LifeCapsule]

Ty for all your responses guys
Like I said idk anything about Amps I just said what I experienced with that specific model ... That's all
Btw all people cannot afford expensive Amps
It depends where you were born and live.... Like in Iran monthly salary is 70 $ So no we cannot buy 500$ amps or more expensive ones

I really like it here since people aren't as toxic as reddit ... I asked the same question and got attacked ! They said it's clickbait !

 

[LifeCapsule]

That module has tone controls in various configurations. Are they flat? My version doesn't even have detents for the center flat position so hard to get them flat, and they are quite sensitive. For sure they include some other wonky stuff on various versions (I think even have stereo blend control).
Likely you haven't measured the output, but the tone controls can be used to flatten or make the midrange recessed.

To your question, no Class D amps in general don't have a unique sound. Amps in general don't have a sound. Some amps like these cheap ones will have a sound, in this case likely from tone controls, also possibly from the amp's intrinsic performance.

I use one for a DIY boombox, it is a fine-sounding boombox built into a suitcase. The tone controls help, and TBH the amp does a fine job considering how cheap it is. I would test it, but for what I paid not really worth the time.

Yep it has tone controls but they don't make a difference in mid-range TBH not that much difference, I tried every possible configuration to make it sound good and realized the problem is with the module itself , even my old noisy AC amplifier board sounded better than m139 garbage unlike that it gave me a warm and wide sound ...
About m139 you don't really notice it with songs but mostly while playing games like valorant in the training base when you shoot you can clearly hear the difference with the bass nub high I had flat shooting sound maybe the board was faulty idk really I will send back the board to the seller .. btw the inductors were getting hot while the board was idle
I couldn't to hold my hand more than 10 seconds on them
...

 

[MAB]

Ty for all your responses guys
Like I said idk anything about Amps I just said what I experienced with that specific model ... That's all
Btw all people cannot afford expensive Amps
It depends where you were born and live.... Like in Iran monthly salary is 70 $ So no we cannot buy 500$ amps or more expensive ones

I really like it here since people aren't as toxic as reddit ... I asked the same question and got attacked ! They said it's clickbait !

Yes, this is an important perspective. And I totally appreciate.

And even the tests I have suggested might seem financially insurmountable. That being said, if you have a computer with a soundcard that has both an output and a line-in, you can measure the basic performance of your amp. REW (Room Equalization Wizard) is free, and has a nice tutorial on how to do this.

Impedance Measurement

A member who also writes for AudioExpress also has a series of articles on how to do this, starting with a soundcard.

Practical Test & Measurement: Sound Cards for Data Acquisition in Audio Measurements

A great test and measurement article series by Stuart Yaniger, which started to be originally published in audioXpress, June 2015.

audioxpress.com

I made a measurement rig to test speaker impedance using the same method, and get better results than a DATs which cost 100 monies.

What do these symbols mean in this diagram for creating an impedance rig in REW?

I was thinking about building a rig for testing my speakers impedance (for funsies) since I have a couple sound cards just sitting around, but I am unfamiliar with what these ovals in the diagram below mean and can not find their equivalent in searching. Any help is appreciated!

www.audiosciencereview.com

It is very possible to measure your amp, if you have the card, even with a few spare parts. The only thing that might be hard is the load resistor, but even that can be hacked - people use water heater parts as load resistors.

How to Build a Dummy Load for Testing Large Amplifiers

In this article, Pat Brown from SynAudCon shares how he built a dummy load used for testing amplifiers.

www.prosoundtraining.com

Cheers and keep us posted if you need help.

 

[LifeCapsule]

Yes, this is an important perspective. And I totally appreciate.

And even the tests I have suggested might seem financially insurmountable. That being said, if you have a computer with a soundcard that has both an output and a line-in, you can measure the basic performance of your amp. REW (Room Equalization Wizard) is free, and has a nice tutorial on how to do this.

Impedance Measurement

A member who also writes for AudioExpress also has a series of articles on how to do this, starting with a soundcard.

Practical Test & Measurement: Sound Cards for Data Acquisition in Audio Measurements

A great test and measurement article series by Stuart Yaniger, which started to be originally published in audioXpress, June 2015.

audioxpress.com

I made a measurement rig to test speaker impedance using the same method, and get better results than a DATs which cost 100 monies.

What do these symbols mean in this diagram for creating an impedance rig in REW?

I was thinking about building a rig for testing my speakers impedance (for funsies) since I have a couple sound cards just sitting around, but I am unfamiliar with what these ovals in the diagram below mean and can not find their equivalent in searching. Any help is appreciated!

www.audiosciencereview.com

It is very possible to measure your amp, if you have the card, even with a few spare parts. The only thing that might be hard is the load resistor, but even that can be hacked - people use water heater parts as load resistors.

How to Build a Dummy Load for Testing Large Amplifiers

In this article, Pat Brown from SynAudCon shares how he built a dummy load used for testing amplifiers.

www.prosoundtraining.com

Cheers and keep us posted if you need help.

Ty I'll try this but I don't have a line in port for sound it's only output
Maybe I'll just give up on trying to get better sound.
There is a saying ... You get what you paid for And I got what I paid for
Some things aren't meant for some people... Like sound stuff isn't my thing I guess

 

[MaxwellsEq]

It depends where you were born and live.... Like in Iran monthly salary is 70 $ So no we cannot buy 500$ amps or more expensive ones

In your position, I would absolutely look for a good 2nd-hand receiver or Hi-Fi amplifier rather than buy very cheap and dubious products.

Class D and Class AB can sound equally great, but there are simply no real bargains as new products under $75+.

It might sound silly, but actually you would better off saving up rather than buying bad $10 product after bad $10 product all of which will disappoint. Much of the gear I have bought has lasted decades, making each piece cost the equivalent of much less than $5 a month ..