Why are you doing this, what is your point/goal? I understand you are an experienced engineer, yet making a border-line religious faith statement.Band aid to poor design, which works suboptimally.
And this is the frequency response at amp speaker output
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I am afraid that this behaviour will be similar for many class D amp with the LC filter out of feedback loop. And the frequency response will be unpredictable and depend on speaker used. So is the sound.
Considering that person was complaining about a 1 db or less rise over half the freq response graph on a 60 dollar amp, i would say dont worry about it too much until more people with different rigs measure it. or something sounds bad. dummy loads and trash JBL speakers dont really make me concerned about real life sound from a cheap amp that is very clean and powerful for the price. the more resolution you measure something with the more edges you will find. there is a point where you have to be practical and either respect something for what it can do or be anal and forever find something wrong with everything until you have a microscope looking at smudges on the PCB and calling it "Band aid to poor design, which works suboptimally."
Sure, but the main point here should be that he spent the time to do the measurements and highlighted them. The results with the cheap speakers were illuminating to me as a lay person.
Sure, i appreciate the measurements and the heads up but its hard to say at least for me who isnt an expert, i cannot find a speaker that looks as harsh at 5k as the dummy load he used. the impedance drop from 32 to 6 and back is quite sharp and maybe the amp cant handle that at the higher freq. most speakers swingin the lower freq where box and port make big difference and slowly rise at the 5k mark if at all, like i said would need more tests with more actual speakers, it could be a huge problem but im not seeing it as of now.
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Klipsh speaker-![]()
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The tpa3255 with PFFB will probably be much better regarding frequency response at 10-20 KHz , with different loudspeakers?Band aid to poor design, which works suboptimally.
If you look at TI's general output filter design doc (SLAA701A) sections 3.4 through 3.6 give worked examples of some output filters, showing how changing the resistive load affects the frequency response near cutoff by changing the Q of the filter. This will happen for all amps using such a filter unless there's some form of compensation such as post-filter feedback to bring it back into line. Some Class D amps have this - see for example the Hypex modules where there's little difference in frequency response plots for 4R, 8R and open circuit - but I don't think it's common at this price range.How do I reconcile @pma 's FR measurements with Amir's (linked below)? I can see there's a difference in the unit used in the 2 charts, as well as a difference in the load presented, but my technical knowledge ends there. What are the likely real world implications?
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Now that the Aiyima amp supply has tightened up, I should probably put an ad on ASR to sell two now, “broken in” Class D Aiyima amps, powered by natural, organic hydro-generated AC - no nuclear power for these amps -and connected with pure copper, oxygen free cables only to Andrew Jones Elac speakers (nothing but the best for my amps) for something like $500 per unit, shipped, but something tells me on ASR, that dog won’t hunt.
I guess I‘ll just add them to my growing collection of favorite Class amps du jour!
Have similar tube pre badged with a different name and I like the way it works with my 3116 D2...no pop on turn on and no hissyes i have the same type of tube pre amp that i love. its the suca audio T1 tube buffer. ive seen some measurements from it and they actually dont mess with the signal in any bad way and do add some sound differences without ruining it. highly recommended and i will never unplug it unless i have super sensitive IEMs where the hum is slightly noticeable at high volume . would love an ASR review of those as well they all have the same board. it really does in an AB test change the sound even with different tubes, the tubes are run at close to 240 volts so its not just "fake" i hate to use the word "creamy" but its what comes to mind and its 100% A/B able no questions, whether its chinese magic or not its repeatable. To keep this on topic i cant wait to try it with these class D amps to see if i can create a little more fun even if its just an EQ.
@guddu
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You're not the first one who preferred the A04. I think daniboun did to and some others. They do chime on the older "black board edition" being a better build than the current one.I must say, I think the A04 sounds even better than the A07 powering the Elacs which are 4R.
Lol... I had a look at Amazon and they all look similar.Have similar tube pre badged with a different name and I like the way it works with my 3116 D2...no pop on turn on and no hiss