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WiiM Amp Streaming Amplifier Review
- Thread starter amirm
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Someone who posts once, and is never seen again?
I'm tempted to say 'hopefully'.
Sonicsound
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Sure my dear expert compatriot , why are you focusing so much in distortion and noise ?
What do you think about about brands that claim transient response is important ? like Focal , Kartesian ( French woofer manufacturer , says that transient response is the most important factor for speaker ) , PSI audio CH brand ( "superior transient behaviours" ... ) ... and the same thing for some amplifier brands ...
I'm not here to "troll" people , but I don't really understand why people on this forum ( and all of forums ... ) do not take into consideration this point which seems major to me in the reproduction of sound ...
staticV3
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Link some actual data, peer-reviewed papers, etc and then we can discuss.
Random claims are not worth discussing. Neither yours, nor those from brands trying to sell you their stuff.
Anything worthwhile is worth publishing. Anything that's not published is likely a waste of time, and will be forgotten before long.
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Sonicsound
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Ok sure , you have the youtube channel Kartesian that I think do a great job to explain woofer behavior :
If you need better translation I can work on this....
Transient reproduction in amplifiers has been discussed on ASR, but mostly in that it is not an issue with any well designed amplifier as long as it has sufficient power and has a frequency response as wide as necessary to reproduce the human hearing range. Amps are not slow, woofers might be. If you know an amps power and its frequency response you can tell if it can handle transients.
See this from our Central Scrutinizer.
I think that they are right. But as you say, these are drivers manufacturers. This topic is about an amplifier. What standards do actually exist to measure transient response, regarding analysis of electronics (Amps, DACs and so on) ? I do not know one from either AES, CEA, IEC or AP.
morillon
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Measuring Slew Rate or Rise Time
Learn to measure slew rate and rise time in amplifier testing in the APx software, their impact on performance, and tools required for testing and analysis.
Sonicsound
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Well I totaly agree with you ... there are no "standards" ( at all ) that 's the main problem...
antcollinet
Grand Contributor
Transient response and frequency (+phase) response are effectively the same thing. One can be derived from the other, and vice versa.
How about you answering a question: What does a real musical transient look like. What instrument produces the most transient like signal, and what does that look like in the time domain?
Sokel
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There is some really good info and charts about attack transients (sound onsets), rapid decay transients (sound offsets), fast transitions (portamentos) and noise/chaotic regimes in this paper:
IndieSynth
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I'm tempted by this for my TV 2.0 system now that it's down to £270. But should I wait for the new version? The main upgrade seems to be flat frequency response. Compared to the original I'm surely not going to notice the difference...am I?
Depends of your speakers. And if you know their impedance curve...
This is what I measured for ON-mag.fr
This FR is done with 24b/88.2kHz signal & within 10Hz to 44.1kHz.
The Speaker Load is a real charge, with Focal Chora 806s plugged (both speakers, and FR averaged), that do have this impedance curve, according to SoundStage:
SoundStageNetwork.com | SoundStage.com - NRC Measurements: Focal Chora 806 Loudspeakers
You better avoid speakers that end at 10Ω or higher at 20kHz. And ideally above 4Ω, to get a reasonably flat FR. Pro version should be flatter under all charges, but that remains to be measured.
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IndieSynth
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Thanks for the info. My speakers are Diamond 12.2. I can't find an impedance curve on Google, just that they are nominal 8, minimum 4. If anyone knows more on those speakers I'd appreciate it.
JeremyFife
Major Contributor
Can't safely interpret this for you (still learning), but someone can: https://www.alpha-audio.net/review/review-wharfedale-diamond-12-2-bright-like-a-diamond-en/4/
IndieSynth
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Thanks. Can anyone interpret these graphs for me? I get the distortion criticism but I can't figure out if this shows the speakers would be affected by the Wiim Amp's frequency variance.
The impedance stays below 8 Ω above 2k, so you should be OK. Even lower would have been ideal, but no big deal.
JeremyFife
Major Contributor
My view ... open to interpretation from those more experienced and referencing @VintageFlanker 's post #953 (avoid speakers that end at 10Ω or higher at 20kHz. And ideally above 4Ω) ... your speakers look ok: impedance at 15-20khz is around 7.5Ω and they don't dip below 3.6/3.7 (reading by eye). No significant issues, related to impedance.
somebodyelse
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Short version: I don't think it's anything to worry about, and if you are worried the Wiim has PEQ to fix it.
At 20kHz it's ~8R which will give ~1dB boost. If I remember the dummy load responses correctly the 15R peak at 1k will probably give a slight boost too, but I think <0.5dB. These might just be audible compared to a flat, load independent amp, but aren't huge - left and right speakers may have bigger differences. Also these boosts are at frequencies where the speakers have dips, so if anything they probably help rather than hurt.
Measurements from @John Atkinson are now online at Stereophile:
www.stereophile.com
www.stereophile.com
WiiM Amp streaming D/A integrated amplifier Measurements Page 1
Sidebar 3: Measurements I performed a complete set of measurements on the WiiM Amp with my Audio Precision SYS2722 system. Before I did so, I installed the WiiM Home app on my iPad mini and connected the amplifier to my network with a CAT-5 Ethernet cable. The app (version 2.9.5.24041612)...
www.stereophile.com
WiiM Amp streaming D/A integrated amplifier Measurements Page 2
Fig.13 WiiM Amp, optical input, impulse response (one sample at 0dBFS, 44.1kHz sampling, 4ms time window).
www.stereophile.com
Assuming that Alpha Audio measurements are correct, then yes, it should be most likely fine.
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