WiiM Amp Streaming Amplifier Review

[JSmith]

The only wish is post output filter feedback to eliminate low dependency of the frequency response.

For sure, however good to see this device tested on your AP, not too bad measurements wise and great functionality. At least that load dependency is not as pronounced.

The guts;

JSmith

 

[Deleted member 48726]

This is a link where you can see the Wiim amp with real loads and how it influences the response according to load-->

Complex impedance load amp FR influence - WiiM Amp review by Erin

Was pleasantly surprised today when I read the review of the WiiM Amp on Erin's website. Erin will be using two complex impedance profiles in all of his amplifier reviews in the future to measure their impact on the frequency response of the tested amplifiers. My only criticism is that the...

www.audiosciencereview.com

 

[HarmonicTHD]

Yes great features and good price. Load dependent FR (and okish SINAD at only 20.5dB) is a „poor“ for me.

I am surprised it got a „recommended“ as that doesn’t seem consistent with other reviews.

 

[Deleted member 48726]

Yes great features and good price. Load dependent FR (and okish SINAD at only 20.5dB) is a „poor“ for me.

I am surprised it got a „recommended“ as that doesn’t seem consistent with other reviews.

PFFB should really be mandatory where we are now with class D and chip amp performance as this has real world consequences. The THD+N seem like is sorted out by a huge margin with these.

 

[amirm]

I am surprised it got a „recommended“ as that doesn’t seem consistent with other reviews.

I have recommended a bunch of other class D amps from AIYIMA to Fosi with similar performance.

 

[voodooless]

PFFB should really be mandatory

It can’t be the component cost involved: it’s a handful of cheap parts. It’s also not rocket science to implement. I think there are some patents preventing the implementation of this feature. Like this one from Texas Instruments:

US10110181B2 - Class-D amplifier with post filter feedback loop - Google Patents

A fixed frequency class-D audio amplifier includes the L-C output filter in a high order feedback loop. An audio amplifier integrated circuit includes an output driver, an output terminal, a first input terminal, a second order filter, and a summing amplifier. The output driver is configured to...

patents.google.com

If so, we’ll have to wait until 2037 or until someone finds another way. It’s interesting that TI would hog the patent, since it’s mostly their chips used in these kind of amps. They could easily make the patent free to use around their own products and create more demand by doing so.

So if covered by patents, it brings up another controversial point about the recently tested 3E audio amps: are they legal?

 

[kemmler3D]

They could easily make the patent free to use around their own products and create more demand by doing so.

I could easily imagine that they just have bigger, better patents to license and so nobody at TI is doing outreach about it. IME whenever a tech company does something that doesn't seem to make sense, (or doesn't do something that does make sense) it's because it's nobody's job to do it, and/or they somehow make more money by not doing it.

If it were me I'd ask for $1-5 per amp in royalties which would be $5-25 more on the MSRP before you get to the parts cost. I think the crowd here would probably pay that just to avoid the frequency dependence, even if SINAD is more than enough here.

So if covered by patents, it brings up another controversial point about the recently tested 3E audio amps: are they legal?

Patent infringement can only ever really be determined in court. So the answer is too expensive for anyone to want to find out for sure.

 

[JSmith]

You are authorized to use, copy and modify any individual TI Resource only in connection with the development of applications that include the TI product(s) identified in such TI Resource. NO OTHER LICENSE, EXPRESS OR IMPLIED, BY ESTOPPEL OR OTHERWISE TO ANY OTHER TI INTELLECTUAL PROPERTY RIGHT, AND NO LICENSE TO ANY TECHNOLOGY OR INTELLECTUAL PROPERTY RIGHT OF TI OR ANY THIRD PARTY IS GRANTED HEREIN, including but not limited to any patent right, copyright, mask work right, or other intellectual property right relating to any combination, machine, or process in which TI products or services are used. Information regarding or referencing third-party products or services does not constitute a license to use such products or services, or a warranty or endorsement thereof. Use of TI Resources may require a license from a third party under the patents or other intellectual property of the third party, or a license from TI under the patents or other intellectual property of TI.

https://www.ti.com/lit/an/slaa788a/slaa788a.pdf

JSmith

 

[HarmonicTHD]

I have recommended a bunch of other class D amps from AIYIMA to Fosi with similar performance.

Ok I understand the consistency argument.

They are just technologically inferior vs. SOTA especially as it also might be audible under certain load conditions as opposed devices with more consistent FR but slightly less SINAD. Maybe, not in this thread, one could start a discussion, what FR load dependence would be considered "great" so you could drive industry to implement improvements (where needed), similar to that when you started way back the SINAD discussion and called out poor designs.

 

[Talisman]

Yes great features and good price. Load dependent FR (and okish SINAD at only 20.5dB) is a „poor“ for me.

I am surprised it got a „recommended“ as that doesn’t seem consistent with other reviews.

I'm the first to complain about the load dependency of small class D designs, but here you guys really don't know how you think that a amplifier plus streamer, plus hdmi in a nice case, with a serious amount of power, that also provides low pass filters and high pass and even integrated peq for 300 euros should not be recommended..... It's an incredible value, and if with your speakers the load dependence should give you excessive brightness you just need to use the peq filters.
This product is exceptional.

 

[HarmonicTHD]

I'm the first to complain about the load dependency of small class D designs, but here you guys really don't know how you think that a plus streamer, plus hdmi amplifier in a nice case, with a serious amount of power, providing also low pass and high pass filters and even integrated peq for 300 euros..... It's an incredible value, and if with your speakers the dependency on the load should give you excessive brightness you just need to use the peq filters.
This product is exceptional.

Yes as I said, price and features are great, technologically not so much and therefore value is relative and very individual.

 

[voodooless]

https://www.ti.com/lit/an/slaa788a/slaa788a.pdf

Isn’t this message basically on all documents? It just says that you may read things in this document that require a license to use. It doesn’t confirm that you actually need it in this particular case. I just checked a few other random TI product documents, and they show similar texts.

 

[Talisman]

Yes as I said, price and features are great, technologically not so much and therefore value is relative and very individual.

I want to repeat it. It's a non-issue. Any response deviations can be corrected in the digital domain without loss of quality.

 

[voodooless]

value is relative and very individual.

That’s why everyone doesn’t vote the same option at the poll, and that’s why you may want to ignore @amirm’s value judgement at your own discretion.

I think it’s a bit silly to dismiss a potential problem with a product when the solution to the problem is already integrated in the product in the first place.

 

[HarmonicTHD]

That’s why everyone doesn’t vote the same option at the poll, and that’s why you may want to ignore @amirm’s value judgement at your own discretion.

Yes of course and that´s why there is discussion.

I think it’s a bit silly to dismiss a potential problem with a product when the solution to the problem is already integrated in the product in the first place.

No need to call me "silly". As for your argument, it only holds, if the effect is linear, which I dont think it is given the quite "erratic" impendence responses of some speakers.

 

[CleanSound]

Why these specifically?

Review

Didn't even know they were review, apparently these were designed before David got his NFS.

 

[taotone]

Voted poor. I do for all amps that will alter the frequency response according to which speaker is connected.
Many speakers have high impedance much higher than 8 ohm in mid to high frequencies. There is a chance this amplifier from 2023 will change how these speakers sound. I think this is more important than how much below threshold the THD+N is.

Also no power cube tests.

Could you say how you could put together a starter hifi system with those features and performance for a similar amount of money? Genuinely curious.

 

[voodooless]

No need to call me "silly".

I don’t call you silly, I call the argument silly, at least in this case.

As for your argument, it only holds, if the effect is linear, which I dont think it is given the quite "erratic" impendence responses of some speakers.

It is a linear function, it doesn’t matter how erratic the impedance is. It will nicely scale with volume until the inductors start to saturate, as in: the difference will be the same at any volume. By then, you’ll have other things to worry about anyway.

 

[JSmith]

Wiim amp with real loads

There is no complex load that represents all speakers though.

Also no power cube tests.

In fairness, Amir has stated before in other threads;

On Powercube, it doesn't like amps like this with high floating ground voltage on one channel. The cause is unknown.

Also, there is a hardware bug in the Powercube load box where if the negative leg of amplifier output is at anything above 0, it will lock up and no longer function.

JSmith

 

[Petevid]

Thanks for the review Amir.

I understood the reviews to be based purely on technical function and not on value for money?