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Topping BC3 Review (Bluetooth Receiver) & BT CODECs

tifune

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Also try sony music center app I heard you can lock in ldac settings per device there
I can confirm this. You don't even need a Sony device, just install this app and enable the setting attached. Strange description, seems like a bit of a Google Translate error, and it doesn't mention LdAC at all but works like a charm
 

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qec

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Was on 11. Updating to 12 now. Will check and report back tomorrow.
 

qec

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Looks like Android 12 is still doing the same thing. I will have to look into there a bit more...
 

pseudoid

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Having put too many years working at Sony, I can honestly say "Sony? Full of Baloney!" without hesitation.
LDAC; SchmalDAC!
If it is a proprietary format from Sony; I'd rather take a 2-bit hit in my audio specs to avoid it.
Their 'shenanigans' did not start with the RedBook but it just made Sony more predatory.
Can anyone say "Beta"? or "Blu-Ray"?
NOT in my house!
 

MalinYamato

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This is a review and detailed measurements of the Topping BC3 Bluetooth receiver and headphone amplifier. It was sent to me by the online seller, Yaoyaotiger HIFI Audio Store and costs US $69. This is a follow up to our previous tests of Bluetooth receivers and investigating performance of various codecs supported within.

The shiny plastic and slick design sets the BC3 apart for the typical Topping desktop products:

View attachment 132115

The touch screen buttons are pretty but with no tactile feedback, they are kind of inconvenient to use. There is a lock button to deactivate them which is nice:

View attachment 132116

Nice to see both headphone amplifier and digital/analog line outs. There is a convenient Toslink mini to full size adapter in the box which I used for my testing. The unit has battery built-in so you can charge it and use it on the go (car, commute, etc.). I did all of my testing while I powered it through USB-C from my computer monitor's hub (same port I use for all of my DAC testing).

Topping BC3 Digital Measurements
This is the first Bluetooth receiver we are testing that has digital output. This is exciting because we can see the true performance of the various codecs without the performance of the DAC getting in the way. The source for the stream was my Samsung S8+ phone running Roon player with Android developer options enabled so I could select the Bluetooth codec. Prior to this test, I was not successful in getting LDAC to work. I figured out the issue here. Turns out in their infinite wisdom, whoever did this work decided that you must enable LDAC both in the developer options and Bluetooth settings!

Let's start with aptX:

View attachment 132117

We immediate see the signature of aptX with that stepped down response in frequencies above 5 kHz. The higher frequencies are more "random" (have higher entropy) so harder to compress. By lowering their levels or truncating them, there is less for the codec to do.

Switching to AAC shows the poor quality we have seen which I am guessing is due to Android implementation of AAC encoder (meant to test this with an iPhone but forgot -- will do so later):

View attachment 132119

We get a big boost in SINAD but I am not happy about all the artifacts. In my prior testing I found SBC to actually sound better:

View attachment 132120

So our previous conclusions more or less hold with the codecs being the limiting factor not the DACs. However, now we have a new kid on the block, namely the Sony LDAC codec. Is it as good as its hype? Let's start showing its performance with 16 bit setting of the codec (source is still 24 bits):

View attachment 132121

Performance jump quite a bit showing a SINAD which is the limit of 16 bit bit depth. Switching to 24 bit mode is this tester gets a big smile:
View attachment 132132

Wow! What an improvement. Then again, all the other codecs should have done excellently with this simple sine wave that is dead easy to encode. But they didn't so LDAC in 24-bit mode wins big time. Even in 16 bit more it leaves the other codecs behind.

All of these measurements are in digital domain. Let's fee the Toslink to a Topping D30 Pro and measure its analog output using LDAC:
View attachment 132123

Hallelujah! We get state of the art analog reproduction despite using a wireless connection that started life for just voice.

Topping BC3 Analog Output Measurements
The DAC here is not a heroic implementation so we are going to get decent but not state of the art fidelity when using LDAC:

View attachment 132124

Dynamic range is basically representative of 16 bit format:

View attachment 132125

Headphone out is essentially the same as line out:

View attachment 132126

Edit: A couple more measurements:

Here is an asynchronous frequency sweep comparing pairs of codecs:

View attachment 132356

That is one nice and flat response for LDAC. SBC on the other hand is filtering above 14.5 kHz. This is done because high frequencies are much harder to encode due to their high speed variations (in sample value)/noise.

I was surprised that AAC was also filters above 15 kHz:
View attachment 132357

aptX as we saw earlier plays some serious games in treble.

This type of sweep also generates THD+N relative to frequency:
View attachment 132358

We see that LDAC continues to be the cleanest codec by far. Note that this is a dynamic sweep signal so more complex than a single tone that dashboard uses. The other codecs trade places in different parts of the spectrum and are generally a mess. aptX by the fact that it chops off high frequencies does better at very low frequencies.

LDAC Codec Licensing
Searching for LDAC lands you on the English translate of a site that is likely hosted by Sony Japan. In there we see the comforting mention of Topping as proper licensee of the codec:

View attachment 132129

Earlier it mentions that the source code for LDAC is part of the Android Open Source. Don't confuse this with it being fee. You still need to license the underlying patents from Sony or they can come after you. What is involved in said licensing? Sony is unusually transparent about that:

View attachment 132130

Predictably they expect you to spend months negotiating the NDA and actual license. Having been on both sides of such licensing, I can attest to this process being long and drawn out because the agreements likely start very one sided which you then kill yourself across countless conference calls to try to soften. Typical clauses are "covenant not to sue" meaning once you license this technology, then you can't sue Sony or their other licensees over any patents you may own. I don't know if such a provision is in there but I am guessing it would be. On NDA front you likely want to have a residuals clause meaning what you remember can't be unremembered. They will say you have to have a button to erase your memory if NDA is terminated.

And oh, after all the above you have to pay the license fee. I see no provision for RAND licensing (Reasonable and Non-discriminator Licensing), meaning everyone pays the same fee. Without it, a competitor to Sony could be charged much more money than a friend and thereby keeping a competitive advantage.

Did someone complain about MQA being bad? Welcome to the world of audio licensing! :)

LDAC Codec Range
I did most of my testing with the phone being a few feet from the BC3 receiver. I did however test to see if I could get performance to drop but could not even after I moved my phone some 20 to 25 feet (7 to 8 meters) away. I had the codec in adaptive mode by the way so it could have switched encoding rates but I saw no glitches to indicate it did so. Your mileage may vary of course depending on the implementation of Bluetooth transmitter in your device.

Conclusions
The previous Bluetooth receivers we tested suffered both from codec losses and less than optimal implementation of output DAC. Topping has the same limitation as far as codecs but since it supports LDAC, for simple signals at least, it eliminates that bottleneck. Its DAC implementation is what you expect: "good enough for 16 bit content." Fortunately with digital output you can connect it to your favorite DAC with balanced out and by using LDAC, you have a superb input path for Bluetooth.

I have not yet tested enough Bluetooth receivers to have a good calibration for what is good and what is great. Still, I was very pleased with the performance of the Topping BC3 and am putting it on my recommended list.

EDIT: video review just posted:


------------
As always, questions, comments, recommendations, etc. are welcome.

Appreciate any donations using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
can I send Dolby 5.1 ch from my PC to this so that it outputs Dolby 5.1 on its SPDIF optical interface?
 

staticV3

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can I send Dolby 5.1 ch from my PC to this so that it outputs Dolby 5.1 on its SPDIF optical interface?
None of the BC3's Bluetooth Codecs support Dolby surround sound.
In fact, I don't think such a codec even exists yet.
The BC3's USB port is only for charging and for firmware updates.
 

apastuszak

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I'm reading through this thread, and I have a few questions about these Bluetooth codecs. I know when you pair a device, it negotiates an A2DP codec. I assume it's also to negotiate a bitrate. Depending on the chip on each end, you may negotiate a good codec, but a lousy bitrate. I'm curious how things stand with Apple using AAC and connecting to a device with an Apple H1 Bluetooth chip in. As far as I know the H1 chip is only found in Apple and Beats headphones, so I don't know if there would be an easy way to measure that.

I've used various Bluetooth dongles with my wired headphones and my iPhone and iPad. And, with the AAC codec, while watching videos, the audio and video would almost always go out of sync, drift back into sync and eventually go out of sync again. If I used a dongle that did not include AAC support, the iPhone or iPad would use SBC and things were always in sync. But when I bought a pair of Apple headphones with an H1 chip in it, I'm using AAC now, and the audio and video is always in sync.
 

Megaken

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I'm reading through this thread, and I have a few questions about these Bluetooth codecs. I know when you pair a device, it negotiates an A2DP codec. I assume it's also to negotiate a bitrate. Depending on the chip on each end, you may negotiate a good codec, but a lousy bitrate. I'm curious how things stand with Apple using AAC and connecting to a device with an Apple H1 Bluetooth chip in. As far as I know the H1 chip is only found in Apple and Beats headphones, so I don't know if there would be an easy way to measure that.

I've used various Bluetooth dongles with my wired headphones and my iPhone and iPad. And, with the AAC codec, while watching videos, the audio and video would almost always go out of sync, drift back into sync and eventually go out of sync again. If I used a dongle that did not include AAC support, the iPhone or iPad would use SBC and things were always in sync. But when I bought a pair of Apple headphones with an H1 chip in it, I'm using AAC now, and the audio and video is always in sync.
Is latency your biggest concern?
 

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apastuszak

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Is latency your biggest concern?
No. The Beats Solo Pro solved my latency issue. I'm just curious if connecting Apple to Apple via Bluetooth AAC would produce better results than what Amir found when he connected an iPhone to the Topping. Apple doubled down on AAC when they made the W1 and H1 chips. Apple uses Bluetooth Class 1, which is much higher power and has a theoretical maximum range of 100 meters. Most Bluetooth devices are Bluetooth Class 2, with a 10 meter range. I wonder if the Class 1 power, coupled with Apple's best in breed AAC encoder (as defined by subjective listening tests on hydrogenaud.io) would give better objective results.
 

Megaken

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No. The Beats Solo Pro solved my latency issue. I'm just curious if connecting Apple to Apple via Bluetooth AAC would produce better results than what Amir found when he connected an iPhone to the Topping. Apple doubled down on AAC when they made the W1 and H1 chips. Apple uses Bluetooth Class 1, which is much higher power and has a theoretical maximum range of 100 meters. Most Bluetooth devices are Bluetooth Class 2, with a 10 meter range. I wonder if the Class 1 power, coupled with Apple's best in breed AAC encoder (as defined by subjective listening tests on hydrogenaud.io) would give better objective results.
Apple to Apple will definitely negotiate better in terms of range and latency.. But from what I understand it will still be 44/16 @ 264 kpbs
 

apastuszak

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Apple to Apple will definitely negotiate better in terms of range and latency.. But from what I understand it will still be 44/16 @ 264 kpbs
44/16 is the full range of human hearing plus room to dither. So, that's not going to be an issue. I'm just curious if some of those audible artifacts in the 1 Khz test tone would still be there if we went Apple to Apple.
 

audiofun

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Is it possible to test both aptx codecs with multitone signal , please ?..

Well after a few minutes of setting I am able to connect to a LDAC device (not BC3 though so cannot get digital signal out) so I can play and measure with REW.

Here we run it with the highest possible sample rate (96kHz) and bit depth (32bits) and enable the highest bluetooth transfer rate ( 990 kbps).

First to replicate amir's test I run it with a sine wave and here's how it behaves

Screen Shot 2022-01-07 at 6.57.17.png



Wow amazing, the FFT looks perfect with a > 110dB SINAD. In fact, this is almost as good as my dac and adc can get with this gain setting.

Then let's do a multitone and here's the result:

Screen Shot 2022-01-07 at 7.04.28.png


Looks bad isn't it? To make sure this is indeed caused by the lossy codec, here's the same test tone performed under lossless connection via USB.

Screen Shot 2022-01-07 at 7.11.52.png



Conclusion: While LDAC performs perfect using one test tone, Noise level rise up significantly when you put more tones into it.
The final result is still good, though --- at least it doesn't cut off the high frequency tones.
 

apastuszak

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I was just listening to a Mac Podcast and they said in an interview with the guy who designed the original Apple AirPods, the guy complained a lot about the limitations Bluetooth imposed on what they could do with the AirPods, sound quality-wise.

With Apple's new push into lossless music, I feel like Apple will release a wireless headphone/IEM/earbud of some kind that will use a wireless protocol other than Bluetooth they develop in house that can do lossless music and has low latency. With Jonny Ive gone, the obsession with "thin" seems to be gone. So, adding yet another radio into an iPhone probably isn't as big a deal as it would have been a few years ago.
 
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