The Hi-Fi + Hi-Res Audiophiles' Bluetooth Headphone Adapter Thread - [17.Oct.21] iFi GO Blu impression added
Jul 19, 2019 at 10:02 AM Post #48 of 1,313
I wish this had ldac, been wanting something like this that has a cable built in so I don't need to clip the BT receiver on my shirt

One has existed for quite some time: Elecom LBT-HPC1000RC
 
Jul 19, 2019 at 12:08 PM Post #49 of 1,313
AAC (from an Apple device such as an iPhone or other good-AAC coding source) is enough to be “Hi-Res”, insofar as actual “SS” goes (see accuracy vs precision, eg). It is just not in the current marketing train with big flashy numbers, and Android AAC implementations are inconsistent at best. However, AAC is a very transmission-efficient codec with high use of psychoacoustics so many ‘high numbers’ can be misleading.

Also, not really sure how one can apples-to-apples “count” 24-bit over a lossy non-PCM coding (of any kind). Could also devolve into the different LDAC profiles..

As iPhone only supports AAC (ignoring SBC), and AAC is arguably still ‘on par’ with aptX HD, I recommend AAC support is also a requirement. Again, only in support of iPhone/Apple usage; Android should use a codec that is ‘better supported’ on that stack.
:shrug:
Not sure I'd consider AAC as hi-res. To be hi-res, you need more bandwidth (typically 47+ kHz) than a CD, and more dynamic range than a CD (typically 20+ bits). AAC comes woefully short - as does SBC, and AptX - on these. AptX-HD gets close, and LDAC at 990 kbps is even closer - but both come short of technically being hi-res.

Here's a measurement of multiple AAC implementations, including one on an iPhone 7: https://www.soundguys.com/understanding-bluetooth-codecs-15352/ - bandwidth extends to ~18 kHz at best. Is that enough? For most people, I would undoubtedly say yes! But it is decidedly NOT hi-res.

Here's an interesting test of the LDAC CODEC: https://www.soundguys.com/ldac-ultimate-bluetooth-guide-20026/ - it's got the bandwidth, but comes up short in dynamic range, mainly because the noise floor grows. it's dynamic range is a solid 16-18 bit solution, and bandwidth is about 47 kHz, so it's really close - but technically not hi-res.
 
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Jul 19, 2019 at 1:45 PM Post #50 of 1,313
@ClieOS - Would any of the BT adapters you've listed can simultaneously connect wirelessly between a phone and a BT IEM?
Generally an audio source device (ie. phone or DAP) can connect to at most ONE Audio BT device at once. However, one can switch between multiple paired BT devices relatively easily through the settings. (I can switch between 3 different BT receivers in a few seconds because I have all of those paired.)

There are some BT receivers that can connect to TWO sources at once (this is called "Multipoint"). However, these are restricted to SBC when connected to multiple devices and BT (Classic / Audio) is really designed for ONE<->ONE.

So, to answer the question: "no". However, the phone can switch between the BT IEM and the BT adapter (or car audio, etc.) relatively easily.
 
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Jul 19, 2019 at 1:56 PM Post #51 of 1,313
Not sure I'd consider AAC as hi-res. To be hi-res, you need more bandwidth (typically 47+ kHz) than a CD, and more dynamic range than a CD (typically 20+ bits). AAC comes woefully short - as does SBC, and AptX - on these. AptX-HD gets close, and LDAC at 990 kbps is even closer - but both come short of technically being hi-res.

Here's a measurement of multiple AAC implementations, including one on an iPhone 7: https://www.soundguys.com/understanding-bluetooth-codecs-15352/ - bandwidth extends to ~18 kHz at best. Is that enough? For most people, I would undoubtedly say yes! But it is decidedly NOT hi-res.

Here's an interesting test of the LDAC CODEC: https://www.soundguys.com/ldac-ultimate-bluetooth-guide-20026/ - it's got the bandwidth, but comes up short in dynamic range, mainly because the noise floor grows. it's dynamic range is a solid 16-18 bit solution, and bandwidth is about 47 kHz, so it's really close - but technically not hi-res.
Alright, I can't argue that .. and I can say I can't hear past ~16kHz :)

41kHz on a CD is fine (with exception of an extreme rarity, humans can't hear more than this can represent, even as a child), although I'll accept 48kHz for pretty conversions. Dynamic range and noise / artifacts and especially re-shaping (uhg, wrong term?) are more relevant when running through lossy compression.

I think, mostly I get grumpy that it's a lot of marking.. anyway, 41kHz/24 meets "Hi-Res Audio" guidelines. Not sure why people like to go off the rails on the sample rate. Here is the "Hi-Res Audio" Gold Sticker manual, for posterity. And here is an example of MISLEADING marketing that I dislike.. anyway, time for a picnic.
 
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Jul 22, 2019 at 5:10 AM Post #52 of 1,313
BTR5 latest update: ETA around late August / September
 
Jul 23, 2019 at 2:23 AM Post #53 of 1,313
BTR5 latest update: ETA around late August / September

Cheers for the update, mate!

I'll be in China in October, so might be a good time to grab one! (I assume stuff like this would be cheaper in China than to purchase delivered to Australia through AliExpress?)

Plus, hopefully you've got one and reviewed it by then! :)
 
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Jul 24, 2019 at 10:50 PM Post #54 of 1,313
FiiO and Shanling won't have any answer for you, mostly because what you are asking make no logical sense.

An BT adapter (or in fact any BT supporting DAC/amp) takes BT signal from a source, in this case most likely a smartphone, then convert it into an analog signal to output to the headphone of your choice. An BT IEM works just the same, except that the BT circuit inside the BT IEM only meant to drive the IEM's transducer and no other headphone. So basically a BT IEM is just a IEM and an BT adapter integrated into single unit., while a standalone BT adapter can be used with (most of) any IEM.

Therefore what you are asking for, is for a smartphone to send a BT signal to an BT adapter to output analog electrical signal, then somehow magically re-encode the signal back into BT and send it to another BT adapter circuit (that built into an IEM) and so it can be turn back into analog electrical signal again to driver the IEM's transducer - (1) the first question you must ask yourself is: what is the point of turning a perfectly fine BT signal into analog signal, just so you need to turn it back to digital BT signal to send and decode back to analog signal again? Logicality speaking, it is a cleaner and more efficient process just to send the BT signal from the smartphone to the BT IEM. (2) The 2nd question is of course, even if you can somehow do what you want it to do (smarphone -> BT adapter -> BT IEM), will it improve the sound? The answer is "no". It is the BT circuit inside your BT IEM that will do the actual decoding and driving the IEM's transducer, so it is the limiting factor of the whole setup. Not only does your BT IEM won't benefit from such a setup, it will most likely degrade the SQ on the process since every time a decoding/re-encoding takes place, the original signal always suffer a little lose of quality - again, the best way is to minimize any extra step in the process so a direct connection between the smartphone and BT IEM will provide the best possible result.

Because of the 2 reasons mentioned above, no BT chipset maker ever design a BT chipset that can receive, decode, re-encode and transmit BT signal from a smartphone to an BT headphone, as it is a waste of time and energy (not to mention the lost of quality) to do so. It will be like designing a battery for smartphone - instead of powering the smartphone by the battery itself, it will first charge a secondary battery inside the smartphone, then the 2nd battery is used to power the smartphone - it is not that you can't have such a design, just that it is gonna be a stupid and wasteful design that has no upside.

So to simplify - you should just connect your BT IEM to your smartphone. A BT adapter main purpose is to add BT ability to normal headphone, not to (nor is it possible to) improve headphone that already has BT capability.

This is very informative. Learned quite a bit here. Appreciate it!
So would this set up improve sound quality instead?
1. DAC/AMP plugged to phone via cable
2. BT IEM connect to DAC/AMP via BT

The assumption is the output from the DAC/AMP sends out digital signal and the BT headphones receive that same signal without going through a process of encoding and decoding.
With the DAC/AMP having a superior BT codec, then that would improve the sound?
Or is the bottleneck still with the BT set plugged to the IEM

For context, I have the MEE Audio BTX2 plugged to a pair of BGVP DM6
 
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Jul 25, 2019 at 12:36 AM Post #55 of 1,313
Generally an audio source device (ie. phone or DAP) can connect to at most ONE Audio BT device at once. However, one can switch between multiple paired BT devices relatively easily through the settings. (I can switch between 3 different BT receivers in a few seconds because I have all of those paired.)

There are some BT receivers that can connect to TWO sources at once (this is called "Multipoint"). However, these are restricted to SBC when connected to multiple devices and BT (Classic / Audio) is really designed for ONE<->ONE.

So, to answer the question: "no". However, the phone can switch between the BT IEM and the BT adapter (or car audio, etc.) relatively easily.
Good to know! Right now leaning on a good DAC/AMP to can connect to IEM via BT. You have any suggestions?
Unless ClieOS points out the BT set connected to the IEM is the biggest bottleneck.
 
Jul 25, 2019 at 12:41 AM Post #56 of 1,313
One has existed for quite some time: Elecom LBT-HPC1000RC
Wow. Wish I knew this one existed. What kind of features to look out for when comparing another BT set? The kinds of codes one have?
Bought the MEE Audio BTX2. Not sure how this compares to the Elecom
 
Jul 25, 2019 at 1:02 AM Post #57 of 1,313
Good to know! Right now leaning on a good DAC/AMP to can connect to IEM via BT. You have any suggestions?
Unless ClieOS points out the BT set connected to the IEM is the biggest bottleneck.
It won’t be using the “DAC/AMP” if connecting to headphones via BT (the “DAC/AMP” converting to analog for the transducers will be in the headphone receiver itself). Do you mean “DAP”?

The “DAC/AMP” should generally be connected directly to the digital source. Be this source a standalone “DAP”, a music player on a phone, or digital/BT PC audio output etc.
 
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Jul 25, 2019 at 1:33 AM Post #58 of 1,313
It won’t be using the “DAC/AMP” if connecting to headphones via BT (the “DAC/AMP” converting to analog for the transducers will be in the headphone receiver itself). Do you mean “DAP”?

The “DAC/AMP” should generally be connected directly to the digital source. Be this source a standalone “DAP”, a music player on a phone, or digital/BT PC audio output etc.
So the DAC/AMP always outputs an analog signal? Hence, renders the point moot for connecting to BT headphones?
Understand that the BT receiver converts the digital signal to analog for the IEMs.
But what if the DAC/AMP outputs a decent digital signal via a superior codec like LDAC and the BT receiver on the IEM also has LDAC?

Or this is simply not how DAC/AMP works?
Meaning DAC/AMPs always take in either digital or analog signal, then converts and outputs only analog?
 
Jul 25, 2019 at 6:01 AM Post #59 of 1,313
There seems to be a lot of misunderstanding, so lets break it down:

This is very informative. Learned quite a bit here. Appreciate it!
So would this set up improve sound quality instead?
1. DAC/AMP plugged to phone via cable
2. BT IEM connect to DAC/AMP via BT

The (2) is, again, non logical - as I have spent some effort on my previous reply to explain to you, such a thing doesn't exist. You CAN NOT connect a BT IEM (any BT headphone) to a DAC/AMP via BT. No chip maker even developed a BT chip that can allow for such function nor does any DC/AMP maker ever attempted to ever design such a thing. What you are asking on (2) is a fantasy setup that never exist before, nor even likely will.

The assumption is the output from the DAC/AMP sends out digital signal and the BT headphones receive that same signal without going through a process of encoding and decoding.
With the DAC/AMP having a superior BT codec, then that would improve the sound?
Or is the bottleneck still with the BT set plugged to the IEM

For context, I have the MEE Audio BTX2 plugged to a pair of BGVP DM6

The output of any DAC/AMP is almost always analog signal (*there are exception with some also outputs SPDIF or Toslink, but NEVER BT). Your assumption is fundamentally based on an erroneous idea that never really exists in the real world.

Good to know! Right now leaning on a good DAC/AMP to can connect to IEM via BT. You have any suggestions?
Unless ClieOS points out the BT set connected to the IEM is the biggest bottleneck.

Again, No such a thing as a "DAC/AMP to can connect to IEM via BT". You are asking people to suggest to you a thing that doesn't exist.

By 'DAC/AMP', we are referring to a headphone amp that also comes with a DAC - which is short for Digital-to-Analog Converter. As the full name suggested, it only does one thing: converting digital signal to analog, not the other way around. A DAC/AMP with BT function has one extra set of BT chip, which takes the BT signal (* = digital) from a smartphone or any BT source, and feed it into the DAC in order to convert it to analog signal, then the amp section amplifies the signal to feed it into the headphone - in NO way you can somehow magically turn any path of the process back into a BT signal unless you use an ADC (*analog-to-digital) circuit - but that will be extremely stupid. The reason is, as I have explained on my previous reply, doing so only cause degradation of signal due to multiple decode/re-encode. There is no benefit to make a device that purposefully decrease SQ when you can just send the BT signal from smartphone to the BT headphone directly.

So the DAC/AMP always outputs an analog signal? Hence, renders the point moot for connecting to BT headphones?
Understand that the BT receiver converts the digital signal to analog for the IEMs.
But what if the DAC/AMP outputs a decent digital signal via a superior codec like LDAC and the BT receiver on the IEM also has LDAC?

Or this is simply not how DAC/AMP works?
Meaning DAC/AMPs always take in either digital or analog signal, then converts and outputs only analog?

A DAC only takes digital and convert it to analog. An amp only take analog signal and amplifies it. You COMPLETELY misunderstand how a DAC/AMP works and just assume it will somehow magically convert whatever you want to any other signal you want - well, it doesn't work that way.

-----------

In any setup, there will always be a bottleneck - for example, if you smartphone only output poor quality SBC codec over BT, somehow you use an BT enable DAC/AMP to convert it to analog signal, then you feed that analog signal into an ADC and resending it over BT (*such a device will be called a BT transmitter), perhaps even using LDAC, then your BT IEM received the LDAC signal and covert it back to analog and feed it to the transducer.

Now the reality is your original music already suffer a lost of quality when it was first send over SBC, then it suffered a 2nd lost of quality when you using an ADC to convert the analog signal to back to digital, then another (minor) lost of quality by sending it over LDAC (note: even LDAC is not a completely lossless codec). Lastly, the DAC inside your BT IEM need to convert the LDAC back to analog and likely it is not going to be a very good DAC due to the size restriction of the circuit inside the IEM, so another minor lost of quality there. In the end, what you really are getting is a process that results in the accumulation of four lost of quality. In comparison, you need suffer 2 lost of quality if you just connect your smartphone to your BT IEM directly.

The takeaway point is, you should stop trying to complicate your BT setup with non-existing dream-up device. The best way of is to get a LDAC enable smartphone and a LDAC enable IEM, then connect them directly. END OF STORY.
 

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