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Kali Audio MV-BT Review (Balanced Bluetooth Receiver)

MayaTlab

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#41
Very interesting Amir, thank you!

Do you have an Apple device to compare AAC from Apple to Android? I think soundguys did such comparison and concluded to use AAC on Apple devices (ok, it also is the only supported codec) and SBC on Android: Soundguys BT Codec comparison
I would welcome a test of various receivers in AAC with the same AAC transmitter (presumably preferably an iDevice as AAC is supposed to be decently handled with them according to Soundguys' article). We already have some evidence that the encoding device's implementation of AAC varies quite a lot, but what about the decoding device ?
 
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#42
I wonder if the shoulders/echo associated to the AAC coded has to do with sampling a single frequency over a fixed time period?

A true sine wave can only exist across infinite time. A sine wave sampled over a specific time period is a sine wave times a square wave with duration of the sample period.

(I obviously know nothing about how codecs work, just not sure how that aspect is handled)
 
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amirm

amirm

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Thread Starter #44
I wonder if the shoulders/echo associated to the AAC coded has to do with sampling a single frequency over a fixed time period?
The same FFT is applied to all codecs and it only shows up on AAC. So it is not an instrumentation issue.
 

LTig

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#46
Oh. Sure. Do you have a recommendation?
I bought an Auvisio BTA-350.ax in 2017, but it's no longer available. On amazon.com I found several ones:
The second one may be better suited for future tests because it contains both transmitter and receiver with SPDIF in and out. Or buy 2 to be able to run full test of digital BT connection.
 

restorer-john

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#47
Bluetooth has been a disaster from day one in my opinion. In terms of consistent connection and connection quality, is has to be the most flawed system ever foisted on the public.

I just don't understand why people bother with it. For anything. Letalone audio.

I see that 920million products shipped last year with some form of BT in them.:facepalm:
 
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LTig

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#48
Bluetooth has been a disaster from day one in my opinion. In terms of consitent connection and connection quality, is has to be the most flawed system ever foisted on the public.

I just don't understand why people bother with it. For anything. Letalone audio.

I see that 920million products shipped last year with some form of BT in them.:facepalm:
Can't second that. Both the Auvisio mentioned in my posting #46 (connected to the Classé Sigma SSP via SPDIF) as my JBL Charge 3 work absolutely flawless with my Samsung S5 neo smart phone.
 

restorer-john

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#49
Can't second that. Both the Auvisio mentioned in my posting #46 (connected to the Classé Sigma SSP via SPDIF) as my JBL Charge 3 work absolutely flawless with my Samsung S5 neo smart phone.
I'm sure there are good connections. Like my apple phone that would connect to any cheap chinese BT module quite happily and hold on no matter what. But connect in the car? Nope. The Galaxy Note 9 that connects in one car, won't in the other. The windows laptops that work so sporadically that I tried USB BT modules instead and they sort-of worked.

The apple air pods are fantastic- only with apple products. But they sound like crap compared to a real headphone. I bought them for my partner and she liked them for about a week and abandoned them due to intermittent connections with her Lenovo Yoga and phone. Everything else is hit and miss- mostly miss. They sit in a drawer- unused.

How many times have you honestly had you or your friends calls drop out, go to a different phone or just not work when making/receiving mobile (car) calls?

It's just not an accomplished, reliable and high quality wireless transmission system. Humans can do much better.
 

respice finem

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#50
Bluetooth has been a disaster from day one in my opinion. ...I see that 920million products shipped last year with some form of BT in them.:facepalm:
Thankfully, perhaps the "lion's share" are mice and keyboards, that's where it works most of the time. Oh, and smartphones...
 
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#51
That would be really odd. and quite complex, and pricy. Do you know other products than cell phones or computers that have a USB output?
Why would be odd, complex or pricey? There are plenty of dongles that transmit from a USB port, the Avantree DG80 for example., why would it be any more difficult to do the reverse?
 
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#52
The same FFT is applied to all codecs and it only shows up on AAC. So it is not an instrumentation issue.
Oh, wasn't trying to imply it was the instrumentation, then it would always look like that. You mentioned AAC broke things up into smaller data segments prior to compressing, thought it could be an artifact of that.
 

PeteL

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#53
Why would be odd, complex or pricey? There are plenty of dongles that transmit from a USB port, the Avantree DG80 for example., why would it be any more difficult to do the reverse?
The Dongle doesn’t transmit over USB, the computer it’s plugged in do. The process of audio packet transfer trough USB require drivers, that talk to the playback application, and also receive handshake data from the receiver. Computer. or computer like devices can do this, in most cases natively from their operating system. SPDIF transfer is order of magnitude simpler. Yes ADC can send data trough USB but they are still managed by a computer, you are talking sending a digital signal from a device to an other, and neither are computers, i don’t think I’ve seen that ever done but am not saying impossible, I said complex and pricey
 

edechamps

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#54
Switching to AAC codec, I was super disappointed to see quantization noise and pre-echo:

View attachment 116954
I'm curious, why do you think the widening around 1 kHz tone is a symptom of pre-echo? To me, pre-echo is a time domain phenomenon and can be seen in an impulse response as content that comes before the main pulse. I'm surprised you can tell it's pre-echo just by using a single pure continuous tone as the test signal, and just by looking at a frequency spectrum graph with no phase information!
 

LTig

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#56

AndreaT

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#58
I had uniformly bad experience with BT devices: their output signal is invariably low for RCA line level inputs and the overall sound quality poor: even bypassing their DAC does not improve matters. Auris HD and Logitech are no exceptions. Is it time for a better software and hardware implementations of wireless local digital communication? Any entrepreneur wishing to fill a potentially enormous market?
 
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