Using BlueTooth receiver/transmitter for subwoofer

benedium

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I think right from the beginning we know your intention or usage requirements. So now just up to u to try. My main concerns would be what physical connections and reliability of wireless transmission. Next would be quality of the sound. So what's your plan?
 

patryn33

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I don't think it's a matter of being too technical. I love a good tech discussion, because hey, I'm in the tech industry. I think we understand the concept of not getting the stuff we're not using, i.e. not transmitting the high frequencies which a sub doesn't need. However, that argument is one of wastage, not one of performance/quality. What benedium and I are asking is, how does this translate to higher quality?

Latency was a performance benefit that was thrown about, but with aptX LL reaching sub 50ms latencies, are there additional advantages to proprietary protocols that transmit only sub 1KHz signals? How low are the latencies for these protocols?

Also, how about sound quality? What is the extra bandwidth that is freed up from not having to transmit high frequencies being used for? Higher bitrate? Higher sampling rate? More bit depth?

aptx LL may solve the latency issue if using HW encoding. apparently phones can use software encoding and latency of over 200msec. tech ppl usually pretty good a googling and reading specs.
aptx is a 16bit vs other at 24bit which explains bit depth or your understanding of bit depth diff from mine?

then u get into things like SNR where its 93 dB (aptx) vs 98 dB (emotiva)
sound quality is by ear or measurement?

with proprietary encoding, if they choose not to disclose and I don't work for them how would anyone know things like sampling rate. That will a question for the vendor who sells the product.

even if encoding is all same, there is this Digital to Analog conversion chip. U get great digital stuff for the transmitter but lame convertor? isnt the sound quality affected?

most impt, if cannot hear all these stuff dont matter.

whats more impt maybe what benedium stress on, reliability on connections due to interference.
 
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benedium

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Hope I'm not blur or wrong but...

I dunno if there might be any issue with connecting AVR's LFE/subwoofer mono output to 3.5mm stereo input on most of the Bluetooth transmitters I've looked at.

So based on that alone, if I were you, i will prefer to get a dedicated subwoofer transmitter receiver complete kit.

Also... amazon price and link for your consideration:
REL HT-Air on Amazon: S$159 (prime free shipping)
 
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galapogos

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aptx LL may solve the latency issue if using HW encoding. apparently phones can use software encoding and latency of over 200msec. tech ppl usually pretty good a googling and reading specs.
aptx is a 16bit vs other at 24bit which explains bit depth or your understanding of bit depth diff from mine?

then u get into things like SNR where its 93 dB (aptx) vs 98 dB (emotiva)
sound quality is by ear or measurement?

with proprietary encoding, if they choose not to disclose and I don't work for them how would anyone know things like sampling rate. That will a question for the vendor who sells the product.

even if encoding is all same, there is this Digital to Analog conversion chip. U get great digital stuff for the transmitter but lame convertor? isnt the sound quality affected?

most impt, if cannot hear all these stuff dont matter.

whats more impt maybe what benedium stress on, reliability on connections due to interference.
Thanks for bringing these points up. They could have been brought up in a constructive conversation from the start, and there's really no need to be condescending. Yes, tech people are pretty good at googling, but have you considered perhaps some people don't have the luxury and time to invest in googling every nitty gritty detail beyond their area of expertise? Perhaps they have a job, family, and other commitments that takes priority, but still want to know enough to get a good solution? Is this not one of the reasons what forums are for? For people with in depth knowledge to share with those who might not? I may not be updated with the latest in the audiophile world, but I'm not asking to be spoon-fed. Unsubstantiated claims were made, and hence I merely sought clarification. This isn't string theory we're talking about here, so please feel free to expound your ideas without thinking people "won't get it". Please also try to engage in civil, respectful discussions. It doesn't make you look any smarter by throwing a claim out there and then saying "oh you won't understand it, it's too technical", or "oh, just go google it" when people ask you to elaborate.
 

galapogos

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Hope I'm not blur or wrong but...

I dunno if there might be any issue with connecting AVR's LFE/subwoofer mono output to 3.5mm stereo input on most of the Bluetooth transmitters I've looked at.

So based on that alone, if I were you, i will prefer to get a dedicated subwoofer transmitter receiver complete kit.

Also... amazon price and link for your consideration:
REL HT-Air on Amazon: S$159 (prime free shipping)
Well, there are 3.5" to single RCA mono adapters such as this, they should work?
 

wwenze

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Well, there are 3.5" to single RCA mono adapters such as this, they should work?

Stereo source to mono input will *NOT* work. Also with that mono 3.5mm connector you'll just be shorting out your right output to ground, while only the left output reaches the subwoofer.

Mono source to stereo input of subwoofer will work all the time. In fact on some subwoofers they just label one input as LFE.

subwoofers-blog-lowres-7321.jpg


Why does it work? Because the circuit inside is just a summer. Which means output = input A + input B. Which is usually done with just 3 resistors. Two, if they want to save money.

With this knowledge, the quick-witted would also realize you can essentially make your own such circuit, or even make use of the series impedance already present inside passive preamps to achieve the same purpose with an RCA y-cable.
 

galapogos

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Stereo source to mono input will *NOT* work. Also with that mono 3.5mm connector you'll just be shorting out your right output to ground, while only the left output reaches the subwoofer.

Mono source to stereo input of subwoofer will work all the time. In fact on some subwoofers they just label one input as LFE.

subwoofers-blog-lowres-7321.jpg


Why does it work? Because the circuit inside is just a summer. Which means output = input A + input B. Which is usually done with just 3 resistors. Two, if they want to save money.

With this knowledge, the quick-witted would also realize you can essentially make your own such circuit, or even make use of the series impedance already present inside passive preamps to achieve the same purpose with an RCA y-cable.
Thanks. So, on the receiver side, could I use a single RCA to mono 3.5mm adapter to connect the receiver's LFE to the BT transmitter, and on the subwoofer side, connect the mono 3.5mm jack on the BT receiver to the subwoofer's RCA inputs (and not use the LFE input on the subwoofer) via a Y-cable?
 

wwenze

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So, on the receiver side, could I use a single RCA to mono 3.5mm adapter to connect the receiver's LFE to the BT transmitter

Yes. Although I will just use one side of a normal stereo RCA to stereo 3.5mm if I already have it lying around. (Note: Unconnected RCA may pick up RF noise)
Alternatively, get a BT transmitter with RCA and just use one side.

and on the subwoofer side, connect the mono 3.5mm jack on the BT receiver to the subwoofer's RCA inputs (and not use the LFE input on the subwoofer) via a Y-cable?
It's the same. 3.5mm out goes to LFE or stereo, it's the same result. Except the stereo method *might* give 6dB extra volume.



Are we still talking about a specific model of transmitter/receiver pair or are we talking about in general? Because if we're talking about the general stereo transceiver pair with stereo input and stereo output you can just use one channel.
 

benedium

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Wow I must say... I had no idea this problem required so much knowledge and discussion.
 

patryn33

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Wow I must say... I had no idea this problem required so much knowledge and discussion.

the amount of time spent asking to save some $$, might as well go buy lol.
or like U said just use wired.

or seek info from audioscience or those pro audio forum.
 
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benedium

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Ok hope I haven't got it wrong...
And lemme attempt a summary...
- Buy a cheap aptx transmitter + receiver set. Also Buy 3.5mm to stereo rca cable.
- Connect one or 2 sides (left or right) of rca plug into AVR subwoofer mono/stereo pre-out. Connect 3.5mm plug into bluetooth Transmitter aux input.
- On subwoofer side, Connect normal subwoofer cable/RCA stereo cable From bluetooth Receiver RCA Out To subwoofer LFE Input Or Stereo Input.

Note: Connecting both sides of stereo rca offers better sound quality than mono because we enjoy gain of +6db in the signal?

Please correct me if I am wrong or if it can be improved. And sorry if I'm merely repeating wwenze's info. I mean no disrespect. Thanks.
 
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benedium

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