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Wireless transmitter RCA

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Maifes
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Maifes posted on Mon, Nov 29 2021 1:59 PM

Hello !

After many hours on the internet i gave up my research and decided to ask if someone has some experience regarding wireless transmission of a signal from my pre-amp to my beolab 8000s. 

Basically due to the shape of my room i cant place my left speaker where i would like to have it since there is no way to lay down a cable to this speaker in a way that i could live with it. 

So my plan is to somehow establish a wireless connection. Is there something on the market that works as a transmitter and receiver unit ?

The basic idea is:

Pre-Amp via RCA to transmitter , Transmitter to receiver and then receiver via RCA or line to my beolab 8000.

I found something from Denon for professional use (Denon DN 202 WR and WT) but those dont have RCA inputs and outputs. 

Maybe someone here has an idea or could help me otherwise !

 

Edit: To make things more complicated, i also use the speakers for my television so there should be no delay

 

Thank you very much in advance,

Felix

 

 

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Maifes
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Hello again,

 

so i did some further research and found out that actually B&O themselves produce the product i want Hmm

Has anyone experience with the Beolab transmitter 1 and the Beolab receivers ?

 

mbolo01
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Yep, it works very well if you can manage not to have conflicting 5 GHz WiFi signals.

I use a TR1 with BL 18, 19 and 8000+RCV1

BS Moment, BS Core, BG 4002, BC 4500, BS1, BL18, BL19, BL8000 + RCV1, A6, M5, M3, A1, P6 (tks Botty), H5, TR1

Maifes
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Thank you ! Do you know if it works with watching TV or is the latency too high ?

Also i have read that BLT1 doesnt have volume control and you need some special USB device for it so you can turn down the volume if you use a fixed source (e.g the opt. Out of my samsung television) ?

 

 

mbolo01
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Maifes:

Also i have read that BLT1 doesnt have volume control and you need some special USB device for it so you can turn down the volume if you use a fixed source (e.g the opt. Out of my samsung television) ?

Correct:

If you connect your Samsung TV to the TR1 Optical In, you’ll need to connect an IR eye to the TR1 USB in order to control the volume via a remote (I have no experience here).

My Samsung TV is connected to a Beosound Core that I also use for music. The Core is connected to the TR1 and I control the volume at the Core level with a B&O Essence remote.

There is no noticeable delay, even with a box between the TV and the TR1.

Depending on the country you live in, there are other Wisa transmitter products that could be tried. Search for the Wisa association web site for more information

BS Moment, BS Core, BG 4002, BC 4500, BS1, BL18, BL19, BL8000 + RCV1, A6, M5, M3, A1, P6 (tks Botty), H5, TR1

Maifes
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Thank you so much, thats everything i have wanted to know !

Geoff Martin
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The WPL transmission does have a small delay of under 5 ms (equivalent to the time it takes sound to travel about 1.7 m). So, lip sync is not a problem. However, if you're connecting a sub-set of your loudspeakers using the wireless path, then you'll need to compensate the other loudspeakers to wait for them, otherwise the asymmetry will move phantom images quite significantly.

The simplest solution is to use the wireless path for all loudspeakers, which time-aligns them automatically (since they all have the same latency). If you choose to mix and match your connections and you do not have a B&O television as the master, then you'll need to compensate for the delay by "faking it" with Speaker Distance modifications in your preamp.

Cheers
-geoff

mbolo01
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Thanks Geoff, an honor to have your comment here!

I have a question for you: BL 18 specs do mention 48 kHz / 24 bits for WPL and 96 kHz / 24 bits for Wisa, does it mean that it is a limitation of the transmitter, i.e. TR1 has the WPL limitation while you can get more from a transmitter such Axiim or Soundsend?

 

BS Moment, BS Core, BG 4002, BC 4500, BS1, BL18, BL19, BL8000 + RCV1, A6, M5, M3, A1, P6 (tks Botty), H5, TR1

Geoff Martin
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mbolo01:

I have a question for you: BL 18 specs do mention 48 kHz / 24 bits for WPL and 96 kHz / 24 bits for Wisa, does it mean that it is a limitation of the transmitter, i.e. TR1 has the WPL limitation while you can get more from a transmitter such Axiim or Soundsend?

Hi,

Any/Every wireless audio system will introduce errors in the bitstream. (Many wired systems do this as well...)

This is a simple fact of life that cannot be avoided.... Death, taxes, and errors in wireless audio signals.

One important thing to remember is that these errors occur on the individual bits, which, in turn, result in errors in the values that those bits combine to represent with varying levels of impact. (For example, Let's say that you send the number 1,923,741 but the number 1,923,748 is received. This is a small error. However, if you received 8,932,740, it's a big error - but in both cases I only turned one "1" into an "8".)

The error rate of any binary system like this is expressed and measured as a probability of errors per some number of bits. For example, if you have a 1% error rate, then, on average, if you measured the accuracy of 1,000,000 bits, 1% of them (10,000) will be incorrect. It DOESN'T mean that you will have 1 error every 100 bits - we're talking about probability here... 

Back to the story: WPL/WiSA has a probability of some (very small) number of errors per some (very big) number of bits transmitted. However, digital audio requires big numbers of bits. The bit rate of the raw audio signal before you add the extra stuff is at least:

sampling rate * word length * number of audio channels

For example:

  • 48000 * 24 * 2 = 2,304,000 bits per second for 2-channel stereo
  • 48000 * 24 * 8 = 9,216,000 bits per second for 8-channel stereo (a.k.a. multichannel)

If you double the sampling rate, you double the number of bits per second.

So, let's say that (just to make the math easy - this is not a real number) the error rate is a probability of 1 error / 2,304,000 bits. Then you can calculate the error rate to be 1 error per second at 48 kHz, but 2 errors per second at 96 kHz.

Or, more generally, the higher the sampling rate, the higher the probability of errors per unit of time.

This is why Wireless Power Link transmitters are limited to 48 kHz instead of going all the way up to WiSA's possible limit of 96 kHz. We made that decision to balance between the sound performance on a single dimension* and the error probability over time.

So, if you with to run at 96 kHz, you will need to use a non-B&O transmitter, but you can still use the B&O receiver (because it's WiSA-compatible). But beware that it is incorrect to simply think that a higher sampling rate is better**.

Also - just to be clear: Before we released WPL in our products, I ran the final test to see how well it behaved. With a transmitter and a receiver that were both sitting on my desk - and with nothing in between them, I measured a 0% error rate on an 8-channel, 24-bit, 48 kHz audio signal transmitted over a duration of 11 days running continuously. That's 0 bit errors... However, if something disturbs the RF signal between the Tx and Rx devices, errors are measurable (which does not necessarily mean that they're audible).

Cheers
- geoff

 

* (1) I intentionally did not use the word "quality" here, because that's perceptual and
(2) I say "single dimension" here - which is audio bandwidth of the transmission system, however higher sampling rates can, in some systems make things worse)

** I wrote a long, boring13-part explanation of this sentence. You can find the links to these at https://www.tonmeister.ca/wordpress/series-of-articles-on-audio/ under the heading "High-Resolution Audio".

 

Geoff Martin
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I just thought of two extra things to add:

- I regretted not intentionally making a single error in that posting, with a moral-to-the-story that my single error (hopefully) did not impact the intelligibility of the message of the entire post. In other words: to make a metaphor of a measurable but imperceptible error. However, in re-reading what I just wrote, I see that I unintentionally have an error there. So, it all worked out.

- I should have added one extra dig in there, which would be that, although digital audio system (both wireless and wired) have probabilities of error rates - so does analogue audio. The interesting thing about analogue audio is that there is a 100% probability of error all the time. Due to the continual and measurable existence of noise - analogue audio ALWAYS has errors. Of course, you can then conclude (correctly) that digital audio also has a 100% error rate, since it probably starts off as analogue (synthetic sounds excepted), and is certainly converted back to analogue before you hear it.

Have a nice weekend.
-g

mbolo01
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Geoff Martin:

We made that decision to balance between the sound performance on a single dimension* and the error probability over time.

Many thanks for this very informative (as usual) and certainly not boring answer. That said, my old ears would not even make the difference at a higher rate …

The only regret I have with the TR1 is not being able to set a channel manually, I regularly run into conflict with my WiFi, I must say less conflict now that I’m forcing DFS channel on it, but still suffering from speakers disconnect/reconnect events and surely some sounds pollution that I hardly hear.

BS Moment, BS Core, BG 4002, BC 4500, BS1, BL18, BL19, BL8000 + RCV1, A6, M5, M3, A1, P6 (tks Botty), H5, TR1

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