cisco telepresence sx20 and Bose L1 Model II speaker with ToneMatch

[snake1134]

Hi guys,

So we have a Cisco TelePresence SX20 in our office for Video Conference and my boss wants to connect it to L1 Model II via ToneMatch. The problem is I'm not sure if it is safe cause the audio ports of Cisco TelePresence SX20 are 3.5mm and the outputs of ToneMatch are 1/4".

Below are data sheet of Bose L1 Model II speaker and ToneMatch:

http://products.bose.com/pdf/customer_service/owners/l1_model_II_guide.pdf

http://products.bose.com/pdf/customer_service/owners/t1_tonematch_audio_engine.pdf

[Wayne DeNardi]

The problem isn't going to be with the size of the connector (3.5mm vs 1/4") - the issue is going to be that the SX20 microphone has a 4-pole connector which carries the power for the mic (and does the mute button).  This isn't going to work without some additional electronics (see one of the many threads about connecting 3rd party microphones to an SX20/C20).

You could connect the SX20 microphone up normally (as Mic1) if you wish, and then connect the ToneMatch to the PC audio input port on the SX20 - and use the SX20 audio output to feed the endpoint audio back.  That's the simplest way I can see to do it... is there a good reason that the person has to use the ToneMatch?

Wayne
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[snake1134]

Hi Wayne,

yes that was actually my solution and I already tested it and it worked with a slight audio feedback. The problem is my boss wants it to be that way and he is asking how can we set that up. Thanks for your knowledge Wayne. 

I will check the thread about third party microphones for SX20. Cheers.

[snake1134]

Hi again Wayne,

I figured that a 4 pole to XLR is what they commonly use as adapter for third party mic. I wonder if that will work since our mic is separated by a ToneMatch unlike theirs which is connected directly to the SX20. I wanna know if this is safe and will work cause we can order a 4 pole to XLR(if available) and connect it from the ToneMatch down to the mic input of the SX20. Thanks in advance.

[t.svatek]

Hi

I also think, that your requirement is unclear. Why do you want to connect Microfone via the Mixer? Do you want to hear yourself via the speaker system? If not, connect the Mic directly to the SX20 or keep sure to not mix all signals together by using the AUX Port of your mixer. Anyway, you will have to bring the mixer output signal to mic level.

regards,

Tino

[snake1134]

Hi Tino,

Yes my boss actually wants to hear himself in the speaker during conference like in the TED talks while others around the globe listen to him via SX20. My question is if it will work, Mic to ToneMatch to SX20.

Also what do you mean by bringing the output signal of the ToneMatch to mic level? Thanks for your help.

[t.svatek]

I don´t know these Bose devices, but in general:

Important is to get 2 different mixes on your mixer:

Mix A: Mic + SX20 Output to the Speakers

Mix B: Mix to SX20 Input

Otherwise, you would feed back the SX20 output to the SX20 input - not a good idea ;-)

Usually, you can do that by using the AUX Channel on your mixer. So put only the Mic to this AUX Channel and use the AUX-Output to connect this signal to the SX20:

Regarding Level: It´s not a good idea to only drop down the volume on the mixers output, because you will get some noise into the signal. Better use an external DI-Box with a pad-switch to do that job. If you do not know, what a DI-Box does: better involve an pro-audio-expert ;-)

[snake1134]

Hi again Tino,

I don't think there are enough AUX to be used as input and output. I don't know what you mean by other AUX channel. The ToneMatch only has one AUX output.

I was planning to connect the Mic to the channel 1 mic input of ToneMatch then the SX20 's mic input will be connected to the 4/5 of the ToneMatch as can be seen in the drawing.

Wayne said though that it won't work because the mic input of the SX20 is a 4 pole. I'm planning to use XLR to 4 pole if that's the case but will it work? Thanks again.

[t.svatek]

I haven´t wrote "other AUX channel". I have wrote "the" AUX channel. Simply use "the" AUX channel ;-). But if you have no clue how to do that, please involve someone, who is familiar with such devices (maybe from where you by the Bose devices or a AV-Pro.) Such guys can also provide you the needed cable (which usually is not available ready-made), a DI-Box and knowhow. Not a big thing for them.

[snake1134]

Did you mean "Aux Channel" and "Aux output" are the same or no? That's what I meant with the "other aux" cause I think you meant two Aux are there. one for input and output but I can only see one Aux output here labeled at the back.

I admit I'm not good with these that's why I asked for help.

[t.svatek]

I mean the "Aux output" and it´s important to only route the Microphone Signal to it. Do not use the Master Output, because it contains the SX20 Output Signal as well.

[Wayne DeNardi]

Given you don't seem to have an XLR on the ToneMatch, you're best to get/make the cable you actually require - otherwise, you'll be going 4 pole 3.5mm to XLR , to then have to go XLR -> 3 pole 6.5mm.

Looking at the documents, I'd be buying/making a 6.5mm Male to a 4 Pole 3.5mm Male (and not connecting the R2 connector), and plugging this from the "Master Output" on the T1 to the SX20.

Use the image in this other thread as a guide, and wire it to the Tip, Ring, Sleeve on the 6.5mm plug rather than the XLR.

Wayne
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[Lawrence James]

As everyone has already said it possible the physical connections are easy to overcome it is the feedback that you must worry about not only on your end which is relatively easy to fix you need to ensure that echo is not sent to the far end as well. And the same problems that cause local feedback also cause echo. There are a lot of means to mitgate the issue - mic, speaker placement, adjusting freqs (if possible), adjusting volumes, and etc... But the only sure way is use Auto Echo Cancelation and Feedback Eliminators found in most DSP's. The CODEC has some built-in AEC but it can be confused by other sound processing devices, mic/speaker placement and etc... What you need is a means to remove the Room Reinforcement Mix from the Mic Mix that goes to the far end.

So if after your config and testing you hear a little feedback then you need to do more - a little now will be a lot at the worst time. The Bose is made for local audio but it has no provision for elimnating the echo to the far end.

Look at some small sound DSPs from Extron or other that have AEC and Feedback processing moduals.  Extron DMP 64 or DMP 44 LC  or MVC 121 Plus

The only sure way to fix is