Music on Hold - 100 Ohm source when PBX expects 600 Ohm?

[Gavin Henry]

Hi,

Would this work where the source is of lower impedance than what the pbx
expects?

Thanks.

 

[Gavin Henry]

BobW wrote:

"Gavin Henry" <ghenry@ghenry.co.uk> wrote in message
news:VJ6dnY117eeOW-rVnZ2dnUVZ8uCdnZ2d@posted.plusnet...
Hi,

Would this work where the source is of lower impedance than what the pbx
expects?

Thanks.

What is the connection? Is it 2WEM, 4WEM, POTS? What's the loop length?

If it's a short loop, and you get the levels correct, it shouldn't matter.

Bob

It's just a bog standard headphone connector/cable, the sort you'd plug
into a mp3 player etc.

 

[Don Bowey]

On 7/11/08 1:44 PM, in article
VJ6dnY117eeOW-rVnZ2dnUVZ8uCdnZ2d@posted.plusnet, "Gavin Henry"
<ghenry@ghenry.co.uk> wrote:

Hi,

Would this work where the source is of lower impedance than what the pbx
expects?

Thanks.

As long as you can set the signal amplitude to what you want, the impedance
won't matter much in this application.

 

[Gavin Henry]

BobW wrote:

"Gavin Henry" <ghenry@ghenry.co.uk> wrote in message
news:_PudnbAHKppwU-rVnZ2dnUVZ8q2dnZ2d@posted.plusnet...
BobW wrote:
"Gavin Henry" <ghenry@ghenry.co.uk> wrote in message
news:VJ6dnY117eeOW-rVnZ2dnUVZ8uCdnZ2d@posted.plusnet...
Hi,

Would this work where the source is of lower impedance than what the pbx
expects?

Thanks.
What is the connection? Is it 2WEM, 4WEM, POTS? What's the loop length?

If it's a short loop, and you get the levels correct, it shouldn't
matter.

Bob
It's just a bog standard headphone connector/cable, the sort you'd plug
into a mp3 player etc.

"600ohms" refers to the characteristic impedance of a twisted pair of
standard telephony wire at audio frequencies. It doesn't sound like you're
interfacing directly with a twisted pair circuit, so its characteristic
impedance doesn't apply to what you're doing.

If you can provide some more details then we can help you make the right
decision.

Bob

Hi,

Thanks. On proprietry PBX and some Open Source ones, they can either
serve up music for when a call is on hold from local storage or an
external source. Most PBXes can take input sources in the range of
600 Ohm to 20K.

The appliance I am looking at is:

http://www.pikatechnologies.com/english/View.asp?x=608

and its audio chip is:

http://www.asahi-kasei.co.jp/akm/en/product/ak2306lv/ak2306lv.html

The appliance states an output impedance of 100 Ohm:

http://outgoingftp.pikatech.com/appliance/1.0/Docs/html/hardware_appliance/frames.html?frmname=topic&frmfile=index.html

But the chip can be set to provide different outputs.

Thanks.

 

[Gavin Henry]

BobW wrote:

"Gavin Henry" <ghenry@ghenry.co.uk> wrote in message
news:4-udnSxVrYKAd-rVnZ2dnUVZ8v3inZ2d@posted.plusnet...
BobW wrote:
"Gavin Henry" <ghenry@ghenry.co.uk> wrote in message
news:_PudnbAHKppwU-rVnZ2dnUVZ8q2dnZ2d@posted.plusnet...
BobW wrote:
"Gavin Henry" <ghenry@ghenry.co.uk> wrote in message
news:VJ6dnY117eeOW-rVnZ2dnUVZ8uCdnZ2d@posted.plusnet...
Hi,

Would this work where the source is of lower impedance than what the
pbx expects?

Thanks.
What is the connection? Is it 2WEM, 4WEM, POTS? What's the loop length?

If it's a short loop, and you get the levels correct, it shouldn't
matter.

Bob
It's just a bog standard headphone connector/cable, the sort you'd plug
into a mp3 player etc.
"600ohms" refers to the characteristic impedance of a twisted pair of
standard telephony wire at audio frequencies. It doesn't sound like
you're interfacing directly with a twisted pair circuit, so its
characteristic impedance doesn't apply to what you're doing.

If you can provide some more details then we can help you make the right
decision.

Bob
Hi,

Thanks. On proprietry PBX and some Open Source ones, they can either serve
up music for when a call is on hold from local storage or an external
source. Most PBXes can take input sources in the range of
600 Ohm to 20K.

The appliance I am looking at is:

http://www.pikatechnologies.com/english/View.asp?x=608

and its audio chip is:

http://www.asahi-kasei.co.jp/akm/en/product/ak2306lv/ak2306lv.html

The appliance states an output impedance of 100 Ohm:

http://outgoingftp.pikatech.com/appliance/1.0/Docs/html/hardware_appliance/frames.html?frmname=topic&frmfile=index.html

But the chip can be set to provide different outputs.

Thanks.

Gavin,

Thanks for the additional info. I'm not sure what your whole hookup is, but
if this Pika device is the source for the music-on-hold signal then its
output impedance is fine for driving your PBX. Even if the PBX says it takes
"input sources in the range of 600-20Kohms", in reality, it will work with a
source of ANY output impedance as long as you get the levels correct.

I'd say just hook it up, get the levels right, and then go out and have some
fun.

Will do!

Bob

You know, since I started computers late, around 2000 (actually did a
degree in Electronics and Communications BEng(Hons) but forgot
everything), I got into newsgroups, then I found Open Source and
GNU/Linux in 2001. I hadn't been back to a newsgroup since then and
always used mailing lists.

I remembered yesterday how *big* usenet was, and wasn't sure about the
*is*. I couldn't find any electronics mailing lists so came back here.

Great to see it's exactly the same as I remember it!

Thanks bobw, I'll make sure I subscribe to more and help out others, as
is the ethos.

Gavin.

 

[Tom2000]

On Fri, 11 Jul 2008 21:44:03 +0100, Gavin Henry <ghenry@ghenry.co.uk>
wrote:

Hi,

Would this work where the source is of lower impedance than what the pbx
expects?

Thanks.

From my experience, PBXs will take just about anything as their MOH
source. I used to use cheap tabletop radios, with the amp's speaker
output connected directly to the PBX. Your 100 ohm source should be
just fine.

This is one situation in telephony where proper impedance matching
isn't at all important.


Tom