You must log in or register to post. Registration is free! [ Register ]

The Recording Project Forum Index -> Creative Ideas

FAQ Search Photo Album!
 Interfacting audio with telephones
View previous topic :: View next topic 
Post new topic  Reply to topic
Author Message
gfh Offline
Giant Member


Joined: 02 Dec 2003
Posts: 3721
Location: Scenic NJ
Age: 41


PostPosted: Wed May 16, 2007 10:07 am    Post subject: Interfacting audio with telephones Reply with quote

The business below mine moved out, and the building management let us ransack what was left of their server room. One of the things I picked up was a module that apparently fed audio into their PBX for their hold music.

It's got a single RCA in, and RCA out, and two screw terminals that are labeled PBX out. The only control is gain, and it's set with one of those tiny trim pots that you turn with a small screwdriver. I know very little about how phones work, but do you think there's any chance I could rig this up to make audio sound like it's coming out of a phone? I've tried to reproduce that effect in the past when doing sound for film and would up recording it by literally holding a mic up to the phone and calling it, but that method is kind of a pain.

Thanks!
Back to top
View user's profile Send e-mail
RedStone Offline
Giant Member


Joined: 27 Nov 2004
Posts: 1431
Location: British Columbia, Canada


PostPosted: Wed May 16, 2007 12:47 pm    Post subject: Reply with quote

have you tried searching for an impulse response over at noisevault ... I'm sure they've got something. Telephones tend to have a narrow frequency response - primarily from something like 300hz to 4khz. Two sharp filters at either point might work as a decent emulation.
_________________
I feet the flatline of my existence disrupted with heartbeat hills and vallies
http://www.levityproject.com
Back to top
View user's profile Visit poster's website
gfh Offline
Giant Member


Joined: 02 Dec 2003
Posts: 3721
Location: Scenic NJ
Age: 41


PostPosted: Wed May 16, 2007 1:02 pm    Post subject: Reply with quote

I mostly just want to make this box work. I'm more into the quest than the result.
Back to top
View user's profile Send e-mail
mblindsey Offline
Active Member


Joined: 04 Mar 2007
Posts: 157
Location: Kansas
Age: 44


PostPosted: Wed May 16, 2007 1:37 pm    Post subject: Reply with quote

What is it? Manufacturer/model.

(i work for a phone company)
Back to top
View user's profile
gfh Offline
Giant Member


Joined: 02 Dec 2003
Posts: 3721
Location: Scenic NJ
Age: 41


PostPosted: Wed May 16, 2007 2:57 pm    Post subject: Reply with quote

It's some generic piece of crap. I'll post the details tonight, but I could barely even find mention of it on Google.
Back to top
View user's profile Send e-mail
MDK Offline
Active Member


Joined: 28 Mar 2006
Posts: 175
Location: North Carolina
Age: 56


PostPosted: Wed May 16, 2007 3:02 pm    Post subject: Reply with quote

I made a phone recording interface with a 600:600 ohm phone isolation transformer, a capacitor and a resistor. I don't recall the values off the top of my head, but I can probably find out if needed.
I've also created a phone effect using Cooledit based on some knowledge of telephone specs. I cut everything below 300Hz and everything above 3300Hz, then convert to 11Khz/8-bit sample rate. I then had to convert back to 44.1kHz/16-bit to import it back into my Sonar project, but it sounds like the real deal.
Back to top
View user's profile Visit poster's website
gfh Offline
Giant Member


Joined: 02 Dec 2003
Posts: 3721
Location: Scenic NJ
Age: 41


PostPosted: Wed May 16, 2007 6:21 pm    Post subject: Reply with quote

mblindsey wrote:
What is it? Manufacturer/model.

(i work for a phone company)

It's a Music Source Adaptor, Model MSA-9101 from Telecom Periherals. There's a sort of diagram on the back that indicates audio in, audio out (both RCA mono, apparently) and screw posts for Tip/Ring wires on the "PBX Music Extension." It appears to be passive, although there's a gain trim pot accessible from the outside through a small hole in the back, so maybe it gets power from the PBX.
Back to top
View user's profile Send e-mail
mblindsey Offline
Active Member


Joined: 04 Mar 2007
Posts: 157
Location: Kansas
Age: 44


PostPosted: Fri May 18, 2007 6:20 pm    Post subject: Reply with quote

Sorry gfh, I tried. I couldn't find any "old timers", or anyone else for the matter, that could tell me about this piece of equipment (or others like it). Seems like VOIP has taken over everyone's brain....
Back to top
View user's profile
gfh Offline
Giant Member


Joined: 02 Dec 2003
Posts: 3721
Location: Scenic NJ
Age: 41


PostPosted: Fri May 18, 2007 7:09 pm    Post subject: Reply with quote

Cool, I appreciate you checking. I'll keep experimenting.
Back to top
View user's profile Send e-mail
Display posts from previous:    View previous topic :: View next topic 
Quick Reply      
Use this form to post a quick reply without having to go through the normal reply process.    
     
Post new topic   Reply to topic    The Recording Project Forum Index -> Creative Ideas All times are GMT - 7 Hours
Page 1 of 1
Jump to:  


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum