Whole house audio with voice announcements

[WayneW]

Over my head on the "audio-taper pot...

I assume that's some kind of potentiometer? How would I control the resistance or is it automatic some how?

Potentiometers (pots) basically come in two flavors, linear and audio. Linear is, well, linear, so 30% rotation gives you 30% of the resistance. Audio is logarithmic (I think) and has less resistance change per degree at one end. The idea being that turning the knob a little bit when the volume is low only changes the volume a little bit so you don't blast your ears. Linear and audio feel & look the same from the outside and have the same value (which is measured end-to-end).

 

[Dean Roddey]

I thought it was a spliff that reduced your hearing.

 

[johnnynine]

Over my head on the "audio-taper pot...

I assume that's some kind of potentiometer? How would I control the resistance or is it automatic some how?

Potentiometers (pots) basically come in two flavors, linear and audio. Linear is, well, linear, so 30% rotation gives you 30% of the resistance. Audio is logarithmic (I think) and has less resistance change per degree at one end. The idea being that turning the knob a little bit when the volume is low only changes the volume a little bit so you don't blast your ears. Linear and audio feel & look the same from the outside and have the same value (which is measured end-to-end).

I see, I didn't know their were specific ones for audio, thank you.

So I guess I can't envision the wiring that roussell is suggesting...

I can see using a relay to switch the radio audio off or through a preset potentiometer, but I don't see how the the voice announcements get wired in? Would I need another amplifier since it is coming for the pc as line-out?

 

[upstatemike]

What I do is feed the sound card audio to a radio shack PA amplifier. I use the 70 V output from the amp to feed audio to the locations where I want voice announcements. I use a cheap 70V audio transformer to convert back to 4 or 8 or 16 ohms (based on the speakers I am using at that location). The transformer also has different taps to pick the power output which lets me set the announcement volume.

I have a lot of different configurations for announcements. Some places have dedicated speakers (20W Elk units) while in other locations I share a stereo or surround sound speaker or even a speker from a table radio.

In all cases the speaker is attached to an Alarm Controls double pole/double throw relay (very cool cause they only use 11mA). The regular sound feed from the local stereo or whatever passes through the Normally Closed contacts while the speaker feed from the PA transformer goes to the Normally Open contacts.

My stargate controls the relays which interrupt the local program for HA announcements. If I need to pause the local program first, Stargate does it via IR command.

I don't do program pausing for "whole house" synchronized audio programs because a lot of my HA announcements are directed at a particular area only. I don't want to pause the music in the whole house when making an announcement that is directed only at the kitchen for example. (And if I paused it just in the kitchen, it would be out of sync with the rest of the house when it resumed).

 

[roussell]

So I guess I can't envision the wiring that roussell is suggesting...

I can see using a relay to switch the radio audio off or through a preset potentiometer, but I don't see how the the voice announcements get wired in?  Would I need another amplifier since it is coming for the pc as line-out?

Sorry, I should have been more descriptive. I've drawn a quick schematic of a passive 2 channel audio mixer with ducking. Don't laugh at the drawing; it was done in MS paint. :huh:

Basically, it allows you to attenuate both incoming channels to taste and then to further reduce the volume of the main input when a relay is activated. The circuit is pretty simple and could be simplified further if needed but this is an example that should give you the control you need.

R1-R3 are all 10k ohm dual (stereo) audio-taper potentiometers
R4-R9 are 10k ohm 5% carbon-film type resistors
RLY1 is a Double-Pole-Double-Throw relay with a coil voltage of your choosing.

Everything should be available at your local Radio shack and should cost less than $15-$20 including a small enclosure to house it all.

During normal operation, audio signals flow through the input connections, are attenuated and mixed together by the resistors and flow out as one signal through the output connections. When the relay is energized, the main audio is re-routed through the additional pots than can be set to a lower level than the main. That gives you the muting or ducking effect you are looking for. You can also choose to not activate the relay and have the HA speak and the main audio mixed together. That could be useful for normal announcements and then switch on the relay to reduce the main volume for more important announcements.

Hope that makes a little more sense than my first post.

Terry

(Edited to touch-up drawing)

 

[johnnynine]

Thanks you guys for your suggestions. At this point I want to have CQC (when I jump on that bandwagon) doing all my voice announements that way I can do TTS or mp3 files as well as potentially doing some pausing, etc.

So roussell's solution looks pretty slick, but that then requires that I control the relay from the pc using CQC.

I can drive the relay with a Carls Electronics CK1610 for about $65 which is not as cheap as I had hoped but if I must...

I understand what wiring needs to take place but I have 3 questions...

1. For the DPDT relay I would have no idea what kind of voltage I would need.
2. Is this for audio line-out or amplified speaker cable?
3. This is not really important but if you have a minute to explain what the purpose of the 10K resistors I would appreciate it. I understand the resistance in the pot will decrease the volume but I don't know what the other resistors do. It seems like if I turn the Pot volume all the way up I would have a balance of 10K resistance on both sides causing 50% of the sound to go to the ground? Or is that the desired effect since we are joining two audio signals?

Thanks for taking the time to do the schematic, it is awesome!!! I color coded to help me understand it a little more.

Edit 1: Attached image instead of linking it.
Edit 2: Inserted question 2.
Edit 3: Added to question #3.

 

[johnnynine]

Ok after a few hours of researching I think I have the answer to #2 and #3 but not #1...

#1 ??????
#2 line level
#3 Most amplifiers have about 10k ohms at the line out at somewhere between 200mV-300mV. However I didn't really find an exact # for either but I assume there is a standard. By combining the wires in parallel the impedence stays at 10k, volts stay around 300mv but our ampres double (causing the power to double. So to half the power back down the original watts the 10k resistors are added.

I hope that's right. :huh:

Edit: However when I look at the specs for an Outlaw 990 it shows:

Input Impedance, output 1 V
Phono (MM): 2.5mV/47kohms
Line (CD, Tape, Video): 200 mV/47kohms

So if I was using it would I want 47k resistors?

 

[pkoslow]

Johnny,

There are a number of commercial mixers that will do this with ease and come up on Ebay often for ~$100 or less. They'll even provide for multiple sources and zones but the ones in this price range can only be controlled manually (no remote or RS-232)

A couple examples are the Rane CP series and the BiAmp SPM Series

http://cgi.ebay.com/Rane-CP-64-with-Two-Se...1QQcmdZViewItem

http://cgi.ebay.com/ADVANTAGE-SPM412e-STER...1QQcmdZViewItem

I've owned and used both and they work great as they will automatically "duck" the audio while TTS announces and then restore it to the previous level once complete.

If you can find a deal on a BiAmp SPM723, these are EXCELLENT preamps for this application with 7 stereo inputs, 3 zone outs and 2 mic inputs. These are completely configurable using RS-232 and even have presets that you can recall. The audio ducking for TTS announcements is completely configurable so that music can be completely muted, or just reduced by a certain amount. The delay before the music returns is also configurable as well as the ramp rate which allows the music to slowly fade back!

The SPM723 was the heart of my home grown audio system before moving to the Russound CAV6.6 (I really miss the music fading back up after an announcement). These often go for more money when they show on Ebay, but I just searched and here's one that sold for under $100 including shipping a couple days ago:

http://cgi.ebay.com/BIAMP-Advantage-SPM723...1QQcmdZViewItem

You can find the manual here:
http://www.biamp.com/manuals/SPM723%20mnl.pdf

If anyone gets one of these I can provide some scripting examples that show the RS-232 control commands.

Cheers,
Paul

 

[upstatemike]

This looks pretty cool. If I could find one for under $100 I would definitely give it a try!

 

[Stinger]

I have a whole-house system that connects to my Stargate, XM radio and computer for MP3 playback via a receiver. The receiver then connects to the speaker distribution system.

The way I switch between different sources on the receiver is via IR commands from my stargate. When I send a command (from X10, touchscreens or even my pronto) to start different MP3 lists playing, it sets a flag on my stargate to let it know that MP3s are playing (MP3 =1) and sets other status flags off (stargate voice=0, xm=0). If the phone rings, I have logic to check to see if the speakers are currently in use, and if they are, they will change the source via IR back to the stargate so it can announce caller ID. 10 seconds later it will resume back to the MP3s playing on the speakers, unless the phone goes off the hook, which will keep the speakers silent. Once I hang up the music will go back on automatically. This is one very useful feature of the stargate phone board. The same action occurs when any other stargate announcement needs to take place, such as motion detected around the perimeter of the house or doors/windows opening.

Of course everything I said above can have stargate substituted with homeseer software and misc hardware connected to it (IR interface).

I've used this setup for years, and it's been just as reliable as a hardwired switching system.

 

[roussell]

Ok after a few hours of researching I think I have the answer to #2 and #3 but not #1...

#1 ??????
#2 line level
#3 Most amplifiers have about 10k ohms at the line out at somewhere between 200mV-300mV. However I didn't really find an exact # for either but I assume there is a standard. By combining the wires in parallel the impedence stays at 10k, volts stay around 300mv but our ampres double (causing the power to double. So to half the power back down the original watts the 10k resistors are added.

I hope that's right.

Edit: However when I look at the specs for an Outlaw 990 it shows:

Input Impedance, output 1 V
Phono (MM): 2.5mV/47kohms
Line (CD, Tape, Video): 200 mV/47kohms

So if I was using it would I want 47k resistors?

Sorry for the late response, I've been away from the 'net for a few days.

#1 It depends on the "thing" you're going to switch it with... If, for example, you are using an X-10 appliance module, then you might want to go with a 120V AC coil (although I'd avoid this to keep out and 60Hz hum in the lines). A better solution in an X-10 environment might be a 12V DC coil powered from a wall-wart plugged in to an appliance module.
#2 Yep, sorry for not mentioning that
#3 You're correct, the input impedance is at least 10K on most audio amplifiers, but can also be 22K of as you noticed 47K. The 10K fixed resistors will work as they are the minimum value the amp would expect to see. You can also go with the 47Ks and be fine as well. The difference between the two will be that the 10Ks will sound a little "brighter" than the 47s.

Since you are driving such a great amp (I've been looking at the same one), Your best bet may be to go with pkoslow's recommendation of the BIAMP SPM723. I used to install these and they are excellent.

Terry

 

[johnnynine]

Thanks for the awesome technical info roussell!!! That was a good learning experience.

Just for clarification, I don't have an Outlaw 990 and likely won't due to the hefty price tag and need for separate amplifiers. I do plan on upgrading in the next year or so... when I find an amp that supports Dolby TrueHD and DTS-HD, has HDMI inputs, and RS232.

Edit: typo