A new possible client called on us to work out headphone listening for him and his wife. While there, a much larger problem reared its head. This thread is devoted to the other problem.

It's a Matrix M-series head unit with 8 LEDs across the front and 8 keypads. The keypads look like AMX product model DAS-KP-4E-G. The firmware updates shown for this product all have AMX part numbers.

It seems that AMX has acquired this "Matrix" company, but while I can find an image of the discontinued keypad, there are no images of discontinued Matrix units at the AMX site. Any help on that would be appreciated!

Anyway, we looked at the back of a keypad. It had four 16 ga conductors going in and four 16 ga conductors going away from it. Despite there being ICs and LEDs on the keypad, there are no dedicated power or data wires. (I'm wondering if they put left and right grounds at different potentials and get DC and data out to the KP that way, but I see problems with that.)

One keypad, which I'll call A, worked fine. Keypad B worked fine but seems to have one LED out. Two other keypads, C and D, worked fine. I did not try the other three or four.

As we were checking out how the system worked, we found a problem: a horrid noise came out of speakers in zones A and B. The noise sounds a bit like a tone being modulated by FM interstation noise. A spectral analysis shows a major frequency of about 390 Hz with other noise strong up to 3.5 K but declining up to there and beyond.

After some testing, it comes down to this:
*The keypad accomplishes volume control via a pushbutton to lower and a pushbutton to raise volume.
*We checked four zones, A, B, C, and D.
*This noise occurs in both zones A and B, not in C or D, when the volume for BOTH A and B is anywhere above zero.
*The sound never played in zones C and D
*Volume control adjustments in zones C and D did not affect the noise in zones A and B.

The client had to leave the house then so we had to quit testing.

First, any idea what this might be?
Second, since the brand is now owned by AMX, and the client is underwhelmed by the original installer, do we need to locate an AMX dealer for any work on this system?

edit: clarified the title

Can you post a photo of a keypad?

Is this the same Matrix company that was part of Marantz?

The description seems like IM distortion- what is the speaker load?

I don't know what it was part of.

The keypad is shown at [Link: amx.com]

IM distortion is a signal that is a product of two other signals. It changes as sound level changes, but not directly. This sound occurs when no audible signal is coming out of the speakers, and when the sound is turned up the signal stays at the same level. It also occurs when I've selected the CD Player but the CD is paused, so there's not even a low level signal going out of the amp.

I don't know what the speaker load is; I can see there's one pair on each amp output pair.

Maybe I'm right about the keypad being powered in a strange way, and something's wrong with those two keypads. I need the manufacturer!

Matrix Audio was a Canadian company. I installed about 15 of their systems. They were purchased by AMX shortly after their 2nd gen stuff came out. It was the only keypad systems that didn't require a CAT5 or some type of control wire. It hooked up in place of a volume control

They have a problem with their second gen stuff where the zone boards go bad. One Zone board has the routing and amp for 2 zones. Zone A and B are on one board. We put these systems in in 2005-2006. In 2008 we started having problems with them. They would send me the zone board, and I could send the old one back. It's very easy to change. Call AMX and see if they will send you a zone board. I have since changed most of my Matrix systems over to Sonos.

FYI you can control the Matrix via another type of Control system. There is an RS232 on teh back, and you could use RTI, URC, etc to control it if you need. I think I have the RS232 protocol somewhere for it.

The keypad in the link looks familiar, from working on a Matrix system in the past but I don't remember the wiring scheme. I think I may have a manual from them- did you, or can you, get the model of the controller? It's going to be easier to get info if you use that when looking online and I think the AMX part number is going to lead you to more dead ends.

I'll look in my other laptop and hard drive for the manual but I don't know how long it will take- I'll post it if I find it.

The one I worked on had been place under a shelf at the client's bar area and some kind of liquid had dripped in causing it to lose a couple of channels- I would inspect the main unit for evidence of liquid. IIRC, the one I worked on had water damage to one of the keypads, which caused the main unit to need repair but this was in '05 and they were still being repaired at that time. The keypad had been installed in an outside wall that had water intrusion but in an Arlington LV-1, not a sealed box. The insulation that was pressing against it was wet, too.

If you get more time to check this out, I would remove the offending keypads and wire them directly to the main unit, AT the unit. Also, I would check the wiring to the disconnected keypad(s) for shorts between each wire and also to the electrical ground. Ask if the start of this problem coincided with work that was done on the house. If the house has a basement or crawl space, I would look there- if a plumber was sweating pipes near the cables, they may have burned something without admitting it.

I would hesitate to connect an offending keypad to a different zone, but you could have them sign a release if you want to risk it.

This link doesn't show a date, but might be relevant to your search-

[Link: amx.com]

Here is a webcache of an early Matrix Audio install manual.

[Link: webcache.googleusercontent.com]

These units come up on eBay from time to time.

Here's an early one.
[Link: ebay.com]

And a later version.
[Link: ebay.com]

The link that highfigh provided shows an image of the unit we're dealing with: [Link: amx.com]

It's been in a closet, six feet off the floor and thus dry. It's in the San Fernando valley, which can be hot, but has a truly effective exhaust fan and a thermostat in the closet. The closet walls are drywall and there's no evidence of any kind of damage to the walls, so, no leaks.

There hasn't been any recent work on the house and the client didn't even know the system made that noise. It didn't show up until the other day when two A/V guys, one of them me, came in and turned on more than one zone at a time.

highfigh, what is your purpose in removing the keypads and wiring them directly to the main unit? Is it for testing? I can't imagine he'd be happy having the outdoor control and upstairs bedroom control in the downstairs closet!

jmitch, do you know of a way to save that manual other than as an .htm file?

Thanks for the help, everybody!

Moving the keypads to the controller eliminates the wiring and lets you know if that's the problem and it's no more time-consuming than removing the keypad, disconnecting the wiring from the controller and testing. I didn't mean you should move it permanently, just test it.

regardless of whether the unit is near water, I would look inside with the cover off- they have termites and other insects that could get inside and become the load.

To save as something other than HTML, Right click, click on Select All, select Copy and then paste to a Word doc, or whatever you use.

Does the owner have big breasts?


Btw, where are all the model numbers? You wouldn't want to be labeled a hypocrite.

I do believe the #1 answer was given in post number 4.

I believe the post number 10 to be correct.

The first line of my first post says:


His wife wasn't there; he doesn't appear to have large breasts; I didn't rummage through the refrigerator for chicken parts just to cover everything for you; why are you asking this about him?


I wrote


We didn't start out by gathering model numbers because a)it was a fluke that we ran across this problem at all, and b)the idiots who put the system together left us NO SLACK in the wiring. When we first tried to move the unit to get info from the back, a keypad wire pulled out, so we put it back in and switched to testing.

It doesn't bother me if you label me a hypocrite. Before I started harping on model numbers, nobody here could have been a hypocrite for leaving out model numbers. Now that you're paying attention to it, we're all more likely to provide model numbers than before, even if only marginally more likely. Thus I've raised the bar here for all of us.

It's a good thing that I could be labeled a hypocrite for not giving model numbers, as it shows the standards are higher here. The only place with no hypocrites, we being human and always likely to fail, is the place with no goals or standards of performance. So yeah, go ahead and label me.

Sounds like a board issue to me, like vwpower44 said.

If you want to replace it, a good option would be Sonos and find something to plug the holes where the keypads were or talk to Nexus Audio Systems.

You don't know what motorboating is?

http://m.

Yeah. That was it. And yet, I still have no idea how large the client's breasts are.