NEED HELP PLEASE!!! Aftermarket amp to MACH Head Unit issues.

[97SHOgt]

Alright everybody, I need some help bad. I had another thread going about adding an aftermarket amp to replace the facotry amp for the sub in a 99 MACH system. I have everything wired up correct I think, the power comes on and off when I turn the radio on and off, YET NO SOUND WHATSOEVER!!!

Here are some pics of what I have...

It says to connect it to the left and right speakers. But in the MACH system those speakers receive no bass signal correct? So I connected it to the sub wires coming from the head unit. First I connected both + wires from the PAC together and connected it to the + sub wire, and the same for the negative. NO SOUND! Then I tried just connecting one set of + and - because I only need one channel. No sound either.

Here is a pic of the second try.

Here is where I grounded it, could this be a problem?

Here are the amp connections...

When I adjust the bass boost setting the sub moves in and out. It seems like it just isn't getting the signal.

Please throw me any ideas you have. I'm going to lose it. As you can see the two heads up pennies in the first pic have brought me no luck! Thank you everybody.

 

[97SHOgt]

Sorry, I meant to edit the first post...

 

[diamondback2k9]

Your ground should be okay since that is about the same place. Try sanding the air when the ground is touching.

 

[scucci]

Mach sub woofer outputs are not speaker level, they are preamp level differential outputs(balanced outputs similar to xlr microphones and other professional audio equipment)This is done for its superior noise rejection. There is a negative output ( not ground), a positive output and a shield ground. RCA outputs are positive(center pin) and ground known as unbalanced.

http://en.wikipedia.org/wiki/Balanced_audio_connector

I used a soundgate LO CB.2 to convert the differential output to single ended RCA plugs (non balanced). This prevents the negative preamp output of the mach head unit from getting shorted to ground and blowing the differential driver pair. The output of the LO CB.2 goes to the preamp level inputs on the sub woofer amp.
Soundgate.com search for locb.2 to get more info.

The remote turn on lead from the head unit is 5 volt logic level. In order to use it to turn on an aftermarket amp it needs to be converted to 12 volts. I used a Peripheral electronics LVT2 to do this. That way the sub amp comes on with the original delay from the head unit, and the mute button on the head unit mutes the sub woofer, just as the OEM does.

Hope this helps
Scucci

 

[97SHOgt]

Mach sub woofer outputs are not speaker level, they are preamp level differential outputs(balanced outputs similar to xlr microphones and other professional audio equipment)This is done for its superior noise rejection. There is a negative output ( not ground), a positive output and a shield ground. RCA outputs are positive(center pin) and ground known as unbalanced.

http://en.wikipedia.org/wiki/Balanced_audio_connector

I used a soundgate LO CB.2 to convert the differential output to single ended RCA plugs (non balanced). This prevents the negative preamp output of the mach head unit from getting shorted to ground and blowing the differential driver pair. The output of the LO CB.2 goes to the preamp level inputs on the sub woofer amp.
Soundgate.com search for locb.2 to get more info.

The remote turn on lead from the head unit is 5 volt logic level. In order to use it to turn on an aftermarket amp it needs to be converted to 12 volts. I used a Peripheral electronics LVT2 to do this. That way the sub amp comes on with the original delay from the head unit, and the mute button on the head unit mutes the sub woofer, just as the OEM does.

Hope this helps
Scucci

I wish I would have known this before.

That device I have converts does everything your last paragraph says. I tried wiring to the rear speakers and figured that ouldn't work. At least I got sound though.

So there is no way to just tap RCA wires into speaker wires? How does that Soundgate device attach to the factory wiring?

 

[scucci]

The locb.2 has a left channel and a right channel. In the case of the sub woofer you would just use one of those channels. The two output wires from the subwoofer out on the head unit go to one channel. The output of the locb.2 is two rca plugs. Use the output from the channel that is wired to the the head unit to the sub-woofer amp rca preamp inputs. If your amp has two input rca's you can just add a y adapter or wire the head unit to both channels and use both outputs. It sounds complicated but it is not. The locb.2 has a chip inside that has differential inputs and non balanced outputs. It also has a binary switch inside that you can use to set the output swing to match to your amp. It has a ground connection and a 12 volt power wire also. It is a bit pricey -$100 to $130 depending on where you buy it.

You might try contacting pac to see if they have another solution. I don't have anything to do with soundgate, so I am not trying to sell you on them. They are just the solution I used.

Scucci

 

[CDW6212R]

That's good advice, as usual. I found about the two signals on the sub output, and took the suggestion from the man fixing my Mach HU. I have yet to test the sub output yet, but he added five RCA output cables to mine. I don't think I'll have a mute function for the Sub though, he doubted it before doing the work.

The Mach HU is a great radio though, I miss it, haven't driven that truck in months. Regards,

 

[toypaseo]

Are there level adjustments on the trunk-LOC?

Have you tried tapping the sub signal after the OEM sub amp?