Thought you might be interested in hearing the modifications I have done to the audio system in my 98 C5 coupe. I have replaced the Bose Signal Processor (BSP) with the Pioneer DEQ-9200 DSP that was in my other car and also added an automatic audio cut-in for auxillary devices, such as mp3 player, computer, etc. I managed to get the exact connector used in the BSP, so I didn't have to cut any wires. I mounted the connector to some perfboard that I used for the audio cut-in circuit and some input/output conditioning. The DEQ-9200 has RCA inputs/outputs, so I made some short cables that go from the perfboard to the DEQ-9200. The DEQ-9200 has six outputs just like the BSP, so everything matched up nicely that way. I took the BSP apart and used the portion with the mounting holes to mount my circuit board and the DEQ-9200 on. I drilled 3 holes in the shape of a triangle in the BSP bracket, the top of the DEQ-9200 hide-away unit, and in my circuit board. I connected all three using long bolts (and standoffs) such that the BSP bracket is between the DEQ-9200 and my circuit board. It fits perfectly except that the DEQ-9200 sticks down a little too far and pushes the drivers close-out panel down such that the climate control air intake doesn't quite line up with the duct in the close-out panel. I'll fix that when I get a chance. I didn't mount the DEQ-9200 faceplate anywhere yet. It is laying in the center console right now, with the wire running through the center console power outlet hole, under the center console to the BSP location. The wire for the 'accessory' audio cut-in is running from the BSP location, over the propeller shaft tunnel, under the passenger carpeting, and up through the hole in the carpet for the power seat wires. It has a stereo mini phone plug on it.
So, how does the system work. So far, pretty good, but there are still some issues. For instance, when I turn on the headlights, the circuit switches to accessory audio for a few minutes, and switches to accesory audio for a second when turning the ignition off. Obviously, there is some noise problems. I have the circuit set to cut-in on an audio signal of approximately 20 mV, so it won't take much noise to cause a switch. There is a slight high pitched buzz being generated by the DEQ-9200 that can only be heard when the car isn't running. Other than that, seems good. I set all the crossover frequencies to be 200 Hz, hooked up the microphone to the DEQ-9200, hit the auto-eq button and let the system figure out the best levels for each set of speakers, along with the best equalization curve. It does sound better than before. Now, I just have to experiment with microphone placement, since it does make a difference.
By the way, the audio cut-in circuit consists of a DPDT 12V relay, a power MOSFET, a couple of diodes, a 10uF capacitor, and two op-amps (one for each input audio channel), and a few resistors. The op-amps are wired as comparators and will turn-on the MOSFET (through diodes) whenever the audio signal is greater than the preset level, controlled by a potentiometer, which causes the relay to switch to the accessory audio program. About 1 second after the accessory program stops, the system switches back to the normal program.
Re: Automatic accessory audio cut-in and Pioneer DSP (NassauBlue)
I was curious.. is the BSP AFTER the volume control? That would mean that whatever you plug into your audio cut-in will have to utilize its own volume control..? I wanted to be able to use the normal volume control, that's why I went inside the HU for my aux input. Maybe I didn't have to do that?
Gary
Re: Automatic accessory audio cut-in and Pioneer DSP (C5GARY)
The BSP is after the volume control. The DEQ-9200 has it's own volume control, but I leave it at 25 (out of 30) and use the head unit volume control or the volume control of whatever is connected. My primary use for the cut-in will be for intermittent things, such as directions spoken by mapping software on a tablet PC and possibly CB/FRS/HAM radios, things which I don't want to be controlled by the normal volume control, and which have their own volume control. Basically, I need to use the car's amplifiers because those devices can't be heard in the car once moving, since, as we all know, our cars aren't exactly quiet. :)
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I was curious.. is the BSP AFTER the volume control? That would mean that whatever you plug into your audio cut-in will have to utilize its own volume control..? I wanted to be able to use the normal volume control, that's why I went inside the HU for my aux input. Maybe I didn't have to do that?
Gary
Re: Automatic accessory audio cut-in and Pioneer DSP (NassauBlue)
COOL! We are thinking alike. I bought a Ramsey(?) VOX kit that I am going to use for the cut-in.. mainly for the FRS radio. I put 2 relays inside and have a switch on one for the cellphone. Maybe someday I'll go mobile again (I'm WB6OGD) :)
Gary
Re: Automatic accessory audio cut-in and Pioneer DSP (NassauBlue)
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So, how does the system work. So far, pretty good, but there are still some issues. For instance, when I turn on the headlights, the circuit switches to accessory audio for a few minutes, and switches to accesory audio for a second when turning the ignition off. Obviously, there is some noise problems. I have the circuit set to cut-in on an audio signal of approximately 20 mV, so it won't take much noise to cause a switch. There is a slight high pitched buzz being generated by the DEQ-9200 that can only be heard when the car isn't running.
Interesting modification. Just wondering is the closeness of your mounting point allowing your cabeling to act as an antanae and false trip your 20mv signal level? Also would the output level of the Pioneer be enough to generate a (possible?) saturaton conditon creating the noise only heard when the car is off. I'm not an engineer, I just like to learn. :blueangel:
Re: Automatic accessory audio cut-in and Pioneer DSP (JoeyG)
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Interesting modification. Just wondering is the closeness of your mounting point allowing your cabeling to act as an antanae and false trip your 20mv signal level? Also would the output level of the Pioneer be enough to generate a (possible?) saturaton conditon creating the noise only heard when the car is off. I'm not an engineer, I just like to learn. :blueangel:
I don't think the accessory cabling is acting as an antenna. It is shielded, so it shouldn't be affected. However, the plug is not terminated, so it could pick up some noise. As I said in my topic title, this is version 1.0 of the circuit. I will be building another one using lessons learned from this one, which will hopfully solve all the minor problems of this one. As far as the noise, it is the same pitch as a sound that comes from under the instrument panel. I assume that every C5 makes this sound. If you turn the key to accessory and listen (in a very quient place) you should hear this sound. I am guessing that my circuit board (especially some of the wires on it) may be picking this up. Anyone know what is making the noise? Also, the Pioneer head unit makes the same high pitched sound, but I've had the unit connected to a home amplifier and didn't hear the sound through the speakers.
Re: Automatic accessory audio cut-in and Pioneer DSP (RPOZ4Z)
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NassauBlue,
do you still have the BSP?
if you do, would you be intrested in parting with it? :cheers:
I do have the BSP, but I want to keep it. Besides, it wouldn't be a complete unit since I am using the 'bracket' part of the case as a mount for my components. I'm still not 100% sure that I won't put it back. In theory, Bose should have done the same procedure that the Pioneer DSP does during automatic equalization and then hardwired the equalization curve into the BSP.
Re: Automatic accessory audio cut-in and Pioneer DSP (NassauBlue)
[quote]As far as the noise, it is the same pitch as a sound that comes from under the instrument panel. I assume that every C5 makes this sound. If you turn the key to accessory and listen (in a very quient place) you should hear this sound. I am guessing that my circuit board (especially some of the wires on it) may be picking this up.[/Qoute]
Possibly so,but noise is so easy to pick up and troubleshoot. I'd really be interested in hearing about the next version, or furthur developement for that matter. Good Luck
Re: Automatic accessory audio cut-in and Pioneer DSP (NassauBlue)
The VOX kit is a electronic project kit.. Voice Operated Switch(why X? I dunno) designed to switch a tape recorder or radio. Functionally identical to your switch (op-amp, some r's and c's etc). Only $6 parts and PC board, hopefully all debugged! If yours switches for minutes from a headlight transient, maybe you need some better decoupling...?
I don't think I hear any noise under my dash.. you sure its not the fuel pump?
Gary
Re: Automatic accessory audio cut-in and Pioneer DSP (C5GARY)
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I don't think I hear any noise under my dash.. you sure its not the fuel pump?
Gary
It's not the fuel pump. I just checked again. If I put an ear near the steering wheel and put the key in the ignition or open the door, I hear it. It continues for 20 seconds after taking the key out of the ignition. I can't hear it in my normal driving position, though.
Re: Automatic accessory audio cut-in and Pioneer DSP (NassauBlue)
Here is an update:
I've removed the Pioneer DSP and am now using the BSP. All the components for the audio cut-in have been installed inside the BSP housing. I bolted a small board to the rear (away from connector) top of the BSP board where I put my circuitry. This version works much better than the previous version. There are no false triggerings. To interrupt the head unit audio signal, I had to desolder one end of components C1951, C2951, C3951, and C4951 from the BSP board and run a wire from the board to relay and then from relay to the component. I'm not sure what CX951's are - maybe inductors? I drilled a hole in the top of the BSP for the accesory audio wire.
If anyone is interested in the schematic, let me know. I'm not totally done with the circuit, though. I think that some resistor values I am currently using are less than optimal.
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Automatic accessory audio cut-in and Pioneer DSP
