so I got my stock head unit sitting at my house building dust. I decided to embark on a little project to get it to service at home. I did this before on an older GM/Delco radio with decent success so I figure, why not with this one?

Well! So far, my biggest issue has been the power source. In the GM/Delco, I was able to hook up one of those adapters (u know, the big blocky ones that take up too much space on your surge supressors) and life was all good.

Now this time around, I was looking for my 12V adapter, and I recalled that you can supply a little less.. a little more. .. things would still work. Probably not the best practice.. but it can be done nonetheless.

I hook up adapter #1 12V 200mA ... crap .. nothing happens. my voltmeter shows 12V of juice, but nothing happens!

fine .. I hook up adapter #2 7.5V 300mA just for curiousity's sake. I get light!! but it seems to fade and pulse. When the CD goes in and starts spinning, it seems to draw all the power away from the entire system and it practically resets itself.

@#$ .. its probably the current draw. so I started hunting for big current adapters.. I found one !! 15V and 800mA! Everything runs now!! no power draw, no flicker!! cd spins .. etc. but I hook up the speaker.. and I get NOTHING!! not a peep! well, er, I did get a peep when I entered the security code properly . but after that.. nothing!! not even on radio..

so for the rest of the night, I tried a hobby train rheostat too.. It was neat seeing how I could dim the lights that way I didnt know the amperage on this one. wasn't marked.

in the end, it still didn't play anything on the speaker. I'm using the stock speaker.

so now, my question is, did the head unit fry in my experimentation? or is there some kinda internal sensor that wont let the built in amp kick in when it doesn't have enough power? or is there not even a built in amp? I thought there was!

now, I know that a friend of mine has my old rockford amp hooked up on a computer power supply. this is no cheese amp. its a punch 600a4 . .. and it works!! I was flabbergasted. He's powering 2 pioneer 10s in a box and now its part of his home theatre system.

now, new power supplies are ATX style and well.. they dont have that simple switch to turn it off and on. its motherboard controlled. Anyone know which wires to cross to simulate this turn on/off effect? I wonder if it'll even work in my case.. any ideas?

thanks

 

Hey thats a great idea. I have all the bose speakers laying in my room to and maybe I can have a lil bose home system now.

 

What year HU is it? If it's '99 and up the reason it won't work is because the HU is designed to work in conjunction with the factory EQ. The signal is sent from the HU into the EQ and then back to HU and THEN to the speakers.

I assume you clipped the factory harness so this is what you do:

On the black connector follow the diagram below and loop the inputs with the outputs.



Lemme know if it works,

Iggy

 

alright iggy, I'll have to try that. I wish I had some alligator clips right about now. I didn't bring that piece of the harness out from the car.

thanks

 

Nope, leave the EQ in the car.

All you need to do is connect :

orange to white
Orange/blue to black
Blue/green to red

Done!

What you are doing is tricking the HU to think that it is talking to the EQ when actually it is talking to its-self. In other words you are looping the signal back into radio. The only caveat may be that the stock bose speakers may sound even muddier than before because they rely on the EQ to give them some semblance of clarity..

let me know

Iggy

 

miwa,
Iggy is absolutely correct... The stock headunit has two stages. The preamp stage that has the volume control and selects the sources and then comes out at a line level. In the car, it then loops through the horrid EQ box before returning back to the power amp stage. Therefore you would hear no musical sound from the output until you do as Iggy has suggested. Once you jumper the connections as Iggy has outlined, the power amp stage will now be fed.

HOWEVER... You'll probably find that you still need a bigger 12Volt power supply at that point. Using simple Ohms Law with the four speakers, you would require 2amps-2.5amps per 4ohm speaker for full power out. This would be around 10amps total. WHERE DO YOU THINK THIS CURRENT COMES FROM????? It comes from the POWER SUPPLY of course! PLEASE DON'T TAKE THIS AS A FLAME, but it amazes me at those who talk about using gigantic 4 gauge power cable, and huge 1 farad caps, and then still need to upgrade the car to a much heavier alternator and battery in order to properly drive their systems. Then some of these same people expect that the system should work in the house being powered by a "wallwort" normally used to recharge their cell phones!:wow:

Granted the stock system isn't the 1000watt super amp system, but power is a logarithmic function that requires exponential increases for a minimal sound SPL increase. So even the lousy stock system of 10-20watts (times four speakers) requires 10amps to power it. The SUPER mod subwoofer systems require more like a 100amps. IN ANY CASE, a few hundred milliamps is a LONG way from the required 10amps. I think you will find that once you perform the EQ jumpers, you will have sound from the speakers, but if you turn it up much, it will sag the cell phone power supply to the point of having all of the functions crash and stop working again.

There is no reason that you can't use the car headunit in the house, but be realistic about its power requirements... You will have to buy a 12-14volt power supply capable of 10 amps in order to power it properly. 12-14 volts should be just fine for the headunit. The car starts out at around 12volts being powered just from the battery, and then jumps up to around 14volts once the alternator kicks in. If you push things at 15 volts or higher, you will get a LITTLE bit more power out of the headunit, but it will also cause the output stage to possibly overheat. Also, I'm sure that the cheap amp is loaded with tons of 16volt capacitors... you don't want to get too close to their breakdown voltage, or they could all explode and leak. Find something around 12-14volts that can put out 10amps and you should be rocking in the house. But, as Iggy said, without the EQ, the BLOSE speakers may sound more like AM radio speakers...

I could be wrong with all of this, but I don't think so. It's all the same reason why the 200mA and 300mA units wouldn't even power up the CD motor and display. YOU NEED MORE CURRENT! Again, please don't take this post as a flame... but THINK ABOUT IT... you can't expect to get the same results from something that normally uses a 120amp alternator and 300amp/hr car battery fed through a 20AMP fuse, and is now being fed from a cell phone charger

If you do get things up and cranking I would REALLY appreciate it if you could get back to me and report about how hot the back heatsink of the headunit runs while feeding the Bose speakers. IT IS TOO HOT TO TOUCH in the car while driving aftermarket speakers. I assume that this is the nature of the class AB bias employed. I expect that the BOSE load should cause the same heat, but I would love to know for sure...

THANKS!!! and good luck!
Southbound

 

As a quick follow-up 12-12volts at 10amps would be the minimum power supply that you should buy. At full stock power, it would be running at full capacity and it would get REALLY hot as well. Something more like 20 amps would be what you would really want. Remember this is what the stock system was fused at in the car. MAKE SURE THE POWER SUPPLY DOES HAVE A FUSE. It will probably have a fuse on the 120VAC line side, but I would also add a 10 or 20 amp fuse on the 12volt output side to be safe, depending upon how big of unit you can find. A used computer switching power supply might work, but it typically only supplies heavy current at 5volts. But if you have one lying around... try driving the BLOSE headunit from the +12volt power outputs. I'm sure they at least source a couple of amps... and that would be enough for you to see if things sounded good enough for you to want to search for a bigger unit. WATCH YOUR POLARITIES with the computer supply, because it probably has plus and minus 12volts. It may be plus and minus 15 volts. As long as you don't go up to 16volts you should be OK.

Hope I've helped to explain the needs of the situation...
Southbound

 

Miwa,
Ummmmm.........yaehhhhhhhh........... What Southbound said. You did'nt think you would get away THAT easy did you? JK Southy.:p

I reread your post and you mentioned that you did'nt have the connector from the car. So how are you connecting power sources and speakers?

Iggy

 

southbound:

heh .. heh .. b..bb..but I did it before!! granted.. I was not much a stickler for sound quality back in the day but I had it running more for the hack value .. anyway .. as always, your reply is most helpful. I kinda figured from my experiments that 300mA wasn't enough but I just couldn't fathom exactly 'how' much amps was necessary. I figured we powered a big amplifier from a computer power supply with a satisfactory result so that should at least work but I had no idea how much amps that was until today when I looked at one and it said 3A.

iggy:

my installer .. in his inane wisdom (sarcasm) .. decided to splice into the wires on the existing factory harness instead of getting a harness that plugs into that. Thus, I can't pull it out. (the blue one) So I bought another metra one that works just as fine. The black one, for the eq, I can cut out tomorrow I guess.

 

miwa,
Like I said earlier, power is an exponential function. You would be amazed at how loud just 1 watt can sound. Most speakers are rated at 1 watt input. Typically that gives you around 90 db of SPL at 1 meter. 1 watt of power through the 4 ohm speakers would only require .4amps per speaker. This would be 1.6 amps total if the amplifier was 100 percent efficient and not counting the power used for the CD motor and display, etc. But a computer supply that puts out 3amps at +12volts would let you drive the speakers to a couple of watts before clipping. That would be enough power and volume to run the headunit into the Bose speakers for background listening, etc. It would be fine for playing while you are clacking on this damn computer, or in the kitchen while you are cooking, etc. Or while you are in the bedroom with candles... etc:licka:

Just don't expect it to put out the volume that it did in the TL without a 12volt/10amp power supply. However, the difference between 1Watt to the speakers and 10Watts to the speakers is only 10db. The bose are darn efficient, that was the ONLY good thing about them. So they would probably give you 96db at 1 meter with 1 watt. That could be plenty for your purposes. At full power, (If you had a power supply that could stand up to that) you could expect to get around 106-109db at 1 meter. (10-20watts) Remember that twice the power equals 3db change in SPL... Four times equals 6db... Eight times equals 9db... Sixteen times equals 12db, etc. 10 times equals 10db.

If you have a spare computer power supply laying around... try hooking it up to the +12volt output and see how it sounds to you. It should work just fine up to 1 or 2watts, and that may be all the volume you want. BUT If it's for the kids or you to BLAST, then you will probably need something bigger.

Hey, HAVE A GOOD LABOR DAY WEEKEND EVERYBODY!

Southbound

 

I slipped a mental digit in my head and goofed on the math... 1 Watt through the 4 ohm speakers would require .5amps per speaker. So you would need 2Watts for all speakers and then some reserve for the CD motor, display, and amplifier inefficency factor. I'd guess that a 3amp supply would be good for around 1Watt into all four speakers, or 4Watts into two speakers, and not much more. Doubling the voltage or current through a speaker quadruples the power, because it is a "squared" function. But quadrupling the power is only 6db of SPL... Again, that may still be plenty of volume for you.

Give it a try... and give us a report...
Southy

 

alright!! it works!!!

great help, iggy, southbound ..

for the full details:
Hooking up the acura / bose at home

hope you dont mind me mentioning you guys. let me know if you do. As a matter of fact, I'm trying to make a tutorial/journal out of it -- kinda like iggy's adventures with his car upgrade. I'd like to quote some stuff from you two if its okay.

Here's the nitty gritty :

the EQ bypass WAS the problem! I shorted it, and voila!

the 15VDC 900mA adapter works!! it gives a SQ kind of like a clock/radio but it works!!

the computer power supply doesn't work fuh. ATX .. on top of that .. a nonstandard Dell ATX power supply is an issue to turn on without its motherboard. I tried hacking it according to some sites.. but without much success. Maybe I'll just get an AT one or a standalone power supply from radio shack.

 

miwa,
Thanks for the update. Glad to hear that things now work, at least continuity wise.

I can't help but laugh when you compare the "ACURA/BOSE PREMIUM SOUND SYSTEM" to that of a clock radio! It is a testiment to what a POS it really is. Part of the further lack of quality in your home is due to a few things all combined to have it sound like $hit...

1. Without the EQ, there is probably a definite lack of high frequency response.

2. Unless you mount the speakers inside of some enclosure, they will sound fairly weak. If they are just setting open air on top of your dresser or something, there will be NO punch to them.

3. The 900mA power supply won't provide enough power to drive them very hard. If you take the current available from your supply and divide it up... you can figure about 200mA per speaker and 100mA for the CD motor, etc. In that case, you would be able to blast each of the four speakers with a whopping 160mW... That's .16Watts into each speaker max...

If you invest in a larger 12-14volt supply, and mount the speakers in an enclosure that you could probably find at some speaker shops, etc. It might start to sound a bit better than a clock radio... Perhaps you could even get it back up to the dentist's office status that it held while in the TLS...LOL

Thanks for the compliments and the updates. Feel free to quote me if you can... That may take a few megabytes for each of my quotes! hahahahaha. What do you think Iggy? I think we could make a good consulting team... As long as you were the editor, so that clients wouldn't have to read all of my run-on jibberish. I'm sure I test the patience of a lot of readers, but they get what they asked for...

Southbound

 

alright, I hooked up the dell 'non standard' atx power supply .. I managed to find out that there was a wire called #PS_ON .. that when shorted, gives the effect of +5VSB shorted on a standard ATX power supply. It turns it on. I found a FIVE(5!) amp bugger !Well, I hooked everything back up to it and I am glad to report that indeed, my bass notes were pounding harder. Definitely feel the power increase there. The table actually vibrated on a beat. If I had some quality speakers, it might've even sounded better. Muddy highs are sorta annoying .

now, my next issue. I can only have the power supply on or off :/ The head unit requires an "always on" 12v to keep the memory of the code/cd position/presets etc. I don't want to keep the power supply on all the time just for that.

I've thought about hooking up the 900mA adapter back up just for that purpose. But now I'd have TWO plugs to plug in when I want to use this. This is getting hairier by the minute.

 

Progress!

You need the amps to produce the power that the headunit is capable of.

BE CAREFUL if you hook both of the supplies up together. YOU NEED TO PUT ISOLATION DIODES BETWEEN THE TWO SUPPLIES OR YOU WILL SURELY SMOKE THE 900MA UNIT!!! Just get some HIGH CURRENT diodes, at least 10amps for the 5amp supply. 20amp diodes if you ever find a 10amp supply... You should be safe to tie the two negatives together, but put a diode in series WITH EACH positive output lead before tieing them together at the headunit connector. This will keep them from feeding into each other and looking like short circuits to each other. Obviously, the larger supply would win the battle and smoke the smaller 900mA supply. With respect to diode polarity, connect the positive power supply wire to the anode of the diode and the cathode of the two diodes tied together feeding the headunit connector. The cathode will be the side of the diode with the BAND on it. The diodes have to be large enough to pass all of the power supply current and then some reserve for heat. If they get hot, you may need to heat sink them to some INSULATED metal somewhere. You can buy mica or silicone insulators to use for this purpose. In fact, they will probably come with insulators and hardware for heatsinks when you buy a diode that's rated for 10amps or more. The voltage rating doesn't need to be that high. Anything above 25volts should be fine.

This will allow you to safely keep the wallwort plugged in at all times to keep the headunit memory up, and then when you want music, just turn on the computer supply. You can plug it into a power strip to use as a switch if need be.

Then mount the speakers inside of some enclosure and you should be replicating the BOSE SUPREME SOUND in the comfort of your own home....LOL

You're almost there... you should be able to make up some kind of adapter for the headunit connector to allow you to more easily connect both diode feeds from the two supplies. Molex comes to mind...

Keep up the good work, and GOOD LUCK!
Southbound

 

wow, I'm glad I didn't actually 'try' the hack yet! something about yesterday just made me not want to work on it. I guess it happened for a reason

since you've mentioned diodes, I've read up on them a little and am I safe to assume that I can get 10A diodes for both power lines? the amp rating is just to be able to handle whatever current that is capable of coming through right?

thanks

 

Yes you are correct. You can use a 10 amp diode for a 1 amp application. It's just overkill. It's like using a 12GA piece of wire when all you need is a 28GA piece. As long as you have room for it, it will work just fine and provide you with plenty of headroom.

The same goes with the "Peak Inverse Voltage" rating. In this case, as long as you have a diode that's 25volts or over and 10amps or better, you will fine. I doubt that a 10amp diode will even get hot enough to worry about a heatsink unless you CRANK the music for a long time. If they get too hot to touch for more than a second, then you need to mount them on a heatsink. 20A and 30A diodes typically come in a stud mount package that lets you bolt them through a hole for heat sink purposes. The 10A diodes might just be LARGE versions of the smaller axial lead versions.

And Yes, I would use large diodes for both supplies since they are being tied together. And as you stated, if you every get a bigger power supply then you would want to have a series diode that is larger than the power supply output fuse or its capability. Like you say, you want a diode that is capable of passing the current that the load will draw. In this case, you are working with a 5amp power supply, but the headunit will try to suck over 10amps if given the chance at full output into four speakers. If you can find 20amp diodes, use them because the power supply may or may not fold back at 5amps. It may foldback (lower) the 12volts to keep a steady 5amp output. In that case, the headunit will shut down when the volts get too low... then the voltage will come back up again, and then the headunit will draw too much power again, and then it will foldback again, and you could end up into a harmful feedback oscillation/multivibrator type of situation. If that ever happens just turn the volume down until you get to the point where you are only trying to draw 5amps from the power supply and everything will be happy again. If the power supply doesn't fold back, then it will probably blow a fuse at some point. This may or may not be before 10amps. I would think so, but you never know...

You're still working in a compromised situation, but it should be manageable.

Are you running all four speakers? If you only need two, the power consumption would go down by almost half.

Good Luck!
Southbound