I did try this. Both the "positive" and the "negative" sides of the pre-amp signal read a voltage level of around 1V, slightly less. Because both lines show voltage, I believe that does confirm a differential signal. After the Bose amp the lines tested for me at around 6V or so, clearly a stronger signal.

 

David Navone gave the same advice--I've purchased his N-774V four channel line output converter...

 

mdw,
what volume did you have the stereo at while doing this? did the v fluctuate at all?

also, about your install, where did you attach your remote turn on 12v?

 

Great info, thanks mdw33333! So, if you find yourself an amplifier with a high voltage input option you can omit the signal converter, and if it sports a signal-sensor you can avoid the remote turn-on lead as well. I have verified that the JL audio "slash" series amps can do this, and JL audio seems to be a huge favorite among the RX-8 audio zealots This definately simplifies the wiring for a sub install!

(note, not all the "slash" series amps have the signal-sensor option, check the specs.)

 

Note that two members of this forum have the JL Audio 500.1 amplifiers and they had problems with the signal sensing turn-on. Both resorted to running an ignition turn-on lead. The crazy thing about this Bose amp is that after turning off the HU, I tested 6V in the rear speaker outputs. Only after turning off the ignition, would the leads show no voltage reading. I can't explain why, but that voltage hovering at that 6V mark (after shutting on the radio) is causing a problem for low voltage sensing turn-on units. My line level converter has a built in signal sensning turn-on, and it would turn the amp on, but not off, unitl I shut off the ignition. I ended up tapping an ignition lead for my turn-on because of this.

 

I see, you want the amp to shut down when the HU is powered off but the ignition is still on. How does tapping into an ignition lead help? It still leaves you with a hot lead wire whether the HU is on or off.

 

Right, I was getting a turn off "hum" through my test amplifier when using the turn-on from my converter, so I because of that, I just wired into a main ignition source just under the steering column. Either way, it won't turn off until shut the car off. At this point, I have no turn-on/off noises at all, so I'm happy.

 

I did my testing with volume levels under 7 on the HU.

 

There won't be any huge difference between using the speaker-level outputs of the non-Bose HU and using the signal "after the Bose amp" on the Bose units will there? It seems in either case you're just tying into the speaker lines. Will the presence of the Bose amp really make much of a difference here?

I know most of these discussions have centered around a sub amp...what about the case of adding a 4-channel amp to power the main speakers off the stock HU...is that going to work in this same way, or will the sound be significantly worse when trying to get a full range signal from speaker level outputs?

Hope I'm no too far off topic...

jds

 

Well I must admit, I spoke with David Navone, and he has convinced me that I need to go in after the bose amp. Let me go through his logic.

Since the system has been tested at about 1v+ and 1v- on the leads going into the amp, this is probably indiciative that the signal is Ballanced Differential. Meaning there is signal through both + and - (not just a ground at the - pole), and the amp compares them to ground and eliminates any added noise. This will leave the amplifier with a clean signal to process. I stand corrected that there needs to be three inputs per channel to have differential. It appears that each channel signal can use the standard ground of the system.

You could tap into the 1v signal without going into the amp but amplifying a 1v signal that has had the balanced differential eliminated by some lifted ground situation, or a line driver/converter, will leave a high signal/noise ratio. This will cause the gain to have to be set very high on the amplifier to have the desired output, increasing noise.

If you tap into the signal where the bose amp has had the chance to use the ballanced differential, and then amplify the signal, you will have a strong signal (~6v tested by mddw3333, or 8.94 as quoted by David Navone), and a very low signal to noise ratio. This will have the cleanest and strongest signal. This is the beauty of a ballanced differential, and the only redeming quality of a bose system.

He suggested the use of a N-774v just as cactus george has done after the amp. It looks as though bose does three things well.

1. Marketing

2. Their extended port system (I forgot the name of it, they use for the wave radios).

3. Produce low noise systems from a low volt output via differential signal, to a high or standard Volt output.

Needless to say I bought a N-774v. Orion said that my amp could be hooked up directly (it could handle the Volts), but I have fear for the HU.

Keep the information comming. We have made worlds of progress.

 

I doubt there will be much, if any difference. Just make sure to buy quality line level converters like the ones we've discussed. Also, if you want to run amplifiers to the midrange speakers, you'll want to get a 4 channel line level converter, and tie into both the front and rear leads for signal.

 

Did I miss where the N-774v could be purchased? I don't recall seeing it in this thread. Can someone post a URL? Sounds like I will be doing this very soon. Damn, now what am I going to do in the mean time? I spend 1.5 hours a day on the road, I can't be without my sound. I guess I could pull the RCAs off the amp to play it safe until I get the N-774v...

Thanks to all who were really persistant on this.

 

eXcentric,

http://www.davidnavone.com

You can use any line level converter, but these seem to be good.

It sounds like he has them hand built.

 

what do you all thing of this LOC, looks really nice and made by a trusted name, what do you all think?

also there are 2 versions, a 35watt and 55watt (input) what do you think, 35 enough or just get the 55 to be safe?

opions on brands, just looking to do the best conversion after the bose amp...

http://stingerelectronics.com/sting_...lectronics.asp

thanks

also, what are people doing at the actuall battery terminal, adding a regular ring connector, or replacing with a new Terminal totally???

 

I must agree. I purchased the N-774v and installed it last week. I didn't get a chance to post about it until today.

Overall, I'm actually happier with this install then I was with the direct 'preamp' connection I had before. Not only is this approach safer, but I actually do get more bass out of the system now.

Unfortunately, the bass is not as clean as it was before. It sounds a bit more 'muddy' but I still feel it's worth it. I can now agree with the people that argue the Bose amplifier in the rear deck modifies the sound from the head unit. And I think it modifies it quite a bit. Now I'm wondering if it would make a difference if I hooked up to the front speaker outputs rather then the rear ones...

One last note, mdw33333 posted this:

These are the wire colors at the speakers themselves. I used this guide, but when I connected it to the amplifier one side was out of phase. I don't know if these pinouts were backwards or if something inside the N-774v I received was backwards. At any rate, I clipped off the connectors to the Pink and Purple wires on the left side and swapped them (Pink + and Purple -) and everything got much louder.

So, all in all, I would reccommend this approach and I would recommend the N-774v.

eXe

 

I'd also like to add that with the new converter installed, I no longer get any loud 'THUD-THUD' when I start the car.

 

How about if you wanted to add a 4-channel amp for your front/rear speakers, and something like an Infiniti Basslink powered sub...could you use the one four-channel converter and then tie the inputs to the Basslink in parallel? Or would you be losing too much signal that way?

jds

 

Earlier in this thread, I posted a pic of my battery connection. It is simple to connect to. There is 10mm nut on the top of the positive battery post that you can connect to.

As far as that line-out converter is concerned, it is fine. It's essentially the same as the Peripheral adapter that I'm using. They're both made by AAMP of America.

 

A 4 channel line level converter will have 4 inputs and 4 outputs. If adding a 4 channel amp and a Basslink sub, you'll need to y-off the rear outputs. The signall coming from the LOC will not be affected enough for there to be a noticable difference.

 

I apologize for the typo. I didn't mean to goof anyone up! On the left rear speaker the Pink is positive and Purple is negative. My bad...

 

i talked to pac, soundgate, they BOTH recommend right at the head unit.

1 they say after the amp, (tapping the rear speakers) your then stuck with the crossover levels of the bose amp, which totally makes sense, you cant use the LP on your amp then and the 6x9s could be crossed over at a level not condusive to low freq.

2 at the head you get the true output, with a soundgate 4.2 you have 2:1 scaling unline make that are like 10:1 meaning.....if you got 2 volt output, your amp will see 4 volts.

3 the wiring running back to the amp will act as an antenna, possubly causing interference, so its better to run a 10ft RCA then tap into the rear prior to the amp and use a short RCA, how much of a difference, who knows.

so, question here is (well my ?)....is the imputs into the bose amp, coming directly from the BOSE HU, or does it stop off anywhere to give signal to say the doors etc? HOW REALLY DIFFICULT is taking the factory HU out? I think before the amp to me seems like the better soultion.

As for this differential stuff, im not 100% sure if it will even pertain to someone using a LOC, not sure though....

any thoughs?

 

When you say the ADDMAZ doesn't work but you can "hardwire" it, does that mean merely twisting wires together or (somehow) interfacing wires to the bare OEM connector?

Also what is the AMP-RCA, is that just a plain old RCA cable or special OEM1 required part? I can't find any pictures.

 

I completed the install with the N774V, Kicker 30 band parametric (for front channels) and Soundstream amp.

In calibrating the setup using the Radio Shack analog SPL meter, I was noticing some significant "hole" in the response for the front speakers. At first I just compensated for the valleys and peaks with the EQ, but then I thought of a test to try to determine if the Bose amp has built in EQ circuitry.

So I switched the RCAs for the front and rear channels (so now the rear signals were driving the front speakers), and took another set of readings with the SPL.

Surprisingly, the frequency-scape was drastically different. The largest differences were at the following frequencies:
125 Hz: 5 db
200 Hz: 4 db
250 Hz: 7 db
320 Hz: 4 db
500 Hz: 4 db
635 Hz: 5 db
2.5K: 4 db
4K: 6 db
5K: 6 db
6.4K: 6 db
8K: 6 db
10K: 6 db

My conclusion at this point is that the Bose amp DOES equalize for the front and rear Bose speakers. I'm considering trying a different line converter option connected before the Bose amp (this will take some time to setup...)

 

well I just ordered the N-7V (essentially the same as yours just 2 channel).

do you think it has any EQ parameteres on the low end, say im just adding/tapping the LOC for a sub amp?

how is the quality of the davidnavone products....

this is sorta what i was afriad of, that there ar crossovers so if you tap after the amp, you are limiting .....wish I knew if the rear 6x9s ran full range...

 

There are some major things to worry about here. running a ballanced differential signal into a LOC will send one line with signal direclty to a ground. The would be negative side of the Ballanced Dif. signal realy has a volt rating and sending this to the sheild of an RCA can add noise to the system at minimum, or fry the head unit at worst case.

Plus, since it is a differential signal, the bose amplifyer will use this signal to cancel out any acquired noise, then amplify the signal and leave you with many volts of signal power, rather than 1 volt of signal. If you amplify 1 volt with 0.01%noise (I pulled that number out of my ***) to a 10 volt signal you end up with 0.1% noise. Unacceptable. If you throw in the noise that the grounded reverse phase of the ballanced signal will add, it gets even worse.

On the other hand, if you have 6 volts of output from after the amp at about 0.005%noise (the balanced signal has canceled out some), and you amplify it to 10 volts, you have about 0.008% noise. This is very acceptable and will give you a cleaner, safer signal.

To answer your questions however, the signal to the rear deck to my knowledge goes directly to the bose amp. There are seperate lines and amps for the front speakers. Rotary god and eXcentric may be able to answer this question better.

The best way to run the signal from whatever source you choose is to have the highest voltage possible traveling the greatest distance. The noise that will be added to a line is linear, meaning your car will add 0.01% noise to every line that travels 3 feet (I pulled that out of my *** too). Before you amplify a signal, it is bett to have 0.01% noise in a signal that gets amplifyed one time than a signal that needs to be amplifyed 10 times. That way the noise only gets amplified once.

Make sense?

bob