Aki's TL

I installed a new MTX 4250D amp with one 10" Alpine SWR-1041D & QLogic box this past weekend.

I was going to use the ORN wire feeding into the Bose amp, but found that it was generating less than 12V. So, I tried to get to the HU and tap the remote there. Unfortunately there was one stubborn screw that would not move. I was pissed that this install was taking longer than I thought it would.

I decided to disconnect the 12V outlet in the center console and use that as the remote turn on. Once that was done, I gave the new Amp/Sub a test. It worked!

After all that work to get the remote turn-on connected, I finally saw in a seperate paragraph in the MTX manual that stated:

With Smart-Engage auto-turn on circuit, a remote turn on wire is not necessary when connecting the speaker-level input wire to a high powered source unit. "DOPE!"

Sure enough, I disconnected the remote turn-on wire and the amp still turned on ( this time without the loud thump when turning the stereo on and off ).

*Here's the question*

If the amp did not have the Smart-Engage circuit, Could I have used the 12V outlet source for the remote turn-on without any long term effects on the amp and/or sub?

Also, since I am using the amp's speaker level inputs which has a
R+ R- L+ L- .

Can I use the stock Bass +, Bass - , with the R or L +, and R or L - to connect to the amp?

I currently have the Bass + connected to the amp's R+&L+, and the Bass - to the amp's R-&L-. Thus, I only get the Bass output nothing more.

shawhite

humm could you use the 12v oulet source for the remote turn on lead... I would not use it because this outlet is hot when ever the car is on not just when the radio is on. for your remote turn on lead you want it connected to something that is hot only when the radio is turned on. this way when you turn the radio off the amp turns off...

AcuraX2

I agree with Shawhite on this one. You could put alot of undue stress on the amp. Unless of course, your radio is on every and all the time the car is on. If it is not, I would find another source when you can.

bozzchem

This is precisely why I use a relay for this purpose. The power antenna lead only has to turn on the relay rather than two amps and an EQ. I've seen these fry in the past from trying to start too many things. It pulls too much and poof, the HU POA lead no longer works.

The last system I had in my previous car was installed using the factory HU. There was no power on lead. I used a full time 12V so yes, the amps were on whenever the car was on. I figure if I'm in my car an average of 10 hours per week, the radio is on for 9.5 hours of it. I ran the system that way for three years and the amps were still kicking hard.

I'm not telling you what to do, just what I've done. I didn't do it by choice but it still worked out well for me in the end. If nothing else, you could buy a toggle switch to do this for you.

Southbound

I gotta agree with bozz on this one. The remote relay turn on is the safest way to power a high powered external amp. There's no way to really know how much current the stock HU can source as a remote turn on circuit. Depending upon how the circuit is designed, Trying to drive too much could wipe out the pass transistor. But a relay coil would be NO problem. Buy one of those 30amp contact rated relays and you would be golden. To be really safe... install a reverse biased diode across the relay coil. Tie the cathode, (the end with the band) to the POSITIVE terminal of the relay coil, and the anode to the negative side of the relay coil. The actual relay coil has no polarity itself, but connect the diode using the plus and minus wires to determine the polarity of the circuit. A reverse diode across the relay coil will swamp out the counter EMF that is induced whenever power is removed from the magnetic coil of the relay. This will make sure that NO NEGATIVE SPIKE feeds back to the HU remote turn on circuit that could otherwise cause potential damage. A 1amp diode is sufficient for this use. Something like a 1N4002, 1N4003, or 1N4004 should be readily available at any Radio Shack, etc. They are all 1 amp diodes... just with different reverse voltage ratings. 50V, 200V, 400Volt. Some relays already have a built in diode across the coil for this protection. If so, the diode symbol would be molded or printed onto the case so that you would know which terminal to apply the plus and minus voltages to.
Sorry for the rambling... I just always like to feel completely safe than sorry with this damn Blose system!

As far as leaving an amp powered ALL THE TIME... That shouldn't be an issue either. The idle current should be completely negligible and cause no heat or long term damage to the amp. It's only when an input signal is fed to it that it starts to make power. And in that case, the power is MUSIC TO YOUR EARS... While it certainly makes sense to try and use a turn on source that follows the head unit... it is by no means imperative. In fact, some times it could be better than being off all of the time. Bias current would keep all of the caps formed and help keep them from drying out. Obviously, if you play your system once a week, there's no worry about the components going bad... but if you never turn the system on for months at a time, it would actually be better to leave it on ALL OF THE TIME.

Good luck!

My .02cents
Southbound

fsttyms1

i also agree with bozzchem and Southbound

Aki's TL

I'm back from a two day trip to the north - Napa Valley and my system is still working!

Thanks for the detailed feedback! Bozzchem and Southbound, mahalo for the VERY helpful feedback. I think future TL'rs looking to upgrade their subwoofer will benefit as well.

I have been reading the Audio&Electronics postings here for the past 10 months, and I have to say we are all lucky for the shared knowledge and experiences that goes on regularly.

You guys&gals ROCK!!! AKI

PS - To add to the Sub position survey- I have my sub facing the rear and positioned right behind the rear seats. I find the bass deeper and not as overpowering when I had the sub facing the front and positioned in front of the trunk latch. (yes, I tried to noice proof most of the trunk area - that was some work!)
I have not had time to fuss with the stock sub in or out - so for now I still have the stock sub in.