I spliced in RCAs before the BOSE amp and got some weird noises through the rear speakers. I'm thinking it's because I used crap RCAs to tap into the speaker wires. Can I just use a LOC, or does someone manufacture RCA splices? I really don't like dealing with cutting up RCAs.

 

What did you ever find with this? I would think that the line-level input terminals on your amp would be expecting a signal with levels way higher than those from a line output converter used with low-level outputs before the Bose amp. I spliced RCAs from my front speakers to the low levels on my amp and the sound is not all that hot. Not nearly the way it was in my Maxima with my pioneer HU. I'm so disappointed.

 

i connected my amp through an loc on the front preamp outputs to the bose amp and it is working fine and sounds great. from what ive read here on the forums, you need an amp that can take a balanced differential signal, like the jl amps. im no expert at this, so i dont know the details, but i can say that mine are hooked up to an loc with no problems.

 

Here is what I found on another site. It was posted by a JL rep:

If it has a Bose system you don't need LOC's or a CleanSweep. Just
splice a 4 channel RCA cable to the head unit outputs (or the amp input
wires) and plug it into the amplifier (assuming the amp has
differential-balanced inputs, like a JL).

The head unit output with the Bose system is flat (all the EQ is in the
amp).

The LOC's degrade performance and are unnecessary in that system.

 

Hmmm. I would be thinking that the LOC would degrade the performance too. But people on these forums say they are doing it. In another thread, one guy was saying that the LOC wipes out the differential or balanced preamp outputs and makes them "single-ended" or something like that, which is what an amp without balanced/differential inputs is expecting. Your quote from JL says to use a four channel RCA cable. Should I hook up the rear preamps to my sub amp too? Is that why the sound is so blah for me?

I'm hoping it's that and not the quality of my old pioneer HU. It did have sub outs with a crossover. Maybe it was superior to the one on my amp.

 

wait....you have an aftermarket hu and youre taping in to the bose amp harness? that doesnt make sense. how is your system hooked up? if you have an aftermarket hu then you should be using the preamp outputs on the deck, and if it doesnt have preamp outputs, then that would be why your system doesnt sound good since you would be sending speaker level outputs to your bose amp.

as far as the loc goes, if the information i read is correct, the jl rep would be right for jl amps since they take differential-balanced inputs, but not necessarily true for amps that do not take differential-balanced inputs. just buy a cheap loc and test it. if it sounds better then you have your answer.

 

Oh no no no. I had that Pioneer HU in my other car. It had the builtin crossover for the specifically subwoofer preamp outputs. I'm wondering if the reason I'm feeling that my setup with the Bose HU and it's preamp outs sounds so crappy is because I just know how good the Pioneer setup sounded. Replacing the Bose HU and all that junk is a last resort. I hope I don't have to go there because I do not want to pull all that stuff out. I saw the DIY video and I just know I would never get all that junk back together correctly. System would be totally humpty-dumpty. I guess I'll just try a cheap LOC like you say. One question, though: How much more likely is a cheap LOC to make a difference with a differential-balanced signal than the built-in LOC on the amp? I would like to try taking off my RCA ends [from the wires I have tapped into the Bose preamp wires] and hooking the wires into the high levels on the amp first. Although, the manual for my Rockford amp says the line levels can be 0.5 V to 11 V. (RCA inputs can be 250 mV to 6 V.) Somewhere I thought someone said that the Bose preamp voltage is 0.2 V, outside of the acceptable range for the high level inputs on my amp and the preamp inputs, according to the manual. So that might not work at all anyway. And maybe that's why it sounds so not that good. Can an LOC actually raise the signal? I'd rather raise the low, low voltage preamp from the BOSE HU than lower the line-level outputs from the Bose amp. That would be best, right? If an LOC cannot raise the voltage, my only decent sounding option may be just to use the LOC with the line-level outs from the Bose Amp.

 

I am by no means an expert on this subject, so I can only lend you the help of my experience and what I have read...My LOC has gain settings on it, so I am assuming it is raising my bose preamp to an acceptable range. From what I have read, all the eq settings on a bose premium stereo comes from the amp, so it is best to tap in to the preamp outputs and not the speaker level coming out of the amp. Since we already have preamp outputs, I dont know if it would be better theoretically quality wise to tap in to the speaker levels if you have to use an LOC, but I can personally vouch that I hooked up my LOC to the preamp outputs and my system sounds great. I still have some tweaking to do on my front components, but the sound coming from them are clear and crisp with no noise and just as loud/louder than the stock setup.

 

Ok thanks man! I guess it's off to crutchfield.com for a LOC search!

 

Just try your local car audio shop....I got mine for around $20.

 

Yeah I think I'm gonna go and see what they have. Crutchfield has one by Scosche for about 20 bux, but I don't think it will do any real signal processing. The ones that look like they do seem to get expensive quite quickly. How cheaply could I get a JL amp with which I can get 250 to 350 watts to each of my two subs? A 500 to 700 watt JL amp sounds like it would cost 500 to 700 bux.

The LC7 and the one Crutchfield has for 600 bux say specifically they can handle balanced differential signals. The LC8 says it can handle Bose systems, but doesn't specifically mention the ability to handle balanced differential signals. But Crutchfield has a money back guarantee and they let you try the stuff out, so I think I'm probably gonna try the LC7.

 

You dont want signal processing because the preamp outputs are flat with no eq adjustments. The guy at crutchfield that told you to use the MTX one has no idea what hes talking about in our situation, and you would end up wasting your money. If you want a nice LOC i would say go with the LC7, that is the one I was looking at, and might switch to later, but if you want to check to make sure an LOC is what you need and dont want to spend too much right now, just get a cheap one like the scosche one. If you really want to get a nicer one you can also try out ebay, I found a few LC7s for under $200, but like I said, mine was only $20 and I have no problems with it. The only reason I might switch to an LC7 later is so I can add a crossover.

 

Yes... the outputs are pretty flat, but that gives you no real control over your system, hence the need for an outboard eq or signal proc, Imprint, 3sixty, whatever. Splicing in to the DB outs into a JL amp does work very well, but you cannot tune anything based on your speakers and install. With a good signal proc you'll also get time alignment and other goodies. Worth the price if you're into audio.

 

A signal proc wouldn't give you control of your system either unless it has an on-board crossover or eq that you can manually adjust. Also, wouldn't the signal proc be expecting a signal that has been processed by a factory eq? So it may screw with your already pretty flat signal. If you want to actually gain control you should be hooking up to an eq or crossover so that you can adjust it as you see fit, and a lot of amps have on-board crossovers on them now anyways. I dont know about the 3sixty, but I have read stuff saying you should not use a cleansweep on our cars with the premium bose system because it will ruin the preamp signal we are getting from our hu. Some signal processors will give you better control, but you have to look in to what exactly what the unit does and is meant to do.

 

You clearly don't understand the function of a signal processor. Yes, many have built in crossovers and yes, they have multi-band equalization. A cleansweep is just a signal flattener and high volt output, little more. You'd need to look at the PXE-H650, 3sixty.2 or maybe the Audison Bit1 to be more in the range of what I suggest. They can correct OEM signals as needed, but add the afore mentioned features as well.