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Discussion Starter #1 (Edited)
Hello All,
I am overhauling my entire system. I will be keeping the Monsoon amp only to drive the rears. I am tapping into the output of the Monsoon amp and running that into the audiocontrol LC8i Line Out Converter, which will allow me to run a cleaner signal to a 6 channel amp. I am confused about the following:

I am aware that the stock sub is Dual Voice Coil, so there are 4 wires coming out of the Monsoon amp with sub signal. When looking at the wiring diagram, it shows the four wires as follows:

LT/R R Subwoofer (+) DK Blue / White
LT/R R Subwoofer (-) LT Green / Black

R Subwoofer (-) LT Blue / Black
R Subwoofer (+) DK Green

So my questions is, is one set for left signal and one set for right signal, or are they both the same signal? "LT/R R" doesn't mean Left/Right Right, does it? That doesn't make sense to me. Every where else in this diagram Left is written as "LF". Do I use both to feed into the LC8i for subwoofer signal, or just one side. And if one, which one?

I was going to attach a PDF file of this part of the monsoon diagram, but I can't figure out if it is possible to attach that. Since it's a PDF, imageshack won't upload it. I can email it to anyone if they want to see it.

Thanks for your help.
 

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As you noted, the sub is a dual voice coil. Each coil is powered by a seperate amplifier channel within the monsoon amp (one sourced from the left channel and one from the right).

As for which is which, I cannot really tell, but I would assume the one with "L" in it is the left channel (the "R Subwoofer" bit stands for "Rear Subwoofer" I think).

But why do you care? Why not use one pair of the (now to be unused) front channels out of the Monsoon as input to your line converter? I certainly wouldn't use the sub outputs, since the amp may well have a high freq rolloff internally.
 

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Discussion Starter #3
TomatoSoup to the rescue, as usual :thumbs:

Thanks for the reply. This makes sense. Given that it is technically two channels running the DVC of the sub, I will need to tap and run both into the LC8i to get both left and right signal. I didn't think of "R Subwoofer" meaning "rear", but you are probably right. For some reason, whoever drew up the schematic used "LF" to signify Left on all the speakers, but "LT" on the subwoofer. Makes enough logical sense for me to go with it.

As for why I will be using the subwoofer output to convert signal, the LC8i actually has 4 pairs of inputs. It has Input 1, 2, 3, 4. Input one will be the front tweeter signal and input two will be the front mid woofer signal. With that, the LC8i will "sum" those two into one, and that one output will be fed to the passive crossover for the components. Input three (left and right) will be the subwoofer output of the Monsoon amp, and while there will be no input 4, channel 3 output on the LC8i is duplicated automatically (if set that way) to output on channel 4 as well. These two outputs will only be used to send signal into the subwoofer channels of the new amp. I'm not entire sure what you mean when you say "since the amp may well have a high freq rolloff internally", but I figure that with whatever the Monsoon's internal crossover is set at for the sub channels, this signal should be just fine to use for the new sub and Ibeam.

Your thoughts?
 

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First, the other speakers are marked LF,LR,RF,RR - meaning LeftFront, LeftRear, RightFront (etc).

Secondly, I went online and looked at the LC8i user manual. I think one of us is confused as to how to do this :). The manual says:

1. Speaker-level Inputs:
The LC8i has eight speaker-level inputs.
These inputs get their signals from the speaker-level outputs of your factory-installed source unit or amplifier. If your source unit has front, rear, and subwoofer speaker-level outputs, connect them to the first three sets of inputs on your LC8i. If the source unit only has front and rear outputs, the Auto Mode circuitry in your LC8i automatically routes the Channel 3 input channels to the (Channel 4) subwoofer channels.
So I would use only the front door speaker outputs and the rear speaker outputs as inputs to the LC8. Let the LC8 'create' the sub inputs to the new amp. Plus, you don't need to separate the tweeter and door out/inputs and merge them again.

You can ignore the roll-off comment, I was misunderstanding what you were doing with the sub outputs. Still, you don't need to hook up the sub channels to the LC8 anyway.

Lastly, you have a (new) six-channel amp, why still use the Monsoon amp for the rears? New amp would utilize two channels to feed the front component crossovers, two for the rear speakers and two for the sub. Total six, right? Or am I confused?

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EDIT: Ahh, I thought more on this and I think I see why you wanted to have both tweet and mid speakers as inputs. You assume that they are not full frequency channels. I don't know this to be a fact, but I doubt that the door speaker amps include any crossover circuitry (HF rolloff). Thus you should just be able to use those alone for the fronts. Could be wrong though :)
 

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Discussion Starter #5 (Edited)
First, the other speakers are marked LF,LR,RF,RR - meaning LeftFront, LeftRear, RightFront (etc). :)
You're right with that. I mistyped indicating "LF" is left. Oops. But I'm still curious then as to what the "LT/R" stands for in "LT/R R Subwoofer". I agree that the last "R", since it's in both channels, means "Rear". :confused: In looking at the schematic, if LT/R means left rear subwoofer, the other channel is just labeled R subwoofer, for rear... or maybe it's "Left/Rear" for one channel and Right for the other. It doesn't really matter, cause one must be left signal and one must be right.


Secondly, I went online and looked at the LC8i user manual. I think one of us is confused as to how to do this :). The manual says:



So I would use only the front door speaker outputs and the rear speaker outputs as inputs to the LC8. Let the LC8 'create' the sub inputs to the new amp. Plus, you don't need to separate the tweeter and door out/inputs and merge them again.
The manual of for this LC8i is quite confusing. In fact, I read it (twice), and ended up calling them to ask them a couple questions to make sure I was understanding it correctly. So I read your edit... you're right. It's a mystery as to whether there is any crossover settings built into the Monsoon that would effect output to the tweeters vs. mids. That said, since there is a tweeter output and mid output, I might as well use both. Part of what the LC8i does, as far as I understand it, and why it costs a couple hundred bucks (rather than using a $20 converter) is that it adds up voltage put into it, which increases your signal output. That said, any channel will give me x amount of voltage. If I use the tweeter output plus the mid output, it will give me x times 2 volts. I know the voltage coming from the Monsoon (and any stock amp or HU) is very low, so taking adding it up from 4 channels instead of just two should be beneficial. Does that make sense, or have anything behind it?

Lastly, you have a (new) six-channel amp, why still use the Monsoon amp for the rears? New amp would utilize two channels to feed the front component crossovers, two for the rear speakers and two for the sub. Total six, right? Or am I confused?
Good question. You're not confused, my setup is just a little unique (at least I like to think). I would run the rears through the 6 channel amp, if that were an option, but this is why I need to keep the rears on the Monsoon.

The new amp is 75x6 at 4 ohms. Bridging any two channels puts it at 200w per bridged channel at 4 ohms. Therefore, my front components will be running 75w per side. Now where it becomes different is here... I will be running one 8" sub in the stock location, and one Rockford Fosgate I-Beam inside my drivers seat. Channel 3 and 4 of the amp will be bridged for the 8" sub to get 200w (it calls for 120w RMS or 500w max, so I might keep the gain down to not damage it with the 200w), and Channels 5 and 6 will be bridged for the I-Beam. The I-beam calls for 100w RMS - 250w RMS, and the manual from Fosgate says it performs best with 150w - 250w and is recommended at 4 ohm only. So bridging 200w rms should be perfect. That's why I have no room for the rears on this amp. The LC8i comes with a remote knob. I intend to have that operate the I-beam only, so I can turn it up or down depending what mood I'm in.

Let the LC8 'create' the sub inputs to the new amp.
If nothing is in input 3 or input 4 of the LC8i, there will be no sub output. The way it works is the LC8i will "create" a sub output in output 4 based upon whatever is put into the "input 3". In other words, if you put any input into 3 and nothing into input 4, you will get sub output from output 4 (with automode on). If you leave input 3 open and leave input 4 open, you will not get a sub output. Therefore, if I only use input 1 and 2 for tweets and mids (or even one or the other), I will not get a sub output created. [***EDIT: Correction, I just looked back at the manual and rethought this situation. The option to do what you are saying is put Tweeter into input 1 and mid into input 3, which would create a sub. Not my preferred way to do it, but it would work.] I suppose I could either tap into the mids to put into input 3 or tap into sub to put into input 3, and it would effectively do the same thing in my case. One would give me a full range, the other would give me a low crossed over signal... but regardless I can cross it over on the new amp so it shouldn't matter. [EDIT: would I get more voltage out of the sub signal than the rears signal since the rears will still be hooked up? I prefer the idea of rears over mids due to not knowing about the monsoon crossover, while obviously the rears are full range] *This device is quite confusing to me, and I only understand this now after talking with the tech guru at audiocontrol (the company who makes the LC8i). This is not explained in the manual.

I've been thinking my way through this for the last couple weeks. It is a bit confusing to me since it isn't just a standard component, rears, and single sub... and also because my goal is to keep the stock head unit (people might think I'm not smart for doing that, but hey, we all have our preferences. This is why I'm using the LC8i instead of a 20$ LOC, to compensate for the crappy voltage from the head unit/monsoon amp.) I am glad you are asking me these questions cause it helps to talk it through. None of my friends know or care about this stuff, so I'm on my own. And thanks to your originally posted wiring schematic, with all the colors clearly coded, I am comfortable diving in. Oops, this got long! Your thoughts?
 

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The manual of for this LC8i is quite confusing. In fact, I read it (twice), and ended up calling them to ask them a couple questions to make sure I was understanding it correctly. So I read your edit... you're right. It's a mystery as to whether there is any crossover settings built into the Monsoon that would effect output to the tweeters vs. mids. That said, since there is a tweeter output and mid output, I might as well use both. Part of what the LC8i does, as far as I understand it, and why it costs a couple hundred bucks (rather than using a $20 converter) is that it adds up voltage put into it, which increases your signal output. That said, any channel will give me x amount of voltage. If I use the tweeter output plus the mid output, it will give me x times 2 volts. I know the voltage coming from the Monsoon (and any stock amp or HU) is very low, so taking adding it up from 4 channels instead of just two should be beneficial. Does that make sense, or have anything behind it?
Sorry, no it doesn't :). Line-level inputs (to your new amp) don't NEED a lot of voltage (roughly only 1V peak-to-peak, from memory). In fact your LC8 will be (hugely) REDUCING the speaker-level out/inputs to feed them into your amp-that's why you need it in the first place. Higher voltages are counter-productive since they'd cause clipping in the amp's input stage, which not only sounds horrible, but the effect on the amp's output - driving it into clipping - can blow your speakers.

This leads me to another point, you say you are using your Monsoon amp outputs to get a cleaner signal. This too is not likely to be a positive thing. The more circuitry you have between the signal and the output can only HURT the signal, not improve it. Not sure if you already have the LC8, but if not you might want to rethink and/or use the inputs to the Monsoon as input to the line converter (if possible).

... I will be running one 8" sub in the stock location, and one Rockford Fosgate I-Beam inside my drivers seat. Channel 3 and 4 of the amp will be bridged for the 8" sub to get 200w (it calls for 120w RMS or 500w max, so I might keep the gain down to not damage it with the 200w), and Channels 5 and 6 will be bridged for the I-Beam.
Ahhh, OK, fair enough.

[EDIT: would I get more voltage out of the sub signal than the rears signal since the rears will still be hooked up? I prefer the idea of rears over mids due to not knowing about the monsoon crossover, while obviously the rears are full range] *This device is quite confusing to me, and I only understand this now after talking with the tech guru at audiocontrol (the company who makes the LC8i). This is not explained in the manual.
Again, moot. You'll have way more than 'enough' signal whatever you use.

This is why I'm using the LC8i instead of a 20$ LOC, to compensate for the crappy voltage from the head unit/monsoon amp.) I am glad you are asking me these questions cause it helps to talk it through.
As I said before, moot. The voltage from the stock head unit is designed and appropriate to input into an amp. In fact it originates from an amplifier itself - the monsoon and non-monsoon head units use the same internal circuitry, only the internal amp is 'turned down' to feed the external Monsoon amp. I know this because I have both types and have looked inside them. They both have the same IC amp as an output stage.

The only issue with the stock radio output is that it's a balanced output (both 'wires' of each signal go high and low in opposite phase) while most amps are designed for single-ended inputs (one wire stays at ground and the other swings between high and low). There are distinct advantages to the former, especially in noise rejection, but you can't use it if you can't use it! :) So you will need some type of conversion before your amp, anyway.
 

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Discussion Starter #7 (Edited)
I've been pretty busy and haven't had a change to get online to reply. I'm still waiting for a couple parts (rears) before I can do the install, so it looks like I'll probably be waiting another week so I can do it all at once.

Line-level inputs (to your new amp) don't NEED a lot of voltage (roughly only 1V peak-to-peak, from memory). In fact your LC8 will be (hugely) REDUCING the speaker-level out/inputs to feed them into your amp-that's why you need it in the first place.
Okay, so that's why I've heard of the converters that take speaker level wires to rca's called "high to low level adaptors". Makes sense... high voltage which must be necessary for speakers, transferred to lower voltage which is necessary for RCA's to avoid clipping.
Kinda curious then, why do higher end head units use 5V preamp outputs rather than less expensive head units that use 1 or 2V preamp outputs?

This leads me to another point, you say you are using your Monsoon amp outputs to get a cleaner signal. This too is not likely to be a positive thing. The more circuitry you have between the signal and the output can only HURT the signal, not improve it.
I agree. That makes sense, even for a non-technical guy like me.

Not sure if you already have the LC8, but if not you might want to rethink and/or use the inputs to the Monsoon as input to the line converter (if possible).
I do have the LC8i already, so I will be using it, but would it make that much of a difference if it was getting it's input from the speaker wires before of after the monsoon amp? I mean, like you said, the signal will be cleaner before going through the circuitry within the monsoon, but is it enough of a difference to be concerned about? I kinda doubt it, at least from a regular person's ear. I imagine maybe it would be noticeable using high end audio testing equipment, but to the naked ear?
Does the gauge of the wire matter for the wires you're using to tap the stock harness and use as input to the LC8i? I'll be using 14 gauge speaker wire for all my speakers, but probably smaller for input into the LC8i.

The only issue with the stock radio output is that it's a balanced output (both 'wires' of each signal go high and low in opposite phase) while most amps are designed for single-ended inputs (one wire stays at ground and the other swings between high and low). There are distinct advantages to the former, especially in noise rejection, but you can't use it if you can't use it! :) So you will need some type of conversion before your amp, anyway.
So is this what the insides of the LC8i or any other line level converter do? Other than providing you with RCA outputs, is this the main function of this piece of equipment? I'm unfamiliar with this.
 

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Kinda curious then, why do higher end head units use 5V preamp outputs rather than less expensive head units that use 1 or 2V preamp outputs?
I think this is most likely for marketing purposes, but it could also be proposed for better noise suppression (as long as you have an amp that can handle it :))

I do have the LC8i already, so I will be using it, but would it make that much of a difference if it was getting it's input from the speaker wires before of after the monsoon amp? I mean, like you said, the signal will be cleaner before going through the circuitry within the monsoon, but is it enough of a difference to be concerned about?
Prolly not.

Does the gauge of the wire matter for the wires you're using to tap the stock harness and use as input to the LC8i? I'll be using 14 gauge speaker wire for all my speakers, but probably smaller for input into the LC8i.
No. Thin wire is fine. Twisted together is good for noise rejection, but that prolly won't be an issue anyway for speaker-level outputs.

So is this what the insides of the LC8i or any other line level converter do? Other than providing you with RCA outputs, is this the main function of this piece of equipment? I'm unfamiliar with this.
That, and the voltage/level conversion. But some cheapy line-level converters won't work with balanced inputs. Pretty sure the LC8i will (given its cost :))!
 
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