I know this is my first post on this board, but have been reading a little, since I acquired a G37. After reading through some of the audio posts on this board, it seems that many people are confused about whats necessary and what is not.

Although some OEM car stereo systems require a DSP to flatten out the frequency response of the signal that is going to be delivered from the OEM head unit, the Bose system in our car, and most if I recall correctly, do not. The signal coming out of the HU is a line level flat response signal with all DSP activity occurring in the outboard amplifiers.

In actuality, clean sweep will degrade the signal from the HU since it will be going through two transformations steps of the signal--Digital to analog from the HU, back to digital in the cleansweep and then back to analog. After further inquiry, this was confirmed through a well known source at JL. This is not to say that other DSP's, who also accomplish other processing functions, don't have their place. One of the hotly anticipated DSP's is the JBL MS-8. This system, along with others, accomplish more than what the clean sweep does. JL products are awesome, but fortunately or unfortunately, we do not require this particular product they sell.

 

So do you recommend no upgrades when, say, changing all 11 speakers to aftermarket component systems? Or would you say upgrade the bose amps?

 

I could've swear my signal from the HU is not flat. My buddy and I measured with an audioscope (he works for NI). I do not have the Bose system in my G37.

I understand that JL Cleansweep is far from being the best DSP in the market. But at the price I got it for, I considered it a steal. The JBL MS-8 you mention looks awesome but I don't want another screen in my car. I prefer the 3Sixty.2 so I can use my PocketPC as an equalizer. I'm saving for an exhaust and intake before another DSP though.

 

The kenwood one looks REAL NICE!!! but i still dont understand these 100% yet...

 

So then how do you suggest incorporating aftermarket full range amplifiers? Or are you just saying that a cleansweep is not needed for sub amp and a simple line level converter will work fine?

 

exactly, he is saying that the output from the HU is flat and you should be able to directly put that in to an (using a LoC) amplifier before the bose amp.

I still want to confirm that its flat or not. Because Kream says that his is not flat but then he does not have Bose. So the bose HU (if the HU are different) output could be flat like dillyyo said.

 

MS-8 can be used without the screen and just as a black box. One thing many people seem to do is think all DSP's are the same. No other DSP except for the Alpine 650, which is still not as variable and easy, does what the MS-8 does.

Even if the signal is not perectly flat, that doesn't matter. Any current DSP will sum the channels and make thej signal relatively flat anyways.

 

If you don't upgrade the cheese amps then you will deal with their frequency response curve. All of Bose's DSP occurs in their amps. I would definately change the amps and unless you are going with some true sorround (only ambient material coming from the rear) and a center channel to keep up with the components up front, then think about keeping your speakers only up front.

Even though I will most likely be going with teh MS-8 DSP, if I can't get a bigger and better coaxial shoehorned into that dash area, I will be running only a 2 channel front stage with each door holding 3 way components.

 

Wouldn't matrixed sound be, kinda lame, in a car? For instance 2 channel audio being matrixed into the 11 speakers. In this case, you are saying get good components for the front doors, and power them with a good amp, and then put in a new middle/back speaker to keep up on another amp?

Also, since it would be a component system, what kind of amp would you need? Obviously you'd want to only deliver lows to the subs, mids to the mids, and highs to the tweeters. What amp would do that? Its been a long time since I did any custom audio setups, and when I did it was purely 4 channel amps for front/rear and a sub amp, with alpine headunit.


Also, with this MS-8, it is 8 channel. So does that mean 6 of the channels would be used up by the component system for the door? (low/mid/high). BTW, where are all the speakers for our car. 3 in each door, 1 in the middle, 2left back, 2 right back?

Basically, put down in DETAIL how you would wire, connect, output, what amps, what accessories, etc, for use with your MS-8 setup that you will build... I can handle detail, I love that stuff, I'm an engineer

 

All you do is take the line level or speaker level wires and take them out of the input of the stock amp. I am not sure if the non bose have external amps. If they don't then most likely the stock HU is retaining any stock DSP and the signal will need to be flattened by an external DSP.

If you use a DSP, depending on which one, you take whatever output they give you, RCA, balanced etc and input it into the amps. Then you need to rewire whatever speakers your dropping in.

Cleansweep is not needed for any part of the system because the sugnal from -the Bose HU is not processed. So as long as you use the wires after the HU but before the amps, you have a clean signal. Now if you were going with the stock Bose HU and wanted time alignment, crossovers, phase adjustments etc, then you would need a DSP, but again, before the amps. The Bose amps are not to be used since their amps are, for all intents and purposes, mated to their crappy speakers.

This is what i am doing with my system. Keep in mind its the Bose unit and your non-bose might have a processed signal coming from the HU, where mine does not.

stock head unit will be used. If out in time, I will be having a JBL MS-8 DSP. This allows me great flexibility and the most functions as possible. Down below is a brief list of it's attributes:

- 8 speaker leve inputs
- 8 line level inputs
- Auxiliary input
- Fully configurable electronic crossover
- 31-band EQ
- USB port for software updates
-8 x 20 watt internal amp
-time alignement
-Logic 7 w/ channel steering (fully defeatable if wanted)
-fully adjustable frequency curves
-Can use HU volume control


Then I will have two options. If I go with the center channel and the L7 feature, then I will have my Zapco 6 channel amp driving my front stage (left right and center) 3 wat components (Dynaudio 362, DLS 8.3 or Morels). 2 channels on each amp bridged and going to each front part of the stage. This means 3 outputs from the MS-8 will be used. 1 more output will be used to feed my JL sub and the mono block amp. That leaves 4 outputs on the MS-8 left and they will drive, with the MS-8 internal chip amps, the stock speakers in the rear side of the car and rear shelf. Reason I am using these speakers and the MS-8 amp is due to the fact that this is only ambient musical info when in a 7.1 system so they don't need to be as loud and as good as the front stage. Since I have a bridged channel driving the left and right set of 3 ways, a passive crossover will be used. But if I decide to use another amp to drive the center channel, then I will run my left and right 3 way components without a passive crossover and run them with the ZAPCO internal crossovers.

If I wanted to just have my subs and the 3 ways up front without the rear speakers, I could set up the MS-8 with 6 separate outputs going to each component (tweeter, mid range and midbass) and one for the center channel and one for the sub. In this setup, I can use MS-8's fully adjustable crossovers and slopes (1st, 2nd, 3rd and 4th order) and give crossover points to each speaker or I can have MS-8 do it automatically by telling it the size of the speaker and its location.

As a true audiophile, I have always had my front stage in the kicks, but with the advent of the MS-8 and other DSP's, you can get a soundstage that would take pro tuners days to get. I'm all about sound quality so I do like thump, but not at the sacrifice of clear, tonally accurate music.

 

Actually the flexibility of the MS-8 is what is awesome. I am going to provide you a link below to a thread that has taken place on a forum I have frequented for years. The main guy, andy, is head of the MS-8 project.

As far as the matrixed music, I had my skepticism also. But Gary Biggs, who is a competitor for JBL, won the highest SQ scores at Spring Break Nationals last year. People who have heard it, and I mean people who have felt for years the less speakers the better, have said the sound is unbe;lievable. If the center channel is used, the center stage is suppose to be rock solid and the same for every seat in the car. It has to do with teh L7 algorithm. Just read the info below and if you have any questions, just ask me as I can answer some, but some more in-depth might need to be directed to any. He's a good guy and will answer anything.

http://www.audiogroupforum.com/csfor...ad.php?t=63407

 

AFAIK or remember, Bose HU have always been relatively unprocessed until the signal got to the amps, which were either outboard amps or amps that were connected to the speakers. I actually confirmed this with Manville Smith, from JL Audio and he said that an unequalizing DSP is not required for Bose HU. And since the only function of the clean sweep is to flatten the signal;, you just go through an extra D/A conversion, which can only deteriorate the signal.

 

^^^so when is a DSP needed in our case? never? or what...

 

Just a quick start off Q to clarify b/c its been a while, when talking about amps and we say it is a 6 channel amp, a channel is capable of outputting to 1 speaker, i.e. it was a +/- port, 1port for each channel. Obviously certain channels can be bridged. So like, channels 1/2 can be bridged (chan1+ and chan2-) (chand1- and chan2+) which makes a new channel for higher output and lower resistance to the speakers?

Yeah I was reading that forum last night actually. I'll check and see if there is any good info I missed. What I'm really looking for you is a clearcut idea of a good but not a purely high end audiophile setup, for our cars. So, I'm not looking for top of the line Vandersteins, but maybe some decent B&W entry level or above (for the home theatre reference).

So I like to know the exacts of hooking up a decent system, once I'm told one time I can remember it for when I want to do it myself. First off, with that zapco 6 channel amp, I see that it has 6 speaker level outputs, right? So does that mean you hook up +/- of each channel to each of the 6 front door speakers? How exactly does that hook up? What are its inputs ( I realize you take the inputs out of the bose amp, but don't you want the ms-8 to be the input for the 6 channel amp?

Bose HU > (What are its outputs, how many rca's?)

So you could have Bose HU > rca's to ms-8 > ms-8 output to 6 channel amp > 6 channel amp to front door speakers. Leave all crossovers if any on the 6 channel amp off and let the ms-8 do the sound processing. Rear could come unpowered from the ms-8, as well as the center? Details details, thats what I want!! I want wiring diagrams... lol, I'm greedy.

I'd really like to see a basic flow diagram with the Bose HU/any amps needed to get a nice matrixed ms-8 setup going with powered front door components at the least, and maybe a mono sub, and any wiring going to the speakers. Doesn't have to be pretty, use paint or anything you prefer. I realize I may be asking too much.


LAST question, is the center speaker currently wired into the headunit, so that it is used for music in our cars? I know I hear it being used for nav sound and voice activation but I'm not sure its used for music currently. If it isn't, I imagine that means we'd have to tap into that wire and wire it out to the 6 channel amp's bridged 5+6 channel ( Assuming 1+2 for left, 3+4 for right, with passive crossovers )

 

If you have a Bose system then the signal from the HU to the amp is basically clean. If I wanted to keep the stock system and just add a sub, that wouldn't be a problem as long as I took the incoming signal before the Bose amps and fed it into an after market amp. If the after market accepts speaker level inputs , then you just plug and play. If not then you would need a hi-lo converter. The problem with this, in my eyes and ears, is that you will be sending sub frequencies to your after market amp and sub, but the door woofers will also be getting those same frequencies. This will lead the same frequencies coming from the back and front and most likely a muddled sound in the low end. You could try and reverse polarity in the sub and it most likely would help, but not be great.

So, if all you want is to be able to is use your stock HU and run a system after it, whether thats just part new or a whole new system, you don't NEED a DSP. If you want things like digital crossover, time alignment, phase switching etc then you might look for a DSP. Some amps even have internal DSPs in them now.

For a person who wants to keep their OEM HU, but has a processed signal, they need to unequalize that signal. They can either go with a no frills unequalizer like a clean sweep (which is very good but only does one thing) or they can use another DSP who unequalizes, but adds other digital processes like the 360.1, Alpine 650, MS-8. The negative is that when using thnigs like DSP's you go from a digital source (cd) to an analog signal (down the wires to your amp or DSP) then back to digital (DSP) then back again to analog (to your speakers). This flip flopping causes some degradation in the signal.

So, in short, people use a DSP if they don't want to do things physically to make up for the car environment or want it all easily accessible in one unit with acceptable performance.