help with MM6 and C.400

[Astr0LuX]

bear with me:

I needs some help with my system. I installed all of it myself and lately I just havent been hearing the sharpness of the highs I should be getting out of my tweeters. SO I took the amp out and did some adjusting of the crossover settings and all those other fun gadgets on the amp that I dont exactly know what they do. I was able to get my highs back and got it to the point where it sounded beautiful...BUT..only at low-medium volumes. When I turn it up higher the midrange distorts nastily when the bass hits (ftr im playing Thrice - Illusion of Safety to test).

Is this a probelm wit hthe midranges? Can they not handle any bass? What crossover and EQ settings should I ahve the amp at for optimal performance and SQ.

I wish I could limit the amount of bass going to the mid but at the same time keep the highs in the tweeters. I havent been able to achieve this since when I finally get rid of the distortion..the highs are not sharp at all.


Thanks in advance.

[AustinKP]

Are you bi-amping them or going through the MM6's passive crossover?

[IS300]

Astr0LuX is me btw.


well im using both..the C400 and the MM6s crossovers...I think the amp already has the crossovers in it..right?

Im not sure if thered be any negative affects to this. I figured out a fairly good fix for it which was to turn down the main bass on my head unit. It does the job and now I was able to keep the highs and mids.

I just added a single 12" mtx thunder6000 to my C500 and it sounds really good. The single sounds alot better than my dual 12" momo's.

[MacLeod]

That sounds strange. You shouldnt have to turn your bass down at all unless youve got your gain about all the way up.

My first guess at the problem would be your gain settings, especially if your bi-amping them. Im bi-amping my 6x9s with my Crossfire and the gain for my mids are at about 25%! Anymore than that sounded like it was going to tear a hole in the speaker.

[neomagus00]

well, that depends upon the original settings. i would suggest doing the following:

1) Turn off any sound shaping - any bass boost (or cut), any equalization, time alignment, anything.
2) I'd say set the crossover point at 80 Hz, cause you can play with it from there. that is, make the sub's lowpass 80Hz and the mains highpass at 80Hz.
3) I'm assuming you have a separate sub amp. On the 400.4, you don't need the external xovers - simply wire the mids and tweeters appropriately to the amp (look in the manual, make sure you get it right or you'll blow the tweets).
4) Follow these directions for setting the gains on the amp. Basically, you'll tune each set of speakers in turn, and that should remove any possibility of distortion. btw, please read all the way through first, it'll save some grief.

IF you don't want to do a major rewire - and you probably should, unless you've got your sub wired to the 400.4 as well as the mains - then just follow that link as it is now. and follow the mm6 directions, namely the bit about putting the midrange extend switches to off and the tweets to -6dB to begin with, then adjusting from there. the mm6 does not exhibit distortion of any kind until you are pushing it BEYOND its limits - when you hear distortion, for the love of allah, turn it down. and as a final note, the mm6 doesn't do low bass - it's a 6.5" speaker, it's built to do amazing midrange, and it does that quite well, and deafeningly loud when tuned properly.

[exalted512]

thats wierd...i played mine down to 50 running ~225 watts and never had a problem until i started blowing the leads off the terminals
-Cody

[IS300]

Well idk what it is..when I can take a pic of my amp settings and you guys can give me advice from there..Right now I am getting really nice mids and highs. But the lows coming from the 6.5's distort on certain songs. In that event..I turn the main bass on my stock headunit to 4 instead of 5..its not a huge deal but still it sounds nicer at 5.

I am running a seperate sub amp (C500) which works flawless under 2 and 4ohm louds.

My digicam's batteries died and theyre charging..as soon as its ready ill take pictures.

[MacLeod]

well, your bass should be pretty close to 0 on your head unit. Mine never goes above 4 and thats only on CDs like Yes' 90125 which doesnt have much bass at all. For the most part it stays at 1 or 0.

[IS300]

after me fiddling with it all day friday..I came up with these settings that sound good. I honestly dont know what all these things mean..so what I did was just press buttons and turn knobs until it sounded good.

For more clarification if needed. I power my MM6's and MMC690's with my C400

I didnt want to mess with my settings right now because they sound good and Im afraind of messing it up like I have a tendency to do...but heres what I see on the amp:

Front Slope - 24dB
Rear Slope - 12dB

button thing front - x1
button thing rear - x10

Frequency front - \ <--looks like that
Frequency rear - \

LP/HP front - OFF
LP/HP rear - OFF

Both Input controls set to LOW

Gain on both looks like this /

haha..after looking at this..makes me feel pretty rediculous..but it somewhat gets the point across.

[IS300]

Originally posted by MacLeod
well, your bass should be pretty close to 0 on your head unit. Mine never goes above 4 and thats only on CDs like Yes' 90125 which doesnt have much bass at all. For the most part it stays at 1 or 0.

well are we talkin about the same car here. In my old truck that had an alpine head unit the bass was always at 0 or even negative. Ive always had my the bass at 5 in my car (Lexus IS). I did a mod to my stock amplifier so I could retain my stock head unit.

[neomagus00]

ah, you're on a stock HU... does it go to negative numbers for the bass control? i.e. is zero the reference point, or is the lowest number zero or one and it goes up from there?

your amp settings look relatively normal, as does the gain (for a stock HU).

if you want a small tutorial on what each of those controls does, check out your amp manual and if you don't get it (you might not after that) ask away.

fyi, because the fourth control is set at off for both, the first three shouldn't do anything at all. if they do, you've likely got an amp problem, and a serious one at that.

this is what i'd reccommend: set the first control to (front - 24, rear - 12), the second to (front - X1, rear - X1), the third to (front - 80, or closer to 100 than 50 if 80's not listed, rear - 250, or if that's not listed, then around 25 and put the seond control for the rear to X10), and the fourth control would be (front - HP, rear - HP). then do what the link says for the gains.

[IS300]

the range for the headunit is -5 to 5.

Basically what I did was solder rca connections to the circuit board on my stock amp which created pre-outs so I could send the signal to the amps...thats all it does. I wasnt planning on changing my headunit because I like the clean stock look of my center console.


I will try your settings tomorrow when I get the chance.

Thanks for the help so far guys...anymore input is greatly appreciated.

[neomagus00]

okay, did you put the rca adaptors before or after the amplification bit of the stock amps? and your bass should be around zero, not more than three, especially since you have a sub. the fact that you need that much extra bass relative to the rest of the music indicates an issue, probably due to a lack of balance between the mains amp and the sub amp. that link should allow you to fix that.

fyi, the preouts and the sound shaping are two of the primary reasons to get an aftermarket HU :p... you may wish to consider it; many companies offer stock-look HU's, too...

[IS300]

Originally posted by neomagus00
okay, did you put the rca adaptors before or after the amplification bit of the stock amps? and your bass should be around zero, not more than three, especially since you have a sub. the fact that you need that much extra bass relative to the rest of the music indicates an issue, probably due to a lack of balance between the mains amp and the sub amp. that link should allow you to fix that.

fyi, the preouts and the sound shaping are two of the primary reasons to get an aftermarket HU :p... you may wish to consider it; many companies offer stock-look HU's, too...

Well what my mod does is keep the signal from being amplified and reroutes the signal before it gets to that point. Heres a pic of it:



the wires are soldered to the RF LF RR RL solder points on the board.

I have tried turning the gain down on my amps but then I have to turn my knob nearly 360 to get it loud.

[IS300]

Im just curious to know..but could using the MM6 crossovers and the C400 cause uneeded resistance? What are negative affects of doing it this way? I mainly did it because i thought the crossovers were cool lookin so I wanted to show them.

[bknauss]

Assuming you add an outboard crossover after an amp, you're gong to add resistance no matter what. Yea, it might only be the characteristic resistances of the caps and inductors, and they might be in the milliohms, but its a resistance none the less.

[Joelsbass]

i'm wondering what the voltage supply from those rca's is... that could be causing part of the problem they could be going into clipping quickly...

[LittleCar_w/12s]

Ok, my first question for you is:
The wires that go to the stock amp are what?
-- Are they harnessed from the main deck? The main deck has no other output of any kind?
The wires leaving the stock amp are what?
---Did these used to go to the speakers?

Second question:
Do you have an oscilloscope or a VOM capable of measuring AC voltage?

Here's my reccomendation:
You have solder, you have wire, you have a detatchable harness from the stock amp - this is GOOD!
What you need to do is break down that stock connector to see what the leads in it are. You are still providing power to that stock amp, and those spots WILL NOT WORK the way you think. By you adding the line out there it changes the stages in the stock amp as well as the new amp to have weird impedances and such. Break down that connector to it's roots and use that for your outputs.

Additionally, IF the harness voltages are above 5-6v you may need speaker level inputs on that new amp, or you can get a converter. If it is less you'd be ok to form the end of the harness directly to RCA OUTs

Hope that helps a little. If you need to, see if you can find a reference on that harness from the dealer or somewhere online.
-Jerry

[LittleCar_w/12s]

if you need help using the osc or VOM to read the output on those lines, let me know.

[IS300]

well my dad has a voltage meter to measure that stuff. Hes an electrician (an electrician with a masters in electrical/computer engineering..though he has no time to help me..go figure) so I doubt that will be a problem.

As far as your questions:

The wires going into the stock amp are a harness that is directly connected to the stock headunit. The only other harness coming off the head unit is for Lexus factory Navigation that I dont have ( and it is not connected to anything).

These are the instructions I followed to add the preouts to my stock amp:
http://www.digital-mix.com/rob/is300-amp/

The only reason I did this mod was because I was told by many members of IS300.net that using an LLC will cause the sound to degrade. Although, some say it doesnt really make a difference. Could there be an alternate benefit to using an LLC instead of this?


I researched some more..and I found that the voltage coming off the preouts is about 200mV. Many say they have to turn the gain on their amps way up to hear anything..which is something I am doing. Would it be wise to get one of these?:

http://www.davidnavone.com/detail.asp?PRODUCT_ID=N-645


So little car..what you are saying i should do is open up the harness going into the stock amplifier..find the wires that indicate the output from the stock amp and wire those directly to my aftermarket amps bypassing the stock amp all together? And by reference what do you mean? My manual tells me where each wire goes and what it does coming out of the HU.

[Joelsbass]

yeah, you're probably pushing it into clipping which could cause the sound quality issues you've noticed... you realy should just replace the headunit... you could go with an eclipse, they have a very toned down look and have good soundquality...

[LittleCar_w/12s]

Yes, I am reccomending connecting your deck's outputs directly to the amp. This is going to be of the best possible quality you can get. No matter what you do to add pre-outs to an amplifier, you will degrade the sound, unless you want to build a real pre-out into it, which you should just bypass it anyway, as you need a lot of experience for making the right circuit.
Even if your signals on your deck give 202 mv, most amps will read down to 100mv, or 0.1v You will be able to use them. What you have now is eating that signal down very badly... both in quality and voltage.

[IS300]

wow..ok. Well as soon as I get a chance Ill get on this. When tapping off the stock head unit..do I add an rca to those wires to connect to the rca's that run to the amps? That confused me but it sounds right.

[IS300]

Ive researched some more and Im not sure that tapping the wires directly off the headunit will work. It is believed that the signal coming out of the head unit is digital (thus the reason forthe LLC or stock amp mod). And the channels are not split up at that point its just raw signal..here is the wiring diagram for pre-amp post-amp wiring:

from head unit: http://www.teckkits.com/IS300/Audio/radio1.jpg

stock amp:
http://www.teckkits.com/IS300/Audio/radio2.jpg

Is using an LLC really that bad? What kind of sound quality degration(sp?) should I expect?