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      09-13-2012, 12:59 PM   #5
mob17
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Drives: E92 335D
Join Date: Mar 2012
Location: East Midlands, UK

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Quote:
Originally Posted by afsar
In step 1-4 you seem to set highest undistorted high level for the headunit and amp volume - This ofcourse will be very loud when we are doing it in a residential street, how did you circumvent this? Also what is point in setting highest undistorted volume where they have to be matched to 30-40w each MS-8 channel, they aren't so powerful and all the amps are easily producing 70+ watt per channel. Aren't these steps redundant?

My amp is PDX-4.150, so 150 watt each channel set for 2v could fry the stock L7 speaker, atleast it will be too loud.

What is the idea here, is this understanding right?

1) Get the SPL level from all the speakers same, but in this case what is the use of having extra amplifier as you will have to reduce SPL level to minimum to match non-amped channels.
2) Do driver and passenger seat acoustic calibration after reducing volume a bit - Do you know what volume is best for calibration, I have read it at various threads that reduce your amp gain to 0 to do this calibration, that will undo the first step.

Excuse me for these noob questions.
Regarding playing it in a street its simple, turn the ms-8 volume down and then use the pink noise to set gains. The pink noise is unfiltered so you have to do it at lowish volumes. Obviously you have to ensure that you dont give a speaker too much power. The point of level matching the speakers is that it gives the ms-8 ideal conditions to calibrate and process all that info. You can increase the gains after but obviously this would cause the ms-8 powered channels to be attenuated. So it wouldnt be a good idea if you have a ms-8 powered centre.

I think the best course of action would be:

1) find out at what gain position is the maximum safe gain for each speaker. Either do this by ear or multimeter.
2) level match. So probably means reduce your amp gains to match rears and any other ms-8 powered channels. I think even if you dont reduce the gains, the ms-8 will limit the power of your amped speakers anyway.
3) increase gains to level desired.

In my set up this worked because the only ms-8 powered channels are my rears. So after calibration i can increase my amp gains, with only my rears being attenuated, which i dont really care about. However if you have an unamped centre (which i think you do?) then it would really mess with your front stage if you increased the gains after calibration. So you have 3 options:

1) Level match and leave the gains as they are. This is the best solution if you don't want to add anything else.

2) Get a very efficient centre speaker, like a DLS 424, so its "louder" for a given wattage. So it might even match your amped channels but still running off the ms-8. Even if it doesn't match exactly, it will be louder than what you have, therby reducing the amount you turn your amp gains by.

3) Amp your centre. Might be able to amp your rears for similar prices.

For calibration volume its the same way as i pm'd you. Basically level match with the pink noise in test menu, then using an iphone app adjust the ms-8 volume until you get a 50-55db reading. This will give you a range of 5 ms-8 volumes which you should try.
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2008 E92 335D SE - Ohlins
2010 E90 320D SE
1994 E36 318I SE
1996 E36 316I SE