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      12-02-2012, 04:03 AM   #1
mistryn
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How to set amplifier gains help

I have read various guides and youtube and pretty much understand how to set gains with multimeter but one thing im confused is when they say to turn the volume 3/4 up on hu. How can you tell? Because on mine it does not show volume level figure?
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      12-02-2012, 04:18 AM   #2
davyk31
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Just take it to a loud listening level, just above a comfortable loud level.
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      12-02-2012, 04:32 AM   #3
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What setting shall i have on my amp?
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      12-03-2012, 04:38 AM   #4
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Your right you cannot tell what level the headunit its at,
I would
Turn all the gains down on the amp/amps

Turn the headunit all the way up then knock it back a tiny bit, from my experience the BMW headunit is programmed so it does not distort like after market units.

Leaving the headunit at this level increase gain until you hear the speaker starting to distort then knock it back around 10%, once completed unplug those channels and go to the next ones so you can hear them properly.

One other thing to take into account is the crossover settings/filters, depending on your configuration you will need to filter the bass going to the mids & tweeters however if your running them on the same channels as the underseat woofers then this is not really feasible.
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      12-04-2012, 06:09 AM   #5
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Quote:
Originally Posted by Bomber
Your right you cannot tell what level the headunit its at,
I would
Turn all the gains down on the amp/amps

Turn the headunit all the way up then knock it back a tiny bit, from my experience the BMW headunit is programmed so it does not distort like after market units.

Leaving the headunit at this level increase gain until you hear the speaker starting to distort then knock it back around 10%, once completed unplug those channels and go to the next ones so you can hear them properly.

One other thing to take into account is the crossover settings/filters, depending on your configuration you will need to filter the bass going to the mids & tweeters however if your running them on the same channels as the underseat woofers then this is not really feasible.
+1
Bmw (alpine) has done something that the sound does not distort at all on max volume (with proper drivers).

I always adjust my gains on max volume and I know pros and cons of it.
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      12-04-2012, 06:32 AM   #6
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Good advice above, I use SMD DD-1 (I sell/import these) which is infact little better than a oscope at picking up distortion. Multimeter or scope won't find that, let alone a dodgy RCA cable.
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      12-04-2012, 06:53 AM   #7
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Quote:
Originally Posted by Mr Singh View Post
Good advice above, I use SMD DD-1 (I sell/import these) which is infact little better than a oscope at picking up distortion. Multimeter or scope won't find that, let alone a dodgy RCA cable.
Sounds interesting, I had 20 years in the business been out of it for 9 years or so now it was just down to my acute hearing then
I would expect there's lots of new tools and gadgets to help out now.
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      12-04-2012, 07:37 AM   #8
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Quote:
Originally Posted by Bomber View Post
Sounds interesting, I had 20 years in the business been out of it for 9 years or so now it was just down to my acute hearing then
I would expect there's lots of new tools and gadgets to help out now.
https://www.youtube.com/results?sear....1.0cXIQeD56Vg

Plenty of videos on there. Designed by ex Rockford Fosgate engineers (D'Amore) also produce CC-1 a crossover calibrator and recently a signal generator to find check enclosure tuning frequency driver Fs etc...

Edit, out of interest which shop/company did you work for? been in the business for 10 yrs but I know quite a few of the old timers
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      12-04-2012, 07:46 AM   #9
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I dont have any experience in setting gains as I have always got someone else to do it for me, but this time I thought i give it a try. Read a few guides and yutube videos - particularly one where the guy creates a tone on Audacity - plays it through the HU - and adjusts via multimeter whilst setting the gain.

I tried to do that but when I got into the car i failed at first hurdle as I could not see what volume i was at. So I set it as high as I thought was safe and unplugged all speaker/sub connectons from the amp. I played the 60 hz tone through and conencted the multimeter but I did not get any readings, it stayed at zero (I had the multimeter set as per in the youtube video)

i then played a normal bassy track and mid volume and the reading was fluctuating all over the place - I dont know what I am doing wrong
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      12-04-2012, 09:30 AM   #10
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Can you tell us your set up and how you have it configured?
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      12-04-2012, 10:28 AM   #11
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Original base hu set up
HU coded to hifi
Technics harness
JL xd400/4 4channel amp
channels 1+2 powering sws 8 earthquake underseat subs
Channels 3+4 powering front logic 7 speakers and tweeters
Rear speakers left standard running off hu

Channels 1+2 freq set at 65HZ, LP filter
Channels 3+4 freq set at 120HZ, HP filter

Last edited by mistryn; 12-04-2012 at 12:41 PM.
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