Using DMM and Setting Gains

[seg_representin 10+ year member]

I got my hands on a DMM and i don't exactly know how to use it. There are 4 places where i can put the 2 cords. 2 red and 2 black. Which red do i put the red cord in and which black do i put the black cord in? And then i just set it to AC voltage? And when i'm setting the gains what test tone should i use?....20 hz, 30 hz, 40 hz, or 45 hz? Gonna be doing this tomorrow so i need a lil help on this guys.

Click to read more...

 

[Johnny Drama 5,000+ posts]

So you will want to put the cords in the V/ohm (red) and grnd/com(black)

You also want to use AC voltage witht he setting of 200 if your DMM isnt automatic setting.

Finally, the best bet for setting your gain will probly be the 40 or 45hz tone. If you are going to be using bass boost, find out what frequency you amp has the boost at and set it with that tone.

Hope this helps,

Justin

 

[fawd06 10+ year member]

where do u put the dmm at? by the amp out put or what?

 

[luvinthebass 5,000+ posts]

at the speaker terminals of the amp

 

[fawd06 10+ year member]

at the speaker terminals of the amp

ok thanks and what is it suppose to read? srry for the noobness

 

[wilzyx 5,000+ posts]

you need to find out how many volts it need to put out, how much power rms do you need and at what ohm?

 

[seg_representin 10+ year member]

I know that i already calculated the volts and ohms. i have a nine.1 so 1200 at 1 ohm which is 34.64 volts. And thanks for the info jntar that did help alot. Thats exactly what i wanted to know. After i get outta basketball i'm gonna get to work on that so i'll let you all know if all goes well. Yea i might set my bass boost a little bit so i'll prolly end up using a 45 hz tone but if i don't use bass boost i'll use a 40 hz tone.

 

[kbkid 10+ year member]

I've always known to use a 50Hz test tone. I'm sure a 40 or a 45Hz will work as well, just thought I'd throw it out to you.

The procedure to setting the gains are:

1. Set any bass boost, equalizers, or any other type of setting first.

2. Unhook the positive speaker wire from the terminal

3. Play the test tone CD, might wanna set it to repeat if it is a short track

4. Place the red(+) probe into the disconnected terminal and place the black(-) probe into the still connected negative

5. Your MultiMeter should be set to AC Voltage somewhere close to 200

6. Once you have the multimeter hooked up, slowly turn the gain knob/screw until the voltage reads what it is suppose to. You already determined it should read 34.64, so basically thats all.

Did I miss anything?

 

[seg_representin 10+ year member]

Nope that sounds like everything. I've read the tutorials and that sounds good. Thanks for the help guys.

 

[questionaire 10+ year member]

Arent you suppost to use square root of something to find the number to reach??

 

[Johnny Drama 5,000+ posts]

Arent you suppost to use square root of something to find the number to reach??

(power*resistance)sqrt

 

[kicker06 10+ year member]

Put the Black Cord (neg) into the Common Hole, and the Red Cord (pos) into the V/Ohm(left) hole and you'll be set.

That works for both the volt measure and the ohm (impendence) measure.

Wait I got a Q.

Do you have to have the sub connected to the negative speaker output terminal on the amp when setting your gains? I did it without and got my 34.6V and the gain ended up between 1/2 and 3/4.

 

[seg_representin 10+ year member]

I went to set my gainst today. And it seemed like everything was good but it just seemed weird that the voltage came out correct when the gain knob was set not even half way and my deck only gives out like 2v preouts. So i would think that it would be farther then half. What do you guys think? Did i do something wrong. I used a 45hz tone at 0db and i set the volume to 18/35 cuz thats where i listen to it at and my gain knob wasn't even half the way up. I just thought something seemed a little weird.

 

[Silver 10+ year member]

Go by ear.

 

[kicker06 10+ year member]

I went to set my gainst today. And it seemed like everything was good but it just seemed weird that the voltage came out correct when the gain knob was set not even half way and my deck only gives out like 2v preouts. So i would think that it would be farther then half. What do you guys think? Did i do something wrong. I used a 45hz tone at 0db and i set the volume to 18/35 cuz thats where i listen to it at and my gain knob wasn't even half the way up. I just thought something seemed a little weird.

Yea does seem a little low. What voltage were you aiming for?

What's your battery voltage?