How do you set your gains using a DMM?

[grampi 10+ year member]

Where do you take your measurements with the DMM?

Click to read more...

 

[jco1385 5,000+ posts]

sticky ftw!!

http://www.caraudio.com/forum/showthread.php?t=63933

or

http://www.caraudio.com/forum/showthread.php?t=164826

 

[04_edge 10+ year member]

are you asking where you put the leads?

 

[jco1385 5,000+ posts]

are you asking where you put the leads?

if this is the question, be sure it's set on ~200v AC and put the leads on the speaker outputs of the amp. be sure no speakers are hooked up when you play the test tone.

 

[grampi 10+ year member]

So you take your measurements at the speaker outputs and not at the RCAs coming from the HU to the amp? Do you put the DMM + lead on the speaker out+ and neg DMM lead on the same channel's speaker - lead? Should these measurements be taken with HU's volume control turned up to max volume? And using what source material?

 

[aeon 10+ year member]

This should help.

http://mobile.jlaudio.com/products_amps_pages.php?page_id=30

click on the "Interactive Input Sensitivity (“Gain”) Setting Tutorial" link

 

[jco1385 5,000+ posts]

So you take your measurements at the speaker outputs and not at the RCAs coming from the HU to the amp? Do you put the DMM + lead on the speaker out+ and neg DMM lead on the same channel's speaker - lead? Should these measurements be taken with HU's volume control turned up to max volume? And using what source material?

check post #2 for reference

 

[grampi 10+ year member]

So since I'm bridging my amp @ 300wrms into 4 ohms, I should be setting its gain for 34.64 volts, or should I be looking for only 24.49 volts because the amp is only "seeing" 2 ohms because it's bridged? Also, where can I get this CD that plays the test tone I'm supposed to use for this setup?

 

[12Voltz 10+ year member]

You need to set your gains to the input voltage of your head units RCA outputs. If you have a 5v preout, then you can just set your gain to 5v. If you want to be more accurate, Set your DMM to read 12vdc then check the output voltage of your RCA's by placing the positive lead on the center conductor of the RCA, and the negative lead on the outside conductor of the RCA. This will only work if you have a scale on your gain that shows you the voltage setting.

 

[jco1385 5,000+ posts]

You need to set your gains to the input voltage of your head units RCA outputs. If you have a 5v preout, then you can just set your gain to 5v. If you want to be more accurate, Set your DMM to read 12vdc then check the output voltage of your RCA's by placing the positive lead on the center conductor of the RCA, and the negative lead on the outside conductor of the RCA.

never heard of this. how would you set the gain to 5v?

OP, test tones are available at ROE. did you even look at the sticky?

 

[grampi 10+ year member]

never heard of this. how would you set the gain to 5v?
OP, test tones are available at ROE. did you even look at the sticky?

What's a ROE? I did looked at the sticky, but it's like 42 pages long.

 

[jco1385 5,000+ posts]

realmofexcursion.com

look under downloads

 

[12Voltz 10+ year member]

i made an edit in my previous post. My partner just pointed out, that not all amps have markings on the gain control indicating the actual input voltage setting. So this will only work on amps that have voltage indicators on the gain control. To set a gain on other amps, you will need to know the reccomended output voltage for the amp to maximize performance. Unfortunately, not all amp manufacturers provide this information.

To avoid issues with clipping i reccomend using a high performance line driver. This will allow you to set your gain to the lowest setting, and allow for least amount of THD. We like the memphis line driver, so long as the amp will handle a 9v input.

 

[jco1385 5,000+ posts]

to eliminate clipping use an o-scope

 

[grampi 10+ year member]

realmofexcursion.com
look under downloads

Which one do I need to download?