Question about gain and tuning a Lc7i and 5 channel Amp

[1aespinoza 10+ year member]

It was an easy fix, you grounded the RCA jackets to the HU chassis.

Dang it! I have been operating on one set of RCAs for ever. Thanks man. I will try this.

 

[1aespinoza 10+ year member]

I've set by ear forever.

Same here. For my own gear, I do it by ear.

 

[JasoninDLH]

Correct. From the amp, disconnect the RCAs that come from the LOC. The picture below points to where you will connect your multimeter test leads. Be cautious that positive and negative do not touch each other. The guy in the video made that pigtail to avoid this issue. Set multimeter to A/C volts. After downloading that 1000 Hz. test tone, play it on your radio at ~75% volume. Now sweep the gain on the LOC until you read the 5 volts that your amp can handle. Boom, Jalapeno solutions. Before reconnecting the RCAs to the amp, turn down the gain at the amp. Turn it up judiciously after that with the radio at ~75% volume.View attachment 47064

So I have an amp that has an input value of 14v and my LC2i has a 9.5v preout. I wouldn’t have to worry about testing with a DMM (as shown) to set the correct gain on the LOC. I would just put the gain all the way up on the LOC? And keep the gain on the amp as low as possible?

Strangely, the more I know…the more I don’t know. On previous builds I would just wing it and push some buttons here, turn some dials there and call it a day.

 

[1aespinoza 10+ year member]

So I have an amp that has an input value of 14v and my LC2i has a 9.5v preout. I wouldn’t have to worry about testing with a DMM (as shown) to set the correct gain on the LOC.

Correct.

And keep the gain on the amp as low as possible?

No. For the sub amp's gain setting, you go by the sub you will be using. Formula for that is-
A/C Voltage= Square root of Watts × Ohms.
If you want your 4 Ohms sub to play 300 watts. 4 × 300= 1200. Square root of 1200= 34.64 A/C volts.

Strangely, the more I know…the more I don’t know

Yup, I know that feeling all too well.

On previous builds I would just wing it and push some buttons here, turn some dials there and call it a day

Yup, this too.

 

[JasoninDLH]

Correct.

No. For the sub amp's gain setting, you go by the sub you will be using. Formula for that is-
A/C Voltage= Square root of Watts × Ohms.
If you want your 4 Ohms sub to play 300 watts. 4 × 300= 1200. Square root of 1200= 34.64 A/C volts.

Yup, I know that feeling all too well.

Yup, this too.

Thanks for the info! Super excited to finally dial this stuff in after 25 years of winging it.

 

[chornet44 10+ year member]

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