Why is the gain reversed on my amp?

[ericnord 10+ year member]

Hey everyone,

I have 2 10" 2-ohm DVC Type-R subs. I have them wired to end up at a 2-ohm load and go into my alpine mono-sub amp. I was setting the gains yesterday and started at .5v. The DMM came back at 33v. I was aiming for 36 so I bumped it up to .7v and DMM read 26v. I then bumped it up to 1.0v and it read 19v. I went down to .4v and it came back at 39v so I left it there. Isn't this reversed though, why is less voltage on the gain leading to more voltage at the speaker outs?

Thanks

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[theCybe 5,000+ posts]

The gain is "Input Sensitivity;"

My understanding is that the lower voltage signal coming into the amp, the more sensitive the amp has to be to enlarge the signal;

So a tiny .5 signal will need more "gain" than a 5v signal; I think your gains are not backwards, just your understanding of what the gain does. The .5 isn't "how much gain," it's how strong the signal from the RCA is.

Right? Did I learn something? I want a cookie. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[johnecon2001 5,000+ posts]

yeah thats correct. would you like milk with that?

 

[ericnord 10+ year member]

So you are saying my amp is getting plenty of power from the HU and this is why it does not have to be very sensitive on its own (i.e. leave the gain low, around .5v) to get the appropriate voltage to the outputs. So I'm actually not using all the juice coming from the HU since an increase in my gain .5v-1v lowers the speaker volts, but with low amp gain adjustment .1v I get a large voltage to speaker.

Is this correct?

 

[squeak9798 5,000+ posts]

So you are saying my amp is getting plenty of power from the HU and this is why it does not have to be very sensitive on its own (i.e. leave the gain low, around .5v) to get the appropriate voltage to the outputs. So I'm actually not using all the juice coming from the HU since an increase in my gain .5v-1v lowers the speaker volts, but with low amp gain adjustment .1v I get a large voltage to speaker.
Is this correct?

You are thinking of it backwards //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

The gain basically just attenuates the incoming signal. That's all. The point is merely just to attenuate the incoming signal to a level that allows the amp to make full power, but without overdriving the amp.

Now, the Voltage settings that you see around the outside dial are a displaying the incoming voltage from the headunit. With a higher incoming voltage from the headunit, we need to attenuate the signal more. With a lower incoming voltage, we need to attenuate the signal less.

So, turning the knob towards a higher voltage number increases the amount of attenuation, decreasing the output. Turn it towards the lower number and it decreases the amount of attenuation, increasing the output from the amp.

Hence why when you turned it towards 1.0V, the voltage output as read by the DMM went down (more attenuation of the incoming signal = less output at the terminals). And the .5V setting allowed for a higher voltage reading on the DMM (less attenuation).

Clear as mud??

 

[squeak9798 5,000+ posts]

Sorry, moral of the story; with a "high" gain setting (the gain set more towards the lower voltage numbers around the outside of the dial), it means that you have a weak voltage output from your HU. So, leaving the gain set to .5V is actually a high gain setting, not a low gain setting.

But, don't worry so much about where the dial is set; just make sure the DMM is reading the correct voltage output from the speaker terminals //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[ericnord 10+ year member]

Thanks everyone,

I have it now!

 

[theCybe 5,000+ posts]

I want another cookie. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[squeak9798 5,000+ posts]

I want another cookie. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

Here's your cookie: