# amp gain chart



## angeljr8282 (Sep 6, 2012)

hey guys i found this gain chart online and wasnt 100% sure on how to use it.


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## angeljr8282 (Sep 6, 2012)

im using a 2500watts amp and sub is a hdc312 D2 SQ and i have it wired for 2ohms.im new to this if you wired your sub for 2ohm is it still 2ohm to the amp or 1 ohm


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## xt577 (Apr 19, 2011)

What amp is it?


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## benny (Apr 7, 2008)

How exactly did you wire a D2 sub to a 2 ohm final load?


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## ATOMICTECH62 (Jan 24, 2009)

angeljr8282 said:


> im using a 2500watts amp and sub is a hdc312 D2 SQ and i have it wired for 2ohms.im new to this if you wired your sub for 2ohm is it still 2ohm to the amp or 1 ohm


This calculation only applies when bridging a 2 channel amp to mono.


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## xt577 (Apr 19, 2011)

angeljr8282 said:


> hey guys i found this gain chart online and wasnt 100% sure on how to use it.


1) if you don't already know, you need a *D*igital *M*ulti *M*eter
2) if your amp is the Alpine MRD-M1005, you're _maybe_ getting 1000w rms 
3) your sub handles up to 1000w rms
4) find appropriate ohm and (<=) 1000 rms watt value in chart & use digital multi meter to adjust gain until volt value from chart is reached (method can be researched online, do with car running). 
5) OPTIONAL see if someone will hook up an oscilloscope to your speaker outputs to ensure that your signal isn't clipping (unless you like distortion, which apparently some do). But if you pay someone to do this, you might as well pay them to set the gains for you in the first place. An oscope is the most accurate method to ensure full power and an unclipped signal. 

Caveats to the DMM approach: Manufacturers do their power ratings based off of a 14.4v power supply, a value that most cars almost always provide less than. This factor, combined with the variability from amp to amp, leaves one unsure of exactly how much their amp is capable of producing without the signal clipping. The one exception to this are amps that use regulated power supplies which make the voltage and corresponding wattage more predictable (although even here there there is still some variability between amps, manufacturers underrate their products, etc). 

http://forum.sounddomain.com/ubbthreads.php/ubb/showflat/Number/65167/page/1

research
set gains with DMM
set gains with o-scope

Good luck!


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## ZAKOH (Nov 26, 2010)

You don't need the chart. Just use the formula V=sqrt(W*R) where W is output power and R is resistance. The way you use it is that first you decide what's the highest head unit level position you will ever use. Most people just stick to say 3/4 position of volume. This will never be exceeded after the calibration. Turn off bass boost functions, any "sound enhancers". If the head unit has a subwoofer level adjustment, set it at 0dB. Turn off crossovers of the subwoofer. Turn off all other speakers, or set their high pass crossovers so they're not damaged during test. Play a test tone and then adjust the amplifier gain to match the target output voltage. Some people recommend using 0dB test tone, which I think is a waste. Make a -5dB 60Hz test tone, as most normal music does not exceed -5dB. Note that this method gives you the maximum "safe" gain setting for the subwoofer. This does not give you the appropriate gain level (e.g. such that the subwoofer and other speakers blends well together). It's entirely fine to turn the gain down below that point.


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## angeljr8282 (Sep 6, 2012)

I'm using a 2500 watts autotek amp and when I wired the sub I went from pos to pos and neg to neg that should give me 2ohm right. Is that the best way to wired that sub its the first time im useing sound qubed..and I'm only using 1 sub


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## angeljr8282 (Sep 6, 2012)

And I'm also using my stock head unit of my Infiniti fx35


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## 07azhhr (Dec 28, 2011)

angeljr8282 said:


> I'm using a 2500 watts autotek amp and when I wired the sub I went from pos to pos and neg to neg that should give me 2ohm right. Is that the best way to wired that sub its the first time im useing sound qubed..and I'm only using 1 sub


No. Since your sub is a D2 that means it is a 2 ohm per voice coil sub then when you wire it in parallel like you did then you get a 1 ohm final load at the amp.


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## angeljr8282 (Sep 6, 2012)

So on the chart I'll be looking at 2500 watts 1ohms and turning my gain to my meter shows 50.00V


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## 07azhhr (Dec 28, 2011)

If this is the amp you are using then you will not be able to see 50v ac out of it. Besides that you will need to know the actual input voltage coming from your car to determine the actual voltage needed from the amps outputs. Also incase you did not know this already, the amp wil output ac voltage.
Autotek M2500.1D 2500W Max Mean Machine Series Mono Amplifier


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## angeljr8282 (Sep 6, 2012)

OK I'm a noob to this I'm guessing the last time I check I was getting 14v out of my car


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