How to tune an amp when in Series?

[JZeFF]

I just threw another set of my rear 6x9's in the back... they are 2ohm infinity speakers. I wired them in series so that each channel now runs at 4 ohms... when im calculating to figure out what my gains should be set at do i calculate using 4ohms?

Its an easy question, but idk the answer.

Thanks guys

[dugee81]

you must take the overall wattage times the present ohm load in which your speakers are wired to (4 ohms), then find the square root of that to find what voltage you should set your amp to (using a dmm). i have 400 RMS running to my mids/highs @ 4 ohms bridged, so i do 400*4 = 1600. the square root of 1600 is 40, so i adjust my gain accordingly to 40 volts.

[JZeFF]

Thanks man... i knew how to do it for single speakers, i just was not sure if it was the same with speakers in series and parallel..

[JZeFF]

Alright.. well im about to do this.. and im kinda confused.. so im just gonna ask which of these is correct.

Its a DAT 4125,

Channel 1 and 2 are running a set of Rockford components at 4ohms per channel.

Channel 3 is running 2 sets of 2 ohm infinity speakers in series... so its a 4 ohm load.

Channel 4 is running the exact same thing ^^

A, B, or C, which method is correct?

A. 500 x 4 = 2000 Square root of 2000 = 44.72 (500 being the total power of the amp, 125w at 4ohms times 4)

or

B. 250 x 4 = 1000 Square root of 1000 = 31.62 (250 being the 2 rear channels of the amp, 125w at 4ohm x 2)

or

C. 125 x 4 = 500 Square root of 500 = 22.36 (125 obviously being 1 channel of the amp at 4 ohms)

Im almost positive Letter A is the correct answer, but i just wanted to make sure before i blow something, haha.

[Guest]

for a 4 channel i know theres 2 gain knobs, one for each side (front and rear)

ok so your rockford components are hooked up in stereo at 4 ohms. that means to get the full power, you need to tune the gain on that side of the amp to 250rms at 4 ohms = 31.62v at the speaker terminals

ok now your infinity...wait how did you wire 4 2 ohm speakers to get a 4 ohm load? 2 2 ohm speakers in series is 4 ohms and another 2 speakers all combined in series is 8 ohms...anyways you would tune the gains to 250rms at 4 ohms, so 31.62v again.

[skittlesRgood]

for a 4 channel i know theres 2 gain knobs, one for each side (front and rear)

ok so your rockford components are hooked up in stereo at 4 ohms. that means to get the full power, you need to tune the gain on that side of the amp to 250rms at 4 ohms = 31.62v at the speaker terminals

ok now your infinity...wait how did you wire 4 2 ohm speakers to get a 4 ohm load? 2 2 ohm speakers in series is 4 ohms and another 2 speakers all combined in series is 8 ohms...anyways you would tune the gains to 250rms at 4 ohms, so 31.62v again.

he said channel 3 has 2 speakers (4ohms) and channel 4 has 2 speakers (4ohms).

you measure voltage of just one channel. unless im very mistaken you want to do option C. that will set each channel to 125w.

[JZeFF]

Im getting two respectable answers from two respectable members (high post count)

Im not sure what to do here... lol

And yes, i have 2 speakers on channel 3, and 2 speakers on channel 4.

each channel has the 2 speakers run in series, to give me a 4 ohm load per channel.

Amp is rated at 125w per channel at 4 ohms...

[cqtama]

if each chanel is seeing a 4 ohm load then you're going to tune based on that 4 ohm load because thats what your putting on the amp

[JZeFF]

So.... A, B, or C.... lol

Im sorry guys, im just getting confused here...

[dugee81]

Ur gonna wanna do C in my opinion, if each channel is seeing a 4 ohm load.

Edited March 15, 2010 by dugee81