fresh1

iTrader: (2)

sooooo heres a question, when tuning an amplifier, is it good to use math?

i just bought new subs, and i'm trying to break them in, and getting ready to retune my amp, and i've been looking for the best way to tune the amp. the last time i just turned up the gain and bass boost til it sounded right and was good to go for 2.5 years, but now i want to be professional about it. i ended up finding a "calculator" and then found the equation they along with a lot of other people use (volts^2 / resistance) and wondered if thats how you guys set your gains.

basically, with a 50 hz tone at 0 db, the equation says my meter should read about 35.3 volts and will give me 1250 rms at 1 ohm from my amp. i figured i would use this as a benchmark and then fine tune from there, but i wanted to know if that equation works.

Father Yuli

iTrader: (17)

let me know how that goes, try to video tape it.

fresh1

iTrader: (2)

something tells me that wasn't a vote of confidence. but for real man these subs are taking forever to loosen up. i'm afraid they're not broken in and end up turning down the gains

lpchouinard

Your math are good, BUT you are working with impedance not resistance.

I think you can do it with a clamp to measure the amps and a DMM for the volts, but for me the best is still to go by ear.

fresh1

iTrader: (2)

well i first tried a sheet, and then found the equation, and then i found this

Ohms Law Calculator

all of which give me 35.3. my biggest worry is that i've never used a dmm before to tune, just done it by ear, but if i do it now i feel like it will result in me tuning for the same sound as my last set up ie using the same amount of watts as last time when double that amount is available for use. i figure its best to use a combo of gain and bass boost on the amp to get it right, but like i said i've always done it by ear so i'm scared i might put it up to high.

to be honest i was gonna leave it at like 33 volts or something just to be safe, but i'm wondering what would be the best tone to test it with. everyone seems to say 50 or 60 with the occasional 45 hz, but i also figure lower notes require more power from the amp, so maybe using the frequency my subsonic filter is set to would be useful as well?

Dukk

Your math is technically correct. The fundamental flaw in it all is that the woofer, in a box, in a car, is not 1 ohm.

And even if you did get a static impedance reading at some nominal frequency, it will be different at other frequencies, and increase overall as the coil heats up.

Tubeamp

Sounds like you've put some thought into this... honestly (if you have access to one) the best way is to use an oscilloscope to view the waveform for any distortion. This way you can actually see the sign wave/voltage in real time while moving between frequencies to get your best overall setting.

If you don't have a scope. They can be found at any electronics surplus store for cheap (just make sure they have been calibrated). Or, there are pc kits available that work through your computer's usb port.

Hope this helps!

fresh1

iTrader: (2)

Thanks Dukk (is that another way of saying impedance rise?). And Tubeamp I've been considering trying it on an oscope, but at the same time I figure theres got to be another way. From what it sounds like from you guys though the best way (aside from an oscope) is the turn it up til it distorts then back off method, either that or pay to get it done, but theres no fun in that.

Soundigital

iTrader: (1)

You did right the first time, by ear...

Using all this internet technology and scopes, math and calculators will make you set the amp for a low power, because a music signal normally have lots of attenuation compared to a sine wave. This is a very safe mode to not clip the amp, but will require at least 6dB headroom to make it nice sounding...

Soundigital

iTrader: (1)

And dont test that on subs, they don't deserve it, test on resistances, you can buy heater resistances, cut them and sink on water.