Measuring Frequency
 

Anyone know if a device is available to measure frequency output on an amp. I have an amplifier that I would like to set at 90 hz. lp but the amp has no marking for that freq. only a from 30-350 hz. I can do some math and go halfway and halfway to reduce the numbers but feel more comfortable with true measures instead of guessing if I am anywhere near close to the freq. on the dial. Any input would be appreciated. Thanks

Well, you could play pink noise and have an RTA in the car, adjust the x-over until you see it start to drop off at 90 hz...?

Setting the crossover point
 

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if you had an RMS meter you can measure output versus tone frequency to determine when it starts to drop off.... many also have frequency counters... my fluke 111 was only like $200 and handheld oscopes can be found on ebay for alittle more...

anyway, make sure you measure using a non inductive load similar to the DC resistance of your subs or the measurement won't mean much.....

Well. . . you could use a LOC network to drop the amp output level to line level, then plug it into the line in of the RTA. then feed the amp pink noise..... and just watch the display while you adjust.

Check out Stereo System Test & Analysis Tones by Nino B.
This website offers free individual test tones you can download and burn...Choose whatever frequency / frequency range you want, burn it, play it and tune accordingly...