Lee
07-16-2002, 05:47 AM
5.8 How do I flatten my system's frequency response curve? [IDB, DK]First, you'll need a good quality equalizer - either a 2/3 octave (15-band) or 1/3 ocatve (30 band) equalizer or a quasi- parametric equalizer such as PPI's PAR 224 that allows you to choose the center frequency and bandwidth (Q) of each knob on the EQ. This will allow adjustments to very specific frequency ranges. Next, you'll need to get a hold of an RTA (Real Time Analyzer), which is an expensive piece of equipment that good shops will usually have. The shops can then equalize the system by making a measurement with the RTA, and varying the levels on the equalizer in order to make the overall response curve flat.
Unfortunately, most shops will not do this for free, since proper equalization can take anywhere from a half hour to many many hours.
Another method involves buying an SPL meter (available from Radio Shack for between $32 and $60) and a test disc (Autosound 2000 makes one that runs about $25) that plays discreet frequency ranges - in 1/3 octave groups. Then, moving through the range of frequencies, SPL measurements can be taken at each range, and you can plot out a "response" curve. You'll be able to see what frequency ranges need to be boosted and which need to be cut. This process will be time consuming (more so than an RTA, which can analyze the entire frequency spectrum simultaneously), but should be much less expensive than having it professionally done.
One last note: While a smooth curve will get the most points at an auto sound competition, you must NOT rely only on the RTA to tell you what sounds good. Use the RTA to get a good start, and then use your (better, use someone experienced in tuning systems) ears to do the fine-tuning.
Unfortunately, most shops will not do this for free, since proper equalization can take anywhere from a half hour to many many hours.
Another method involves buying an SPL meter (available from Radio Shack for between $32 and $60) and a test disc (Autosound 2000 makes one that runs about $25) that plays discreet frequency ranges - in 1/3 octave groups. Then, moving through the range of frequencies, SPL measurements can be taken at each range, and you can plot out a "response" curve. You'll be able to see what frequency ranges need to be boosted and which need to be cut. This process will be time consuming (more so than an RTA, which can analyze the entire frequency spectrum simultaneously), but should be much less expensive than having it professionally done.
One last note: While a smooth curve will get the most points at an auto sound competition, you must NOT rely only on the RTA to tell you what sounds good. Use the RTA to get a good start, and then use your (better, use someone experienced in tuning systems) ears to do the fine-tuning.