GioRF Posted July 20, 2010 Report Share Posted July 20, 2010 Adding gain overlap when setting amp gains is recomended by Rockford Fosgate they recomend a -10 db of overlap for subs and -5 db for fullrange. My question is what are tha pros and cons of setting with overlap? Quote Link to comment Share on other sites More sharing options...
BeachJoshua Posted July 20, 2010 Report Share Posted July 20, 2010 Adding gain overlap when setting amp gains is recomended by Rockford Fosgate they recomend a -10 db of overlap for subs and -5 db for fullrange. My question is what are tha pros and cons of setting with overlap? My question is what is gain overlap? Quote | S-10 | 4.5^3 ft | 33Hz | SAE-1000D @ 1 Ohm | 2 SA-12s | SPL: 143.7 Sealed | 153.4 Port Wars Link to comment Share on other sites More sharing options...
ib2loud Posted July 20, 2010 Report Share Posted July 20, 2010 Gain overlap is a compensation mechanism to account for the fact that we don’t listen to test tones in mobile audio systems, rather we listen to music. Test tones are great for setting up the input levels on each component of the signal chain, but test tones are constant levels all of the time. Music has levels that simply are not constant all of the time. There are loud passages and soft passages in music, and these are constantly changing. Due to this fact, the maximum unclipped output levels determined by test tones will seem as if the system doesn’t play very loud. Certainly it’s free of clipping and audible distortion, but it’s not as loud as it seems like it could be overall. This process allows a measured amount of increase to be implemented without “guessing” by just turning up the gain controls on a random piece of equipment. Adding extra gain to the signal chain whether it’s at an upstream signal processor or at the amplifier at this point is a trade-off of benefits and drawbacks. Most people find that there is a good compromise of these trade-offs When you raise the gain above the levels achieved with a test tone, you will lower the signal to noise ratio of the system. In this scenario, the trade-off is higher output at maximum levels trading off for more hiss and system noise with the volume at lower levels. There is always an acceptable compromise. Additionally, when you raise the gain above the levels achieved with a test tone, you will increase audible distortion of the system. In this scenario, the trade-off is higher output at maximum levels trading off for more frequent moments of “clipping” with both the volume and the music at their maximum levels. Check out the amount of time that there is added distortion in the signal based on the amount of gain overlap added. Once again, there is always an acceptable compromise. Add in 5dB of gain overlap to achieve a higher volume with music (rather than test tones). It’s a safe compromise between slightly increased distortion (Less than 0.1%) and louder output (nearly 5dB). Less critical listeners could tolerate 10dB of gain overlap, but look what happens to the distortion increase. Some people will easily hear that with a great set of mid and high frequency speakers (certainly more evident on compressed audio tracks as well). Reserve 15dB of gain overlap for subs, if at all. If you are using this setting, chances are you can go to a bigger amp for better sounding results at the same volume levels with less distortion and more headroom. Use the gain overlap tracks on the RTTI/3Sixty set up disc to achieve the gain overlap safely without causing damage to the speakers. Simply play the same frequency (HP/BP/LP) as before and increase the voltage levels to the same place the recorded measurements were at 0dB levels for 5dB of overlap. If you use the 0dB tracks to increase the output voltages to do this, you will almost certainly damage the speakers if not using load resistors. Don’t forget to disconnect the speakers when setting up gain overlap!!!! Quote "If it has tits or tires, its gonna be a problem..." Potential for good and greatness, the human race never fails to consistently excel in ignorance and idiocy. Link to comment Share on other sites More sharing options...
Decaf Posted July 20, 2010 Report Share Posted July 20, 2010 0db is for competitors or people who are very scared to turn it up on music, no music is this loud, only sine waves -3db is good for most people, stuff like Dj Billy E and Bass Mekaniks gets this loud -4.6db is the test tone i use, it gets the most out of ur amp safely on most music -5db/-10db RF suggested levels... lots of music is louder than -10db... so i wouldnt use that personally Quote Link to comment Share on other sites More sharing options...
GioRF Posted July 21, 2010 Author Report Share Posted July 21, 2010 0db is for competitors or people who are very scared to turn it up on music, no music is this loud, only sine waves -3db is good for most people, stuff like Dj Billy E and Bass Mekaniks gets this loud -4.6db is the test tone i use, it gets the most out of ur amp safely on most music -5db/-10db RF suggested levels... lots of music is louder than -10db... so i wouldnt use that personally So where could i find 50hz and 1khz tones at -3dbs and -4.6dbs? Quote Link to comment Share on other sites More sharing options...
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