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MikeMartel

Setting Gains by Ear.

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Is this a terrible idea? Iv set my gain using the way JL audio reccomends, and i seriously get little output with this way to do it. I basically need to turn my bass boost on my HU from 3 (where i orignally set the gain) up to 7 before i even feel likes my 18" BTL is up to the output my old 10's have.

Tips for setting my gains by ear?

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If you are using a 0db test tone with the DMM method of setting a gain (the "JL Audio" method), then yes, output will suffer. It's an extremely conservative gain setting because (ideally) you would only be able to obtain full power output from the amplifier with a 0db signal.....which rarely ever occurs in actual music.

If you feel more comfortable with the DMM method, you can use a test tone recorded at a lower signal level, for example -6db. This will allow for higher average power output with music while still providing a reasonably low level of clipping during musical peaks.

The other method is, of course, to set the gain by ear. I normally still use a test tone so driver stress is more apparent.

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Thanks Impious, ill try the -6db tone, but now with the ear method. Is all you do listen for distortion and look for stress? Im not sure what else you can do.

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Where can i get -5db tones? And also, if i set my gains using -5db tones... If i ever go to a competition should i burp using the same tone? Or would i burp with a 0db tone?

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I know where they are on other forums lol.

if you're burping, eh, I can't say. My car is set with all 0db tones.

If you know what soft clipping sounds like, I think you'll be ok with burping 0db tones with gain matching to -5

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Where can i get -5db tones? And also, if i set my gains using -5db tones... If i ever go to a competition should i burp using the same tone? Or would i burp with a 0db tone?

Scroll all the way down. http://damoreengineering.com/dd1.html

Its a .rar file. I recommend the program "WinRar" to extract the file.

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Are you looking to set the gain on a sub woofer amplifier?

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Amp gain?eek5wavey.gif

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Where can i get -5db tones? And also, if i set my gains using -5db tones... If i ever go to a competition should i burp using the same tone? Or would i burp with a 0db tone?

If you set the gain with a -5db test tone and then played a 0db test tone, you would be asking the amplifier to output approximately 3.25 times the power with the 0db tone compared to the -5db tone. This can lead to clipping and possibly a release of the magic smoke depending on the situation. The reason this isn't as big of an issue with music is because music will only reach that level during very brief transient dynamic peaks (tenths of a seconds) and the distortion is largely masked. But with a test tone being played for a (comparatively) long period of time it's possible heavy clipping from the amplifier can occur, which could potentially overpower the driver.

As for setting the gain by ear yes, about the only thing you can do is listen for audible distortion, driver stress, and desired output levels. With a test tone distortion is much more audible than it is with music, although your ears are less sensitive to the subbass frequencies. The "tone" of the test tone should change a bit when distortion levels are higher as the harmonics will be more audible.

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It also depends on what type of music you listen to as well. If you're listening to rock, you can easily get away with setting the gain with a -6 dB tone and a -10 dB isn't out of the question because you won't have periods of extended bass and most of the bass generally doesn't come close to 0 dB (plus you're filtering much of it out on a sub amp between the LPF and SSF).

If you listen to rap, electronic, or anything else with long, droning bass, you're best off with somewhere between a -3 dB and a -6 dB tone, in my experience.

Tuning the gain by ear is fine (recommended) for full-range amplifiers, but it definitely shouldn't be the primary method for subwoofer amplifiers, IMO.

I set my gains in the following way (assuming, of course, I don't have access to a spectrum analyzer):

- Disconnect all amplifiers

- Connect DMM to front RCA outputs and measure DC voltage

- Play 0 dB tone on HU

- Turn volume up until I hit the advertised pre-amp output voltage. This is what I refer to as the reference volume (RV). Write this number down.

- Turn volume all the way down on HU.

- Set gain on speaker amplifier(s) to minimum sensitivity, connect speakers, and power up.

- Play music I'm familiar with at RV and turn the gain up on the amplifier until I'm comfortable with the sound output. If the amplifier's output at minimum sensitivity is too loud, I reduce the volume on the head unit until it's comfortable and this becomes the new RV.

- Power down speaker amplifier and turn volume all the way down on HU

- Set gain on the subwoofer amplifier(s) to minimum sensitivity and power up. Do NOT connect subwoofers.

- Hook DMM up to relevant outputs

- Play <insert suitable tone here> at the RV and turn the gain up until it reaches the desired voltage (using the Voltage = SQRT(Power*Impedance) equation)

- Turn volume all the way down

- Hook up all amplifiers and speakers/subwoofers

- Slowly turn volume up until you reach RV playing music you're familiar with. If you find the volume of the subwoofer(s) to be overpowering the rest of the system, reduce the sensitivity on the gain until it matches well with the rest of the system at RV.

From there, it's just a matter of setting the filters. SSF should be done with a DMM based on how the subwoofers model in one of the available enclosure design programs (i.e. WinISD, which is free. I personally use BassBox Pro, which is not free). You'll want to use the DMM method again and set it so that the frequency that would cause the sub to meet Xmax is at -3 dB (71% voltage) relative to the rest of the system. You'll need a 0 dB tone set to that frequency in order to do this. The LPF and HPF should both be set to the same frequency, but this is something you should do by ear from the driver's seat. You want to set the LPF low enough that you can't tell the sub-stage is behind you (it should just envelope you), but at the same time, you don't want your midbass drivers playing too low as they may bottom out or distort as a result. Also, depending on how "rattly" your vehicle is, it may not be possible to get a proper sub-stage, so just worry about the safety/sound of the midbass drivers and go from there.

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Awesome :) Thank you very much guys. Ill do my best to get my amp finally to a desired output. ^^

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