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Output Test Results with 1k,500,100 hertz test tones experiment at set levels
Wanted to share some testing insight I did tonight to show how output changes in various frequencies. Now this was with amp without a load ( no dummy load) and I was surprised how much the output spiked at the lower frequency. The point of this test was to see the head unit vs amp clipping points again and I also changed all my music from 98db to 93db. Going to 93 my output was over half it was at 98. I use the test tone with mp3 gain set to my desired level I am setting my music at , then use my volume offset @ -5 to give me some gain overlap still. This way there is zero discrepancy between the output levels on the test tones. I also know my head units levels both flat and set at my normal level adjustments. In these test all xovers are set as well as my eq. So in the following pictures I will let them speak for themselves. Your just viewing a sine wave with corresponding Freq and the Voltage RMS. Take a huge notice at the head unit at 100hz. The preout level more than doubled as well as the amp output as I doubles the input voltage. Also take notice the big difference between the Rockford and the Arc at the same frequencies. I can't explain why the Arc maintained a more stable output voltage vs the Rockford at the 110 and 100 hz tones? So when running your test tones Stick with 1K. I have heard a few mention using 100hz on multiple sites and complain they couldn't get the amp from distorting without it being too soft. Well the test show why. A 100hz tone will have the lowest gain setting. Should I set to that level? Personally with music as dynamic as it is and also running full range I am not quite so concerned at this point but if I was to wanting to really boost the low end ( WE don't on a bike anyway) I would likely set gains off the 100hz results. Now for the pics of the results. Each amp and head unit freq are labeled below each photo!
do yourself a favor and stop worrying about what you see on an oscilloscope. Download TrueRTA, get an inexpensive USB microphone from Parts Express, and actually measure the frequency response of your system.
that aside, all you've demonstrated is that there is some equalization present in the system. Which is typical; vehicle audio systems (especially cars!) require some degree of equalization to sound decent. the jump in output at 100 Hz is probably due to some "bass boost" dialed in to try to get some bass output. Unlike with a car, on a bike you don't have a closed cabin to give you a natural bass boost.
do yourself a favor and stop worrying about what you see on an oscilloscope. Download TrueRTA, get an inexpensive USB microphone from Parts Express, and actually measure the frequency response of your system.
that aside, all you've demonstrated is that there is some equalization present in the system. Which is typical; vehicle audio systems (especially cars!) require some degree of equalization to sound decent. the jump in output at 100 Hz is probably due to some "bass boost" dialed in to try to get some bass output. Unlike with a car, on a bike you don't have a closed cabin to give you a natural bass boost.
Good post JZ! I agree.
Last edited by Gannicus; Jul 17, 2016 at 12:10 PM.
do yourself a favor and stop worrying about what you see on an oscilloscope. Download TrueRTA, get an inexpensive USB microphone from Parts Express, and actually measure the frequency response of your system.
that aside, all you've demonstrated is that there is some equalization present in the system. Which is typical; vehicle audio systems (especially cars!) require some degree of equalization to sound decent. the jump in output at 100 Hz is probably due to some "bass boost" dialed in to try to get some bass output. Unlike with a car, on a bike you don't have a closed cabin to give you a natural bass boost.
Pump them brakes. There is no "Bass Boost" ran on my setup. Im in no way measuring my systems response or even care. This is for gain setting purpose only. The Only point of eq change on the low end is 2db on 63 and 1db on 100. I run a very flat flat eq. Ask ?'s before you jump in with conclusions. Any setup using 100hz will always show a higher output level and clipping point. The point of the demo is to show why using a 1k tone vs another tone is the ideal point for setting gains on a full range setup. The difference between the 2 amps running the same tone is the strange part. Also notice that the head unit doesnt clip at the higher pre out voltage on 100hz. Again this is solely gain setting. Also to double your output voltage would require at least 3db of increase. No where on my eq am I at 3db. Third the dd1 is the mainstream device now to set gains. Does the dd1 show distortion outside of 1k besides the 40 hz subwoofer frequency? No. Why is that for full range it is likely irrelevant . My point here is just showing at a range of freq what happens as the freq is lowered. Im not reduced and still flat at 500hz range yet it shows less output. This was just a clipping test on gains already set that had some results that should be evaluated and considered.
I will also add I do fully get that if I was attempting to optimize my system response I would get a sa from work and go to town, but that is not the intention as I shoot for a flat eq. What I am showing here is how the signal changes deviating from the 1k tone. Just showing how frequency on setting gains varies, and if one wanted to optimize low end 100hz would be the ideal tone vs 1k on full range. Also shows what minor eq adjustments change and also should have recorded flat. I may tonight to show the difference for even myself to see what 2db of equalization does. Again only to show clipping outout. My intention is to limit guys from using too much bass increase in their setups. You cant go back and check your adjustment with a dd1 and know if you changes causes any added clipping without at least a scope. There is relevance in the test.
1 kHz is typically the standard tone used for testing and calibration for one reason only, and that is because it's the reference point for any and all weighting curves. the output level at 1 k should be the same whether your system is unweighted, A-weighted, C-weighted, etc.
Any setup using 100hz will always show a higher output level and clipping point.
loudness curves aside, that shouldn't be. any amplifier which isn't essentially flat from 40-16 kHz (and less than -2 dB at 20 Hz and 20 kHz) is a piece of junk.
Also notice that the head unit doesnt clip at the higher pre out voltage on 100hz.
are you sure there isn't some kind of loudness curve/compensation active? Again, if you're seeing a different output level at different frequencies, there's some sort of EQ or loudness happening somewhere. You may not have done it yourself but it might be something built in to the equipment.
Also to double your output voltage would require at least 3db of increase.
a doubling of voltage is 6 dB. a doubling of power is 3 dB.
Ok, I'm gonna be the cave man in the room here and not really advise anyone to pump the brakes but to slam on the brakes, then hit reverse as soon as possible!!!
Is there anyone that is actually using a test tone other than the 1k tone that is posted in the sticky, other than maybe a -5 or -10 solution?
I think I'm in the 99.99999% of the audience that is tuning their sleds realizing they r just that and riding sleds and not in a recording studio.
Don't get me wrong here as there r some that r impressed with and can find value in the detail associated with the initial research / presentation associated with the origination of this tread and others that r very impressed by the old school deep knowledge in rebut but man, is there anything that the 99.99999% of us that can take away from this thread other than to follow the sticky and ride on?
Respectfully scratching my head!!!!! Might even have a bit of a headache.
1 kHz is typically the standard tone used for testing and calibration for one reason only, and that is because it's the reference point for any and all weighting curves. the output level at 1 k should be the same whether your system is unweighted, A-weighted, C-weighted, etc.
loudness curves aside, that shouldn't be. any amplifier which isn't essentially flat from 40-16 kHz (and less than -2 dB at 20 Hz and 20 kHz) is a piece of junk.
are you sure there isn't some kind of loudness curve/compensation active? Again, if you're seeing a different output level at different frequencies, there's some sort of EQ or loudness happening somewhere. You may not have done it yourself but it might be something built in to the equipment.
a doubling of voltage is 6 dB. a doubling of power is 3 dB.
This is good response. The goal is for guys to know what happens after setting at 1k and then adjusting their settings and walking away. I am just diving into the depths of the unknown experimenting to see what the amps waveform does at a low frequency still in the full range spectrum. I found introducing the dummy load, flat EQ, zero sound enhancements still, that I was still clipped there. I believe I am either seeing a lack of headroom or the digital output at 100hz vs 1khz, is flawed or a inaccurate measurement or possibly the order of harmonic from setting at the higher tone. Maybe it is a harmonic level that shows why 100hz had a higher amplified output ( 44vac) compared to 1khz which was (30.5 amp A and 35 amp B). With the dummy load both amps showed same vac at 100hz. I would conclude that not really worthless, the test is really inconclusive without other data to support what should happen there. I would also conclude that as you stated, a Spectrum Analyzer would be the only tool with accurate reference to see what the system does at lower freq, but also doesn't explain the square wave. I also found that likely no system will be unclippped ever per Perry Babin (BCAE Author and page owner).
Ok, I'm gonna be the cave man in the room here and not really advise anyone to pump the brakes but to slam on the brakes, then hit reverse as soon as possible!!!
Is there anyone that is actually using a test tone other than the 1k tone that is posted in the sticky, other than maybe a -5 or -10 solution?
I think I'm in the 99.99999% of the audience that is tuning their sleds realizing they r just that and riding sleds and not in a recording studio.
Don't get me wrong here as there r some that r impressed with and can find value in the detail associated with the initial research / presentation associated with the origination of this tread and others that r very impressed by the old school deep knowledge in rebut but man, is there anything that the 99.99999% of us that can take away from this thread other than to follow the sticky and ride on?
Respectfully scratching my head!!!!! Might even have a bit of a headache.
T.
T, I am playing in uncharted waters just to see some things not thought about or even discussed. Maybe a waste of time or a useful thought to say HEY if you set it flat keep it flat, or limit your adjustment dependent upon power driven. IDK man I have a headache even now. Just have some tools to play with while I had the fairing off.
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Output Test Results with 1k,500,100 hertz test tones experiment at set levels
