Menu
Forum
General Car Audio
Subwoofers
Speakers
Amplifiers
Head Units
Car Audio Build Logs
Wiring, Electrical and Installation
Enclosure Design & Construction
Car Audio Classifieds
Home Audio
Off-topic Discussion
The Lounge
What's new
Search forums
Gallery
New media
New comments
Search media
Members
Registered members
Current visitors
Classifieds Member Feedback
SHOP
Shop Head Units
Shop Amplifiers
Shop Speakers
Shop Subwoofers
Shop eBay Car Audio
Log in / Register
Forum
Search
Search titles and first posts only
Search titles only
Search titles and first posts only
Search titles only
Log in / Join
What’s new
Search
Search titles and first posts only
Search titles only
Search titles and first posts only
Search titles only
General Car Audio
Subwoofers
Speakers
Amplifiers
Head Units
Car Audio Build Logs
Wiring, Electrical and Installation
Enclosure Design & Construction
Car Audio Classifieds
Home Audio
Off-topic Discussion
The Lounge
What's new
Search forums
Menu
Reply to thread
Forum
Car Audio Discussion
General Car Audio
setting gain with test tone
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Message
<blockquote data-quote="Immacomputer" data-source="post: 4321640" data-attributes="member: 570419"><p>You guys are getting different voltages at different frequencies for a few reasons. First, to Colby, if your low pass filter is set on the amp and not disabled when you test, you should see the voltage getting lower and lower as you increase frequency. Crossovers on the amps are not ideal which means that they have slopes that come with them. The "slopes" come from the crossover analysis in the frequency domain (power over frequency). An ideal filter would have peak voltage right up until the cutoff frequency and then have 0 voltage right after the cutoff frequency. This isn't possible in real life so there are slopes associated with the different crossovers. If your low pass filter is set to 80hz as a cutoff point, the voltage will be .707 times the voltage in the pass band. Before that point though, the voltage will have already started to lessen. This is also probably the reason that the OP's sub is louder when he sets the gain at 70hz instead of 40hz. He has to turn the gain up higher to get the same voltage since the crossovers might be affecting it.</p><p></p><p>Another reason for the difference in voltage could be an EQ setting on the headunit. If the bass on the headunit doesn't give a specific frequency, it's probably centered between 50-65hz. Above and below a small range of frequencies you will see a different voltage because of the boost or cut applied.</p><p></p><p>It could also be that some DMMs (read cheap DMMs) don't read very accurately for some frequencies far from 60hz. An octave above or below it and you may get crazy numbers. DMMs, especially cheap ones, are not as accurate as people believe. I had one that would tell me that my battery in my car was doing 16.9v!</p><p></p><p>Colby, your subsonic filter may also be too high and it might be affecting the power in the 30-40hz range.</p><p></p><p>A good way to set a subsonic filter would involve playing a 20hz test tone (something from 20-24hz would probably do the trick) with the SSF turned as high as it will go. Then slowly turn up the volume and see how the reacts. Make sure that it is not moving too much or over-excurting. Turn the volume to where you would normally have it maxed at if it is safe to do so (it should be if your subsonic filter is all the way up). Then slowly lower the subsonic filter until it appears that the sub is beginning to struggle (your eyes and ears are important tools here, more-so than the DMM) and then turn it up only slightly from there. That should be a nice setting and it shouldn't affect your bass much.</p><p></p><p>It could be argued that you could even turn it lower because there is not a lot of music that has 20hz content in it. But, that is user and music dependent.</p></blockquote><p></p>
[QUOTE="Immacomputer, post: 4321640, member: 570419"] You guys are getting different voltages at different frequencies for a few reasons. First, to Colby, if your low pass filter is set on the amp and not disabled when you test, you should see the voltage getting lower and lower as you increase frequency. Crossovers on the amps are not ideal which means that they have slopes that come with them. The "slopes" come from the crossover analysis in the frequency domain (power over frequency). An ideal filter would have peak voltage right up until the cutoff frequency and then have 0 voltage right after the cutoff frequency. This isn't possible in real life so there are slopes associated with the different crossovers. If your low pass filter is set to 80hz as a cutoff point, the voltage will be .707 times the voltage in the pass band. Before that point though, the voltage will have already started to lessen. This is also probably the reason that the OP's sub is louder when he sets the gain at 70hz instead of 40hz. He has to turn the gain up higher to get the same voltage since the crossovers might be affecting it. Another reason for the difference in voltage could be an EQ setting on the headunit. If the bass on the headunit doesn't give a specific frequency, it's probably centered between 50-65hz. Above and below a small range of frequencies you will see a different voltage because of the boost or cut applied. It could also be that some DMMs (read cheap DMMs) don't read very accurately for some frequencies far from 60hz. An octave above or below it and you may get crazy numbers. DMMs, especially cheap ones, are not as accurate as people believe. I had one that would tell me that my battery in my car was doing 16.9v! Colby, your subsonic filter may also be too high and it might be affecting the power in the 30-40hz range. A good way to set a subsonic filter would involve playing a 20hz test tone (something from 20-24hz would probably do the trick) with the SSF turned as high as it will go. Then slowly turn up the volume and see how the reacts. Make sure that it is not moving too much or over-excurting. Turn the volume to where you would normally have it maxed at if it is safe to do so (it should be if your subsonic filter is all the way up). Then slowly lower the subsonic filter until it appears that the sub is beginning to struggle (your eyes and ears are important tools here, more-so than the DMM) and then turn it up only slightly from there. That should be a nice setting and it shouldn't affect your bass much. It could be argued that you could even turn it lower because there is not a lot of music that has 20hz content in it. But, that is user and music dependent. [/QUOTE]
Insert quotes…
Verification
Post reply
Forum
Car Audio Discussion
General Car Audio
setting gain with test tone
Top
Menu
What's new
Forum list
