amp freq setting?
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=41121
Printed Date: May 14, 2025 at 5:06 PM
Topic: amp freq setting?
Posted By: /R7
Subject: amp freq setting?
Date Posted: October 18, 2004 at 12:11 PM
well i've been pondering the idea to accurately set the frequency on a amp so your not far below 100hz or well above.
idea:
burn a CD of sine waves with frequencies you want to use.
play the track with the frequency you want to run, probably best setting it to repeat while doing this. (and keep your volume low enough so you dont cause damage to your speakers.
with the amps frequency setting turned clockwise enough to cut off the frequency your trying to achieve, start bringing it down until you hear that frequency you have playing.
--- now this is just an idea, would this accurately work? or can anyone suggest a better idea?
Replies:
Posted By: DYohn
Date Posted: October 18, 2004 at 12:16 PM
That would work just fine. Burn your 100Hz track at 0db and use it to set both your HP and your LP filters. ------------- Support the12volt.com
Posted By: Lizardking
Date Posted: October 18, 2004 at 6:05 PM
Dyohn, Will this really work for setting the LPF to 80hz or 100hz?
Posted By: stevdart
Date Posted: October 18, 2004 at 6:26 PM
I've posted this a few times on here. Make yourself a test tone CD using a program like Frequency Generator. Select sine waves, enter the value of Hz you want to record, set to 0 db......use the Help file for specifics. With this program, which I've used to make a CD (but can't use anymore now that the free trial is over), you make .wav files of frequencies at whatever duration you want. I've been using the test CD for setting gain and also setting crossover freqs. You have a lot of room on a CD, so make the files long enough so that you can work on the system without having to run up and push repeat over and over. The trick when setting crossovers is to have many freqs recorded in sequence...such as 75, 77, 79, 80, 81, 83 (Hz)...etc. You get the picture. As the tracks of the CD play through in sequence, and you are adjusting the crossover, you want to get to a point where the 80 Hz track (if that is what you are adjusting to...in this case as lowpass for the sub) is just noticeably softer than the 81 Hz tone. This would be like a crossover normally crossing a frequency at -3 db. Then, compare the 81 to something like the 85 Hz....they should be the same loudness. Check the 77 Hz, it should be even softer than the 79, and so forth. There, you have adjusted to 80 Hz. You can use a variety of CD burning programs to make the CD. And a note of caution: playing a sine wave for very long will burn up a speaker. If you start smelling an odor turn everything off until later. I smelled the burning odor for quite awhile when I first tried this before it finally dawned on me it was the speakers! But no harm came to them. A side note: I didn't realize I should look for db setting, so when I made mine I don't know if I had the tones set to 0 db. And now I can't use that nice easy program again without paying. So I'll wonder about whether its right until I get another test CD made... ------------- Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.
Posted By: /R7
Date Posted: October 18, 2004 at 6:36 PM
stevdart i could probably do up an ISO of frequencies, not a big deal for me, 80hz-120hz
any other frequency ranges let me know, i'll probably do a 30second track, most cd-players probably support a 'repeat track' feature, so it shouldnt be a problem with 30second tracks
Posted By: stevdart
Date Posted: October 18, 2004 at 6:39 PM
Yeah, 30 secs would be plenty of time. 5 to10 seconds would probably be more realistic for setting crossovers. But if you want to set to 80 make sure you have freqs below that recorded, too. A couple of longer tracks are good for setting gain, because you need to be able to read the meter, hold the probes, all that. One for subs, another for the mids/highs. Those tracks should be a good 30 seconds long. ------------- Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.
Posted By: /R7
Date Posted: October 18, 2004 at 7:39 PM
i've started with 70hz - 84hz being 30seconds long with (70,72,74... ect), i may redo them, and i've done frequencies 86-240 at 20seconds,
any ranges i should focus on post in here
i can fit about 350 tracks on a cd, so there should be plenty of space for whatever frequency ranges you want on em.
i personally dont really know what i should record.
70-240 is probably going to be enough in that range.
990hz-1020khz maybe?
suggestions welcome, this will be a good mind numbing passtime.
Posted By: stevdart
Date Posted: October 18, 2004 at 8:29 PM
stevdart wrote:
you want to get to a point where the 80 Hz track (if that is what you are adjusting to...in this case as lowpass for the sub) is just noticeably softer than the 81 Hz tone. This would be like a crossover normally crossing a frequency at -3 db. Then, compare the 81 to something like the 85 Hz....they should be the same loudness. Check the 77 Hz, it should be even softer than the 79, and so forth. There, you have adjusted to 80 Hz.
I'll correct this here. What I was describing was actually for setting high pass for the mids/highs....for the sub would be a bit different, with the higher tones less audible and the lower ones the same. ------------- Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.
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