settings my gains?? deck settings?

[cbuts 10+ year member]

Well, i know im supposed to set my amp to 34.4 or something to be 1200rms.

im running 2 sa 12s, with a rockford fosgate 15001bd.

this is my deck:

JVC KD-R620 Premium MP3/WMA CD Car Deck With iPod Control (KD-R620) : Single DIN Car Decks - Future Shop

these are the deck settings:

Pro Equalizer:

bass 60hz q 2.0

mid 1.0hz q 1.25

treb 10.0hz q FI

Audio:

Sub W LPF - Low 55hz - goes up to 200?

Sub W LVL - 8/8

HPF on

Amp gain - high power

loud OFF

Tuner:

area us

all set to 0

Source select am on

when i plugged in my ddm to my amp, and turned up the gain, it was at about 4 or 5, and it was reading like 38volts or so, which is over 1200 rms? the bass boost is all the way down on my amp, and the equalizer or whatever is set to a little over 65.

when i turned hpf on, and set the bass hz to 55 it seemed to drop the volts alot on the amp, but i dont think its as loud?

subsonic filter is ON on the amp aswell.

can someone SET ME UP PLEASE

im running 4g wire, with 80A fuse ( getting a 100A on monday ) (till i upgrade my 4g to 0g etc)

i just feel like these subs should be louder at 1200 rms, i dont know what 1200 rms feels like but this dosnt feel as good as i thought it would,

also when i checked with my ddm on the battery, it wasnt even really moving from 14.1 when the bass was hitting

i have the big 3 done aswell.

thanks alot.

Click to read more...

 

[Moble Enclosurs 10+ year member]

There is a lot to know about what is going on here. The first thing to know is, as long as everything is set up correctly with the wiring, is the gain settings. When doing this, your deck settings should start all on flat, as any alteration to this, will affect the input voltage to the amplifier. Its like using a test tone to set it from an ipod, but not knowing why the radio sounds so much lower in volume. Same concept. So, best way to do this is with a cd test tone, and not with an external source unless the external source is the main source of music. Make sense?

So, setting the actual gains, there are a few ways to do this. I use my O-scope, but if you do not have one, you can effectively use the DMM( to a point of acceptance). The first thing you want to know is the cutoff point (in a conventional design such as a ported enclosure[bR]). This is the point of maximum excursion within the passband. So, setting the gains at any other position, may cause this to over-excurt the sub and cause distortion, and later on-damage. So, tuning to the max excursion point of the passband is ideal. Lets say it is 44Hz. Then you will want to set the test tone at 44Hz(not the common 50 or 60 that most say-or have said in the past).

You need to know then, the actual voltage, current, and resistance of the setup. This can be done before any setup is required. Using the 44Hz, play the tone at say mid volume, with all gains on the amplifier set on minimum. Now, hook up the DMM and set to VAC. You should know the voltage level that this should be at for maximum output at the subs without distortion(or minimal at the least). You have to calculate for this. You were close on your 34.4V setting if you are getting a real 1200W to a 1Ohm setting. But here is a better way to do it......Take the peak power of the amplifier, and multiply it by 70%(0.7). This is what the amplifier will actually do at peak levels considering the charging system involved(even with the big 3). So, say this amp is rated at 24oowpeak. That would be efficiently 1680W peak. Now, RMS is not always half of this, but lets say for ease, that it is. Actual RMS may be calculated by current, but say we calculate it at .7 again. This would be about 1176watts RMS, close to 1200, but a bit more accurate-generally. So, now we need to figure for resistance. With the subs wired up, but not connected to the amplifier, as this may change the reading a bit, get the actual resistance measured. Lets say you got 0.97Ohms instead of 1 exactly. Then you take Ohms law to get your needed RMS voltage. That would come up to 33.75V@0.97Ohms to get 1176 watts (efficiently).

Now that you know that, you can hook up the subs, turn the tone on at 44Hz, and gradually turn up the volume on the deck(up to 70% of the max volume[this is where I like to use the o-scope, because it can figure for clipping at max HU volume before this is even done]), and monitor the voltage to reach the desired voltage of 33.75V or as close as possible.

Now, you can figure for actual voltage that the sub will be able to handle, if 33.75V is actually too much. This will require a free air test. This will ensure that any other frequency played on that setup will have a voltage less than what is at resonance, which causes Ohms law to pass through less current, thus any other frequency played, will not reach the excursion of that . At that point, you will have the amplifier putting out the best it can for the entire passband for the setup. This can be done to free-air drivers before installation to see how much the subs can actually handle...and you will be surprised, if you calculate it correctly, that this can be sometimes, much lower than needed, or expected to power a sub!

i typed this really fast, so please, anyone with corrections, feel free to do so.

Now, as far as the issues, This was explainged a bit in the example. If you are setting the HPF at 55Hz, you change the voltage requirements of the amplifier to produce the output a 1Ohm(or whatever ohms setting you are using). The reason is because of the filter. it will drop the voltage output because it is using the filter to do so. Setting the HPF to 55Hz may be a bit low, especially if you are already utilizing a SSF. You are essentially bandpassing the output, hence the lower output. But this is ok, as long as the filters allow the passband of frequencies to be much broader than what you have set up so far. it seems like you are only allowing maybe less than or equal to an octave, when the output passband can be made much broader than that, up to about an octave and a half. But this also depends on the design you are using as well. I am automatically assuming a conventional Bass-Reflex design as an example.

Set the HPF higher than 55Hz, most set it at like 80Hz or 120Hz or so. You should get much better output that way. The HPF says it is allowing higher frequencies to pass through, and attenuated the lower ones. So, setting it low, will result in bass frequencies suffering, hence lower voltage.

As far as not moving much from 14.1, that is awesome, but check the voltage drop by adding other components as well, and also with the vehicle off. Read it palying before everything else is turned on, then turn on the ac, door lights, rear view mirror lights, cycle the ac within the car by closing the vents, etc. Then check voltage. if it only drops about .1-.3 at the most, that is good. Hope that helps. And please, if anyone sees an error here, correct it righ taway. i typed it very fast and im not sure what flow i was on when I typed it. I have a lot on my mind right now, lol. Thanks guys.

EDIT: I have to note that I made a clarification to this in the next post of a reply. Please refer to that for any concerns. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[cbuts 10+ year member]

thanks for the reply mate.

so, i know my box is tuned to 32hz, so should i be using a 32hz tone?

this is my box http://i91.photobucket.com/albums/k302/prorabbit/Designs/cbuts.png

and the only thing i need to change on my settings is the hpf to 85 instead of 55 ?

anything else?

thanks, i just dont want to blow my new subs or mess up my amp, it was reading really high like 38, and i feel like i should be able to turn the gain up more.. i was using a 50hz tone

 

[CAT MAN 5,000+ posts]

There is a lot to know about what is going on here. The first thing to know is, as long as everything is set up correctly with the wiring, is the gain settings. When doing this, your deck settings should start all on flat, as any alteration to this, will affect the input voltage to the amplifier. Its like using a test tone to set it from an ipod, but not knowing why the radio sounds so much lower in volume. Same concept. So, best way to do this is with a cd test tone, and not with an external source unless the external source is the main source of music. Make sense?So, setting the actual gains, there are a few ways to do this. I use my O-scope, but if you do not have one, you can effectively use the DMM( to a point of acceptance). The first thing you want to know is the low impedance point of the subsystem, the "tuning" per-say (in a conventional design such as a ported enclosure[bR]). This is the point of maximum excursion within the passband. So, setting the gains at any other position, may cause this to over-excurt the sub and cause distortion, and later on-damage. So, tuning to the max excursion point of the passband is ideal. Lets say it is 44Hz. Then you will want to set the test tone at 44Hz(not the common 50 or 60 that most say-or have said in the past).

You need to know then, the actual voltage, current, and resistance of the setup. This can be done before any setup is required. Using the 44Hz, play the tone at say mid volume, with all gains on the amplifier set on minimum. Now, hook up the DMM and set to VAC. You should know the voltage level that this should be at for maximum output at the subs without distortion(or minimal at the least). You have to calculate for this. You were close on your 34.4V setting if you are getting a real 1200W to a 1Ohm setting. But here is a better way to do it......Take the peak power of the amplifier, and multiply it by 70%(0.7). This is what the amplifier will actually do at peak levels considering the charging system involved(even with the big 3). So, say this amp is rated at 24oowpeak. That would be efficiently 1680W peak. Now, RMS is not always half of this, but lets say for ease, that it is. Actual RMS may be calculated by current, but say we calculate it at .7 again. This would be about 1176watts RMS, close to 1200, but a bit more accurate-generally. So, now we need to figure for resistance. With the subs wired up, but not connected to the amplifier, as this may change the reading a bit, get the actual resistance measured. Lets say you got 0.97Ohms instead of 1 exactly. Then you take Ohms law to get your needed RMS voltage. That would come up to 33.75V@0.97Ohms to get 1176 watts (efficiently).

Now that you know that, you can hook up the subs, turn the tone on at 44Hz, and gradually turn up the volume on the deck(up to 70% of the max volume[this is where I like to use the o-scope, because it can figure for clipping at max HU volume before this is even done]), and monitor the voltage to reach the desired voltage of 33.75V or as close as possible. This will ensure that any other frequency played on that setup will have a voltage less than what is at 44Hz, which causes Ohms law to pass through less current, thus any other frequency played, will not reach the excursion of that 44hz(within the passband-and be careful of "unloading issues" as this is not a part of the tuning process, and deals more with cutoff points and filters and enclosure design control, etc). At that point, you will have the amplifier putting out the best it can for the entire passband for the setup. This can be done to free-air drivers as well before installation to see how much the subs can actually handle...and you will be surprised, if you calculate it correctly, that this can be sometimes, much lower than needed, or expected to power a sub!

i typed this really fast, so please, anyone with corrections, feel free to do so.

Now, as far as the issues, This was explainged a bit in the example. If you are setting the HPF at 55Hz, you change the voltage requirements of the amplifier to produce the output a 1Ohm(or whatever ohms setting you are using). The reason is because of the filter. it will drop the voltage output because it is using the filter to do so. Setting the HPF to 55Hz may be a bit low, especially if you are already utilizing a SSF. You are essentially bandpassing the output, hence the lower output. But this is ok, as long as the filters allow the passband of frequencies to be much broader than what you have set up so far. it seems like you are only allowing maybe less than or equal to an octave, when the output passband can be made much broader than that, up to about an octave and a half. But this also depends on the design you are using as well. I am automatically assuming a conventional Bass-Reflex design as an example.

Set the HPF higher than 55Hz, most set it at like 80Hz or 120Hz or so. You should get much better output that way. The HPF says it is allowing higher frequencies to pass through, and attenuated the lower ones. So, setting it low, will result in bass frequencies suffering, hence lower voltage.

As far as not moving much from 14.1, that is awesome, but check the voltage drop by adding other components as well, and also with the vehicle off. Read it palying before everything else is turned on, then turn on the ac, door lights, rear view mirror lights, cycle the ac within the car by closing the vents, etc. Then check voltage. if it only drops about .1-.3 at the most, that is good. Hope that helps. And please, if anyone sees an error here, correct it righ taway. i typed it very fast and im not sure what flow i was on when I typed it. I have a lot on my mind right now, lol. Thanks guys.

you took more time than i did....... good write up lol

 

[cbuts 10+ year member]

thanks for the reply mate.
so, i know my box is tuned to 32hz, so should i be using a 32hz tone?

this is my box http://i91.photobucket.com/albums/k302/prorabbit/Designs/cbuts.png

and the only thing i need to change on my settings is the hpf to 85 instead of 55 ?

anything else?

thanks, i just dont want to blow my new subs or mess up my amp, it was reading really high like 38, and i feel like i should be able to turn the gain up more.. i was using a 50hz tone

im also using my USB stick for my music, which is what i always play music off, and used the 50hz tone off, so should i play it off this like im doing? my usb seems to be louder than a CD aswell.

 

[Moble Enclosurs 10+ year member]

thanks for the reply mate.
so, i know my box is tuned to 32hz, so should i be using a 32hz tone?

this is my box http://i91.photobucket.com/albums/k302/prorabbit/Designs/cbuts.png

and the only thing i need to change on my settings is the hpf to 85 instead of 55 ?

anything else?

thanks, i just dont want to blow my new subs or mess up my amp, it was reading really high like 38, and i feel like i should be able to turn the gain up more.. i was using a 50hz tone

Did I say tuning, Im sorry, what I meant was cutoff when in a box, but low impedance when free air. I dont know if I said that right or not when typed. I want to clear that up. So, if doing this while the sub is in the box, it should be at LF cutoff, where excursion starts to be a concern below that. And yes, HP should be higher. Also, dont use 50Hz, because below that, distortion and over excursion may be an issue AS LONG AS....tuning is lower than 50Hz.

 

[Moble Enclosurs 10+ year member]

im also using my USB stick for my music, which is what i always play music off, and used the 50hz tone off, so should i play it off this like im doing? my usb seems to be louder than a CD aswell.

As far as the USB, yes, that can be fine to use. And the fact that it has a higher input voltage, seemingly to create a small gain, like a powered device would, then it would be better to use it for setting, and the radio may be a bit quieter when used, but do not be tempted to turn the gains up because of this. Volume should be used at this point. Once the gains are set, you should not mess with them again. In some cases, the gains can be all the way down and the amplifiers may be able to provide proper voltage without even turning them up. If this is the case, you have more power than you need, which is ok.

 

[accuab 10+ year member]

Did I say tuning, Im sorry, what I meant was cutoff when in a box, but low impedance when free air. I dont know if I said that right or not when typed. I want to clear that up. So, if doing this while the sub is in the box, it should be at LF cutoff, where excursion starts to be a concern below that. And yes, HP should be higher. Also, dont use 50Hz, because below that, distortion and over excursion may be an issue AS LONG AS....tuning is lower than 50Hz.

I was reading through your posts from this topic and your idea of setting the gains seems much more concrete than just choosing some arbitrary frequency and tuning with that. Cause I would imagine tuning needs to be done as the point of most stress on the system. So how would you know what your cutoff is?

 

[Moble Enclosurs 10+ year member]

I was reading through your posts from this topic and your idea of setting the gains seems much more concrete than just choosing some arbitrary frequency and tuning with that. Cause I would imagine tuning needs to be done as the point of most stress on the system. So how would you know what your cutoff is?

Thats where design comes into play. With the design, you can figure for cutoff by this: Fc=(Vas/Vb)^1/2(Fs). So, if you driver's VAS is 126.8 liters(4.48cFt), and Vb is 4 cubic ft, and Fs is 27.8Hz, Then the ideal cutoff is 29.42Hz(-3dB). Vas has to match Vb, so if you use cubic ft in acoustical compliance, the box volume has to be in cubic ft as well. With 4th orders, this may seem to be lower than normal due to the peak, but it is reference.

I am not sure how well "programs" may agree with this. I do not use them. Maybe winisd or hornresp may say different, idk.

Now, I believe with the 4th orders, since this may be different, that the formula for them may be different, because of the sealed portion of the design having an effect on it. Ill have to check my worksheet for the formula on that. But after that, the actual tuning may be calculated as: Fb=0.42(Fs)/Qts^0.9, which would equal 54.65Hz or thereabouts.

Ironically, I have seen this fc formula used in a "cookbook" worksheet somewhere. Google it, might come up with more info on it, idk.

 

[Moble Enclosurs 10+ year member]

Also, remember that this is conventional. I will have to verify horn design Fc by reversing the formulas, if you want me to do that as well.

 

[d77543020 10+ year member]

Buy a dd1 takes the guess work out of it

 

[cbuts 10+ year member]

im so confused...LOL never was good at math. this formula is NOT for me haha

 

[Moble Enclosurs 10+ year member]

Yes, it can get pretty confusing if you are not used to it. But one step at a time will do wonders with mathematics. So, let me know what you do not understand and I will explain it to you one step at a time.

As far as the formula, it involves speaker parameters as well as box parameters to get it to work.

Here is the first basic part of it:

The formula is this Fc=(Vas/Vb)^1/2(Fs). So, let's break it apart.

What is Fc? That is the cutoff frequency that we are looking for. Vas= the acoustical compliance of the speaker, which is the point of volume where the subwoofer will match the acoustical pressure of the environment, normally involving impedance, at the point where Z(acoustic impedance) nominally=413.3Ohms at about 68degrees. This is what I use to calculate it from scratch. But without all of that, just remember that VAS is a volume-thats all you need to know about it right now.

^1/2 is the same thing as saying a sqrt, but for simplicity just use a calculator for the power of the variable Xy. To do a power on a calculator, type in the numerical value, then the ^1/2 is hitting the Xy button, then 0.5.

Fs=the drivers resonant free-air frequency, or 0 referenced impedance point where excrusion is maximum, and do not confuse this with a box's Fs, where conventionally, it is impedance minimum, not flat referenced at 0 on a graph. So, the Fs of the driver is in the specs you get from them.

Vb=the volume of the enclosure, in any cubical form, cFt, cc, Cin, m^3, etc.

THE KEY IS TO MATCH THE VAS WITH THE VB in reference, so if VAS is in cubic ft, VB should be in cubic ft as well, and the solution will be in cubic ft.

Calculate: Everything in parenthesis first. PMDAS is the mathematical key for any formula as an orer of preference. This means: parenthesis, multiply, divide, add, subtract. This is the order of any formula. So, whatever is in parenthesis first, do that. If all is in (), then multiply, etc.

So, in this formula, first is VAS/VB. Say VAS is 68 liters(2.4 cubic ft). And VB is 2.5 cubic ft. So, 2.4/2.5=0.96. Now, this needs to be powered. The power of a solution takes presidence over PMDAS order. The solution that has a power HAS TO BE powered first, and here the solution is VAS/VB because it is in parenthesis and the power follows the parentheses.

SO, the ^1/2 power or sqrt of 0.96=0.9798. This is then multiplied by the next order, which is in parentheses all on its own. This means, if it is on its own, it is already a solution within the PMDAS rule, so everything outside of it can be done first. Then 0.9798(Fs) is the same thing as multiplying them together. So, 0.9798*Fs, if Fs is for example 41Hz, then the final solution is =40.17Hz for the cutoff point of that design volume with that speaker. This is based on a dB scale and mechanical scale of excursion control, so port calculations are not figured in. Tuning calculations are done separately, and that is where the port is figured in.

Keep in mind that this is not shown on the response likely, but more so for setting the gains for excursion control. The port, again, will have its own cutoff point, which WILL show up on a design. This is for setting gains, not showing response graphs. If it has to do with response graphs, then it would be the -3dB point, which Im sure they might not be the same thing. ALSO, that this is for a smooth response using a Q of 0.707. And with the Q changed, this may change the solution. The ^1/2 is the key to the 0.707 Q factor. So, this is with optimum volumes. I am not sure if I mentioned that before. And this is also based a LOT on the drivers resonance free-air but works in the real world. Most of the time, the solution is pretty low, which is good for excursion control.

 

[Moble Enclosurs 10+ year member]

So basically if I have a 4volt sub preout, I will not need to turn the gain up on my Rockford 1500.1BD?? Or it will clip, correct?? What if i dont have a oscope or a dmm?? How can i manually set the gains?

Well, preout voltage is based on sensitivity of the signal to the amplifier for amplification. So, a 2V vs a 9V preout, which some HUs can get up to, is like saying 14V from the battery or alternator to supply the amplifier. BUT, the difference is, the ones from the HU are low level inputs, so this does not necessarily mean clipping if turning gains up, BUT tricky words are needed here....You should not be setting gains to INCREASE output rather than decrease voltage. So setting gains, should be used mainly to match impedance of high level output(the amplifier itself), So, in most cases, you should be only turning gains to control voltage to match levles and not output as a volume control to increase bass response. The filters will have much more control over bass response than gains. The whole purpose is to get the most out of the amp, and this is done once impedance levels are matched as close as possible. If you do not have a DMM, take the sub out of the box, play the resonance tone of the driver and turn it up until you hear clipping. THIS CAN BE DANGEROUS, so I always recommend getting electrcial equipment to help you out with this, but it can be acceptable. AND when you hear clipping, turn it down a bit. This wil ensure that the subwoofer, even installed, will not ever exceed xmax(audibly). This usually results in less output, but also less distortion, which is very important for the life of the driver. This is where the enclosure will need to do the work. i can put 5 watts into a 12, and hit well over 110dB if done correctly....I have done it many times before for show. its about matching everything and having the RIGHT amount of power, not what you think you have, etc. And more importantly, having the right box.

So, manually setting them, I dont recommend, but if you have to, do it without the box involved. This ensures proper voltage at all frequencies, even down to the lowest VLF possible. You will not be able to blow the sub on that voltage as the frequency drops, so does voltage. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif Pretty neat really. Those who tune high need to do this way, those who tune low, shouldnt have many problems either way, with Fc or audible gain effects as the result will likely be low as well.

 

[Moble Enclosurs 10+ year member]

I have to go to work now //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif But Ill be back on later. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif I typed a lot of this fast, so if there are needed corrections, I will not be ashamed to have them done. Please anyone who know what I am talking about, if you see any needed corrections, do it. Let me know. I will change them if your answer is correct.