Final steps: Help with setting gains and crossover points

[JungleGym]

I have 4 Alpine SPR-60 speakers hooked up to a PPI P900.4. (I'm thinking about swapping in some Polk DB 6501 components for the front, any advice on that choice is welcome)

When setting gains with a DMM, when I calculate the voltage, SqRt(RMS x Impedance) = VAC, do I calculate for one speaker? Like this: sqrt(100 x 4) = 20 VAC

Or for the RMS of one set of speakers? There is one gain control for front speakers, and one for rear.

So would I calculate it sqrt(200x4) = ~28.28 VAC?

Second question, where should I set my crossover points using my head unit?

I was given an Alpine Type-R 12" and an Alpine MRP-M500 wired for 2 ohms.

I've searched around but haven't found any threads about setting HPF and LPFs, only mainly about what they do.

Any help much appreciated.

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[JungleGym]

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[JungleGym]

Bump. Anyone?

 

[JungleGym]

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[robert420 10+ year member]

the way i usually set the gain is start with it all the way down, turn the volume all the way up on the HU. then slowly turn up the gain until you hear distoriton, then turn it down just a tad

 

[i2ain2thunder 10+ year member]

the search feature does wonders.....

anyway when using DMM you should be checking the channel on the amp not the speakers. Check the output voltage on every channel of every amp. a channel produces the RMS, how many speakers u hook up to that channel is up to u

 

[fasfocus00 5,000+ posts]

turn everything to it's max than start turning things down till all the distortion goes away.

 

[robert420 10+ year member]

turn everything to it's max than start turning things down till all the distortion goes away.

if you turn everything to its max before you start actually tuning, you will blow your sub

 

[i2ain2thunder 10+ year member]

the equation works like this example:

channel on amp u want to produce 700watts rms

speaker(s) are wired to the amp at lets say 2 ohms whatever you are going to have for an impedance on that channel

multiply channel rms by ohm load, so 700x2=1400

square root that number sqrt (1400)=37.416

now plug dmm into channel on amp, check ac voltage.

turn gain on amp to 0

turn head unit volume to whatever u want the max to be, typically choose around 70% volume or so to avoid clipping signal on head unit.

then turn gain on amp up untill your dmm reads 37.416

Whatever your HU is volumed at is now your max volume, whatever your amp gain is at is now your max gain.

 

[tommydh 10+ year member]

the way i usually set the gain is start with it all the way down, turn the volume all the way up on the HU. then slowly turn up the gain until you hear distoriton, then turn it down just a tad

I generally use 3/4 of the max vol on HU as the max. For ex. Pioneer usually has 62 has max i ususally stay around 45 sometimes 50 if really feeling goofy but if you use that then tune the gains 90% of he time you will be in good shape.

 

[fasfocus00 5,000+ posts]

if you turn everything to its max before you start actually tuning, you will blow your sub

no chit noob

 

[robert420 10+ year member]

no chit noob

your one to talk "turn everything to its max"?

 

[i2ain2thunder 10+ year member]

HPF=high pass filter, filters out sounds below a set frequency. Use this on your speakers to keep them from getting frequencies too low for them to handle.

LPF=low pass filter, filters out sounds above a set frequency. Use this on your subs to keep them from getting frequencies that they are not meant to reproduce.

Generally speaking subwoofers should be crossed over below 90hz to keep the bass from being heard from an ascertainable position. Essentially you don't want your listeners to hear the bass coming from the back, it should be almost sounding like it's coming from everywhere. You can cross a subwoofer over at a higher frequency, it is not recommended though.

As far as where your crossover setting should be for your other speakers, this is left up to you to hear and distinguish how the blend of the sound from all your speakers sounds best. Typically speaking you want to cross the other speakers over as low as they can tolerate without producing distortion. generally for people this can be from around 50hz-150hz.

the reason for crossovers is to protect speakers from getting frequencies they can not handle properly, this applies more readily to smaller speakers as in general their ability to tolerate lower frequencies is not as good as larger speakers. Every speaker is different, but these are generalities that point you in the right direction.

Now crossovers also depend on their slope. Crossovers do not simply cut off frequencies above or below a set point. for good reason their job is to protect the speakers and to help blend of the speakers together. The lower the slope (db amount) the more frequencies beyond that set point are allowed through, the higher the slope, the sharper the cutoff is.

You will need to play with your crossover settings to see when they sound best, remembering that little speakers cannot handle low frequencies as well as bigger speakers, (this is why subwoofers are big, and tweeters are small)

Not having crossovers in a system means that little speakers are getting all the low frequencies they are not supposed to. This is the number 1 reason everyone who has a regular radio in their car with no crossover blows out their speakers. Those speakers are getting the low frequencies they are not meant to reproduce, what makes it worse is people try to achieve more bass by cranking the bass knob on their radio. This adds distortion to the already on the edge speakers creating a situation where their speakers will blow at some point.

Remember the best way to get bass is not to crank bass settings up, but to have adequate speakers and amplifiers. Gains and crossovers are designed to protect your speakers and subwoofers from receiving too much current or improper frequencies.

 

[robert420 10+ year member]

I generally use 3/4 of the max vol on HU as the max. For ex. Pioneer usually has 62 has max i ususally stay around 45 sometimes 50 if really feeling goofy but if you use that then tune the gains 90% of he time you will be in good shape.

my JVC HU has a max of 50. when i tuned everything i put it at 50, but for everyday play i keep it within 20- 30

 

[tommydh 10+ year member]

my JVC HU has a max of 50. when i tuned everything i put it at 50, but for everyday play i keep it within 20- 30

I would then set the vol somewhere between 37-40 and then you would be able to then use 40 as max not 30. But its only an oppinion and we all know what they are like. I think you may be pleased with the results and not to big of a process to try it and reverse if do not like. set EQ flat also then you will be able to add little boost after but you will be sending cleaner signal.