Tuning a Memphis 16-PR1.500

[Memphis2011 10+ year member]

Hey can anyone help me I have a Memphis 16-PR1.500 and 2 Memphis 10s how do I go about tuning the amp with the sub sonic freq. LPF , Bass Boost and of course the gain whats the proper and the best way to do it with a multi meter are by ear?

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[JoshC 10+ year member]

subsonice= 5-10Hz below port tuning, if sealed 30-35Hz

LPF= 80-120Hz based on what sounds best to you

Bass Boost= everyone says turn it off, i keep mine at half. lol

Gain= Can go by ear, should be at half or a little more depending on how it sounds(turn it to max lissening volume when ure agjusting it so u know it wont overpower it or send it into clipping if u turn it up later)

Or if u have a multimeter, google test tones. Download a 50Hz tone(i used 40 but w/e) Add the rms of your speakers together(or how ever much u wanna give them) then times it by your final independance. (hook your meter up to read it, dont asume there 2 or 4) Then get the square root of that number. That will be somthing between 23-28(just guessing) thats the AC voltage you will look for on your meter(connect meter to speaker wires). Turn your volume up to max lissening volume, play the 50Hz tone. Slowly turn you gain up until your meter reads the voltage you calculated earlyer. Then ure all good man, also make sure the subwoofer level on your HU is turned to max(your output voltage wont be at 2v's or w/e u have till its at max)

I have a memphis PR1000.1 for the record lol

 

[wenn_du_weinst 10+ year member]

do not put your sub sonic 5-10hz below tuning you will kill your low freq response, turn stereo up to max volume (where ever you set gains to) play tones decreasing in freq until you max sub out, that is where you set the ssf. mine is at 15hz

lpf you set either 5-10hz above the high pass on your mids or around 50-60hz any higher it will get directional

bass boost off

gain you can set by dmm but it will not be as clean as oscope

 

[Memphis2011 10+ year member]

When you say times the RMS by your final independance where will I get the number for final independance maybe a dumb question?

 

[wenn_du_weinst 10+ year member]

your speakers impedance rating, it depends how you wire it up post up how it's wired and I'll tell you.

A dmm does not read what impedance your coil is, it reads dcr which is different

 

[JoshC 10+ year member]

In a sealed box: The lower the frequency, the more excursion your subwoofer exhibits in order to play it loudly and accurately. A sealed box is tuned by enclosure volume, larger enclosures tune lower, smaller enclosures tune higher.

Subsonic frequencies potentially damage your subwoofer because they make it expend a lot of energy, travel right to the limits of its excursion and play below the enclosures tuning.

So for safety, we want to cut those frequencies out. For a sealed enclosure you adjust the subsonic filter to 25-35 Hz, to filter the extremely low bass frequencies your woofers unable to play.

In a ported box: You tune the port to a certain frequency, the enclosure is then capable of playing all frequencies above that tuning without an issue. The enclosure can also play below that frequency, but only half an octave, before the cone starts over-excurting and there's potential for damage.

So for safety, we set the subsonic to 1/2 an octave below our tuned frequency. Whats half an octave you say ? Lets do some maths ! One octave up is double the frequency, One octave down is half the frequency.

Lets say you are tuned to 45 Hz:

- 45 Hz / 2 = 22.5 Hz (one octave lower)

- 22.5 Hz /2 = 11.25 Hz (half an octave lower)

So we take 45 - 11.25 = 33.75 Hz (rounded up to 34 Hz)

If your ports at 30Hz then you would need to set it to 23Hz(22.5 really) So yea 5-10Hz below port haha

 

[Memphis2011 10+ year member]

The 2 10s are bridged inside the box

 

[Memphis2011 10+ year member]

The Memphis 10s are 250rms and 500 Peak 4ohm

 

[wenn_du_weinst 10+ year member]

good rule of thumb but as we all know generic tuning of your amp is like a generic tuned enclosure, only half as good as you can get. You do not want to play with me kid. Not only are sealed enclosures used world wide in HT systems playing into the single digit freq, but they have more control the lower you play. You also totally ignored the impedence curve, suspension compliance, and fluid dynamics of the enclosure. All of those play a huge role in how far your cone will travel before your suspension either maxes out or you bottom your coil out on the bottom plate. You can do math all you want real world crushes theory any day. Your also ignoring the size of the enclosure, and position of any adjacent walls that will also affect the loading or unloading of the cone per freq.

OP what coils do your 10's have single 4?

use 2

so 2x500 sqrt = 31.62

 

[JoshC 10+ year member]

Whatever you say. For some reason engineers and technicians never get along ha. But i will admit you more then likely have a much greater deal of experance then me. I have had great results using that formula though, better sounding then anywhere else i set the **** thing

 

[Memphis2011 10+ year member]

MY Memphis box is ported so is the total my final dependeace? Should they not be bridged ?

 

[JoshC 10+ year member]

are they single or dual coils, 2 or 4 ohms. I have no idea what "bridged" means, they can be in series or parallel.

 

[Memphis2011 10+ year member]

They are single coils and 4ohm. Which is better series or parallel? what do you suggest?

 

[Memphis2011 10+ year member]

so guys whats the formula for adjusting the amp by multi-meter ?

 

[Z1NONLY 10+ year member]

Turn gain on amp all the way down.

Play a 50hz 0db test tone on your HU and set to "repeat".

Connect meter to output of amp and set to "AC voltage".

Calculate how many volts you need for your target wattage at the impedance your sub(s) present to the amp. The square root of PXR.... (the power you want)X (the impedance you have) = the voltage you want.

Turn up the HU to it's max un-clipped signal. (Even with the gains down on the amp, you should be able to hear when the HU signal gets distorted and back off the volume a bit.)

Now turn up the gain on your amp until your meter reads your target voltage.

Some amps, like the JL slash amps allow you to do this with no speakers connected, because the amp will ensure the given voltage happens with almost every load. However, with most amps, I would do this wile the amp is under load to be sure of what the amp does with the speaker connected. (Just make it quick. No need to run your maximum power to your sub just to "play" with the gain.)

You're done.

Using an O-scope to look at the wave form is an even better way, but most people don't have one handy. Using an O-scope would allow you to tune for actual maximum clean output vs "claimed" max output.