How to set crossover point on an amplifier/pre amp

[RAJIE]

Ok im using a soundstream xtream 720.4 to run an entire system in my mom car
2channels for bass. 2 channel for mids
what i need help is setting the correct cross points for the bass

amp bass setting:
1)gain
2)subsonic:10hz-30hz
3)bass eq: 0-18db
4)HPF:50-500hz
5)HPF/FULL/LPF
6)LPF:30hz-500hz

bass subwoofer is DD 512.. in dd full size box (2.5cuft)
http://ddaudio.com/sites/default/files/ ... t_size.pdf

also have a ppi par 650 pre amp
subwoofer:30hz-70hz
sub frequency:30hz-400hz
hpf: 30hz-400hz at 12db octave

anyone could assist me on how i should set both amp and pre amp for a good loud & low bass
thanks

[BushmanStarz]

put everything on high

[nervewrecker]

What deck?

What's the tuning freq of the box, type of car and define lows?

[blackberry1234]

where ya from

[vishnu2112]

Its hard for sum 1 to tell u wat and hw to set ur gains an freq controls wit out seeing and hearin d set up bro. But best i cud say is set d voice side to hpf and d bass half to lpf. An adjust d lpf to around 30 to 35 hz dependin on wat freq ur port is tuned to. An adjust ur hpf to a reasonable point where it filters out most of d low freqs. Also match ur rca's frm bass out on ur preamp to d bass half of ur amp. Otha wise is jus fine tuning till u get it right. Or u cud probly jus use full an adjust frm ur preamp

[nervewrecker]

But I have my lpf set to 63hz, I can't play lows?

Why to adjust the hpf to filter out low freq? Ssf is best set to about 5hz below tuning freq depending on the slope.

Why half for? What's up with this half thing?

[Master of Disaster]

Hope this can help mines set lpf @100hz box port tunning is 33hz . hpf front doors is 120hz and rear hpf @ 90 hz this is my amplifier settings .preamp is 80-120 set@ 80 gain is half . midds heights is 125-130 and low mids is 80-90 preamp vol is 2\3 up bass vol is 1\2

[nervewrecker]

But my next system have a low pass of 31.5hz on the sub.

How you guys keep arriving at half BTW?

I set the old fashion way, by ear. *rolls eyes*

System 1 has sub low passed at 63hz -12db slope, phase inverted, box slightly bigger than manufacturer recommendation to increase low freq extension but at the expense of power handling. Sealed box so no ssf.

Mids high passed at 63hz and band passed at 4khz, -12db slopes. Inverted phase, midbass extension well into 60hz so no gaps.

Tweeters crossed at 6.5khz, same slope, one have inverted phase I think.

Has a nice thump, nice rumble, no gaps, sounds very clean and can play anything.

First two bands on the deck boosted a bit to increase low freq response.

I asked type of car and tuning to recommend a center freq and possibly lpf to start with. I'll need your idea of lows to know where you crossing.
Rule is ssf about 5hz below box tuning freq BTW, so stick to it.

If you still work same place and want me take a listen I can swing by a day as is right up the road.

I asked the deck to find out if the pre is necessary. From my experience deck to amp with slopes added and tuning freq set accordingly can get you sounding real real clean.

[nervewrecker]

And if BIM, bam and bamscee who commenting in here had a clue about what they saying they will tell you no gains, the pre spits out 10v RMS on sub and 6v front and rear. All you can use is front or rear with a 2 ch, not both.

http://www.sonicelectronix.com/item_613 ... R-650.html

[evolution7tt]

System 1 has sub low passed at 63hz -12db slope, phase inverted, box slightly bigger than manufacturer recommendation to increase low freq extension but at the expense of power handling. Sealed box so no ssf.

Mids high passed at 63hz and band passed at 4khz, -12db slopes. Inverted phase, midbass extension well into 60hz so no gaps.

Tweeters crossed at 6.5khz, same slope, one have inverted phase I think.

Has a nice thump, nice rumble, no gaps, sounds very clean.

Nerve, am I right in thinking that the only driver you have in electrical phase is a single tweeter?
What was the reason for that?
Has this combination given you better tonality and imaging?

I'd like to hear it sometime.

[nervewrecker]

Staging and center is a bit off as I did some tuning recently. Odd enough the best response is one I got by mistake and can't have....its with the door open. I kid you not! With the driver side door open about one foot and the driver about 6" further away and at a different angle the center is dead center!
Heard from some knowledgeable guys if a tweet sounds like its too close it may be put of phase. Weird I know, both have the same slope so I gave it a try. Really can't remember the results or if I left it that way.

The box is out the van right now so when I put it back in. I does pass close to your workplace on evenings to duck traffic.

[kavaninho]

keeekeeekkeeke Some guys funny in here! lol
OP, Nervewrecker is giving you the best advice here, please follow through with it.

[buckredan]

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)


In other words, you set your sub-sonic to 34 hz. So that way, if there's music below the ports frequency, it gets filtered out protecting your woofer.
Always remember the subsonic filter is NOT a cut-off. It has a roll off "slope" where whatever frequency its set to will be attenuated, and the attenuation effect increases as the frequencies get lower. Thus the power to the woofer decreases at filtered fequencies, which reduces the excursion and risk of damage.

As a final note for the audio geeks: Subsonic filters have steep slopes such as 3rd or 4th order(18 or 24dB/Oct) this is so u can set it nice and close to your 1/2 octave frequency, or 25-35 Hz sealed, without losing power in the neighboring frequency

[buckredan]

to set gain properly
https://www.youtube.com/watch?v=JLvSgucNARs