Impedance Rise

[Nikuk 1]

YOu guys and your fart machines.

Funny thing is, most people never realize how much this will affect your typical DD sytem.

<{POST_SNAPBACK}>

Oh You mean how ssf's are unecessary in most installs because of it? and HU settings can be set around it, and amp choices made, and fusing choices made, electrical system choices, yadda, yaada, yaaaada.

[Nikuk 1]

Ok, so if you are playing a song with varying freqs, why does 1 spike really matter?

<{POST_SNAPBACK}>

ONE PEAK, doesnt matter, depending on how You look at it.

But on the other hand.. a few weeks ago Kent was worried about running a Mojo amp that is stable to 2ohms, because his Woofer is wired to 0.5 ohm nominal. Now, take a look at the graph he came up with and You tell me if the mojo woulda been alright

[djjdnap 78]

oh so thats what you meant by that.

I guess thats why they say you should always try and have some head room when buying an amp.

So if i really think i have 1ohm i prolly have 3, lol, and im only running 500watts when i thought it was 1500...lol

theoreticlly speaking..

So a sealed box doesn't have spikes?

And is that why it is harder to blow subs in a sealed box, if so i thought it was because a sealed box didn't allow as much ....throw if you will ....excursion is the word.

[mrray13 30]

Ok, so if you are playing a song with varying freqs, why does 1 spike really matter?

ONE PEAK, doesnt matter, depending on how You look at it.

But on the other hand.. a few weeks ago Kent was worried about running a Mojo amp that is stable to 2ohms, because his Woofer is wired to 0.5 ohm nominal. Now, take a look at the graph he came up with and You tell me if the mojo woulda been alright

yeah, yeah..wiseass...

and with the 2200wrms+ it puts out at 2 ohm or so, i'd hit a lil better number at 52-53hz because i would've had about 600wrms more then i did.....give or take...

u have taught me something i will forever use to determine my amping needs...lol...

oh....

150, here i come..lol....gots some plans, gots some plans!!!

wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee

[Supa_c 1]

150 sounds more like it

[mrray13 30]

150 sounds more like it

with 1700wrms and a really inefficient woofer...i'll take the 144.4...but i don't like it..lol..

next time....it'll be a 150 or s18x in the trash (with an orion!)

just kidding

wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee

[jellyfish420 0]

Ok, so if you are playing a song with varying freqs, why does 1 spike really matter?

<{POST_SNAPBACK}>

it doesn't really....but when ur playing tones and trying to break 150....

btw, here's my graph....

wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee

<{POST_SNAPBACK}>

man...your spike is over 6ohm!!!

i feel lucky now. mine doesn't even get to 4ohm

[mrray13 30]

Ok, so if you are playing a song with varying freqs, why does 1 spike really matter?

it doesn't really....but when ur playing tones and trying to break 150....

btw, here's my graph....

wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee

man...your spike is over 6ohm!!!

i feel lucky now. mine doesn't even get to 4ohm

lol...but at 6ohm i should still be at or around 1kwrms..so that's not too bad..

but i believe the smaller box ha something to do with it...i imagine a 7.5ft^3 or larger box just might drop that impedence a bit...make the sub more efficient and result in a bit higher number..

maybe even a 10ft^3 box....

wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee

[Nikuk 1]

::shakeshead::

Bigger boxes generally equal higher impedance. So I've read.

In my toying around, by adding internal ballast (to bring box size down) imp tends to drop a little bit. Also, adding reflection boards right under the woofer has seemed to help me in score & impedance lately. The DD and the SX's would drop imp a little. The stroker, atomics, and old shocker sigs would make no differnce in imp or go up. Keep in mind, these were all different boxes too.

[mrray13 30]

::shakeshead::

Bigger boxes generally equal higher impedance. So I've read.

In my toying around, by adding internal ballast (to bring box size down) imp tends to drop a little bit. Also, adding reflection boards right under the woofer has seemed to help me in score & impedance lately. The DD and the SX's would drop imp a little. The stroker, atomics, and old shocker sigs would make no differnce in imp or go up. Keep in mind, these were all different boxes too.

hmmmm...i wonder why?

well, i'm still going to build larger, to better take advantage of what power i have, and i'll test to see just what kinda of rise it is.

and i might be switching amps anyway..lol...to better take advantage of what rise there is...

wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee

[jellyfish420 0]

::shakeshead::

Bigger boxes generally equal higher impedance. So I've read.

In my toying around, by adding internal ballast (to bring box size down) imp tends to drop a little bit. Also, adding reflection boards right under the woofer has seemed to help me in score & impedance lately. The DD and the SX's would drop imp a little. The stroker, atomics, and old shocker sigs would make no differnce in imp or go up. Keep in mind, these were all different boxes too.

<{POST_SNAPBACK}>

do you think you could maybe throw together a quick picture in paint so i can see what this reflection board is, that is oh so talked about...i can see it in my head...but it don't look right

[djjdnap 78]

hmm, so i should build a small box? lol

i thought bigger boxes usually would usually yield you with more bass.

But if both are the case y not find a way to not get a high imp and still have a bigger box, that would deff get some higher numbers.

[mrray13 30]

hmm, so i should build a small box? lol

i thought bigger boxes usually would usually yield you with more bass.

But if both are the case y not find a way to not get a high imp and still have a bigger box, that would deff get some higher numbers.

a larger box will usually yeild two things for certain...

it'll reinforce the lowend

it'll make the sub more efficent, allowing for more excursion and possibly more output based upon similiar power..

however, it'll also, typically, lower power handling...

and, evidently, raise impedence and actually lower the available power...but we shall see.

wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee

[chinny 0]

in a 3.8ft^3 for 2 rl-p 15's sealed the impedance rise will be 3.93Ohms, thats bad, i need a low box and sealed since i will be feeding 1000rms to each sub. Mike recommended this box.

[mrray13 30]

in a 3.8ft^3 for 2 rl-p 15's sealed the impedance rise will be 3.93Ohms, thats bad, i need a low box and sealed since i will be feeding 1000rms to each sub. Mike recommended this box.

unless ur going to compete..i don't think impedence rise should worry ya, unless u want it too..

that box mike suggested will get plenty loud and low..u'll like it.

wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee

[Nikuk 1]

:werd:

You wouldnt believe how loud some woofers get with merely 700rms on 'em (being rated to take 2kw rms).

Not too mention, the difference between 700rms & 1kw is a theoretical 1.5dB... You're prolly not gonna hear that.

[chinny 0]

i hope not, but if im going to pay the money for a 2000 watt amp i want that going to my 15's, if not then ill go for something else, get me?

[jellyfish420 0]

in a 3.8ft^3 for 2 rl-p 15's sealed the impedance rise will be 3.93Ohms, thats bad, i need a low box and sealed since i will be feeding 1000rms to each sub. Mike recommended this box.

<{POST_SNAPBACK}>

hmmmm....and the bigger the box the higer the impedance rise?

my 6ft ported @ 23 peakes at 3.3ohms. wonder why that is?

[mrray13 30]

in a 3.8ft^3 for 2 rl-p 15's sealed the impedance rise will be 3.93Ohms, thats bad, i need a low box and sealed since i will be feeding 1000rms to each sub. Mike recommended this box.

hmmmm....and the bigger the box the higer the impedance rise?

my 6ft ported @ 23 peakes at 3.3ohms. wonder why that is?

mostly because u've actually tested urs..lol

chinny is going by the bb6p graph. he's trying to figure out the best box available and bb6p at the same time.

i think he'll be more thne happy with the 3.8cubes, and then he should actually measure the rise and see how close bb6p was.

but still yet, ur box is a touch larger then mine (and yeah, given the varibles, more efficient subs, wired differently) and yet, ur impedence rise is quite a bit lower.

so, that brings me to this question(s)..

does the impedence the sub(s) are wired to, make that big of a difference with the inbox impedence? (as far as the spike is concerned)

does the efficiency of the sub(s) matter?

box tuning?

port size?

if more volume tends to spike higher, how can it also make the sub more efficient?

hopefully, u see what i'm trying to get at...it seems as though the more efficient subs are spiking lower, yet they are in a larger enclosure. so if i can make the s18x more efficient with a larger enclosure, shouldn't i also help the spike to lower a bit? and with the new box is coming larger ports (for comp, they will be quite a bit larger, and shorter..lol)

looks like i gotz some testing ahead of me...lol

wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee

wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee

[Nikuk 1]

every motor is different... even in the same exact box. When I dropped one of the SX15"s in the box that the DD99 was in, the imp. topped out around 3.9 ohm when wired to a 0.7 nominal load off of one amplifer. In this same box, 20 minutes earlier, the DD 99 (dual 0.9 coils wired individually) had each coil standing at 7.4ohm.

This is where the whole discussion about BL curves, saturation, guassation, and motor itself come into play. <shrug>

Every woofer, in every box is different. If You have the same volume box, but it has different dimensions, the imp chart can (but not always will) change. I've seen this myself.

As far as bbp6, it doesnt account for Back EMF from the motor, the dampening factor of the amplifier, the changes in port area, among a few other things.

I'm sorry... I don't have all the answers. Time for a group study...

-Nick

[mrray13 30]

I'm sorry... I don't have all the answers. Time for a circle jerk and i'm the pivot man...

-Nick

well...if u say so...

but i see ur point, hence the "i've gotz some testing ahead of me"

then i'll make my amplifer choice based upon that...

wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee

[Nikuk 1]

LMAO... I use that line all the time on others around here... most of the time the girl doesnt know what I'm talking about!

BTW, that post was more about the BBP6 reference a few posts ago. Not aimed at You buddy.

[mrray13 30]

LMAO... I use that line all the time on others around here... most of the time the girl doesnt know what I'm talking about!

BTW, that post was more about the BBP6 reference a few posts ago. Not aimed at You buddy.

i know, but i'm learning as i go here...and what u wrote applied to me as well....lol..

wheeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee

[jellyfish420 0]

i also believe(i'm not for sure) that the way the subs are wired makes a difference. ie. dvc 4 ohm wired series has diff t/s parameters then the same dvc 4 ohm wired parallel.

[chinny 0]

Will a ported box have less impendance than a sealed box?