Impedance calculation

[IamDeMan 0]

I need clarification on something. I am doing a weird wiring scheme for some tweeters, well I think I might.

I have 10 tweeters that have a nominal impedance of 6 ohms. I need confirmation on the load if wired in this fashion.

3-2-2-3

By my calculation this would give me a final load of 3.75, correct?

Each set is wired in series, then all 4 sets are wired in paralell.

[Adrian_D 520]

3 in series is 18ohms.

2 in series is 12ohms.

1/R = 1/9 + 1/6 = 10/36

R = 3.6ohms.

[IamDeMan 0]

3 in series is 18ohms.

2 in series is 12ohms.

1/R = 1/9 + 1/6 = 10/36

R = 3.6ohms.

<{POST_SNAPBACK}>

It appears I am wrong then. That is not how I cam up with my answer.

Thanks. I am teh ohms n00b

Can you answer this question for me then?

If A passive crossover is a 5th order elliptic high pass set to 4.3Khz for a 4 ohm driver, how much difference will being .4 under make?

[Adrian_D 520]

3 in series is 18ohms.

2 in series is 12ohms.

1/R = 1/9 + 1/6 = 10/36

R = 3.6ohms.

It appears I am wrong then. That is not how I cam up with my answer.

Thanks. I am teh ohms n00b

Can you answer this question for me then?

If A passive crossover is a 5th order elliptic high pass set to 4.3Khz for a 4 ohm driver, how much difference will being .4 under make?

it will screw up the transient response of the gravty valve that blocks the intake part of the spaker manifold...

in other words, i have no fawkin' clue.

Edited August 21, 2006 by Adrian_D

[IamDeMan 0]

3 in series is 18ohms.

2 in series is 12ohms.

1/R = 1/9 + 1/6 = 10/36

R = 3.6ohms.

<{POST_SNAPBACK}>

It appears I am wrong then. That is not how I cam up with my answer.

Thanks. I am teh ohms n00b

Can you answer this question for me then?

If A passive crossover is a 5th order elliptic high pass set to 4.3Khz for a 4 ohm driver, how much difference will being .4 under make?

<{POST_SNAPBACK}>

it will screw up the transient response of the wiggle valve that feeds the intake port of speaker.

<{POST_SNAPBACK}>

Funnay.

I am not that much of teh n00b lol.

I know it will affect the point at which the frequency gets attenuated, but I am not sure which way and by how much.

[Adrian_D 520]

already have the x-over ?

[ramos 2]

Going from 4ohm to 8ohm with the same caps and or coils raises the cutoff frequency if I'm not mistaken. So in your case it would lower it . Not sure exactly how much though. Where's jim when ya need him

[IamDeMan 0]

already have the x-over ?

<{POST_SNAPBACK}>

Ya. I just wanted to make sure it isn't terrible to use in this instance.

[IamDeMan 0]

Going from 4ohm to 8ohm with the same caps and or coils raises the cutoff frequency if I'm not mistaken. So in your case it would lower it . Not sure exactly how much though. Where's jim when ya need him

<{POST_SNAPBACK}>

That's what IO was thinking is that it would be lowered. I just want to make sure it wouldn't lower it too much to make it useless on a tweeter. The tweeter has a fs of 1700, so technically I can cross it at 3400 steeply and be fine in theory. So I just wanted to confirm I was lowering my point below this. Otherwise it's back to the drawing board.

[///M5 2,833]

If you are doing this active you will have no problem; however, passive it may not be great. The reason being is that an elliptical crossover is typically a LR crossover with a notch filter. These are both tuned to the impedance of the circuit so if you change the impedance the zobel and the crossover may no longer line up and therefore create a strange response. If you are running that many drivers that are capable of playing beyond the frequency range that you require I would stick with a more simple crossover design.

[IamDeMan 0]

If you are doing this active you will have no problem; however, passive it may not be great.  The reason being is that an elliptical crossover is typically a LR crossover with a notch filter.  These are both tuned to the impedance of the circuit so if you change the impedance the zobel and the crossover may no longer line up and therefore create a strange response.  If you are running that many drivers that are capable of playing beyond the frequency range that you require I would stick with a more simple crossover design.

<{POST_SNAPBACK}>

Well I just have a set of CDT Satnet 480s lying around doing nothing. I was thinking of using them in my home line array project. So yes, it is a passive setup. I am using a crap load of the NSBs that I bought quite a while ago and a good amount of 3/4" dayton tweeters.

[IamDeMan 0]

Where's jim when ya need him

<{POST_SNAPBACK}>

Looks as though I may need to link him here via PM lol.

[PaulD 0]

I know I would never even attempt that in a car ..... a line array for a home speaker might sound good though. And yea, those CDT satnet's are specifically made for the drivers it came with.

[IamDeMan 0]

Well I guess I will just stick to some simple 12db crossovers @ 4500 then.

I will design the cabinet so I can switch out XOs and try others in there or build one specific to this appliaction.

[///M5 2,833]

Do you have a way of measuring the impedance after wiring up your tweeters? You may need a zobel circuit to compensate for impedance rise if you are really getting deep into it. It isn't all that hard though, but a little time consuming to do with just a signal generator and DMM. It can be done though.

[IamDeMan 0]

Do you have a way of measuring the impedance after wiring up your tweeters?

Edited August 23, 2006 by IamDeMan