Capasitor helps to match ohms ?

[Kamranbites]

3.3µF, 100V capacitor connected on positive wire on my tweeter and connecting it to the any speaker in parallel , the impedance consistently remains at 6 ohms. How can this be explained?

 

 

Past this bookshelf speakers had two way setup one woofer 6ohms and 4ohms tweeter connected in parallel with woofer(capasitor inline with tweeter) this gives exactly 6ohms when checking all setup.

When i change woofer to 8ohms in exact setup still ohms be 6 how is it possible the capasitor is doing something?

 

 

 

 

 

 

[Psittac]

I don't think you're on the correct forum for such a technical question.  I know there are a couple who know about such low level stuff but I can't remember their names.

[Kamranbites]

2 hours ago, Psittac said:

I don't think you're on the correct forum for such a technical question.  I know there are a couple who know about such low level stuff but I can't remember their names.

Thank you for the information, can you provide any additional guidance on where I might find the experts I need?

[circeseye]

On 9/30/2023 at 10:50 PM, Kamranbites said:

3.3µF, 100V capacitor connected on positive wire on my tweeter and connecting it to the any speaker in parallel , the impedance consistently remains at 6 ohms. How can this be explained?

 

 

Past this bookshelf speakers had two way setup one woofer 6ohms and 4ohms tweeter connected in parallel with woofer(capasitor inline with tweeter) this gives exactly 6ohms when checking all setup.

When i change woofer to 8ohms in exact setup still ohms be 6 how is it possible the capasitor is doing something?

 

 

 

 

 

 

if i remember right that cap has nothing to do with ohms....its to remove lower frequencies (bass) from going to the tweeter so it doesnt blow....a crossover like design

[Spuriae]

How are you measuring the impedance? Impedance should vary based on frequency.

 

If you're doing a resistance measurement, the capacitor acts like an open circuit with a DC input so you're essentially measuring the resistance of the wire in the woofer. 6Ω (resistance) on an 8Ω (nominal impedance) woofer is normal.

[cmndr]

Here's a thread where people talk about software for simulating cross over designs. You should be prepared to spend A LOT of time designing a cross over and probably a decent amount of cash since the first design or two probably will be "ehh"

https://www.audiosciencereview.com/forum/index.php?threads/crossover-software-for-windows-linux-macos.26180/

If you're doing this "right" you'd be designing a custom cross over for the unique combination of woofer+tweater+speaker cabinet that you have. 
You shouldn't just be replacing the capacitors and resistors like for like in this case because you're using a different woofer from what the speaker was designed for. 

When you changed out the busted woofer from your speaker for a different, non-identical woofer (which might have a similar F3 but likely has very different frequency response and sensitivity characteristics) you changed the characteristics of the overall speaker. The old crossover design won't necessarily work anymore so the parts inside the speaker's crossover network (capacitors, resistors) would all ideally be swapped out. 
It's like changing one wheel on a car for a bigger wheel... EVERYTHING else needs to be adjusted (the wheel on the other side needs to be swapped, you might need to redo the brakes, you might need to change the calibration for the speedometer and odometer, etc.)

You shouldn't be building your first crossover from scratch.
Ideally you're following a guide and using a pre-built kit. Or you're replacing a part like for like. 
This is NOT the same as getting a mismatched woofer that happens to have the same F3 and trying to "make it work"

As stated in other threads, you run a very real risk of trying to fix a broken $20 speaker by using $50 worth of parts and $1000 worth of time. 
If it's for fun, go for it. If it's for practical utility, you should've thrown away the old speaker and bought a new one. 

[Kamranbites]

10 hours ago, circeseye said:

if i remember right that cap has nothing to do with ohms....its to remove lower frequencies (bass) from going to the tweeter so it doesnt blow....a crossover like design

So how ohms is set to 6 when two speakers of 8 and 4 ohms are connected in parallel.

I have tired with diffrent multimeter too got same result when measuring individual getting 4 and 6 but when  measuring overall impudence it is 6ohms 

[circeseye]

17 minutes ago, Kamranbites said:

So how ohms is set to 6 when two speakers of 8 and 4 ohms are connected in parallel.

I have tired with diffrent multimeter too got same result when measuring individual getting 4 and 6 but when  measuring overall impudence it is 6ohms 

well lets look at it...one speaker is 8ohm and one speaker is 4ohm separate. but when you connect to 2 together it normalizes as 6ohm. its all i can come up with.
when combining speakers you dont mix ohm for one thing. you use all 8ohm, 6ohm, or 4ohm...but you dont mix them

[Kamranbites]

4 hours ago, circeseye said:

well lets look at it...one speaker is 8ohm and one speaker is 4ohm separate. but when you connect to 2 together it normalizes as 6ohm. its all i can come up with.
when combining speakers you dont mix ohm for one thing. you use all 8ohm, 6ohm, or 4ohm...but you dont mix them

Many bookshelf speakers have 4 ohms tweeter and 6ohms woofer 

[circeseye]

33 minutes ago, Kamranbites said:

Many bookshelf speakers have 4 ohms tweeter and 6ohms woofer 

hmmm read this it has a lot of info, maybe it will help
https://www.the-home-cinema-guide.com/speaker-impedance-matching.html

[Heats with Nvidia]

On 10/3/2023 at 2:59 AM, circeseye said:

well lets look at it...one speaker is 8ohm and one speaker is 4ohm separate. but when you connect to 2 together it normalizes as 6ohm. its all i can come up with.
when combining speakers you dont mix ohm for one thing. you use all 8ohm, 6ohm, or 4ohm...but you dont mix them

I am sorry, but that is just wrong. A 4Ohm speaker and a 8 Ohm speaker in parallel (considering they otherwise are the same and knowing that this impedance is only given for one frequency) is:

 

1/((1/8)+(1/4))=2,67Ohms

 

On 10/3/2023 at 2:43 AM, Kamranbites said:

So how ohms is set to 6 when two speakers of 8 and 4 ohms are connected in parallel.

I have tired with diffrent multimeter too got same result when measuring individual getting 4 and 6 but when  measuring overall impudence it is 6ohms 

What multimeter did you use? If its a normal one in the resistance setting, you only measure at one frequency and that is 0Hz because you are measuring with DC. But that is a frequency your loudspeaker optimally never has to endure.

 

 

So for the multimeter, both are not parallel at all. The tweeter is in series to a capacitor that blocks low frequencies from getting to it and almost all multimeters measure with the lowest frequency that there is and that is 0Hz. You can even disconnect or short out the tweeter without changing anything for the multimeter.

 

Since i already tried to explain this to you, i think your problem is more the understanding of what i mean with frequency.

 

Maybe this helps with that. When you understand this, i recommend you read up on series and parallel connection of resistors and then what capacitors and inductors are and how they behave at certain frequencies and how to build filters with these components.

[circeseye]

4 hours ago, Heats with Nvidia said:

I am sorry, but that is just wrong. A 4Ohm speaker and a 8 Ohm speaker in parallel (considering they otherwise are the same and knowing that this impedance is only given for one frequency) is:

 

1/((1/8)+(1/4))=2,67Ohms

 

What multimeter did you use? If its a normal one in the resistance setting, you only measure at one frequency and that is 0Hz because you are measuring with DC. But that is a frequency your loudspeaker optimally never has to endure.

 

 

So for the multimeter, both are not parallel at all. The tweeter is in series to a capacitor that blocks low frequencies from getting to it and almost all multimeters measure with the lowest frequency that there is and that is 0Hz. You can even disconnect or short out the tweeter without changing anything for the multimeter.

 

Since i already tried to explain this to you, i think your problem is more the understanding of what i mean with frequency.

 

Maybe this helps with that. When you understand this, i recommend you read up on series and parallel connection of resistors and then what capacitors and inductors are and how they behave at certain frequencies and how to build filters with these components.

i never said i was right just all i could come up with. then i found that site i linked him that helps explain it all better

[cmndr]

16 hours ago, Heats with Nvidia said:

I am sorry, but that is just wrong. A 4Ohm speaker and a 8 Ohm speaker in parallel (considering they otherwise are the same and knowing that this impedance is only given for one frequency) is:

 

1/((1/8)+(1/4))=2,67Ohms

This reminds me a lot of the harmonic mean formula. I'm guessing the overall resistance of devices in parallel is:
1 / SUM(1/n)
where n is the resistance for one resistor and all all resistors are accounted for. 
So 2, 4, 8 would be 1/ (.5 + .25 + .125) = 1.143.

I'm more of a statistician than an electrical engineer though so... 

[Heats with Nvidia]

4 hours ago, cmndr said:

This reminds me a lot of the harmonic mean formula. I'm guessing the overall resistance of devices in parallel is:
1 / SUM(1/n)
where n is the resistance for one resistor and all all resistors are accounted for. 
So 2, 4, 8 would be 1/ (.5 + .25 + .125) = 1.143.

I'm more of a statistician than an electrical engineer though so... 

That is absolutely correct and a better way to write it than i could think of at that moment. Thank you!

[Kamranbites]

13 hours ago, cmndr said:

This reminds me a lot of the harmonic mean formula. I'm guessing the overall resistance of devices in parallel is:
1 / SUM(1/n)
where n is the resistance for one resistor and all all resistors are accounted for. 
So 2, 4, 8 would be 1/ (.5 + .25 + .125) = 1.143.

I'm more of a statistician than an electrical engineer though so... 

overall impedance of my speakers (4 ohms and 6 ohms) connected in parallel with a 3.3uF capacitor at 1 kHz should be approximately 2.289 ohms. But i tired with many multiple multimeters it shows 6ohms only 

[Heats with Nvidia]

6 hours ago, Kamranbites said:

overall impedance of my speakers (4 ohms and 6 ohms) connected in parallel with a 3.3uF capacitor at 1 kHz should be approximately 2.289 ohms. But i tired with many multiple multimeters it shows 6ohms only 

What multimeters did you try? Like i have written above almost all of them measure with DC, not 1KHz.

I work with loudspeakers quite a lot and i don`t own a multimeter capable of that.

Also the impedance of a 3.3µF capacitor at 1KHz is 48.23Ohm and that in series to a speaker that has 4 Ohms at that frequency would be 48.23Ohm+4Ohm=52.23Ohm. That in parallel to your 6 Ohm woofer is:

 

1/((1/52.23)+(1/6))=5.38Ohm

 

And that is only true if your woofer alone at that point really has 6Ohm and not more like 7Ohm.

 

The tweeter and the capacitor are in series, not in parallel and both are in parallel to the woofer. That is a very important distinction.

[cmndr]

12 hours ago, Kamranbites said:

overall impedance of my speakers (4 ohms and 6 ohms) connected in parallel with a 3.3uF capacitor at 1 kHz should be approximately 2.289 ohms. But i tired with many multiple multimeters it shows 6ohms only 

Overall impedance doesn't necessarily matter THAT much (Imagine someone who needs 3 cups of water a day overall, giving 6 cups for a month and then 0 cups for 1 month = dead person). You also need to consider impedance at the crossover point where you'll transition the sound from being played from the tweeter to the woofer. The impedance is different at different frequencies. You should be thinking of this more in terms of designing a custom cross over. Ideally you know MORE than a 1 year class in basic electricity/magnetism physics from high school. 

Normally it doesn't make sense to take the time and money to design a custom cross over network unless you're going to be using it 100+ in 100+ speaker builds. If you're doing a "not bad job" it will take a lot more resources than just throwing away your old, broken speaker. It's not impossible to get something that will "work" albeit kind of "meh" but you'll still have a mismatch between your two speakers because your "new" speaker has a different driver and a different cross over design. The best case scenario is that you have two mismatched speakers that sound weird when used together. 


You probably should throw away your old, broken speaker. It's broken. You don't have an identical replacement part to fix it. If you had an IDENTICAL (not "same specs") woofer from the manufacturer, it's an easy enough swap out. 

https://www.diyaudio.com/community/threads/introduction-to-designing-crossovers-without-measurement.189847/