Ohms issue bookshelf speakers 6ohms

[Kamranbites]

Hi guys, hope all are doing well 

 

Recently I visited a speaker repair site  for replacing my woofer cone and spider he said coil was good so he kept the same one

 

The woofer was 6ohms 

Now comming home if I measure it, the meter shows 5ohms 

Is this ok or will cause some big issue this decrease ohms will effect only one channel of amplifier and other channel speaker was not repaired just one channel speaker

 

What do you guys suggest

 

Thanks 

 

[Biohazard777]

56 minutes ago, Kamranbites said:

The woofer was 6ohms 

Now comming home if I measure it, the meter shows 5ohms 

Are you measuring the right thing?
Resistance =/= Impedance.
https://soundcertified.com/what-will-2-4-8-ohm-impedance-speaker-measure-dc-resistance/

Edit: so that people don't have to follow the link (though it is a nice article, worth a click) or it ceases to function :

[Kamranbites]

37 minutes ago, Biohazard777 said:

Are you measuring the right thing?
Resistance =/= Impedance.
https://soundcertified.com/what-will-2-4-8-ohm-impedance-speaker-measure-dc-resistance/

Edit: so that people don't have to follow the link (though it is a nice article, worth a click) or it ceases to function :

Yes also before sending to repair i have measured it and was exactly 6ohms,May be he cut coil threads and placed it as it will be hard to get it out and also to make through the new cone again he need some wire of coil so he might have used some of the coil wire so 1ohms reduced,

I said him better we use new coil while reparing but he said only 8ohms coil is available not 6 ohms so I decided to use old one

 

 

 

[geo3]

Impedance is highly frequency dependant, so if your expressing it as a single number rather than a plot over the frequency domain you're already wrong. 

[cmndr]

Which frequency?

This is something which will vary by frequency. 
Here's an impedance plot for the speakers that I have. Notice how some frequencies have higher impedances (e.g. 80Hz peaks at ~24Ohms while 200Hz is around 4Ohms)

 

 

 

As an FYI if you have mismatched speakers (non identical woofers, non-identical crossover designs) there is a possibility that you'll slowly damage the amplifier driving them 

[Kamranbites]

3 hours ago, cmndr said:

Which frequency?

This is something which will vary by frequency. 
Here's an impedance plot for the speakers that I have. Notice how some frequencies have higher impedances (e.g. 80Hz peaks at ~24Ohms while 200Hz is around 4Ohms)

 

 

 

As an FYI if you have mismatched speakers (non identical woofers, non-identical crossover designs) there is a possibility that you'll slowly damage the amplifier driving them 

1 ohms difference too will cause such problem

So what do you suggest should I get that 8ohms coil, normal my woofer was built to handle 6ohms 

Nothing to worry about amplifier as it has wide range 4-8

[Kamranbites]

5 hours ago, geo3 said:

Impedance is highly frequency dependant, so if your expressing it as a single number rather than a plot over the frequency domain you're already wrong. 

Yes but I have measured in stable state

[cmndr]

16 hours ago, Kamranbites said:

So what do you suggest should I get that 8ohms coil, normal my woofer was built to handle 6ohms 

Nothing to worry about amplifier as it has wide range 4-8

Ideally you use IDENTICAL speakers. If you do a repair, you swap the parts identically on both speakers or you get an identical replacement part. Identical as in same product name/number, not same F3 and sensitivity ratings (since those are often NOT measured well and don't tell the whole story). 

It's often NOT worth it to repair speakers.

[Kamranbites]

 

I have a pair of Aiwa bookshelf speaker when I messure one bookshelf speakers it shows 6 which is rated ohms but other shows 30ohms why? It's a 3 way bookshelf speaker both used to measure 6ohms previously

[mariushm]

The  3 way speakers may have a passive filter inside the "split" the sound into low frequency and high frequencies and maybe a wire in the filter broke or maybe something on the circuit board doesn't work anymore.

 

You could try to open that speaker and visually inspect the internals to see if something changed.

[Heats with Nvidia]

If you measurements are correct, there is either a loose or wrong contact or the woofer is fried.

[Kamranbites]

5 hours ago, Heats with Nvidia said:

If you measurements are correct, there is either a loose or wrong contact or the woofer is fried.

Woofer is working fine. I had pair of these so i compared sound from both they sound similar 

So i think no issue with speakers or crossover 

[Heats with Nvidia]

8 hours ago, Kamranbites said:

Woofer is working fine. I had pair of these so i compared sound from both they sound similar 

So i think no issue with speakers or crossover 

Then either your measurement was wrong, you didn`t hear the problem or the problem. A loudspeaker that changed its impedance that drastically, can`t sound like a working one.

[Kamranbites]

1 hour ago, Heats with Nvidia said:

Then either your measurement was wrong, you didn`t hear the problem or the problem. A loudspeaker that changed its impedance that drastically, can`t sound like a working one.

I think the issue is with my  banana plugs when i took out  them and measured ohms  they measured correctly. 

 

Attached pic of Banana plugs I am using 

 

 

[Kamranbites]

This is crossover setup

[Heats with Nvidia]

I don`t even know, where to begin. I didn`t even have a look at the calculation, but even if that is correct, the text makes absolutely no sense at all. None. 0.  For example,  why are tweeter and woofer in parallel? This means by definitiion, that they get the exact same signal and there is no crossover. All this describes, is a filter that prevents any signal to go to both of them.

 

To calculate the approximate crossover frequency for a tweeter, all you need is the capacitance of the capacitor and the impedance of that tweeter. Not that you would get an accurate value, since the tweeter won`t have the given impedance at that frequency, but you will at least roughly know where you land.

 

The woofer has no role in this calculation.

 

PLEASE read up on what a parallel and series connection are and how at least basic filters with capacitors and resistors work in general. I am sorry, but i think your problem is even reading a schematic that contains three components at this point.

[saintlouisbagels]

Everything is wrong.

You've explained nothing about your situation and the ChatGPT text makes no sense.

[Kamranbites]

Then can somone say what is the crossover frequency in my setup 

 

5.5 inch 6ohms 50w woofer

2.5inch tweeter 4ohms  10w (capasitor 100v 3.3uf inline)

 

Both connected in parallel

 

[cmndr]

To get the frequency for where you'd want to cross, you'd want to use a calibration microphone to measure each part separately. 

Something like u-mik1 and REW. 
https://www.minidsp.com/products/acoustic-measurement/umik-1

Making cross-overs is a lot of work and if it's your first time A LOT of trial and error and wasted expenses from buying the wrong parts. You'd also probably want to skim through a basic course on electricity. https://www.khanacademy.org/science/electrical-engineering/introduction-to-ee/intro-to-ee/v/ee-current


I basically "noped" out of it even though I love tinkering. I have better things to do with my time. 

-----

One warning, chatGPT is useful when you have a GOOD idea of what you're talking about and have enough background knowledge to know when it's being crazy and just making stuff up. Pretend that it's a 5 year old super genius child that LOVES to play pranks. ChatGPT struggled with basic math FYI and what you're doing requires intermediate math (e.g. calculating harmonic means is usually not taught in high school) moreso than basic math. 

[Heats with Nvidia]

On 12/4/2023 at 7:23 PM, Kamranbites said:

Then can somone say what is the crossover frequency in my setup 

 

5.5 inch 6ohms 50w woofer

2.5inch tweeter 4ohms  10w (capasitor 100v 3.3uf inline)

 

Both connected in parallel

 

Please read and try to understand what i wrote above. I am sorry, but this is getting nowhere.

[Kamranbites]

5 hours ago, Heats with Nvidia said:

Please read and try to understand what i wrote above. I am sorry, but this is getting nowhere.

 

[Heats with Nvidia]

Its just slightly off. The frequency in this calculation is: 12.06KHz. But now we are getting somewhere. In an ideal world, where this speaker has an impedance of exactly 4 Ohm at 12.06KHz and the capacitor has no tolernce, the crossover frequency for the tweeter would be these 12.06KHz. Now you need to find out, why the woofer didn`t matter in this calculation.

[Kamranbites]

woofer handles the full range of frequencies sent by the amplifier, as woofer is directly connected to the amplifier, so it is not affected by the capacitor or the crossover frequency designed for the tweeter.

[Kamranbites]

29 minutes ago, Heats with Nvidia said:

Its just slightly off. The frequency in this calculation is: 12.06KHz. But now we are getting somewhere. In an ideal world, where this speaker has an impedance of exactly 4 Ohm at 12.06KHz and the capacitor has no tolernce, the crossover frequency for the tweeter would be these 12.06KHz. Now you need to find out, why the woofer didn`t matter in this calculation.

Woofer is directly connected to amplifier is it a problem, should i use coil (0.33mh) in series with woofer  or let it run as is 

[Heats with Nvidia]

That depends on the woofer. At a that high frequency, most won`t produce much sound anyway. The problem is, you either try it and see, what happens, or you measure everything there is to know about this woofer and enter this into a program, where you can simulate the results and try it, after you got a decent result in the simulation. Both ways require a lot of experimentation. Also, at this point, a measuring microphone wouldn`t hurt, because hearing the difference all day, can be very tiring to the point that you go into the wrong direction.