8 ohm tweeter with 4 ohm speaker

[Megatron12]

Hey guys, just want to confirm this information real quick. I want to wire my tweeter with my speaker in the same channel. I read that if you wire an 8ohm speaker in parallel to a 4 ohm speaker the impedance will drop to 2.6 ohms. The 8ohm speaker will receive 33% of the power and the 4 ohm speaker will receive 66% of the power. Is this true? Thanks.

 

[Jimi77]

Hey guys, just want to confirm this information real quick. I want to wire my tweeter with my speaker in the same channel. I read that if you wire an 8ohm speaker in parallel to a 4 ohm speaker the impedance will drop to 2.6 ohms. The 8ohm speaker will receive 33% of the power and the 4 ohm speaker will receive 66% of the power. Is this true? Thanks.

No. You need to run those speakers thru a passive crossover. At the frequencies sent to the tweeter the amp will see 8 ohms and at frequencies sent to the woofer the amp will see 4 ohms.

 

[Megatron12]

No. You need to run those speakers thru a passive crossover. At the frequencies sent to the tweeter the amp will see 8 ohms and at frequencies sent to the woofer the amp will see 4 ohms.

So on one channel the amp will see two separate resistances loads based on the frequency? I was planning on running an in-line crossover on the tweeter. Sorry, I’m just a little confused and couldn’t find a whole lot on this specifically.
I guess my goal is to drop the impedance as low as I can (2ohms ideally) and manage to power the tweeter and woofer on the same channel.

 

[2023 LTZ]

I have only a theory on this. Some background on my thoughts, I replaced my oe 6x9s w focal 4ohm. The Bose option included a 3.5” on the same channel. I replaced the traditional 6x9 speaker ring w the oe Bose one and re installed those 3.5s in the original location. I believe the oe system was 2 ohm. So my thought was a 2 ohm plus a 4 ohm equals 2 3ohm speakers on each of the rear channels. I’m not sure how this translates for the fronts as each of those are 4 ohm. I have a 4 ch and believe these components are hooked up parallel which …, idk.

I know I didn’t answer this question but shared this to see if there’s comments to come which offer clarity about this for you, me and others.

 

[2023 LTZ]

Using my theory your speakers would show a 6 ohm load on each channel they’re hooked up to.

 

[Jimi77]

Using my theory your speakers would show a 6 ohm load on each channel they’re hooked up to.

Wrong. I already answered the question correctly.

 

[Jimi77]

So on one channel the amp will see two separate resistances loads based on the frequency? I was planning on running an in-line crossover on the tweeter. Sorry, I’m just a little confused and couldn’t find a whole lot on this specifically.
I guess my goal is to drop the impedance as low as I can (2ohms ideally) and manage to power the tweeter and woofer on the same channel.

Yes, the amp will see different loads depending on the frequency. You'll need a crossover on the midrange too or you'll end up with comb filtering. General rule of thumb is you want cross around 2x the FS of the tweeter. If you end up crossing at ~5khz or higher, then you can probably forgo the crossover on the midbass driver.

You will not be able to drop the impedance with your current equipment. I would ignore the impedance of the tweeter and focus on just the midbass driver. You could get another 4 ohm midrange driver and run them parallel or get a 2 ohm midbass driver. In your case, I'd probably just buy a 2 ohm comp set. Something like these:

CDT Audio CL 61

I suggest a comp set because the crossover is designed for the drivers being used and the crossover is as important as the drivers. Buying off the shelf crossovers can be a disaster waiting to happen. You have to take into account if a tweeter attenuation circuit is needed and will it be driver side or amp side. There maybe a tweeter protection circuit built into a crossover that comes with a set. The crossover frequencies are important too.

 

[2023 LTZ]

Copy that.
So bc my 4 ch is 2 ohm stable it’s fine that those 2 ohm 3.5s are sharing w the 4ohm?

If however the amp was not 2 ohm stable I’d run the risk of damaging or overheating the amp?

 

[Megatron12]

Yes, the amp will see different loads depending on the frequency. You'll need a crossover on the midrange too or you'll end up with comb filtering. General rule of thumb is you want cross around 2x the FS of the tweeter. If you end up crossing at ~5khz or higher, then you can probably forgo the crossover on the midbass driver.

You will not be able to drop the impedance with your current equipment. I would ignore the impedance of the tweeter and focus on just the midbass driver. You could get another 4 ohm midrange driver and run them parallel or get a 2 ohm midbass driver. In your case, I'd probably just buy a 2 ohm comp set. Something like these:

CDT Audio CL 61

I suggest a comp set because the crossover is designed for the drivers being used and the crossover is as important as the drivers. Buying off the shelf crossovers can be a disaster waiting to happen. You have to take into account if a tweeter attenuation circuit is needed and will it be driver side or amp side. There maybe a tweeter protection circuit built into a crossover that comes with a set. The crossover frequencies are important too.

Okay, so this website is incorrect? Check it out if you want. https://geoffthegreygeek.com/multiple-speakers-share-power/

 

[Megatron12]

Copy that.
So bc my 4 ch is 2 ohm stable it’s fine that those 2 ohm 3.5s are sharing w the 4ohm?

If however the amp was not 2 ohm stable I’d run the risk of damaging or overheating the amp?

It’s going to be dependent on how they’re wired and what the final impedance is.

 

[Jimi77]

Okay, so this website is incorrect? Check it out if you want. https://geoffthegreygeek.com/multiple-speakers-share-power/



View attachment 49479

It's not incorrect. It's very dumbed down and incomplete. Impedance is reactive, that site is treating impedance like resistance, which is non-reactive.

For example, SPL competitors can hook up a 2000wrms sub to 10kw amp for 45hz burps because they're calculating for impedance rise. Play bass heavy music on that same system and you'll likely fry the sub if you don't turn down the gains. And that's despite the fact that the sine wave/burp contains much more AC voltage than music.

 

[Jimi77]

Copy that.
So bc my 4 ch is 2 ohm stable it’s fine that those 2 ohm 3.5s are sharing w the 4ohm?

If however the amp was not 2 ohm stable I’d run the risk of damaging or overheating the amp?

I have no idea how the system is wired, what drivers you are using, if there is a passive crossover involved, what load the amp is seeing, if the gains are set properly, etc.

 

[2023 LTZ]

They are wired parallel. No cross overs to these as rears. The 4 ch is 2 ohm stable and I could not make a definitive conclusion after reading the article enclosed previously.
I cut power to the original amp, ran 12ga through the vehicle to the 4 corners of the sound stage. Focal something components which are 6.5” and 1”. I blew the focal tweets and replaced them w hertz 1”.
Rears are also focals in a 6x9 configuration but added back in the Bose 3.5” in parallel.
Rf t400x4 which can deliver 85wx4 at 4ohm. This is close to the speakers recommended input, same w the fronts. 75-80 front 90-100 or so to rears.

Before adding the 3.5s I could turn volume all the way up w no distortion. 5v preouts on the jvc kwv960.
Sounds amazing, just curious after reading the first post of this thread.

 

[2023 LTZ]

They are wired parallel. No cross overs to these as rears. The 4 ch is 2 ohm stable and I could not make a definitive conclusion after reading the article enclosed previously.
I cut power to the original amp, ran 12ga through the vehicle to the 4 corners of the sound stage. Focal something components which are 6.5” and 1”. I blew the focal tweets and replaced them w hertz 1”.
Rears are also focals in a 6x9 configuration but added back in the Bose 3.5” in parallel.
Rf t400x4 which can deliver 85wx4 at 4ohm. This is close to the speakers recommended input, same w the fronts. 75-80 front 90-100 or so to rears.

Before adding the 3.5s I could turn volume all the way up w no distortion. 5v preouts on the jvc kwv960.
Sounds amazing, just curious after reading the first post of this thread.

 

[2023 LTZ]

Pretty great internet right here lol.