Is it ok to have multiple tweeters in each channel? - diyAudio
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Old 21st July 2013, 11:37 PM   #1
Zertman is offline Zertman  United States
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Default Is it ok to have multiple tweeters in each channel?

In my current home theater system I have (for each front 3 channels) one tweeter with a attenuating resistor in parallel with two identical 5" woofers.

Here is a schematic of my each front channel speakers:
Click the image to open in full size.

It sounds good but I like to have more high end. I have 3 more of the same exact tweeters. So I was wondering if I could replace the resistors with another tweeter.

Here is a schematic of the new way:

Click the image to open in full size.

Would this sound ok? If so, where should I position the tweeters in relation to the woofers?

Last edited by Zertman; 21st July 2013 at 11:38 PM. Reason: Fixed image
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Old 21st July 2013, 11:46 PM   #2
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I presume the 4 ohm woofers are in series not parallel?
If you want the tweeter hotter why not switch it to a true 4 ohm design?
Switch the woofers to parallel and pull out the resistor entirely.
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Old 21st July 2013, 11:58 PM   #3
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I bought a pro pair of speakers with 4 tweeters in each channel.

Its more a matter of getting a balanced sound.
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Old 22nd July 2013, 12:32 AM   #4
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When you put two crossovers in series they effect each other so I do not recommend that each tweeter have its own crossover.

If you really want two tweeters than remove the resistor and redo the crossover for the new impedance of the drivers in series. IIRC it will net you 3db increase in the highs but could cause some phase anomalies.

If you want more highs without the phase issues than you could remove the 4 ohm resistor and redo the crossover for the lower impedance which will get you the same 3DB increase of the highs.
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Old 22nd July 2013, 03:42 AM   #5
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Why don't you just add a wire to short the 4Ω resistor on the one tweeter? 6dB treble boost and done. Too much? use a resistor instead of a wire to short the resistor.
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Old 22nd July 2013, 04:44 AM   #6
Zertman is offline Zertman  United States
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Thanks for the replies.

The reason I put the resistor in there is so I wouldn't pull too much current from my receiver. On the receiver's back, it says a minimum of 8 ohm and my tweeters are 4 ohm so wouldn't that pull too much current without a resistor?

One thing I forget to include in my schematic is a .6 mH inductor in series with the woofers to block out the frequencies put out by the tweeter. I can't redo the tweeter's crossovers because they are sealed PCB boards.

I didn't know that about crossovers having a problem in series with each other. Good thing I checked here before I rewired everything! What about removing the inductors so the woofers would put out the higher frequencies?

Last edited by Zertman; 22nd July 2013 at 05:06 AM. Reason: spelling
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Old 22nd July 2013, 08:50 AM   #7
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removing the inductors is a bad idea. Lots of reasons but mostly because the mid woofer will have break up nodes at the high end that will sound pretty awfull, removing the inductor will deteriorate the sound quality massively.

Are these commercial speakers or did you build them? the reason I ask is because you said you put the resistor in there, but then that you can't change the XO.

Can you give more details? what drivers are they, what's the actual crossover schematic?

I don't know everyone else's opinion but I'd have thought you could have got away with removing the resistor as dumptruck says even with the 8 ohm requirement, the power consumption of the tweeter compared to the mid and low frequencie is very small, but I'm sure there's an electronics guru on the forum who can answer that in more detail.
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Old 22nd July 2013, 08:59 AM   #8
jwmbro is offline jwmbro  United States
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Quote:
Originally Posted by Zertman View Post
The reason I put the resistor in there is so I wouldn't pull too much current from my receiver. On the receiver's back, it says a minimum of 8 ohm and my tweeters are 4 ohm so wouldn't that pull too much current without a resistor?
This shouldn't be a problem. The woofer section is still 8Ohm, and most of the power draw is in the woofer frequency range anyway. I wouldn't worry about the tweeter impedance mismatch. If anything, you need to be careful you don't fry the tweeter once you're using that much power that it would be a concern. Just bypass or remove the resistor before the tweeter, that will give you 6dB more high end, or use a smaller value for 0-6dB more high end, depending on the exact resistor value.
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Old 22nd July 2013, 03:15 PM   #9
Zertman is offline Zertman  United States
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The speakers are from an Onkyo HT-S790 7.1 Home Theater system but I bought just the speakers used. The tweeters are Pyramid TW22M. When I first opened the enclosures for the Onkyo speakers, the woofers were wired in series with a tweeter in parallel with the woofers. They also had a capacitor before the tweeter. They did not come with the resistor or inductor. I disconnected the stock tweeters to use my Pyramid tweeters that I had bought earlier. I don't know the tweeter's XO schematic because they are sealed boards.

The receiver says it puts out 100 watts rms @ 8 ohm and tweeter's specs say they can handle 100 watts rms but they are 4 ohm. So if I take out the resistors, wouldn't I have to worry about frying the tweeters?
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Old 22nd July 2013, 04:34 PM   #10
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doubt you'd fry the resistors. Have you measured the woofers at all?
particularly for impedance i mean
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