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Multi-Way Conventional loudspeakers with crossovers

Introduction to designing crossovers without measurement
Introduction to designing crossovers without measurement
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Old 4th January 2018, 07:34 PM   #581
scottjoplin is offline scottjoplin  Wales
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You would waste half of the power unnecessarily doing that
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Old 6th January 2018, 07:59 AM   #582
AllenB is offline AllenB  Australia
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It is not very helpful to use a resistor to increase the impedance, I would not do that. If your amplifier can handle 4 ohms, this will allow you to use a smaller inductor in the crossover.
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Old 7th January 2018, 05:51 PM   #583
Cirrus57 is offline Cirrus57  Canada
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My amp can do 4 ohms . Since I am bi-amping I can get away with no resistor .I'm guessing the crossover will add resistance also . I'm guessing the crossover values for capacitance and inductance are doubled ? The tweeter sits at 92 db and the midrange is 89 db . They will run off their own channel . The cutoffs I picked are 1000 hz and 3500 hz . my amp AVR-X4300H | Powerful 9 channel Network AV receiver with HEOS and 3D Sound | Denon .
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Old 8th January 2018, 06:05 AM   #584
AllenB is offline AllenB  Australia
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Such a resistor would not be in a convenient place anyway as you'd have to consider it against a complex impedance, so it's good your amp is OK with 4 ohms as is.

A series inductor will add some resistance but not much at all. The inductor will add reactance (somewhat similar to resistance), but only at the top end. The resonance impedance will be higher than 4 ohms. This just leaves a small region in the low hundreds of Hz that might be close to 4.

Double capacitors and halve inductors and resistors.
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Old 9th January 2018, 11:02 PM   #585
MITsound is offline MITsound  Canada
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Introduction to designing crossovers without measurement
Quote:
Originally Posted by AllenB View Post
Such a resistor would not be in a convenient place anyway as you'd have to consider it against a complex impedance, so it's good your amp is OK with 4 ohms as is.

A series inductor will add some resistance but not much at all. The inductor will add reactance (somewhat similar to resistance), but only at the top end. The resonance impedance will be higher than 4 ohms. This just leaves a small region in the low hundreds of Hz that might be close to 4.

Double capacitors and halve inductors and resistors.
A couple of woofers I'm using for a centre channel are nominal 8 ohm woofers.
Their minimum resistance is 5.2 ohms, and I've a 5.6 ohm series resistor on each.
For the amp's sake, is this okay, or am I better off just running these woofers in series.
The minimum resistance is in the middle of the vocal range. There's power to spare, even in series.
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Old 10th January 2018, 12:13 AM   #586
AllenB is offline AllenB  Australia
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Dropping the resistors and putting the drivers in series, they should remain at around the same level. Your amp should draw around half the current. You might find that the response changes.

Having the drivers against a series resistor, one impedance varies with frequency and the other doesn't.. so the Voltage doesn't divide equally at some frequencies. When you use two of the same driver in series they each vary the same way at the same frequencies, so they share fairly (assuming they are well matched).

If you look at the impedance plot you can see the areas that would be affected. These should be a peak around the bass resonance, and a rising response toward the higher frequencies using a resistor compared to not.
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Old 11th January 2018, 11:49 PM   #587
MITsound is offline MITsound  Canada
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Introduction to designing crossovers without measurement
Thank you, the advice is appreciated.
Subjectively, they sound better in series; less dynamically strained sounding.
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Old 22nd January 2018, 03:16 AM   #588
thaotrieuan is offline thaotrieuan  Viet Nam
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thank you so much for sharing
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Old 7th February 2018, 11:44 AM   #589
argentinaCile is offline argentinaCile  Italy
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About flattening the impedance of the woofer:

Quote:
Originally Posted by AllenB View Post
We'll need to use one resistor and one capacitor (per woofer).
Excuse me AllenB, what do you mean with "(per woofer)"? I'm designing a creossover for a speaker with 2 woofers and 1 tweeter, so do you mean that i have to consider 2 resistors and 2 capacitors? If so, how? Because i'm treating the 2 woofers as one (in parallel).

Thanks for your article, it has helped me so much!!
Nicola
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Old 7th February 2018, 03:31 PM   #590
AndrewT is offline AndrewT  Scotland
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Quote:
Originally Posted by argentinaCile View Post
About flattening the impedance of the woofer:



Excuse me AllenB, what do you mean with "(per woofer)"? I'm designing a creossover for a speaker with 2 woofers and 1 tweeter, so do you mean that i have to consider 2 resistors and 2 capacitors? If so, how? Because i'm treating the 2 woofers as one (in parallel).

Thanks for your article, it has helped me so much!!
Nicola
Put two 8ohms drivers in parallel and the crossover sees them as a 4ohms load.
You design the crossover for that 4ohms load.
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