Crossover for 2 way with 4 woofers?

[thought]

Hello folks. This is my first post of diyaudio, about what should be my first pair of speakers. I'm trying to make a 2 way, with one tweeter and 4 woofers. My only idea is to run them all in parallel, but wouldn't that lower the impedance to unsafe levels?

 

[Lojzek]

Hi and welcome! Post as much details as you can so the members can offer a better overall advice.

 

[rayma]

Hello folks. This is my first post of diyaudio, about what should be my first pair of speakers. I'm trying to make a 2 way, with one tweeter and 4 woofers. My only idea is to run them all in parallel, but wouldn't that lower the impedance to unsafe levels?

Yes, instead connect them in series-parallel, wired like a figure 8.
Then the total impedance seen by the amp is the same as that of a single woofer.
The woofer positive terminals all go towards the positive amp terminal.
Similar to this: https://www.allaboutcircuits.com/uploads/articles/series-parallel-combination-circuits.jpg

 

[thought]

Yes, instead connect them in series-parallel, wired like a figure 8.
Then the total impedance seen by the amp is the same as that of a single woofer.
The woofer positive terminals all go towards the positive amp terminal.
Similar to this: https://www.allaboutcircuits.com/uploads/articles/series-parallel-combination-circuits.jpg

In this configuration, would I just go ahead with a normal 2 way crossover?

 

[Galu]

In this configuration, would I just go ahead with a normal 2 way crossover?

Yes, simply treat the series/parallel woofer combination as a single woofer.

The attachment shows the simplest possible arrangement, but you'll be wanting a more sophisticated crossover.

P.S. Disregard the 'Out' connection, this only applies to a PA cabinet!

 

[rayma]

Yes, simply treat the series/parallel woofer combination as a single woofer. The attachment shows the simplest possible arrangement, but you'll be wanting a more sophisticated crossover.

Yes, but do use the jumper between the centers of the two woofer strings.
I think you'll find that it sounds better that way than without it.

 

[Galu]

Hi Rayma!

Your wiring is parallel/series while mine is series/parallel.

Is there really a difference soundwise?

 

[rayma]

Hi Rayma!
Your wiring is parallel/series while mine is series/parallel.
Is there really a difference soundwise?

Yes, think about the Thevenin source impedance that each 8R woofer sees with a low Zo amp.
Without the jumper, each woofer sees 8R. With the jumper, each woofer sees 8/3 R.
It makes a difference (an improvement) in the sound. This also works for multiple FR or tweeters.

 

[Cal Weldon]

So, what's the best option if a woofer(s) blows and goes short circuit? Which schem is safer for the amp? I think the poster needs to know gents.

 

[Galu]

Isn't a driver more likely to fail open circuit?

If we assume 8 ohm drivers and one fails short circuit, then the difference in load terms is small: 4 ohm versus 5.3 ohm.

 

[rayma]

So, what's the best option if a woofer(s) blows and goes short circuit? Which schem is safer for the amp? I think the poster needs to know gents.

Not much difference there. Without a jumper, a shorted woofer causes the amp to see
an impedance of 16//8 = 16/3 = 5.3R. With the jumper, the amp would see 8//8 = 4R.

 

[Galu]

It makes a difference (an improvement) in the sound.

What is the nature of the improvement?

All the major speaker manufacturers I can locate on the web recommend the series/parallel arrangement e.g.Wiring Diagrams | Jensen Loudspeakers

 

[rayma]

What is the nature of the improvement?
All the major speaker manufacturers I can locate on the web recommend the series/parallel arrangement

That's because it's easier to do the wiring in production. Try it, the sound is better with the jumper,
clearer and more transparent. Each driver really should be driven directly from the amp. The version
with the jumper is closer to that ideal.

 

[thought]

It's no big deal if a driver fails. I've got over a hundred of them.. anyways. Galu mentions that I should be using a more complex crossover.. I was honestly just planning for a first order. would that not work?

 

[Galu]

I was honestly just planning for a first order. would that not work?

That depends on the specifications of your tweeter and woofer choices, which you have not yet divulged.

 

[thought]

Vifa D26TG-05's, pulled from a pair of Snell E/III's, and some mystery mids. I can send pics.

 

[halo71]

Vifa D26TG-05's, pulled from a pair of Snell E/III's, and some mystery mids. I can send pics.

I'm curious, why did you scavenge drivers from an awesome pair of speakers?

 

[Galu]

The Vifa D26TG-05 tweeter has a resonant frequency of 1.5kHz.

http://www.tymphany.com/wordpress/w...10/Discontinued-Vifa-Products-D26TG-05-06.pdf

If you wish to employ a first order crossover (6dB/octave), I suggest you crossover no lower than 6 kHz in order to avoid exciting the tweeter resonance.

 

[Galu]

What diameter are your woofers?

I would be interested in seing photos.

If the diameter is large, you may be better to crossover at 3kHz using a second order (12dB/octave) crossover.

The tweeter contains ferrofluid so its fundamental resonance is well controlled.