|13th September 2013, 03:39 AM||#1|
Join Date: Sep 2013
Wiring speakers and anti-phase problems
Hello, sorry for this newb question but I need an answer tailored to my situation for me to best understand the right way to do it.
I am doing an open baffle project(in the design phase) and I am new to speaker building. I have chosen a couple speakers for the job. I have narrowed the woofer down to two different sizes from acoustic elegance the dipole 15 and dipole18. The dipole 18 has two voice coils (16 ohms each) wired in parallel to equal 8 ohms and the 15 has two 8 ohm voice coils wired in series to equal 16 ohms. So that means the dipole 18 should be treated as an 8 ohms speaker correct? And can be wired with another of the same ohms in parallel to equal 4 ohms?
I don't understand the principle behind wiring in series and parallel in a loudspeaker. Wouldn't they be anti-phase? Wouldn't the volume and sound quality be affected since I am using a woofer/full range driver open baffle?
If I have one full range 8 ohm plus woofer 8 ohm plus woofer 8 ohm what would it equal? 2.7 ohms?
if two full range and two woofers equal 2 ohms?
I know some amps will drive this, but in the future choosing amps will be hard. It takes a quality amp with good cooling to drive 2 ohms, right?
Do I bi-amp? Use multiple amps, one for full rangers and one for woofers?
What about an amp with two sets of out puts per side? Wouldn't that amp be seeing 2 ohms still?
I just need to know how to wire this speaker without affecting the sound quality.
I need wiring for speaker using dual and another using single woofers.
And each must use both the 8 ohm and 16 ohms. I need to know what to do with either woofer in each case. Also one design with one full range and one with two 8 ohms full ranges.
Also what is your opinion, do I only need one full range or two? One woofer or two?
|15th September 2013, 07:45 AM||#2|
Join Date: Jul 2003
Location: Newcastle, Australia
You are probably better off posting this in the FR forum as they do deal with this type referred to as a FAST loudspeaker. I'll give you some comments on your post.
OB can be a pain to design as you have to deal with Fe (Fequal) and Fp (Fpeak) and generally you need active equalisation for best results. There are some tricks with passive filters and resistors, which I will not go into, plus using the second woofer crossing over between Fe and Fp to assist the lower octaves from the baffle loss. Have a look at these sites for some information:
The Subwoofer DIY Page v1.1 - Dipole Bass Systems
Linkwitz Lab - Loudspeaker Design
You are on track with the wiring as 16R + 16R (parallel) = 8R and 8R + 8R (series) = 16R. Be aware that the loudspeaker driver may have a nominal impedance of say 8R, but can drop much lower at certain frequencies. Look at the driver impedance plot to see this. As long as the drivers are connected to +ve (same on all drivers), they will be in phase and will not cancel out. For a guide see:
You need a crossover just below Fp for the FR driver from the woofers to the FR driver with a minimum of an inductor for the woofer(s) and cap for the tweeter. Without these the impedance and phase will suffer plus the amp will surely leak smoke. Another way is using an active crossover. Do not run the FR + WW with any form of crossover. The location of the FR crossover depends on driver behaviour, order of the crossover etc as both drivers need to sum correctly and to have good phase over the crossover point. Bi-amping can help and would be suggested for this type of speaker. So you could end up with: equaliser > active crossover > bi-amp.
Number of drivers used depends on SPL and power handling required but generally in OB, FR + WW should be ample as the FR driver should have the lower octaves removed via the crossover which will increase the power handling.
Can't help any more but it may point you in a direction. Good luck with the project as it is ambitious for a newbie.
No longer DIY active
Last edited by rabbitz; 15th September 2013 at 08:00 AM.
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