Sub wiring, paralell vs series. - Page 1
Forum section: electronics / general

author: David97
author_rank: Contributor
timestamp: July 15, 2015, 03:49:31 am
content: Hi everyone. I have two dual voice coil subs, each coil is 4 ohms. I am wanting to run them from a mono amp I have that is 2 or 4 ohm stable. Is it better to wire each sub's coil in parallel two give 2 ohms per sub then wire the subs in series to get 4 ohms. Or should I wire each sub's coil in series to give 8 ohms, then wire the subs in parallel to get 4 ohms. Which is better? thanks.

author: ludzinc
author_rank: Unknown
timestamp: July 15, 2015, 04:03:10 am
content: P = V^2 / RHalf your R, double your power.Wire them up in parallel and present a 2 ohm load for each sub, that way you get more power delivered into each sub.

author: suicidaleggroll
author_rank: Super Contributor
timestamp: July 15, 2015, 04:12:26 am
content: Quote from: ludzinc on July 15, 2015, 04:03:10 amHe has two dual coil subs and a single output from the amp. He will get a 4 ohm load regardless, he's asking whether he should go series/parallel or parallel/series.OP - I would wire each sub's coils in parallel, and then wire the two subs in series. My reasoning behind that is due to impedance mismatches between the individual coils and the subs. It's the current that creates the magnetic field to drive the sub, so ideally the current through each sub would be the same. The only way to accomplish this is by wiring the subs in series. It's fine wiring the individual coils in parallel because it's all part of the same sub, if one coil gets slightly more current than the other it won't matter, as long as the total current through both coils in sub A matches the total current through both coils in sub B.But honestly I don't think it really matters either way, I highly doubt you'd be able to hear or even measure any significant difference. But since you have to pick one, the above is what I would pick.

author: Zero999
author_rank: Super Contributor
timestamp: July 15, 2015, 11:21:52 am
content: Quote from: suicidaleggroll on July 15, 2015, 04:12:26 amThe trouble with that suggestion is that speakers are designed to run from a low impedance source to provide a good damping factor which reduces the effect of resonance, therefore giving a flatter frequency response.Try gently tapping the cone of a large speaker, once with the terminals open circuit and then with the terminals short circuited. When the terminals are open circuit, the speaker resonant more and sound like a drum. When the terminals are short circuited, the resonance will be damped because any current induced in the voice coil will be short circuited, providing a force in the opposite direction.Wire the coils on each speaker in series, giving a a pair of 8 Ohm speakers, then connect them in parallel. As both of the coils on each speaker are mechanically coupled to ether this will not affect the damping factor.

author: Psi
author_rank: Super Contributor
timestamp: July 15, 2015, 11:24:33 am
content: I reckon all 4 coils in parallel. 1R load across the amp. What could go wrong

author: David97
author_rank: Contributor
timestamp: July 16, 2015, 08:31:25 am
content: Thanks guys. Looks like I will wire the subs together for 8 ohms then wire those in parallel for 4 ohms.The other thing I'm wanting from this set up is to be able to swap it between cars. I was looking at adding a plug to make it easier rather than using the screw block. The sub is capable of 700Wrms, but since Im running 4 ohms I will be running 600Wrms. Is there a plug that I could use so that I could take the 600W rms (50 amp) of my amp? Or will I need to use the screw block. Thanks.

author: suicidaleggroll
author_rank: Super Contributor
timestamp: July 16, 2015, 01:46:21 pm
content: Quote from: Hero999 on July 15, 2015, 11:21:52 amDamping factor is the ratio of the amplifier output impedance to the final load impedance. In either case the final load impedance is a nominal 4 ohms, so damping factor won't be affected in the slightest.The easiest way to think about damping factor is in the frequency domain. The amp's output impedance and the load impedance give you a voltage divider, with the load impedance varying with frequency. Whether the coils are wired in series/parallel or parallel/series, the final load impedance will be the same at all frequencies, so the divider and resulting voltage across the load as a function of frequency will be the same, and damping factor won't be affected.I stand behind my earlier suggestion.

author: Zero999
author_rank: Super Contributor
timestamp: July 16, 2015, 03:01:19 pm
content: Quote from: suicidaleggroll on July 16, 2015, 01:46:21 pmThat's no longer the case because you've added a resistor in series with the amplifier's output impedance.With two separate speakers connected in series, the damping factor will be reduced.It's better to connect the two voice coils on each speaker in series, because they're mechanically coupled to one another.

author: ajb
author_rank: Super Contributor
timestamp: July 16, 2015, 03:08:02 pm
content: Quote from: David97 on July 16, 2015, 08:31:25 amhttp://www.neutrik.com/en/speakon/

author: macboy
author_rank: Super Contributor
timestamp: July 16, 2015, 05:15:08 pm
content: Quote from: David97 on July 16, 2015, 08:31:25 amI agree with 8 parallel with 8.As for connectors, look at the ones that hobby R/C guys use for their batteries. They easily handle at least 30 A continuously which is many thousands of watts at speaker impedances. They are also relatively cheap and readily available (you likely have a hobby shop somewhere nearby).