Series vs Parallel Driver wiring

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mojave

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Series vs Parallel Driver wiring
« on: 22 Jul 2015, 01:51 pm »
From an amplifier designer's perspective, is there a difference (besides impedance) in series or parallel driver wiring? Some driver manufacturers like Stereo Integrity and JL Audio say, "Please note that when wiring multiple drivers, it is recommended that series connections between drivers be avoided at all costs."

steve f

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Re: Series vs Parallel Driver wiring
« Reply #1 on: 22 Jul 2015, 07:09 pm »
It depends on the amp,, and the number of speakers. Most ss amps do well with four ohm loads. Some robust models can run two ohm loads with ease.

I've found that most transformer coupled tube amps sound best when light loading is used. As in the four ohm taps with eight ohm speakers. (Credit to Modjeski)

There is always an exception. In this case its output transformer less, OTL, amps. They usually provide the most power into sixteen ohms.

If you are using a lot of drivers, common wisdom is to wire series parallel to maintain an eight ohm load.

Evoke

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Re: Series vs Parallel Driver wiring
« Reply #2 on: 22 Jul 2015, 07:37 pm »
Most OEM drivers are available in 4 or 8 ohms so that the final load can be easy for the amp to run. If you have two woofers in series, you are running through two voice coils. It's not ideal and does nothing for power handling. In parallel you get many benefits - but it would be two 8 ohm woofers for a resultant 4 ohms. Neither accounts for the large variances in woofer impedances based on frequency - that's a different conversation. In that case of four 8 ohm woofers in series / parallel - the result is 8 ohms. I don't believe that any speaker should pose a ridiculous load to any amplifier. If a designer wants to create a very specific subwoofer - they will most likely build an amp-specific to make the combination an ideal match.

mojave

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Re: Series vs Parallel Driver wiring
« Reply #3 on: 22 Jul 2015, 09:48 pm »
I said "besides impedance" and both answers so far seem to deal with impedance.  :) I have Digital Amp Company amps and have used the Maraschino with 1 ohm loads and the Cherry Mono's with 2 ohm loads without any problems. I'm trying to figure out if wiring 8 drivers in series-parallel or parallel-series will have any differences.  It seem like when wiring the drivers in series first for 4 drivers and then the two groups in parallel that the second group of 4 drivers  has less output. With the drivers in parallel first for 4 drivers and then the two groups are in series they all seem to have the same output. I hope to do some measuring tonight.

steve f

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Re: Series vs Parallel Driver wiring
« Reply #4 on: 23 Jul 2015, 06:37 am »
Unless I'm misunderstanding, it is an impedance issue.

mojave

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Re: Series vs Parallel Driver wiring
« Reply #5 on: 23 Jul 2015, 04:59 pm »
Unless I'm misunderstanding, it is an impedance issue.
In the two different wiring schematics below, the second set of 4 drivers seems to behave different. Do you mean the impedance is different for each set of 4 drivers wired in series and then two sets of 4 drivers wired in parallel vs wiring 4 drivers in parallel and then wiring both 4-driver sets in series?





Or is it a back EMF or damping issue - which I guess also might be related to impedance?

Speedskater

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Re: Series vs Parallel Driver wiring
« Reply #6 on: 24 Jul 2015, 03:36 pm »
In the above drawing, the first circuit has 4 times the impedance of the second circuit.
So different amplifiers might be happier driving a low impedance or a high impedance load.
Only identical drivers should be wired in series.
If the amplifier has a high output impedance (tube) and the parallel drivers have a very low impedance then it might be a damping problem.

mojave

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Re: Series vs Parallel Driver wiring
« Reply #7 on: 24 Jul 2015, 04:37 pm »
The eight drivers are all identical. Here are their parameters:

137.07 sq cm (SD)
36.14 Hz (Fs)
3.36 Ohms (Re)
5.17 (Qms)
0.46 (Qes)
0.42 (Qts)
0.62 (LE)
27.32 l (Vas)
18.92 g (Mms)
1.025 mm/N (Cms)
5.6 Tm (BL)
7.8 mm (XMax)

Like I mentioned, I am using Digital Amp Company amps with extremely low output impedance.

Last night I directly compared the wiring. When four drivers were wired in series and then the two sets of four drivers were wired in parallel, the furthest set of four drivers had much less output/excursion than the first set.

When four drivers were wired in parallel and the two sets of four drivers wired in series, the output from all eight drivers was identical.





AmpDesigner333

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Re: Series vs Parallel Driver wiring
« Reply #8 on: 31 Jul 2015, 01:00 am »
Parallel preferred, because speakers are driven by the amplifier, not each other.  Another way to put it....  No two speakers are exactly the same or will react exactly the same, so when they are in series, they affect each other.  When in parallel, and assuming adequately low impedance wiring, they are driven tightly by the amp.  Of course, a higher damping factor will mean more control over the speaker, and it matters even more when the speakers are in parallel.  YMMV.

Cool topic!

-Tommy O

mr_micus

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Re: Series vs Parallel Driver wiring
« Reply #9 on: 28 Jun 2021, 02:37 pm »
I don't understand why, of four possible arrangements for connecting eight drivers, only two are commonly illustrated. And there are conflicting views of impedance totals. I'd like to use 8x 8-ohm woofers and end up with a 4 ohm-load, which seems possible with two wiring schemes . . . or am I being dumb?


AmpDesigner333

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Re: Series vs Parallel Driver wiring
« Reply #10 on: 17 Jul 2021, 04:18 am »
I don't understand why, of four possible arrangements for connecting eight drivers, only two are commonly illustrated. And there are conflicting views of impedance totals. I'd like to use 8x 8-ohm woofers and end up with a 4 ohm-load, which seems possible with two wiring schemes . . . or am I being dumb?

1 and 3 preferred (less in-series connections) and they are also theoretically identical assuming identical impedance curves for all drivers.