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Author Topic: SPL Calc: cabs wired in series v. cabs wired in parallel  (Read 2504 times)

Paul Dershem

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SPL Calc: cabs wired in series v. cabs wired in parallel
« on: February 16, 2013, 01:26:36 PM »

I have two 4-Ohm loudspeakers, each of which has two 8-Ohm drivers wired in parallel. I am currently powering them with a single-channel amplifier rated to handle 2-Ohm loads; it sounds good, and I've never had any overheating problems.

Out of curiosity, how do you calculate the difference in SPL one can expect when wiring the two cabs in parallel (2-Ohms) versus series (8-Ohms)?

Thanks!
« Last Edit: February 17, 2013, 01:25:32 PM by Paul Dershem »
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Ivan Beaver

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Re: SPL Calc: cabs wired in series v. cabs wired in parallel
« Reply #1 on: February 16, 2013, 01:51:48 PM »

I have two 4-Ohm loudspeakers, each of which has two 8-Ohm drivers wired in parallel. I am currently powering them with a single-channel amplifier rated to handle 2-Ohm loads; it sounds good, and I've never had any overheating problems.

Out of curiosity, how do you calculate the difference in SPL one can expect when wiring the two cabs in parallel (2-Ohms) versus series (16-Ohms)?

Thanks!
The max SPL is going to be the same-no matter how you wire it-assuming plenty of power is available for either configuration.

The sensitivity (to a particular input voltage) will be around 9dB higher when wired up in the 2 ohm load.

The choice comes down to what amplifier you are using-the length of the speaker cables etc.
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Paul Dershem

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Re: SPL Calc: cabs wired in series v. cabs wired in parallel
« Reply #2 on: February 16, 2013, 01:58:27 PM »

Thanks!
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Mac Kerr

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Re: SPL Calc: cabs wired in series v. cabs wired in parallel
« Reply #3 on: February 16, 2013, 02:57:51 PM »

I have two 4-Ohm loudspeakers, each of which has two 8-Ohm drivers wired in parallel. I am currently powering them with a single-channel amplifier rated to handle 2-Ohm loads; it sounds good, and I've never had any overheating problems.

Out of curiosity, how do you calculate the difference in SPL one can expect when wiring the two cabs in parallel (2-Ohms) versus series (16-Ohms)?

Thanks!

How do you get those impedances? The 2 cabinets in parallel would be 2Ω, the 2 cabinets in series would be 8Ω. Each cabinet on its own would be 16Ω in series, and the standard 4Ω in parallel.

Mac
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Paul Dershem

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Re: SPL Calc: cabs wired in series v. cabs wired in parallel
« Reply #4 on: February 16, 2013, 03:03:35 PM »

You're right, Mac; thanks.

Brain fart on my part.
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Ivan Beaver

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Re: SPL Calc: cabs wired in series v. cabs wired in parallel
« Reply #5 on: February 16, 2013, 03:59:35 PM »

How do you get those impedances? The 2 cabinets in parallel would be 2Ω, the 2 cabinets in series would be 8Ω. Each cabinet on its own would be 16Ω in series, and the standard 4Ω in parallel.

Mac
DUH- I had a brain fart on that one.  After reading the question my "natural" answer was 6dB, but then I got to thinking- (you know what happens when you do that------) and I figured the difference between 2 and 16 ohms would be 9dB-hence my answer.  So I was correct on that-but you cannot get those impedances with the cabinets in question.

Once again not thinking it all the way through-thanks for the correction.
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Brad Weber

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Re: SPL Calc: cabs wired in series v. cabs wired in parallel
« Reply #6 on: February 17, 2013, 07:47:13 AM »

How do you get those impedances? The 2 cabinets in parallel would be 2Ω, the 2 cabinets in series would be 8Ω. Each cabinet on its own would be 16Ω in series, and the standard 4Ω in parallel.
Thus the theoretical difference would be +6dB for the 2 Ohm configuration, but that assumes that everything remains the same except that your amplifier provides 4 times the output into 2 Ohms that it does into an 8 Ohm load, which is not necessarily true.
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David Parker

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Re: SPL Calc: cabs wired in series v. cabs wired in parallel
« Reply #7 on: February 17, 2013, 05:23:11 PM »

I have two 4-Ohm loudspeakers, each of which has two 8-Ohm drivers wired in parallel. I am currently powering them with a single-channel amplifier rated to handle 2-Ohm loads; it sounds good, and I've never had any overheating problems.

Out of curiosity, how do you calculate the difference in SPL one can expect when wiring the two cabs in parallel (2-Ohms) versus series (8-Ohms)?

Thanks!

the only way you could do that would be to wire the two cabs in parallel and then run your amp in bridged mono. theoretically that would give you more power, but your amp couldn't handle the heat from 2 ohms bridged mono. The option that you might be looking for would be to get another identical amp and run one amp on each cab in bridged mono mode. That would increase your power and output. If it's more output you need, a better choice would be to get two more identical subs and run two subs on each side of your amp. This would give you the theoretical 6 db increase in power.
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Re: SPL Calc: cabs wired in series v. cabs wired in parallel
« Reply #7 on: February 17, 2013, 05:23:11 PM »


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