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Some help: single sub 2ohm vs dual sub 4ohm
Some help: single sub 2ohm vs dual sub 4ohm
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Old 6th February 2018, 12:19 PM   #1
firoo is offline firoo
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Default Some help: single sub 2ohm vs dual sub 4ohm

Subs: dual 4ohm, each wired paralel for a 2ohm each sub
Amp: monoblock 2ohm stable

Experiment hooking the subs in series to the amp (4ohm) load VS single sub hooked as (2ohm) load.

The amp has 2 mono speaker terminals, the sub wires twisted in series, i connect - of one sub to the - at the amp, and + of the other sub at the + of the amp. I know details are boring buti wana be as clear as possible.

To perform the experiment i play moderate music level and listen to the output and I touch the bare twisted link to either amp terminal posts. This shorts one sub to resist its movement and prevents spl absorption, and runs the other sub on the amp as 2ohm load.

I dont see any audible differnce in output. I can.not understand why? Unless running multiple cones doubles the sensitivity?

At moderate listening levels the 2ohm load should be seeing twice the power.. nothing is running at any stress...

Last edited by firoo; 6th February 2018 at 12:40 PM.
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Old 7th February 2018, 01:19 AM   #2
Jeff Mills is offline Jeff Mills
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Remember I'm a old dude and honestly sub-woofer are new to me. I had a pair of single voice coil 4 ohm sub woofers that I wired in stereo. I tied both ported and sealed boxes. I never liked the thin sound they produced. I ditched them for dual 4 ohm coils and wired them in series for a total of 8 ohms each and hooked them up to the same amp and I really like the full sound they produce. As a matter of fact all my 12 door speakers (8", 6 1/2" and 4" tweeter) are all 8 ohm coils, wired in parallel for approximately 2.6 ohms per door and I really like how they sound.

If I could get decent speakers in 16 ohm coils I would trade them out. Personally I think the higher ohm coils produce a fuller and richer sound. But what do I know? I'm just a old rock-n-roller.

Last edited by Jeff Mills; 7th February 2018 at 01:32 AM.
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Old 8th February 2018, 09:04 AM   #3
firoo is offline firoo
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I cant figure out why it sounds the same. Using the same at same gain level with same song mysic headunit all runing the same.
The single sub at 2ohm load sounds the same as the two subs at 4ohm load, no audible difference!

Maybe ill get somone to sit with me in the car and see if he or she will hear audible difference
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Old 8th February 2018, 07:55 PM   #4
Jeff Mills is offline Jeff Mills
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Did you try a AC clamp meter with peak hold function? You can get both peak AC volts and amps - use ohms law to figure out the power your amp is able to produce with both the single and dual voice coils. Have a look here for the general idea --->Clamp Testing

Last edited by Jeff Mills; 8th February 2018 at 08:00 PM.
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Old 8th February 2018, 08:33 PM   #5
firoo is offline firoo
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But even if i found that out how would that help understand...
i have realized the same observation with different amps. Regardless if thier regulated, which none of mine are, like jl amps. Im not resetting the gain nor the volume.
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Old 8th February 2018, 08:56 PM   #6
Sonce is offline Sonce  Macedonia
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Quote:
Originally Posted by firoo View Post
I dont see any audible differnce in output.
That is perfectly OK, there should be no audible difference. Long story short: two subs in series rises total impedance twofold so amp delivers half of the wattage, furthermore each sub receives half of the delivered wattage, but two subs are louder than one for exactly the same amount, so in the end there is no difference.
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Old 8th February 2018, 09:07 PM   #7
nigelwright7557 is offline nigelwright7557  United Kingdom
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The maximum sound output is the sum of cone areas times the sum of speaker xmax's.
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Old 9th February 2018, 04:16 AM   #8
firoo is offline firoo
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Quote:
Originally Posted by Sonce View Post
but two subs are louder than one for exactly the same amount, so in the end there is no difference.
So we can say doubling the subs , doubling the number of cones at work in fact doubles the sensitivity??

200watts on 2 subs is louder than 200watts on one sub?
We Will need 400watts for one sub (of same sensitivity rating) to have equal loudness and output of two subs!!??
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Old 9th February 2018, 09:02 AM   #9
Sonce is offline Sonce  Macedonia
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An ideal amplifier will output 400 W at 2 ohms and 200 W at 4 ohms. One 2-ohm sub, with 400 W delivered from the amp will be equally loud as the same two subs in series (total impedance 4 ohms) because amp will than deliver 200 W to both, (i.e 100 W per each sub).

Last edited by Sonce; 9th February 2018 at 09:21 AM.
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Old 9th February 2018, 12:48 PM   #10
firoo is offline firoo
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Great! Confirmed then, doubling the subs (with same input) doubles the efficiency of the subwoofer system, for every watt input im getting 3db (twice as loud), hence the system is more sensitive (efficient) a 90db 1w/m sub adding another creates a 93db 1w/m system.

Adding to that the fact that we are halving the impedence and doubling the input power we gain another +3db

So adding a sub (when the amp can handle it) gives a +6db increase !!!
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