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wiring parallel or series sensitivity rules?
wiring parallel or series sensitivity rules?
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Old 21st February 2008, 07:07 AM   #11
BlueWizard is offline BlueWizard  United States
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Here is the odd thing about that sensitivity standard, if you really are using one watt for all impedances, then you are applying a different signal voltage in each of the three cases we have discussed.

Working backwards, knowing impedance and power, we can find voltage.

E = SqRt(P x R) where SqRt() = square root

8 ohms

E = SqRt( 1w x 8 ohms) = SqRt(8) = 2.828 volts

4 ohms

E = SqRt(1 x 4) = SqRt(4) = 2 volts

16 ohms

E = SqRt (1 x 16) = SqRt(16) = 4 volts

That brings up the question, which is more fair, to test all speakers with the same signal voltage, or to test all speaker with the same power consumption?

Actually, various manufacturers do it differently, some always use 2.83 volts, other use 1 watt.

Personally, I think the same signal level is the more accurate test. It is going to give me a sensitivity relative to a fix setting of the volume control.

Still for this question, maybe actually power is the better test.

Confusing.

Steve/bluewizard
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Old 21st February 2008, 12:02 PM   #12
roddyama is offline roddyama  United States
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What type of amplifier would be used to drive a speaker at a constant 2.83V? What type of amplifier would be used to measure a speakers frequency response?
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Old 21st February 2008, 12:24 PM   #13
cs is offline cs  United Kingdom
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Default Re: wiring parallel or series sensitivity rules?

Quote:
Originally posted by Toast_Master
Hello

I need to clarify these rules, I know how to wire in series and parallel like anyone would but I don't know how this affects sensitivity's
This issue is covered very well by Martin J King, in his articles. It is actually very straightforward :-

SPL is a vector quantity (like voltage), not a scalar quantity (like power). So, if you feed the same signal to two drive units in phase, you will get an SPL 6dB higher than either of them individually.

So, in a parallel connection, you get +6dB more.

But in a series connection, the available voltage is divided equally between them, giving a 6dB loss, so you are then back to 0dB overall.
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Old 24th February 2008, 07:18 PM   #14
myhrrhleine is offline myhrrhleine  Belize
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Quote:
[i]That brings up the question, which is more fair, to test all speakers with the same signal voltage, or to test all speaker with the same power consumption?

Actually, various manufacturers do it differently, some always use 2.83 volts, other use 1 watt. [/B]
Using a standard voltage is better.
We must remember an 8ohm speaker isn't 8ohms!
It's impedence will be 'all over the map'
It may be 4 ohms or 40 ohms or...

unless your adjusting for the power at each frequency, you'll never have 1 watt.
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Old 24th February 2008, 08:30 PM   #15
roddyama is offline roddyama  United States
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Actually using either voltage or power as the fixed source is valid as long as it is stated and is common in any comparisons made. There are upsides and down sides to using either.

Power is used in the IEC standards and power is more "real world" since the typical SS amplifiers deliver power to a speaker in proportions to a given input voltage regardless of the speakers impedance. Also flat response from a speaker is in response to a fixed power input not voltage. Chances are slim that you will ever apply 2.83V to your speakers at home unless your amp is broken.

However, design engineers want a vector quantity such as voltage to use in their calculations to deal with phase. This becomes necessary in multi-speakers systems where phase is a crucial components of the end design. It is also nice for the marketing departments that get a few extra db in the sensitivity specifications when 2.83V is used instead of 1W. This makes the speaker look more efficient when they're trying to sell speakers with less than 8ohms at the spec frequency (which is most commercial speakers today).

If you're going to make these measurements at home using the voltage standard you will need an amplifier on which you can adjust the output voltage to 2.83V. In any case, make sure you know what standard is being used in any comparisons you make.
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Old 24th February 2008, 09:53 PM   #16
rl guy is offline rl guy  United States
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Default sonic difference?

hi, i'm sorry to go off topic somewhat, but are there any advantages other than sensitivity and ohms rating by wiring speaker in parallel vs in series, are there any sonic advantages between series and parallel wiring?

i have 4 saba greencone midrange drivers, and i dont know if i should just use one driver per side or 2 drivers per side wired in series. i can not wire it in parallel because they are 4ohms each.

thanks for all the expert help.
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Old 25th February 2008, 06:08 AM   #17
Andy G is offline Andy G  Australia
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And just for a bit of fun, the link is to a little Excel file that calculates impedance and gain of sets of drivers wired in series then paralleled. ie for a line array.

http://members.optusnet.com.au/~grad...0calc%20V3.xls

right click and save as

ps.. if you want to view the formulas etc, just "unlock" the protection.
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Old 25th February 2008, 06:21 AM   #18
Andy G is offline Andy G  Australia
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Default Re: sonic difference?

Quote:
Originally posted by rl guy
hi, i'm sorry to go off topic somewhat, but are there any advantages other than sensitivity and ohms rating by wiring speaker in parallel vs in series, are there any sonic advantages between series and parallel wiring?
The only real issue is if the drivers in series are significantly different in spec. eg quality control. They may then start trying to influence each other. This may also apply if wired in parallel, where impedance difference between drivers may alter the balance at different frequencies etc.

Another benefit of a pair wired in series or in parallel is that each does less work.
Doing less work is good !!
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Old 3rd January 2014, 03:21 PM   #19
zead is offline zead  United States
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Default differet size drivers (aka wilson speakers) 12 & 10) in parallel

interested in creating a woofer system to play up to 200hz... would like to combine SS 13inch (90db) with SS 10inch (88.5db) ... they have same 8ohm... what i want to do is have these in the same box connected in parallel, with a highpass on 10inch so that it works 60hz up to 200hz and have either a low pass on the 12 at 100hz or just let it also get the same 200hz upper cut-off. How difficult is that?
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Old 3rd January 2014, 04:40 PM   #20
Lojzek is offline Lojzek  Croatia
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zead,

There is no such school like doing it actually and
process the data afterwards. If you're into making
something like Wilson, I say go for it. If not, you can
do very well by just using single 13" woofer and with
its spl one should be more than pleased.

Mr.Wilson likes to make impressions by building
speakers with multiple woofers and it certainly has its
effect. We at diy community have the means, know how
and imagination to do the same if not better and be happy
not to have to spend a fortune to achieve similar results.
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