Ok to wire line array in series? Why?

jaekfre · 31st July 2009, 08:00 PM

I can't find anything info dealing with this on diyaudio or any place else.

I've been told and read in many places that one should not wire two drivers in series because of the back EMF that it produces.

However, why is that one of the accepted ways of wiring line arrays?

Makes no sense to me. But of course, I'm new to speaker building.

Thanks in advance.

chris661 · 31st July 2009, 08:11 PM

Most people go for series/parallel groups that end up at 4-8ohm. This means the load on the amplifier is what it's designed for. If you had 9 8ohm speakers in series, you would end up at 72ohm, which the amp will drive, just very quietly.

So, to take the 9x 8ohm speakers, if you made 3 groups of parallels with 3 drivers each, you'd get an 8ohm load exactly (neat, huh?) and your amp would be fine with that.

If, however, you wired all the 9 speakers in parallel, you'd get a 0.9ohm load, which the amp wouldn't go well with. It would **try** to give 3x it's rated power (into 8ohm) into the speaker, which would lead to damage and nasty smells.

Basic rules (dunno if you know this, handy to have) calculating overall impedance:

two speakers in series: add the impedances together.
two speakers in parallel: (gets more complicated) you do 1/(1/R+1/R+1/R.....) where R is the impedance, and the number of 1/R s is how many speakers there is.

Hope this helps

Chris

PS - you shouldn't wire two *different* drivers in series, as bad things can happen (according to Dad, the electrical engineer, off whom I got the info for the impedance calculations).

slam · 31st July 2009, 08:28 PM

I once opened up a McInstosh XRT-22 line array to fix a loose connection and found that the 23 tweeters were in a mixed parallel / series configuration to get to around 8 ohms.

BTW those speakers sound very good. So don't worry.

jaekfre · 31st July 2009, 08:47 PM

That makes sense.

But from what I've read is that no two drivers are identical - even though they be the 'same' driver from the same manufacture.

Supposedly, the slight variations will cause distortion because of back EMF.

Is this something that is theoretically true but not going to be a huge deal with just two of the 'same' drivers wired in series?

jaekfre · 31st July 2009, 08:55 PM

ok, i'm still in 'moderation mode' until i make some more posts so the lag in my posts showing up is pretty annoying!

anyway, thanks a lot guys for the replies.

guess i'll try some experimenting

jaekfre · 31st July 2009, 08:57 PM

Quote:

Originally posted by jaekfre
That makes sense.

But from what I've read is that no two drivers are identical - even though they be the 'same' driver from the same manufacture.

Supposedly, the slight variations will cause distortion because of back EMF.

Is this something that is theoretically true but not going to be a huge deal with just two of the 'same' drivers wired in series?

Slam - I posted the above before you replied to the thread.

You pretty much answered the question. Thanks again.

Cal Weldon · 31st July 2009, 09:15 PM

You are now registered.

kipman725 · 31st July 2009, 10:30 PM

yep series parallel works listening to 9 drivers sereis paralel right now:
+ 3 > 3 > 3 - It's just not sane to try and drive loads of less than an ohm!

jaekfre · 3rd August 2009, 02:23 PM

awesome! thanks kipman.

31st July 2009, 08:00 PM	#1
jaekfre diyAudio Member Join Date: Mar 2009	Ok to wire line array in series? Why? I can't find anything info dealing with this on diyaudio or any place else. I've been told and read in many places that one should not wire two drivers in series because of the back EMF that it produces. However, why is that one of the accepted ways of wiring line arrays? Makes no sense to me. But of course, I'm new to speaker building. Thanks in advance.

31st July 2009, 08:11 PM	#2
chris661 diyAudio Member Join Date: Feb 2008 Location: Lancashire Blog Entries: 7	Most people go for series/parallel groups that end up at 4-8ohm. This means the load on the amplifier is what it's designed for. If you had 9 8ohm speakers in series, you would end up at 72ohm, which the amp will drive, just very quietly. So, to take the 9x 8ohm speakers, if you made 3 groups of parallels with 3 drivers each, you'd get an 8ohm load exactly (neat, huh?) and your amp would be fine with that. If, however, you wired all the 9 speakers in parallel, you'd get a 0.9ohm load, which the amp wouldn't go well with. It would try to give 3x it's rated power (into 8ohm) into the speaker, which would lead to damage and nasty smells. Basic rules (dunno if you know this, handy to have) calculating overall impedance: two speakers in series: add the impedances together. two speakers in parallel: (gets more complicated) you do 1/(1/R+1/R+1/R.....) where R is the impedance, and the number of 1/R s is how many speakers there is. Hope this helps Chris PS - you shouldn't wire two different drivers in series, as bad things can happen (according to Dad, the electrical engineer, off whom I got the info for the impedance calculations). __________________ "Throwing parts at a failure is like throwing sponges at a rainstorm." - Enzo My setup: http://www.diyaudio.com/forums/multi...tang-band.html

31st July 2009, 09:15 PM	#7
Cal Weldon Speakerholic diyAudio Moderator Join Date: Jan 2004 Location: British Columbia	You are now registered. __________________ Next stop: Margaritaville Some of Cal's stuff \| Cal Weldon Consulting

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Line array tweeter line - On left or right?	dhenryp	Multi-Way	4	9th March 2005 11:35 PM
MacIntosh XRT series line array speakers	chipco3434	Multi-Way	0	25th October 2004 04:51 PM
Line array wire	AJ	Multi-Way	4	2nd October 2004 05:09 PM
New Eminence "line-array" series?	Ap	Multi-Way	0	5th May 2004 12:53 AM
how to combine Line array and transmission line together	Jared	Multi-Way	5	19th April 2004 10:32 PM


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

31st July 2009, 08:28 PM	#3
slam diyAudio Member Join Date: Jan 2005 Location: CA	I once opened up a McInstosh XRT-22 line array to fix a loose connection and found that the 23 tweeters were in a mixed parallel / series configuration to get to around 8 ohms. BTW those speakers sound very good. So don't worry.

31st July 2009, 08:47 PM	#4
jaekfre diyAudio Member Join Date: Mar 2009	That makes sense. But from what I've read is that no two drivers are identical - even though they be the 'same' driver from the same manufacture. Supposedly, the slight variations will cause distortion because of back EMF. Is this something that is theoretically true but not going to be a huge deal with just two of the 'same' drivers wired in series?

31st July 2009, 08:55 PM	#5
jaekfre diyAudio Member Join Date: Mar 2009	ok, i'm still in 'moderation mode' until i make some more posts so the lag in my posts showing up is pretty annoying! anyway, thanks a lot guys for the replies. guess i'll try some experimenting

31st July 2009, 10:30 PM	#8
kipman725 diyAudio Member Join Date: Jun 2007 Location: London/N.lincs	yep series parallel works listening to 9 drivers sereis paralel right now: + 3 > 3 > 3 - It's just not sane to try and drive loads of less than an ohm!

3rd August 2009, 02:23 PM	#9
jaekfre diyAudio Member Join Date: Mar 2009	awesome! thanks kipman.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read