Series vs parallel (again!) - diyAudio
Go Back   Home > Forums > Loudspeakers > Multi-Way

Multi-Way Conventional loudspeakers with crossovers

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
Reply
 
Thread Tools Search this Thread
Old 19th September 2010, 12:42 PM   #1
Elipse is offline Elipse  United Kingdom
diyAudio Member
 
Join Date: Sep 2010
Location: London
Default Series vs parallel (again!)

I know this one has been rumbling around for ages but the last posts I can find are some years ago now and although I think series seems to be the generally accepted fave..................

Opinions please. 2 x "identical" woofers for a single centre channel, 8 ohms nominal each and a sensitivitly of 85.5dB (2.83V/1m). In series, therefore, 16 ohm, 4 ohm in parallel. The separate mono amp to drive these quotes (RMS) 190W into 8 ohms, 300W into 4 Ohm and also 300W into 2 Ohm. So it would appear it should be able to "happily" drive these units in parallel.

On paper, correct me if I'm wrong, (be gentle, novice here!), I would prefer them in parallel due to their relatively low sensitivity compared to the single midrange to be used which has a quoted sensitivity quoted of 91dB. So, in parallel the combined woofer output would be relatively greater, therefore requiring less "correction" in the XO due to the sensitivity difference?? The less "correction" required in the XO the better IMHO.

I would be grateful for and comments and any other factors to consider. Thanks.
  Reply With Quote
Old 19th September 2010, 01:11 PM   #2
diyAudio Member
 
chris661's Avatar
 
Join Date: Feb 2008
Location: Sheffield
Blog Entries: 8
You'll be somewhere near. Due to the Fletcher-Munson curve, you might need to pad the mid down a little, but this will be dependant on personal tastes and listening volume, so don't worry about it too much. Just be prepared to tweak if it's not quite there.

When drivers wired in parallel are given the same voltage as before, you get a 6dB increase in level. The current for a set voltage doubles as there's half the impedance, and the radiating area doubles, each of which gives +3dB.

You'd end up with around 91dB at 2.83 volts through the lows and mids, so, as I said above, you'll be somewhere near.

Chris
__________________
"Throwing parts at a failure is like throwing sponges at a rainstorm." - Enzo
My setup: http://www.diyaudio.com/forums/multi...tang-band.html
  Reply With Quote
Old 19th September 2010, 02:56 PM   #3
Elipse is offline Elipse  United Kingdom
diyAudio Member
 
Join Date: Sep 2010
Location: London
Thanks very much. Sounds good, hope so anyway!
  Reply With Quote
Old 19th September 2010, 03:47 PM   #4
Speakerholic
diyAudio Moderator
 
Cal Weldon's Avatar
 
Join Date: Jan 2004
Location: Near Vancouver
What woofers are they?
__________________
Next stop: Margaritaville
Some of Cal's stuff | Cal Weldon Consulting
  Reply With Quote
Old 20th September 2010, 08:08 AM   #5
Elipse is offline Elipse  United Kingdom
diyAudio Member
 
Join Date: Sep 2010
Location: London
Hi

Midwoofers really, space being somewhat limited. 2 x Scanspeak 15W/8531K00 5.25" in a nominal 15.6L enclosure.
  Reply With Quote
Old 20th September 2010, 01:43 PM   #6
Speakerholic
diyAudio Moderator
 
Cal Weldon's Avatar
 
Join Date: Jan 2004
Location: Near Vancouver
Yes, looking at the FR curves of your woofs, you will likely need to pad the mids a bit.
__________________
Next stop: Margaritaville
Some of Cal's stuff | Cal Weldon Consulting
  Reply With Quote
Old 21st September 2010, 11:37 PM   #7
Spatz is offline Spatz  Germany
diyAudio Member
 
Join Date: Jan 2008
Location: Hamburg
Another problem when going serial is the slighty different impedance response of the woofers around their resonance frequency. Voltage drop will be different, thus will be the SPL of the woofers.

For example, one woofer has its resonance frequency at 50 Hz, the other one at 45 Hz (10% tolerance, that's realistic). So one woofer will get much more power at 45 Hz, as his impedance is much lower at this point than the impedance of the other woofer, and the other way round.

I would always connect woofers in parallel to avoid this problem. A pack of two parallel woofers can then be connected with another pair of parallel woofers as the tolerances should be less this way. Midranges and tweeters that are not used at their resonance frequency can be connected in serial, if thats necessary.

Bye,

Spatz
  Reply With Quote
Old 22nd September 2010, 10:18 AM   #8
Elipse is offline Elipse  United Kingdom
diyAudio Member
 
Join Date: Sep 2010
Location: London
Many thanks to you all.

I feel much more confident progressing this project now.
  Reply With Quote
Old 1st October 2010, 05:17 PM   #9
Pan is offline Pan  Sweden
diyAudio Member
 
Join Date: Sep 2002
Quote:
Originally Posted by chris661 View Post
You'll be somewhere near. Due to the Fletcher-Munson curve, you might need to pad the mid down a little, but this will be dependant on personal tastes and listening volume, so don't worry about it too much. Just be prepared to tweak if it's not quite there.

When drivers wired in parallel are given the same voltage as before, you get a 6dB increase in level. The current for a set voltage doubles as there's half the impedance, and the radiating area doubles, each of which gives +3dB.

You'd end up with around 91dB at 2.83 volts through the lows and mids, so, as I said above, you'll be somewhere near.

Chris
Chris, a speakers response should not be shaped with equal loudness curves in mind.

Speakers are and should be more or less flat. Sound shaping should be left to the artist, audio engineers (recording/mix/master) and architects.. ;-)


/Peter
  Reply With Quote
Old 1st October 2010, 05:30 PM   #10
diyAudio Member
 
chris661's Avatar
 
Join Date: Feb 2008
Location: Sheffield
Blog Entries: 8
You have a point, though I did mention that it would be down to personal taste/preference.

That said, equal loudness curves are also volume dependant (which is why the old loudness button is still going strong), so this will also be a factor to consider when setting the levels.

Chris
__________________
"Throwing parts at a failure is like throwing sponges at a rainstorm." - Enzo
My setup: http://www.diyaudio.com/forums/multi...tang-band.html
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Three 10" 4Ohm subs, wired in series or series-parallel? Nagamitsu Car Audio 38 19th February 2014 11:16 PM
Series-Parallel Or Parallel-Series shaan Full Range 43 13th December 2009 04:10 AM
series or parallel? medicman Tubes / Valves 5 22nd January 2009 04:42 PM
Series vs parallel? legendaryfrog Full Range 5 14th December 2006 02:50 PM
What would you do? series/parallel MtnBob Multi-Way 13 14th April 2005 10:17 PM


New To Site? Need Help?

All times are GMT. The time now is 05:32 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2