2-layer vs 4-layer voice coil - 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 11th March 2013, 08:41 AM   #1
diyAudio Member
 
StigErik's Avatar
 
Join Date: Feb 2008
Default 2-layer vs 4-layer voice coil

What are the pros and cons of a 4-layver voice coil vs a 2-layer?

Obviously, the technical data changes. Most significant is the inductance, resulting in a rolled-off HF response. Anything else?

I have compared Seas L26ROY in 2-layer and 4-layer versions here:

Click the image to open in full size.

Frequency response - blue line is the 4-layer version.

Click the image to open in full size.
__________________
dipoles dipoles dipoles dipoles dipoles dipoles dipoles dipoles and dipoles
  Reply With Quote
Old 11th March 2013, 10:02 AM   #2
JMFahey is offline JMFahey  Argentina
diyAudio Member
 
JMFahey's Avatar
 
Join Date: Mar 2009
Location: Buenos Aires - Argentina
Thanks for posting the data.
Basically, the 4 layer version is horrible compared to the 2 layer one, loses a lot at about any frequency except at the lowest ones.
On average it's 3 dB less efficient, while between 300/600 Hz loss is around 5 dB and above some 1200 Hz it worsens to 10 dB or more.

Then why on Earth is this speaker built?
Only justification I find is that from, say, 40 to 100Hz efficiency is almost the same, but VAS is halved, which roughly means you can have a box half as large with basically same output and efficiency.
Which is very low anyway, in the low 80's.

Only place I find this an advantage is in Car Audio Subwoofers, where you are severely limited in box size but the "listening room" is also very small.

EDIT: shame on these cheaters!!!!!
Efficiency is even *worse* than stated, on both models.
The standard reference point is 1W RMS@1 Meter distance, which for 8 ohms amounts to 2.83V RMS
For 4 ohms speakers, the proper value is 2V RMS ... but they use the 8 ohms value with a 4 ohms speaker, doubling the power fed to it.
So all SPL values must be corrected down by 3 dB.
Oh well

Last edited by JMFahey; 11th March 2013 at 10:13 AM.
  Reply With Quote
Old 11th March 2013, 10:10 AM   #3
diyAudio Member
 
Join Date: Feb 2008
Location: Enschede
Bl is higher at the cost of higher inductance. Moving mass is also higher, which will result in a lower Fc, although in this case the suspension has also been stiffened to support the higher Mms. But in most (smaller) enclosures the compliance of the air volume will dominate and the compliance of the speaker is only a minor factor.

Higher Mms and Bl will make it more suitable for small subwoofers. The higher inductance also limits the driver to subwoofer applications. I'd choose the 4-layer version in most cases.
  Reply With Quote
Old 11th March 2013, 11:00 AM   #4
Jonasz is offline Jonasz  Sweden
diyAudio Member
 
Jonasz's Avatar
 
Join Date: Feb 2003
Location: Kristinehamn
I think it was SL that developed this for the Orion and now the LX521 speaker. Four layers can probably take a lot more power (wich it need to to compensate for the lower sensitivity) and maybe the cone is stiffer, at least it weighs a lot more.
  Reply With Quote
Old 11th March 2013, 11:17 AM   #5
diyAudio Member
 
StigErik's Avatar
 
Join Date: Feb 2008
Yes, the L26RO4Y was designed specifically for Linkwitz LX512.

The added moving mass is mostly caused by the heavier voice coil I think.
__________________
dipoles dipoles dipoles dipoles dipoles dipoles dipoles dipoles and dipoles
  Reply With Quote
Old 11th March 2013, 11:18 AM   #6
diyAudio Member
 
Join Date: Feb 2008
Location: Enschede
Power handling is the same for both versions. The higher Mms is indeed (mostly) caused by the heaver voice coil.
  Reply With Quote
Old 11th March 2013, 11:21 AM   #7
diyAudio Member
 
Join Date: Feb 2008
Location: Enschede
Quote:
Originally Posted by JMFahey View Post
EDIT: shame on these cheaters!!!!!
Efficiency is even *worse* than stated, on both models.
The standard reference point is 1W RMS@1 Meter distance, which for 8 ohms amounts to 2.83V RMS
For 4 ohms speakers, the proper value is 2V RMS ... but they use the 8 ohms value with a 4 ohms speaker, doubling the power fed to it.
So all SPL values must be corrected down by 3 dB.
Oh well
They are not cheating, since they are using the correct term: (voltage) sensitivity (@2,83 V). This is not the same as efficiency @ 1W.

Yes, efficiency is low. But small closed box subwoofers inherently have low efficiency if you want a low Fc.
  Reply With Quote
Old 11th March 2013, 12:27 PM   #8
diyAudio Member
 
StigErik's Avatar
 
Join Date: Feb 2008
Long voicecoils ("long-throw") also results in low efficiency.
__________________
dipoles dipoles dipoles dipoles dipoles dipoles dipoles dipoles and dipoles
  Reply With Quote
Old 11th March 2013, 12:57 PM   #9
diyAudio Member
 
StigErik's Avatar
 
Join Date: Feb 2008
I simulated both version of this driver in small closed box. The 4-layer version is 2-3 dB less efficient, with no higher power handling... it really makes me wonder what the point of 4-layer coil really is.
__________________
dipoles dipoles dipoles dipoles dipoles dipoles dipoles dipoles and dipoles
  Reply With Quote
Old 11th March 2013, 01:29 PM   #10
diyAudio Member
 
Join Date: Feb 2008
Location: Enschede
Indeed, the 4-layer version performs disappointingly... and for dipole use the higher sensitivity of the two-layer version is an advantage. Strange.
  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
Dual layer PCB with second layer being only ground Th3 uN1Qu3 Class D 16 6th February 2011 10:32 PM
midbass - 3" 2 layer or 2" 4 layer? jayam000 Multi-Way 2 20th December 2009 10:53 AM
Constrained layer damping / thin metal / fibreglass layer RobWells Multi-Way 3 6th August 2007 05:50 AM
Single Voice Coil Vs Double Voice Coil Subwoofer Workhorse Car Audio 6 12th April 2007 06:36 AM
single layer djronbxs Everything Else 0 15th January 2007 06:52 PM


New To Site? Need Help?

All times are GMT. The time now is 01:35 PM.


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