SpeakerTalk Forum Index SpeakerTalk
This forum has been set up to facilitate discussion of 1970s KEF speakers and drive units. The owner of the Forum has no connection with KEF Audio.
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

A DCR of 7.1 Ohm does NOT guarantee a functional drive unit.

 
Post new topic   Reply to topic    SpeakerTalk Forum Index -> KEF speakers
View previous topic :: View next topic  
Author Message
ColinR
Über Contributor 1000+


Joined: 31 Jul 2004
Posts: 1175
Location: Staffordshire

PostPosted: Thu Nov 24, 2005 3:21 pm    Post subject: A DCR of 7.1 Ohm does NOT guarantee a functional drive unit. Reply with quote

I've noticed recently that some "ePay vendors" are stating a drive unit's DCR or showing a picture of the meter reading alongside the available driver.
This does NOT guarantee that even at the time of testing that the driver was working correctly.

Why not?

Case 1.
Mechanical shock or over enthusiastic removal of a driver from a cabinet such that the adhesive bond is broken, so the rear pole assembly is shifted with respect to the magnet, causing the gap to narrow and voice coil to lock.
This will have a DCR of 7.1 Ohm, but you won't get much sound out of it.
Therefore drivers that may have been "tested in" or "taken from working" cabinets should be treated with some caution.

Case 2.
Overdriving loudspeakers (party time) can cause the lacquer holding the voice coil onto the card former to fail.
I've got a T27, which has a DCR of 7.1 Ohms, but the complete voice coil is sitting at the bottom of the pole piece well.
No sound out of this one either.

So make sure that when buying, that the individual drive unit has been tested with a musical signal from a transistor radio, portable CD or mp3 player, or undergone some form of frequency sweep from an audio oscillator.

If it hasn't walk away.
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    SpeakerTalk Forum Index -> KEF speakers All times are GMT + 1 Hour
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group