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 

IMF RSPM MkIV

 
Post new topic   Reply to topic    SpeakerTalk Forum Index -> Other speakers
View previous topic :: View next topic  
Author Message
django
Junior Contributor 10+


Joined: 06 May 2006
Posts: 14
Location: Walsall West Midlands UK

PostPosted: Tue Aug 22, 2006 4:30 pm    Post subject: IMF RSPM MkIV Reply with quote

Hi,
Does anyone know the correct impedance for the Celestion HF2000 super tweeters used in IMF RSPM MKIV?
In my RSPM MK IV one tweeter is 4 ohms the other is 8 ohms.
The 8 ohm unit is in need of replacement, it has a damaged (pushed in and crinkled) cone, is there a cure for this?
Is there a source for IMF HF2000 type tweeters in the UK?
Many Thanks
Nick Mellor
_________________
django
Back to top
View user's profile Send private message
ColinR
Über Contributor 1000+


Joined: 31 Jul 2004
Posts: 1175
Location: Staffordshire

PostPosted: Wed Aug 23, 2006 8:25 pm    Post subject: Reply with quote

Now you've got a problem as HF2000's are "hunted for" with a vengance.

IMF used both 4 and 8 Ohm units which had the same unit cost, no need to alter the size of C13 (2.2uF - crossover 6dB/octave@10kHz), as a small decrease in impedance only raises the crossover frequency a little.

A 4-6 Ohm unit was in the baffle IMF lent to John Crabbe for his Tip-Top top to his concrete bass horns - crossover frequency 12kHz.

What's a HF2000 worth?

Buy an early pair of Celestion Ditton 25's with rear mounted tweeters and gut Sad . ****

Or spend £50-70 on EPrey for a driver of dubious provenance.

The dome is Mylar like the T27, so no replacements or repairs.

I doubt if you'd be able to persuade someone to do a rewind.

They should have been fitted with brass diffusers, to smooth out the lobes in the polar response.

The Rogers Export Monitor and Lentek Monitor use another varient with a three hole mount, which you can bodge with the three clip mount of the Ditton 44, 66 or later 25's with the grotty square HF1300's - but they're not for you.

How about a couple of Coles 4001K's good from 7kHz cf HF2000 good from 5kHz.

Other than those, you're talking in terms of Raven Ribbons.

**** I've a pair of early Ditton 25s in my garage. ****
Back to top
View user's profile Send private message
Gary
Senior Contributor 200+


Joined: 07 Nov 2004
Posts: 275
Location: Toronto, Canada

PostPosted: Fri Aug 25, 2006 10:38 pm    Post subject: Reply with quote

ColinR wrote:

**** I've a pair of early Ditton 25s in my garage. ****


If I did that, we'd have the racoons rockin' in the garage!

As it is, they only come around during garbage day.

Confused
_________________
Sometimes I lie awake at night, and I ask, "Where have I gone wrong?" Then a voice says to me, "This is going to take more than one night."
-- Charles M. Schulz (as Charlie Brown)
Back to top
View user's profile Send private message
ColinR
Über Contributor 1000+


Joined: 31 Jul 2004
Posts: 1175
Location: Staffordshire

PostPosted: Sat Aug 26, 2006 10:22 am    Post subject: Reply with quote

Quote:
racoons rockin' in the garage



Sounds rather fun Very Happy .

Although I suspect they'd rather live in a pair of IMF TL's.
_________________
This post or any other information supplied to this website or any other by myself is not available for any form of commercial purpose i.e. to hi-fi magazines or as sales and marketing material for sleezeBay or Audiodogging pimps and the like.
Back to top
View user's profile Send private message
django
Junior Contributor 10+


Joined: 06 May 2006
Posts: 14
Location: Walsall West Midlands UK

PostPosted: Sat Aug 26, 2006 11:52 pm    Post subject: IMF RSPM MKIV Reply with quote

Colin,
Many Thanks for the reply.
Can you expand, can we talk, about early Ditton 25's?

Nick Mellor
_________________
django
Back to top
View user's profile Send private message
ColinR
Über Contributor 1000+


Joined: 31 Jul 2004
Posts: 1175
Location: Staffordshire

PostPosted: Sun Aug 27, 2006 10:26 am    Post subject: Reply with quote

Yes Nick, you have a PM.
Back to top
View user's profile Send private message
RGBE
Intermediate Contributor 25+


Joined: 22 Sep 2006
Posts: 46
Location: Sevilla, Spain

PostPosted: Tue Oct 03, 2006 10:58 pm    Post subject: Reply with quote

ColinR wrote:



Although I suspect they'd rather live in a pair of IMF TL's.


That reminds me of a cartoon of mine that was published in a Badger catalogue in 1984. See bellow, please.


Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    SpeakerTalk Forum Index -> Other 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