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Replacing T27 with modern equivalent

 
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tolstoy
Junior Contributor 10+


Joined: 31 Aug 2005
Posts: 16
Location: London

PostPosted: Wed Oct 05, 2005 12:00 pm    Post subject: Replacing T27 with modern equivalent Reply with quote

Now for a question that will probably have me ex-communicated from the forum. I’ve been considering replacing the aging T27 HF drivers with a more contemporary design, making use of modern materials and future usage. Speaking to KEF about this they agreed that even some of the cheaper units on the market can out perform the T27. Browsing through Wilmslow Audio’s site I see they recommend a basic replacement of H457 @ £30, the H831 @ £25 or, at my request for something higher up the price range the Scanspeak D2905-9300 (though they display the 9500) @ £88. Considerably more expensive but I’m prepared to go there if it improves the life of these great speakers.

I appreciate that this often comes down to personal preference and basis towards aesthetics over perforfmance but your thoughts as connoisseurs of quality (note the ego stroking) on this would be greatly received in helping me make a decision.

Finally, on a perfectionist note: is there anywhere where I can find a replacement plastic ‘KEF’ logo that sits at the top front of the Corellis’ one has always been missing on mine? It’s a long shot I know but hey… if you don’t ask!
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tolstoy
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Joined: 31 Aug 2005
Posts: 16
Location: London

PostPosted: Thu Oct 06, 2005 10:08 am    Post subject: Reply with quote

See... nobody wants to talk to me now Sad

I should haved added that the speakers I refer to are the Corellis. I guess many would suggest that you just do not do this with vintage kit. I might agree; persuade me.
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ColinR
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Joined: 31 Jul 2004
Posts: 1175
Location: Staffordshire

PostPosted: Thu Oct 06, 2005 2:34 pm    Post subject: Reply with quote

I try not to discriminate, unless you're into gliding via aerotow, then you can (expletive) Evil or Very Mad .

Vifa's used to be the flavour of the month for a T27 replacement as you didn't have to molest the crossover. Others do, so be prepared to play with some resistors.

Regarding the badges, I would have thought with the impending replacement of the T27's you'd be selling your singleton Smile .
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tolstoy
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Joined: 31 Aug 2005
Posts: 16
Location: London

PostPosted: Thu Oct 06, 2005 4:17 pm    Post subject: Reply with quote

Heh. It's subtle Colin but I detect a hint of disappointment there. Okay, I'll stick with the T27 but I'll have to get them repaired which is why I was fishing for options. Will KEF still perform this service or do I have to look elsewhere.

By the way, I appear to have killed one of my capacitors (I switched units to confirm) but prior to that the sound was fine (I tested using spare Audax tweeters). As a general note: apart from a suggestion that I learn to solder properly would I be correct to think I overheated the cap on contact? How sensitive to heat are they?
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proffski
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Joined: 22 Aug 2003
Posts: 1296
Location: Tewkesbury UK

PostPosted: Thu Oct 06, 2005 9:03 pm    Post subject: Reply with quote

Gosh, I have bought replacement KEF badges from Ebay, but they can go for silly money.
Change the T27 with care, you will almost certainly have to change the crossover and maybe even add attenuation.
Non polarised capacitors should be able to take normal soldering procedures no problem, what soldering iron were you using?

Certainly modern tweeters will take more power than the T27, but as far as the sound is concerned look at Falcon or Wilmslow perhaps? They should have some experience with replacements. Good luck!
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tolstoy
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Joined: 31 Aug 2005
Posts: 16
Location: London

PostPosted: Fri Oct 07, 2005 9:32 pm    Post subject: Reply with quote

I wouldn't have expected to find the badges on ebay, but to my surprize their they are! Next dilemma, mine is brown they're black

I hadn't thought about the effect new tweeters would have on the crossovers, so I've decided to stick with the t27 as it seems less hassle. Sadly KEF no longer repair them so I'm looking at the ones on ebay. I'm intrigued that there appear to be so many available given their age.

As for the soldering; yes, it would appear that is where my problems lie as I've been using a 15w and Colin suggests at least 25w. So, off to Maplins tomorrow.

At least it's keeping me busy this project!
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proffski
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Joined: 22 Aug 2003
Posts: 1296
Location: Tewkesbury UK

PostPosted: Fri Oct 07, 2005 9:59 pm    Post subject: Reply with quote

Yes, lingering with a small iron can in fact send more heat to the component than a larger one which will do the job quickly.

I use a Weller 50W for allmy work, the tips dictate the temperature by the Curie point of the magnet.

Go for the 25W Antex they sell, the cheap Weller look alike with a light dimmer for temperature control is very unreliable! I used to sell them...
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