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S-Stop Protection Circuit Gone!!!!

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Intermediate Contributor 25+

Joined: 12 Apr 2010
Posts: 37

PostPosted: Sat Oct 18, 2014 1:04 pm    Post subject: S-Stop Protection Circuit Gone!!!! Reply with quote

So I got my T33 in the mail yesterday. When I went to replace the odd tweeter that was already in my 105.4 speaker (see pic) I was astonished to find that the entire circuit board for the S-Stop system had been removed! The odd tweeter was connected with new wire, and it appears that the wiring was done well, so I just hooked up the T33 and put the speaker back together. It works and sounds great, but I'm wondering if the speaker will suffer damage without that circuitry, or if it was independent of the speakers sound circuitry.
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VIP Contributor 750+

Joined: 18 Nov 2005
Posts: 983
Location: Green Hut, Tovil

PostPosted: Sat Oct 18, 2014 5:11 pm    Post subject: Reply with quote

No the speaker will not be damaged by using it without S-Stop (unless you overdrive it of course).
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Senior Contributor 200+

Joined: 18 Jul 2014
Posts: 218
Location: Netherlands

PostPosted: Sun Oct 19, 2014 6:57 am    Post subject: Reply with quote

Some remove all the extra stuff to get the best sound that is possible. If it really improve the sound will be the question. Here's a review from someone on audioreview, also with the S-Stop removed.

Date Reviewed: June 8, 2005

Bottom Line:
I have used Kef 105/4s on and off for over 14 years now , I listen to all types of music , from Hip hop , ambient , 70s rock to classical .
My 105/4s have been modified though , these had given me a good few years service and had a lot of heavy use , they had been passed around relatives homes , and been a second hand purchase .
I had also been using other speakers , and was starting to question the 105/4s performance .
I found the bass to lack definition during complex music , treble and mids also seemed a little restrained , and I was having problems with the protection circuits cutting in , they seemed to enjoy high power amps but not volume .
Considering the condition and age of these I decided on a little diy .
Now I am not an Expert nor do I assume to know better , but the first item that was holding back performance was those silly wheels , they had to go .
And I am not a fan of skirting round the base of a speaker , I am sure these add colourations .
So I filled the base with concrete , fitted a 1" birch ply base , and added spikes . This brought them back to the correct height , with improvements in bass definition , slam , and detail .
The S stop and protection from the heads was next , this prevents you from blowing your mid and high frequency units .
There was a rumour it also sent part of the midrange to the upper bass driver , or adjusted the midrange level .
Now the two 4ohm bass drivers are wired together to create an 8ohm load , and both drivers share a cab , so this is seems unlikely .
Would lowering the power to the mid at high volume not also adjust the speakers signature ? Sounded like a compromise to me , better to use a decent amp which you dont run into clipping .
Anyway the s stop circuit was removed , along with that rubbish connection at the bottom of the head assembly , and yes I thought it was a huge improvement , like a curtain had been removed .
There was more punch to the mids , treble seemed less grainy , more detailed. I also fitted Audioquest cable throughout with silver solder (an absolute pain to fit) , and used an xlr connection to the head as the 107 uses , i also fitted the newer T33 faceplate to the treble units .
Now I was happy with the performance of these speakers , considering their age etc , and I only carried out these mods because of the condition mine were in. I would not go as far with a mint condition pair. I feel these modifications added to their performance , like adjusting fine focus on a camera. I recommend these speakers highly , their performance and engineering is still top class by todays standards , and their weak points are easily modified. WBT or Neutrik speakon terminals on heads and body. Rewiring with decent cable and soldering.
Bolting base to a concrete , marble or slate plinth.
Overall these are a great speaker , with the right recording they have the ability to disapear , leaving you with a performance in the listening room .
The soundstage has superb width and depth , with images firmly located within the soundstage , which can also seem to reach behind you.
With slight modification these sounded livier and more open , more transparent . Bass lost some of its slightly rich quality , with improved weight and definition. Though I do have reservations about removing the protection circuits, and the resulting reduction in power handling this brings.

Used product for: More than 1 year
Duration Product Used: Casual Listener
Product model year: Pre 1995
Price Paid: $300.00
Purchased At: HI FI corner , Edinb
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Über Contributor 1000+

Joined: 22 Aug 2003
Posts: 1297
Location: Tewkesbury UK

PostPosted: Sun Oct 19, 2014 11:39 am    Post subject: Reply with quote

I am glad that you are continuing enjoying the KEF sound.

We still have a pair of KEF 104/2 in the family and so far they have not suffered the dreaded foam rot but do have replacement tweeters. (The old ones still work) they came with the purchase...

The 105/4s are splendid transducers, should give you many more years of listening pleasure, well done!
I contend that for a nation to try to tax itself into prosperity is like a
man standing in a bucket and trying to lift himself up by the handle.
-Winston Churchill
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Intermediate Contributor 25+

Joined: 12 Apr 2010
Posts: 37

PostPosted: Mon Oct 20, 2014 1:12 pm    Post subject: Reply with quote

Yes. These are great sounding speakers and it appears that circuit will not be missed....
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