Kef reference 101 monitor crossover & binding posts.

[Unreal56]

Hello ,
I want to restore my 101's .
They have some problems , tweeters are crackling some times.
I'm pretty sure it's the crossover (bad caps) or a bad connection in the binding posts.
Does anyone know how to remove the binding posts and how to open the hollow buttom in the cabinets of the speakers where the crossovers are.
I want to recap them and replace the binding posts for newer ones with better connection.

 

[Unreal56]

Thanks , removed the woofers and found a screw under the speaker at the outside. But still can't get to the crossover.

 

[Unreal56]

Oke fixed it , If you remove the screw you can pull the whole bottom off.
I can see there is a protection circuit , I want to bypass it.
How can I bypass this ?
Some of the resistors are corroded like on the picture.

 

[mech986]

Thanks , removed the woofers and found a screw under the speaker at the outside. But still can't get to the crossover.

Oke fixed it , If you remove the screw you can pull the whole bottom off.
I can see there is a protection circuit , I want to bypass it.
How can I bypass this ?
Some of the resistors are corroded like on the picture.

You found out the hidden crossover chamber below the speaker base! Simple to remove the whole bottom. As for the connectors, it will be a simple matter to either remove the old spring clips and replace with good binding posts, or remove the whole wooden piece mount and fashion a new one with proper binding posts at the normal dual jack spacing.

As for the crossover, the resistor corrosion is fairly common due to the coating used, usually the resistor is ok, but if you want to, change out for same value and wattage in a high quality type that will fit. As for the capacitors, contact Falcon Acoustics and they can help you out with new Alcaps which will, in all respects, duplicate the original Elcaps and retain the voicing and importantly, fit the board. Not cheap but the only way to ensure they will sound like the original Reference 101. They would also have the resistors you'd need.

You can also discuss with them ways to defeat the S-Stop protection system.

http://www.falconacoustics.co.uk/re...itor-kit-kef/ssl7-crossover-componet-set.html

As for subbing caps of different types (out with the electrolytics and use polypropylene or polyester), for the small value caps, that might work but you have to add back some small resistance to adjust ESR to match the originals. The stack of 4 x 100uf electrolytics would be much harder to sub because film caps of that size are HUGE, and you couldn't fit that in the space allotted for the crossover. You could consider bypassing the stack with a decent sized PP cap of say 1-10uf and say 100-200V rating, that would not adversely affect the stack and should fit.

Here's some threads about the different crossover and modification approaches. Take every suggestion with some caution as changes can alter the speaker's sound and voicing, and not always for the better.

http://www.diyaudio.com/forums/multi-way/160069-kef-reference-101-loudspeakers-crossover-update.html

http://www.audioasylum.com/cgi/t.mpl?f=speakers&m=231221

http://www.audiokarma.org/forums/showthread.php?t=157004

 

[Unreal56]

Hey , thanks for the information !
Mini-monitors are fun aren't they
I found the secret chamber yes.
Good tip for the ALCAP's , will buy them from falcom.
First I wanted to use Jantzen caps but these look better.
I measured the corroded 15 ohm resistor and measured 16,3 ohm , so replace it or leave it the way it is now ?

 

[Unreal56]

Recapped the crossover with alcaps but still got the problem one speaker cut-out sometimes.
I think it's the relay .
Want to bypass the protection circuit does anyone know how to do this ?

 

[Yvan_donald]

Hi, I own a pair of IMF prof.mkIII who have the same Elcap and just change the 6 uf and 12 uf with Kimber kap 200v. Wow this is a good cap I will follow and change the .47 uf and order Mundorf silver-gold oil bit expensive but I'm pretty confident later I have 10x 2.2 uf to change but didn't make choice for the brand. Believe me it's worth to put money on good parts for crossover,best regards,Yvan

 

[Jokanok]

Kef reference 101 recap

Hi
I just bought some vintage Kef reference 101 (SP1122) speakers manufactured august 1980.
Before hooking them up I decided to take a look at the crossovers. I am afraid one crossover has a leaking capacitor (picture attached). The other components seemed ok (see picture of the whole crossover). The crossover of the other speaker had no visible defaults.
I also checked if I could hear any sound quality difference between the speakers. I am not sure if I did. It is possible that one sounded more detailed, the other (with the defective capacitor) more flat but with seemingly more lows. I cannot tell, taken separately, which sound I preferred.
Should I change all the capacitors? Falcon acoustics sells matched sets at a reasonable price.
Do you think a recap is needed? If not really necessary, do you think the "sound quality" of the speakers could improve after a recap?
Best regards
Joris

 

[writethis]

I just had a set of 103.2 from the early 1980s completely recapped. while I am not a big fan of fixing stuff that doesn't need to be fixed, this truly made a noticeable improvement in transparency, detail and frequency expansion at both ends of the spectrum. Much more of a difference than I was expecting. We also bypassed the protection circuit, I'll never know how much of the improvement is due to that.

This recap was done with the kit from Falcon. I have a second pair of 103.2 which I will soon have recapped by AK'er leesonic, using caps of his choosing.

 

[mech986]

Hi
I just bought some vintage Kef reference 101 (SP1122) speakers manufactured august 1980.
Before hooking them up I decided to take a look at the crossovers. I am afraid one crossover has a leaking capacitor (picture attached). The other components seemed ok (see picture of the whole crossover). The crossover of the other speaker had no visible defaults.
I also checked if I could hear any sound quality difference between the speakers. I am not sure if I did. It is possible that one sounded more detailed, the other (with the defective capacitor) more flat but with seemingly more lows. I cannot tell, taken separately, which sound I preferred.
Should I change all the capacitors? Falcon acoustics sells matched sets at a reasonable price.
Do you think a recap is needed? If not really necessary, do you think the "sound quality" of the speakers could improve after a recap?
Best regards
Joris

If one cap in the system is leaking or showing signs of aging or stress, then realistically, the other caps may be in the same boat. Otherwise, think of the fact that the caps are now 34 years old, and probably not designed to last anywhere near that long, outside appearance notwithstanding.

I would still suggest recapping the crossovers with appropriately chosen good quality electrolytic bipolar caps. Falcon can supply very similar caps of recent manufacture. Some have had good luck with domestically sourced caps as well. many have bypassed the S-Stop circuit also in the R101.

 

[leesonic]

Recapped the crossover with alcaps but still got the problem one speaker cut-out sometimes.
I think it's the relay .
Want to bypass the protection circuit does anyone know how to do this ?

Remove the relay and solder a wire across the normally open terminals.

Lee.

 

[special_20]

Remove the relay and solder a wire across the normally open terminals.

Lee.

Hey lee,

I'm having a similar conundrum and hopefully you're still subscribed to this thread or someone else knowledgeable can chime in. I want to bypass the s-stop on some Kef 101's. I'm a very visual leaner so attached some pics to assist.

sorry bit of a newb with switches and crossover circuits. I have removed the switch (RL1) and inspected the switch. Can anyone check me logic and confirm which switch points need to be jumpered? 2 jumpers: Point 1 to Point 3 and Point 1 to Point 4? In order to totally remove the S-Stop circuit do I need to disrupt the trace behind Point 1 as well?

Thanks!

thanks in advance!

 

[Tinnkindling]

This is an interesting thread. I would like to know if the KEF 101s have the ferro fluid tweeters, and if so, if they tend to go bad.

My 101s have never been worked on, and this type of thread always worries me that something is going to go wrong with my favourite speakers.

Keep the thread going, and let us know how the restoration goes. Also would be interested in whether you choose to replace the spring clips with binding posts or banana plug connectors.

Final question is to ask why you would want to bypass the protection system?

 

[Gruvin']

Final question is to ask why you would want to bypass the protection system?

From some of the reading i've done, some people claim that the speakers actually sound even better with the protection system bypassed!

If you're using mega power amps to drive them and/or you like it loud it may not be such a good idea but with a low powered amp.....why not try it...:yes:

Just my thoughts

 

[Tinnkindling]

OK, and thanks. I'm using a 110 wpc amp, so I'm going to leave them alone. They sound real good, particularly when you consider the small size. They "punch above their weight" for sure.

 

[mech986]

This is an interesting thread. I would like to know if the KEF 101s have the ferro fluid tweeters, and if so, if they tend to go bad.

My 101s have never been worked on, and this type of thread always worries me that something is going to go wrong with my favourite speakers.

Keep the thread going, and let us know how the restoration goes. Also would be interested in whether you choose to replace the spring clips with binding posts or banana plug connectors.

Final question is to ask why you would want to bypass the protection system?

The R101 uses the very common and relatively long lived KEF T27 tweeter which does not use ferro fluid. Used with a correct crossover, the T27 can last a long time so long as excessive or high amplitude High frequency content is avoided. LS3/5a's same T27 tweeters (and crossover) were fried regularly by BBC employees who left the speakers on while fast forwarding RTR tape machines which sent a ton of HF content into them at high amplitude.

T27's are fairly common on Ebay as they were used in a ton of speakers, but it would be best to source a pair from another pair of KEF speakers, like the Corelli or KEF 104. They would have been matched fairly closely at time of manufacture at least.

As mentioned above and below, bypassing the relay reduced a number of contacts in the audio circuit.

From some of the reading i've done, some people claim that the speakers actually sound even better with the protection system bypassed!

If you're using mega power amps to drive them and/or you like it loud it may not be such a good idea but with a low powered amp.....why not try it...:yes:

Just my thoughts

 

[special_20]

Hey lee,

I'm having a similar conundrum and hopefully you're still subscribed to this thread or someone else knowledgeable can chime in. I want to bypass the s-stop on some Kef 101's. I'm a very visual leaner so attached some pics to assist.

sorry bit of a newb with switches and crossover circuits. I have removed the switch (RL1) and inspected the switch. Can anyone check me logic and confirm which switch points need to be jumpered? 2 jumpers: Point 1 to Point 3 and Point 1 to Point 4? In order to totally remove the S-Stop circuit do I need to disrupt the trace behind Point 1 as well?

Thanks!

thanks in advance!

Well, decided to just go for it as I wasn't going to make anything more broken. Sat back and looked at circuit knowing the s-stop was a bit of a vampire. I jumpered points 1 and 4 since that seemed to be the positive leg I wanted to establish. Since there was still a positive leg going into the S-stop I deduced I did not want to connect the negative leg to anything to keep it shorted.

Jumpered my connection, reconnected my driver leads and everything worked! These are some nice little speakers. Originally was thinking of flipping them - may just keep them

 

[sledge93]

Well, decided to just go for it as I wasn't going to make anything more broken. Sat back and looked at circuit knowing the s-stop was a bit of a vampire. I jumpered points 1 and 4 since that seemed to be the positive leg I wanted to establish. Since there was still a positive leg going into the S-stop I deduced I did not want to connect the negative leg to anything to keep it shorted.

Jumpered my connection, reconnected my driver leads and everything worked! These are some nice little speakers. Originally was thinking of flipping them - may just keep them

Some new info. I bought a pair recently and they sounded fine, but I'm always upgrading gear. I installed quality Falcon binding posts and updated the input wiring. The 400uF input filter caps were removed and wired the + input directly to main circuit. Replaced all remaining caps with polycarbonates. Sound was vastly improved, yet one speaker cut in and out randomly. Yesterday I removed R1 and put a high quality 18GA jumper wire in its place. Huge noticeable difference. Today I plan to remove the relay and double up the R1 jumper from the underside.

These are great speakers! They replaced Magnepan 1.7s and in my room image and sound much better.

 

[Dr John]

Hello everyone
Have been a member of this forum for a while but never posted anything just read. Well…..I need help. I just purchased a set of Kef101 speakers and one speaker works great the other has very low output. I have narrowed the issue to the crossover. The vintage is 1981 I have a photo . I know I should recap but I feel the issue may be with the stop circuit. Does anyone have information or a way to bypass this circuit on this model? I saw another picture but the crossover looks different. Any help would be appreciated. @leesonic can you help?

 

[special_20]

... have narrowed the issue to the crossover. The vintage is 1981 I have a photo . I know I should recap but I feel the issue may be with the stop circuit...

Hello Dr. John! Can you catch us up on your issue and how you've narrowed it down to the crossover?

The stated symptom is low output. Is this low output no highs, no low end, or both? Is the LED light triggering?

How did you rule out issues with your source or amplifier?

Have you swapped the crossovers between the speakers and the issue followed the crossover? Etc.

The s-stop is a DC protection circuit within the speaker. It uses a relay that detects DC. If DC is detected it shunts the signal away from drivers (at least the tweeter) and turns on an LED. If it's flaky it could cause you issues though it should be more on/off. Can you get a picture of the other side of the crossover? While it's a different layout, the principle is the same.