i did a search and found some good info, but am curious if anyone has any updates on their findings.
as many KEF owners with ferro-fluid cooled tweeters know, the gel hardens over 20 years and basically renders the tweeters useless. i recently traded my Bozak 302A Urbans for a pair of 104/2. should have hooked the KEFs up while the guy was here, but such is life. he's really nice and offered to give me cash to buy the KEF recommended replacements.
but, I've heard KEF's replacements are both overpriced ($160/pair) and don't even sound that great. as you know, the 104/2 has the tweeter mounted flush behind the mid/tweeter baffle. i do not want to alter the outside of the baffle, but have no problem tweaking it from inside to mount a suitable, if not better replacement. i mean $160 buys you some pretty fricken nice tweeters ;-)
so, what have you guys tried successfully? the tweeter is 1.25", but i can go smaller if necessary. i believe they are 4 ohm. overall sensitivity is rated at 92db at a 4ohm load.
specs: http://www.kef.com/history/1980/model104_2.asp
thanks,
Robby
as many KEF owners with ferro-fluid cooled tweeters know, the gel hardens over 20 years and basically renders the tweeters useless. i recently traded my Bozak 302A Urbans for a pair of 104/2. should have hooked the KEFs up while the guy was here, but such is life. he's really nice and offered to give me cash to buy the KEF recommended replacements.
but, I've heard KEF's replacements are both overpriced ($160/pair) and don't even sound that great. as you know, the 104/2 has the tweeter mounted flush behind the mid/tweeter baffle. i do not want to alter the outside of the baffle, but have no problem tweaking it from inside to mount a suitable, if not better replacement. i mean $160 buys you some pretty fricken nice tweeters ;-)
so, what have you guys tried successfully? the tweeter is 1.25", but i can go smaller if necessary. i believe they are 4 ohm. overall sensitivity is rated at 92db at a 4ohm load.
specs: http://www.kef.com/history/1980/model104_2.asp
thanks,
Robby
Hi Robby,
If the tweeters are not blown, but just gummed up from the dried out ferrofluid, then I would try cleaning out the old ferrofluid before making any baffle mods.
The tweeter dome is bonded to a ring that is stuck to the magnet with double stick tape. It is possible to gently lift it up using a thin bladed knife.
Once off, gently clean off the old ferrofluid from the coil using a soft cloth, then also remove the gunk from the magnet gap. This will be more difficult as it is of course attracted to the gap, but using Q-tips, masking tape wiped into the gap, and lots of patience, you may well be able to get the tweeter working again.
Of course it will no longer have the power handling it once had due to lack of ferrofluid, so be careful.
It may be possible to find a source of new ferrofluid that you could put in.
At least it's worth a try before spending lots of money on alternative drivers that won't match the original!
Good luck
Andrew
If the tweeters are not blown, but just gummed up from the dried out ferrofluid, then I would try cleaning out the old ferrofluid before making any baffle mods.
The tweeter dome is bonded to a ring that is stuck to the magnet with double stick tape. It is possible to gently lift it up using a thin bladed knife.
Once off, gently clean off the old ferrofluid from the coil using a soft cloth, then also remove the gunk from the magnet gap. This will be more difficult as it is of course attracted to the gap, but using Q-tips, masking tape wiped into the gap, and lots of patience, you may well be able to get the tweeter working again.
Of course it will no longer have the power handling it once had due to lack of ferrofluid, so be careful.
It may be possible to find a source of new ferrofluid that you could put in.
At least it's worth a try before spending lots of money on alternative drivers that won't match the original!
Good luck
Andrew
Thanks Andrew!
have you tried this with KEF tweeters in the past?
you are right, it is worth a shot, but i might also just buy replacement tweeters as well. i've read that others have tried to clean out the gunk. it does help a lot, but the T33s still didn't have the output they used to. why does the hardened fliud kill the output?
thanks,
Robby
have you tried this with KEF tweeters in the past?
you are right, it is worth a shot, but i might also just buy replacement tweeters as well. i've read that others have tried to clean out the gunk. it does help a lot, but the T33s still didn't have the output they used to. why does the hardened fliud kill the output?
thanks,
Robby
ferrofluid is easily available on ebay. suprisingly, lots of purveyors. I think they are literally taking it from the loudspeaker arena, and using it as a neo magnet toy. Of course, you have no real idea od the wieght and type you are getting from them. You can't see the bottle close enough in the advert, either.
Madisound.com should be able to hook you up with proper tweeter ferrofluid if you call them up.
Interesting video of PHD's playing with ferrofluid
http://scitation.aip.org/phf/gallery/2003-lorenz.jsp
Interesting video of PHD's playing with ferrofluid
http://scitation.aip.org/phf/gallery/2003-lorenz.jsp
Robby
I have bought T33, T33a and also ferro fluid on e bay. I paid £30 per T33.
The T33 seems to be an excellant treble unit and I would repair if possible otherwise replace with another T33.
I have had correspondence with Kef in the past and they do confirm that the T27, T33 and T52 treble units are all interchangeable if the sensativity is adjusted.
When I was building some Kefkit speakers many years ago I contacted Kef to see if I could use the T52 instead of the T33 as I assumed that the T52 was a better unit. The reply back indicated that the units were all interchangeable as mentioned above. The main difference was in the power handling capabilities and in the temperature that could be sustained in long term use.
If you need more detailed info on the speaker that is available if you search on google.
Hope this helps
Don
I have bought T33, T33a and also ferro fluid on e bay. I paid £30 per T33.
The T33 seems to be an excellant treble unit and I would repair if possible otherwise replace with another T33.
I have had correspondence with Kef in the past and they do confirm that the T27, T33 and T52 treble units are all interchangeable if the sensativity is adjusted.
When I was building some Kefkit speakers many years ago I contacted Kef to see if I could use the T52 instead of the T33 as I assumed that the T52 was a better unit. The reply back indicated that the units were all interchangeable as mentioned above. The main difference was in the power handling capabilities and in the temperature that could be sustained in long term use.
If you need more detailed info on the speaker that is available if you search on google.
Hope this helps
Don
Well, after some research, i tend to agree that both the T33 was never that great and that the KEF replacement is both overpriced and underwhelming. so, i bought a pair of Morel MDT30 tweeters. hopefully they will mate well. wimslow audio uses the MDT29, but the folks at madisound said the 30 will fit the same and sound even better.
yeah, i read lilke 7 reviews on the 107 and 107/2 on stereophile online and all said that the tweeter detracted from an otherwise incredible loudspeaker.
beisdes, madisound has a great return policy, so worth a shot.
Robby
yeah, i read lilke 7 reviews on the 107 and 107/2 on stereophile online and all said that the tweeter detracted from an otherwise incredible loudspeaker.
beisdes, madisound has a great return policy, so worth a shot.
Robby
salas said:
me too !
great thread - i've got a pair of 104/2 that may need tweeter replacement also.
please comment on how the WDT29 works out.
a drop in replacement that's cheaper and sounds better?
am i dreaming ...
http://www.madisound.com/cgi-bin/index.cgi?cart_id=9690868.23241&pid=672
mlloyd1
great thread - i've got a pair of 104/2 that may need tweeter replacement also.
please comment on how the WDT29 works out.
a drop in replacement that's cheaper and sounds better?
am i dreaming ...
http://www.madisound.com/cgi-bin/index.cgi?cart_id=9690868.23241&pid=672
mlloyd1
Re: me too !
no problem!
i'm actually going for the MDT30. a little more expensive but same idea. according to terry at wimslow-audio, the MDT29 drops right in if you take the faceplate off (same procedure for MDT30) and needs no other enclosure or crossover mods. the T33 is 90db sensitivity and the MDT29 is 89db. this is why i went for the MDT30.
BUT if terry says the MDT29 sounds good, maybe the 30 will be too hot? we'll see.
literally all the KEF 107/2 reviews on stereophile.com said that the only thing that detracts form an incredible speaker is the T33. som i guess no love lost with mine dying...
my KEF Calindas do sound incredible with their T277 tweeters. but the T27 is a totally different animal than the T33.
Robby
no problem!
i'm actually going for the MDT30. a little more expensive but same idea. according to terry at wimslow-audio, the MDT29 drops right in if you take the faceplate off (same procedure for MDT30) and needs no other enclosure or crossover mods. the T33 is 90db sensitivity and the MDT29 is 89db. this is why i went for the MDT30.
BUT if terry says the MDT29 sounds good, maybe the 30 will be too hot? we'll see.
literally all the KEF 107/2 reviews on stereophile.com said that the only thing that detracts form an incredible speaker is the T33. som i guess no love lost with mine dying...
my KEF Calindas do sound incredible with their T277 tweeters. but the T27 is a totally different animal than the T33.
Robby
mlloyd1 said:great thread - i've got a pair of 104/2 that may need tweeter replacement also.
please comment on how the WDT29 works out.
a drop in replacement that's cheaper and sounds better?
am i dreaming ...
http://www.madisound.com/cgi-bin/index.cgi?cart_id=9690868.23241&pid=672
mlloyd1
The T27 was their trademark tweeter, had good HF power response back in a time that HF was not an easy goal. But in essence it was a supertweeter. Needs not to be stressed by mid duties.
Although it suffers grainy lispy treble by todays standards is far better than T33 or T52 to my ears. They sound like dead ducks to my ears.
Morel is much much better. The speaker will really open up. I dont know how good a match can they be without crossover alterations and MLS measurements though.
Waiting for your verdict.
In case they sound hot, try to locate the HF branch of the crossover and put the 1 Ohm resistor right before its + feed and not before the MDT30. Maybe its going to take cutting a pcb trace or lifting a component. In case you try out the resistor just before the MDT30 beacause its handy and tempting, the cross frequency is going to slightly shiftt left. This can give more mids. Also the HF snap is going to soften a little because the damping is going to change a bit.
Although it suffers grainy lispy treble by todays standards is far better than T33 or T52 to my ears. They sound like dead ducks to my ears.
Morel is much much better. The speaker will really open up. I dont know how good a match can they be without crossover alterations and MLS measurements though.
Waiting for your verdict.
In case they sound hot, try to locate the HF branch of the crossover and put the 1 Ohm resistor right before its + feed and not before the MDT30. Maybe its going to take cutting a pcb trace or lifting a component. In case you try out the resistor just before the MDT30 beacause its handy and tempting, the cross frequency is going to slightly shiftt left. This can give more mids. Also the HF snap is going to soften a little because the damping is going to change a bit.
thanks salas!
you are teaching me a lot about crossovers. very good descriptions. true, the resistor will lower the crossover frequency a little bit, but being the morel goes flat to 650HZ, maybe i will be okay with the "simpler solution" i think the crossover is a 24db linkwitz-reilly, right? or is it a butterworth? regardless, the cut-off will be pretty fast, so the Morel won't risk going too much lower.
i have no problem doing the x-over mod (if necessary) as you described, but will have to try a simple resistor on the tweeter to first quickly guage it's effect.
still learning here...
Robby
you are teaching me a lot about crossovers. very good descriptions. true, the resistor will lower the crossover frequency a little bit, but being the morel goes flat to 650HZ, maybe i will be okay with the "simpler solution" i think the crossover is a 24db linkwitz-reilly, right? or is it a butterworth? regardless, the cut-off will be pretty fast, so the Morel won't risk going too much lower.
i have no problem doing the x-over mod (if necessary) as you described, but will have to try a simple resistor on the tweeter to first quickly guage it's effect.
still learning here...
Robby
salas said:
If the caps of the crossover HF section see more than anticipated resistance they work as bigger values. Hence the lapse of cross frequency a little lower. It is not directly related to Morel's resonant frequency. Anyway, since this is a complicated issue and we dont know the HF crossover schematic, try and see. First just substitute the T33 with the MDT 30. If all is ok you are finished. If it sounds hot, put the resistor inline with the + terminal of the Morel. If it sounds ok you are done. If the sound turns kinda honky and brilliance is subdued, locate the +HF cross section entry point on pcb and place the resistor by breaking the +signal from red tap to there. Use a multimeter to trace the route.
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