Thanks , a good idea. Problem is that the baffle has an insert cut to the shape of the frame. To align the B110 with fresh chipboard i'd need to route out the shape of the squaroid frame and rotate 45 degrees
Yes, But It will work for the tweeter.
All I can think of righ now, is you buy a clamp, or already have 4 or 8.
Then take 8 small / suited size blocks of ply, and glue them inside the cabinet, behind each of the screw holes, Then ensure there are no air gaps around the holes, And re screw with longer screws right threw the busted chip board, and into the ply.
The main thing is to ensure the driver is mounted solid, with no air leaks
However this method will decease cabinet volume by a tiny amount though, If the cabinet isnt already stuffed, stuffing it could bring it back into alinement, if it is a issue
Also, you need to ensure it is gued well before screwing, as you dont want the pressure from the screws to seperate the bond between the ply and the chip board
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Old chipboard can kinda fall apart. 😡
I fell about laughing reading someone describe the chipboard frame that held the front grille in place on some old speakers. He said it was about as strong as WEETABIX (A popular breakfast cereal here in the UK)...😀
Guess you can reinforce it with a bit of PVA wood glue applied with a brush. 😎
I fell about laughing reading someone describe the chipboard frame that held the front grille in place on some old speakers. He said it was about as strong as WEETABIX (A popular breakfast cereal here in the UK)...😀
An externally hosted image should be here but it was not working when we last tested it.
Guess you can reinforce it with a bit of PVA wood glue applied with a brush. 😎
Ahh I'm with you. Yes , some small pieces of ply glued behind would work, then drill a clean hole then, mount the spiked bolt thing behind. I'd need to fill the brokens bits of chipboard but with the batton behind, this should be easier. many thanks, was starting to think the second pair of cabinets were beyond repair
yes the structual make up isnt to dissimular, Dryed, squashed, horse turd is also remarkably simular 😱
Update
So I now own two pairs of Vintage Kef Cresta Mk 1.s
the units from 1968 have been rebuilt with entirely original components
the units from 1970 have been repaired thus:
1) I repaired the broken chipboard around the B110 insert using ply wood batons behind and filling with wood filler at the front
2) new gaskets for the B110 using draught excluder
3) Some additional cabinet damping using Falcon foam panels
4) The broken T27s were replaced with Morel drop in equivalent cat 298
Morel CAT 298 Tweeter
I did some listening tests last night. I'd already given the 68 set a listen and were generally pleased. The 70 units sounded somewhat better I felt. There is not much bass in either unit. I assume the simple 3 part crossover doesn't give the LS3/5a mid hump, but on vocals they sound wonderful. I listened to a Sandy Denny compilation and I don't think I have heard it sound as good. A velvety top end , not spitty at all. Both speakers are now bees waxed and to be put away til needed. They join a pair of Mission 707's that were refoamed and a pair of Leak Sandwich speakers that suffered a life of abuse. All these speakers now roam free in their paddock
mending things: mending loudspeakers
many thanks for all the helpful suggestions
So I now own two pairs of Vintage Kef Cresta Mk 1.s
the units from 1968 have been rebuilt with entirely original components
the units from 1970 have been repaired thus:
1) I repaired the broken chipboard around the B110 insert using ply wood batons behind and filling with wood filler at the front
2) new gaskets for the B110 using draught excluder
3) Some additional cabinet damping using Falcon foam panels
4) The broken T27s were replaced with Morel drop in equivalent cat 298
Morel CAT 298 Tweeter
I did some listening tests last night. I'd already given the 68 set a listen and were generally pleased. The 70 units sounded somewhat better I felt. There is not much bass in either unit. I assume the simple 3 part crossover doesn't give the LS3/5a mid hump, but on vocals they sound wonderful. I listened to a Sandy Denny compilation and I don't think I have heard it sound as good. A velvety top end , not spitty at all. Both speakers are now bees waxed and to be put away til needed. They join a pair of Mission 707's that were refoamed and a pair of Leak Sandwich speakers that suffered a life of abuse. All these speakers now roam free in their paddock
mending things: mending loudspeakers
many thanks for all the helpful suggestions
Great stuff, Mr. Ives. Enjoyed your Blog very much too. I think it has been "slashdotted" by unusually heavy use right now.
Useful to know that the Morel CAT 298 slots right into KEF speakers too. The KEF B110 is probably one of the few woofers that will run almost unfiltered due to its natural bextrene rolloff characteristic.
The filter is interesting. I suspect the natural proximity of the two coils is doing something good here, but couldn't predict quite what. 😕
Hate to sound like I'm nagging, but those old non-polar 4uF electrolytic capacitors are probably near end of life now. They dry out over the years, being made of foil and blotting paper soaked in electrolyte.
Your effort fixing the Leak speakers was interesting. There was some secret sauce in Wharfedale and Leak designs. It was the clumsy looking big plastic cone tweeter which everybody thought was silly. They were wrong. Thing was it crossed over at 1.2kHz, so avoided a lot of cone breakup region with the woofer. This was why my Wharfedale Melton with the 12" bass worked rather well:
Useful to know that the Morel CAT 298 slots right into KEF speakers too. The KEF B110 is probably one of the few woofers that will run almost unfiltered due to its natural bextrene rolloff characteristic.
The filter is interesting. I suspect the natural proximity of the two coils is doing something good here, but couldn't predict quite what. 😕
Hate to sound like I'm nagging, but those old non-polar 4uF electrolytic capacitors are probably near end of life now. They dry out over the years, being made of foil and blotting paper soaked in electrolyte.
Your effort fixing the Leak speakers was interesting. There was some secret sauce in Wharfedale and Leak designs. It was the clumsy looking big plastic cone tweeter which everybody thought was silly. They were wrong. Thing was it crossed over at 1.2kHz, so avoided a lot of cone breakup region with the woofer. This was why my Wharfedale Melton with the 12" bass worked rather well:
An externally hosted image should be here but it was not working when we last tested it.
Attachments
I'm pretty sure they are non-polars. They would be marked 50V and + at both ends in all likelihood too. Like in this KEF Cadenza crossover.
I have seen similar in IMF crossovers too. The blown up one looks like electrolytic to me. Replace with similar or a polypropylene for tweeters.
FWIW, polypropylene produces frequency response changes with bass shunts due to lower damping factor, so not so straightforward.
I have seen similar in IMF crossovers too. The blown up one looks like electrolytic to me. Replace with similar or a polypropylene for tweeters.
FWIW, polypropylene produces frequency response changes with bass shunts due to lower damping factor, so not so straightforward.
Attachments
Thanks, i see. I ordered some alcaps from falcon.
BTW,
One the B110 drivers the solder tags had snapped on one side on both speakers. I repaired these but its not obvious to me what the phase is. I took some pictures and think i know which tag had which cable soldered to it ( black and red) but the speaker frame doesn't appear to have any indication. Any guidance on how to determine the drivers polarity ? It looks like i can use the three s
Crews on the back of the magnet as a reference point, assuming both were wired the correct way
BTW,
One the B110 drivers the solder tags had snapped on one side on both speakers. I repaired these but its not obvious to me what the phase is. I took some pictures and think i know which tag had which cable soldered to it ( black and red) but the speaker frame doesn't appear to have any indication. Any guidance on how to determine the drivers polarity ? It looks like i can use the three s
Crews on the back of the magnet as a reference point, assuming both were wired the correct way
Hi,
At the moment a pair of Celestion 5000 in
their boxes, the real wood veneer version of :
Celestion 3000 loudspeaker | Stereophile.com
Article | CELESTION 5000 LOUDSPEAKER | Page144 - June1990 - Gramophone Archive
And hooked up a pair of the original Musical Fidelity MC1s, tweaked.
Rare, TPX Audax bass/mid and Elac chambered metal dome tweeter.
Not to be confused with with the rather limp mk2/3 versions.
rgds, sreten.
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I don't think I've ever heard a ribbon tweeter. Surprisingly. Supposed to be good. 🙂
This is an old chestnut. There isn't any real convention on this beyond a red dot or a + for positive. But if you connect a 1.5V battery positive to positive, the cone or dome moves out! Seemples. 😎
First order bass with second order tweeter is a bit rough on phase. Either way can sound good. It's actually quite hard to hear the difference and people do tricks like turning the speakers upside down to change the time alignment to your listening position. So you'd best figure out what KEF found best based on the distance between the acoustic centres of the two drive units. Lucky you've got two pairs. 😀
This is an old chestnut. There isn't any real convention on this beyond a red dot or a + for positive. But if you connect a 1.5V battery positive to positive, the cone or dome moves out! Seemples. 😎
First order bass with second order tweeter is a bit rough on phase. Either way can sound good. It's actually quite hard to hear the difference and people do tricks like turning the speakers upside down to change the time alignment to your listening position. So you'd best figure out what KEF found best based on the distance between the acoustic centres of the two drive units. Lucky you've got two pairs. 😀
Just an update. have fitted one Alcap and probably do remaining 3 this evening. Woofer was wrong polarity (doh) confirmed with the AA battery test.
Many thanks for all the help, I blogged it here
mending things: Kef Cresta speaker renovation
Many thanks for all the help, I blogged it here
mending things: Kef Cresta speaker renovation
Fantastic work, jives11! Enjoyed reading the latest blog. 🙂
On the subject of bass performance, I'd guess these speakers don't have much bafflestep correction, because the bass coil looks as small as the tweeter coil around 0.5mH at a guess. The B110 was 0.55mH inductance IIRC, so the bottom line here is these are bookshelf speakers, not in the modern (and dubious...LOL) trend of standmounters which would have something like a 2mH coil and a huge loss of eficiency. FWIW, the tweeter capacitor won't influence this.
You're never going to get a lot of bass out of such small drivers and boxes, but you will get 6dB more bass by placing against a wall. Pile books flush around the box a la true bookshelf, and you create an effectively bigger baffle and less diffraction loss too. 😎
On the subject of bass performance, I'd guess these speakers don't have much bafflestep correction, because the bass coil looks as small as the tweeter coil around 0.5mH at a guess. The B110 was 0.55mH inductance IIRC, so the bottom line here is these are bookshelf speakers, not in the modern (and dubious...LOL) trend of standmounters which would have something like a 2mH coil and a huge loss of eficiency. FWIW, the tweeter capacitor won't influence this.
You're never going to get a lot of bass out of such small drivers and boxes, but you will get 6dB more bass by placing against a wall. Pile books flush around the box a la true bookshelf, and you create an effectively bigger baffle and less diffraction loss too. 😎
Thanks system7 , hope it was OK to name-check you in the blog
BTW I'd also added one on extreme record cleaning
mending things: LP
BTW I'd also added one on extreme record cleaning
mending things: LP
Wow that looks way cool! A little pricey but sure looks like it's worth it. I too love to browse the thrift stores for LPs. We have a place here called Dimple Records that sells a lot of old and new vinyl. The old ones go for 1 or 2 dollars, and often the only thing wrong with them is they are dirty.
I can get practically any old record on ebay, though it will cost a bit more for shipping and I have to take the sellers word at the condition of the disk. Often, however, there is little choice if it's something I really want, like finally replacing my decades old and worn out copy of Black Moses.
Your post is very helpful. 🙂
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