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flumoxed
Junior Contributor 10+
Joined: 30 Mar 2015
Posts: 19
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 Posted: Sat Apr 04, 2015 12:00 pm Post subject: KEF Q60 BOOKSHELF SPEAKERS - TWEATER IMPEDANCE, ETC. |
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Hi,
I find this website very useful and would like to make a small donation to its maintenance by PayPal. Please advise how to do this.
A month ago I opened my Q60's for the first time and was dismayed to see the following:
1. NT25 Tweaters are SP1276 instead of the advertised SP1353.
2. Measured impedance is 3.3 ohm.
3. The 3.5mm dia. rubber seals had been glued to the bottom of the woofer flange at one point only so they didn't sit properly in the preformed seal channel in the front plastic panel and had been crushed.
4. The person who assembled one speaker had crushed the cables to the woofer on the preformed seal channel. Also, they also hadn't bothered to cut a slot in the black plastic disk at the back of the woofer and had crushed the tweeter feed cables. (The other speaker was fortunately assembled by somebody more diligent and is OK.)
Despite their age and problems, I like these speakers very much. Money isn't a problem but I am reluctant to replace them.
Kindly advise:
1. The NT25 tweeters aren't physically damaged. Is the 3.3 ohm impedance within parameters or does this suggest that the ferrofluid has solidified and they should be replaced?
2. Where can I buy the replacement 3.5mm dia. rubber seals?
Many thanks for your time and expertise. |
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speakerguru
Über Contributor 1000+
Joined: 18 Nov 2005
Posts: 1192
Location: Green Hut, Tovil
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| Posted: Sat Apr 04, 2015 2:37 pm Post subject: Re: KEF Q60 BOOKSHELF SPEAKERS - TWEATER IMPEDANCE, ETC. |
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| flumoxed wrote: | | I find this website very useful and would like to make a small donation to its maintenance by PayPal. Please advise how to do this. |
Very nice of you to offer. I think this is a question for Terry, who set up this site. Terry?
| flumoxed wrote: | 1. The NT25 tweeters aren't physically damaged. Is the 3.3 ohm impedance within parameters or does this suggest that the ferrofluid has solidified and they should be replaced?
2. Where can I buy the replacement 3.5mm dia. rubber seals? |
3.3 Ohms is perfectly OK, but in any case, the d.c. resistance is not indicative of the state of the ferrofluid. I'm assuming you measured the d.c. resistance. If you measured and plotted impedance vs. frequency, you could possibly diagnose more. e.g. if the curve was flat, with no peak at resonance then you could suspect that the voice coil was not moving much. However in my experience dried-up ferrofluid does not normally restrict coil movement. I have seen tweeter impedance curves with two peaks near resonance when the ferrofluid has dried up. This is because of reflex-like action with the magnet cavity at the non-diaphragm end of the voice coil.
Not sure I know what you mean by 3.5mm dia rubber seals. KEF used to use self-adhesive (sim. to draught excluder) neoprene strip on woofers. This is readily available in a number of widths on a well known auction site. |
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flumoxed
Junior Contributor 10+
Joined: 30 Mar 2015
Posts: 19
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| Posted: Wed Apr 08, 2015 3:27 pm Post subject: Re: KEF Q60 BOOKSHELF SPEAKERS - TWEATER IMPEDANCE, ETC. |
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| Quote: | Speakerguru wrote:
Not sure I know what you mean by 3.5mm dia rubber seals. KEF used to use self-adhesive (sim. to draught excluder) neoprene strip on woofers. This is readily available in a number of widths on a well known auction site. |
flumoxed wrote:
Attached photo shows the rubber seal on bottom of the driver flange. The plastic channel it sits in us shown at upper right.
TX
http://img177.imagevenue.com/img.php?image=493518870_DSCF4532_122_233lo.JPG |
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speakerguru
Über Contributor 1000+
Joined: 18 Nov 2005
Posts: 1192
Location: Green Hut, Tovil
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| Posted: Wed Apr 08, 2015 5:17 pm Post subject: |
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You got me flummoxed alright! I see nothing in the photo that I can relate to your descriptions. Sorry.
The photo shows the back of the magnet back-plate, tweeter retainer/spacer moulding and exiting tweeter wires beautifully but not the woofer "flange" as I understand it.
I have been working on the assumption that the "flange" was the inboard part of the outer section of the woofer chassis which mates with the cabinet via an intervening gasket strip. Are we at cross-purposes? |
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flumoxed
Junior Contributor 10+
Joined: 30 Mar 2015
Posts: 19
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| Posted: Thu Apr 09, 2015 1:50 pm Post subject: KEF Q60 B200 bass/midrange unit (SP1280) |
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| speakerguru wrote: | You got me flummoxed alright! I see nothing in the photo that I can relate to your descriptions. Sorry.
The photo shows the back of the magnet back-plate, tweeter retainer/spacer moulding and exiting tweeter wires beautifully but not the woofer "flange" as I understand it.
I have been working on the assumption that the "flange" was the inboard part of the outer section of the woofer chassis which mates with the cabinet via an intervening gasket strip. Are we at cross-purposes? |
But I have been flumoxed since I was born...
Attached is a new photo. 1 is the round soft rubber seal. 2 is the preformed channel that beds the seal.
TX.
http://img208.imagevenue.com/img.php?image=583005231_DSCF4532_122_77lo.JPG |
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speakerguru
Über Contributor 1000+
Joined: 18 Nov 2005
Posts: 1192
Location: Green Hut, Tovil
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| Posted: Thu Apr 09, 2015 7:48 pm Post subject: Re: KEF Q60 B200 bass/midrange unit (SP1280) |
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| flumoxed wrote: |
Attached is a new photo. 1 is the round soft rubber seal. 2 is the preformed channel that beds the seal. |
Looks like the same photo to me and the parts labelled 1 and 2 are what I thought you were describing. The woofer chassis has no pre-formed recess for a gasket so are you saying the cabinet has? It normally is routed out so that the gasket is compressed by a fixed amount and not just crushed.
Remove any damaged gasket/rubber/whatever and replace with closed cell neoprene gasket strip. You will have to cut it to size and make sure it goes all the way round without any gap. |
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flumoxed
Junior Contributor 10+
Joined: 30 Mar 2015
Posts: 19
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| Posted: Fri Apr 10, 2015 1:53 am Post subject: Re: KEF Q60 B200 bass/midrange unit (SP1280) |
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| speakerguru wrote: | | flumoxed wrote: |
Attached is a new photo. 1 is the round soft rubber seal. 2 is the preformed channel that beds the seal. |
Looks like the same photo to me and the parts labelled 1 and 2 are what I thought you were describing. The woofer chassis has no pre-formed recess for a gasket so are you saying the cabinet has? It normally is routed out so that the gasket is compressed by a fixed amount and not just crushed.
Remove any damaged gasket/rubber/whatever and replace with closed cell neoprene gasket strip. You will have to cut it to size and make sure it goes all the way round without any gap. |
Many thanks for your help. |
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