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KEF Reference 104/2 Tweeter

Discussion in 'Speakers' started by kmile, Nov 8, 2009.

  1. kmile

    kmile Member

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    Guys,
    Firstly, I am not an engineer but I will try to explain my problem as clearly as possible.
    And let me tell you, it's a BIG problem...
    I am absolutely devastated. On Saturday 14th Nov 2009 I've organised a dance party for 70 people.
    Today my brother in law visited me and he wanted to see how my lovely KEF Reference 104/2 sound.
    I have Roksan Kandy MKIII amplifier which according to its specification produces 185W at 4 Ohms.
    KEF's speakers are 200W at 4 Ohms.

    So my brother took the amp's remote control, put some music on and turned the volume very high, I don't think it was max, may be 80%. Suddenly the sound turned into some dull music and I knew straight away the tweeters blew up! Both of them at the same time!
    Now, let me tell you the story about the speakers. I bought them a month and a half ago from an ex Hi Fi engineer who bought them with damaged tweeters (original T33 tweeters were fluid cooled and it was a common problem that the fluid dried up especially when not in use for a long time).
    T33's are discontinued and the engineer I bought the speakers from said that KEF supplied him with a replacement tweeters, KEF NT25 SP1353 4Ohms.
    Everything was fine until today...I don't know what to do. Guys please help.

    Do you know where I could get a replacement and what tweeter I should get?
    Also, I am suspicious that the tweeters installed by that engineer may not be suitable.

    Firstly because they are new – should not blow up.
    Secondly a friend of mine has KEF Reference 104/2 with original T33s and all cables are thick including the ones going to the tweeter. The tweeter wires in my speakers are very thin (same diameter as wires found in telephone sockets! These thin wires are then soldered to the thick (proper wires that should be soldered to the tweeter).
    This made me think that the tweeter may not be right.
    Is it common that both tweeters go at the same time?
    Is there some sort of a fuse that could have blown?
    If you have any suggestion please let me know as soon as you can. I will contact KEF tomorrow and try to get more info. I am mostly interested in where to get the replacements (and quicly) I am based in London (UK).

    One thing I am glad about is that they blew up today, not at the party!

    Thank you in advance for your help
    Last edited: Nov 8, 2009
  2. Gixxerblade

    Gixxerblade Member

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    If the volume was turned very high then it is possible the amp was clipping. The following article may be of use to you it is from Rod Elliot's ESP site Why Do Tweeters Blow When Amplifiers Distort?
    You can get replacements from Wilmslow audio and other places. The cabing inside the cabinets from binding post to tweeter can be thin in some designs, some people replace it.
  3. kmile

    kmile Member

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    Thank you for the reply.

    Does anyone know good replacement tweeters for T33s?

    Or may be someone knows where to get original T33s from?

    I know the liquid does harden in them over the years especially when not in use for long time but I know an ex KEF engineer that restores the tweeters for about £70.

    Problem is I don't have the originals.

    For time being all I am interested in is getting the replacements before saturday 14th!

    Will appreciate some help on this.

    Regards
  4. Gixxerblade

    Gixxerblade Member

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    I would call Wilmslow audio. Just in case you didn't fully read the article I linked to you might want to note this bit considering you are having a party!

    With the volume advanced by 10dB above clipping, the average power is well above danger level. The distortion will be audible with most music, but is not at all uncommon. Parties are probably the worst offenders, although I have heard many high power (10kW or more) PA systems driven to at least this level of distortion.

    Bear in mind that most "ordinary" (non-audiophile) people will not be aware that there is anything wrong at this point! Liberal quantities of alcohol enriched fluids will ensure that ears remain unresponsive to the assault. Given the number of times I have heard about peoples' speakers "blowing up" during (or after - allegedly) a party, we can safely conclude that the requirement for more noise is far greater than any need for quality.

    Few tweeters will last long with sustained power at a level easily achieved with an overdriven 100W amplifier - they are simply not designed for it.
  5. kmile

    kmile Member

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    Thank you again.

    One possitive thing is that it's non alcoholic party :)

    I will make sure the music is not too loud...

    I only wish I can find these replacement tweeters by Saturday.

    Regards
  6. sanejo

    sanejo Member

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  7. kmile

    kmile Member

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    Thank you. Will definitely consider this one. Has anyone tried it?

    Here is an update:

    You won't believe this... I have called KEF this morning and told them the story (that the sound engineer I bought the speakers from originally got them with damaged T33 and replaced them with T33 replacements - NT25 SP1353).

    To my surprise KEF said NT25 SP1353 is NOT the replacement for T33! (they said it used to be in KEF 42 model)

    The right replacement should be KEF R1548X tweeter. They quoted me £131.33 for them!

    I did some further research and saw some people got them for about £43 with carriage!

    Now, I have also managed to obtain telephone number of the guy I got the speakers from and told him what KEF told me this morning. He started blaming KEF etc and said he will call them and try to sort it out.

    He apparently lives 400 yard to KEF in Kent and still have the receipt and box for the tweeters he installed in my speakers.

    And I only have a few days to Saturday....

    Any suggestions, comments will be highly appreciated.

    Regards

    P.S. I have just rang Wilmslow Audio and they recommend Morel Tweeter CAT298
    https://www.wilmslow-audio.co.uk/ca...d=809&osCsid=fa3119a0edc04a011574104131fa43a5

    They say the Morel will be even better that the original T33. Will it? In what ways will it be better?
    Now, the original T33 is 4 Ohms, this one is 8 Ohms. Will it be OK?

    Sorry but this isn't my area and I would appreciate some explanation?

    Thank you again.
    Last edited: Nov 9, 2009
  8. Cliff

    Cliff Active Member

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    Don't think that by getting the right replacement your tweeters won't blow up during a party.

    HiFi speakers are not really powerful enough and the volume can creep up and your new tweeters will go the same way.

    Better to use or borrow some load PA type speakers with Piezo tweeters. (under a tenner in Maplins)
  9. kmile

    kmile Member

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    Thank you Cliff. That's definitely worth considering! I haven't thought about hiring speakers and didn't know Maplin rents them!

    I will give them a ring tomorrow.

    Thanks again...
  10. Gixxerblade

    Gixxerblade Member

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    You have a lot of choice if you have a 104mm diameter.
    Here is a design from Troels Graveson's site based on the Seas 27TFFC:
    PMS-
    Have a look at Zaph audio tests here:
    Zaph|Audio

    Take your time and get something with the same sensitivity or as near as possible to the tweeter you are replacing.
    Last edited: Nov 9, 2009
  11. Cliff

    Cliff Active Member

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    kmile. Sorry I was not clear in my post. What I meant to say was that Maplins sell cheap horn tweeters that are ideal for parties

    see Wide Dispersion Piezo Horn Tweeter : PA/Power Tweeters : Maplin
    £4.99 each --- a snip!

    Maplins don't hire stuff as far as I am aware but they do sell PA party type speakers if you want to go that route.

    What you could do, and it is just a suggestion, is buy a couple of these horns and use them on top of your 104s. After the party buy and fit the correct tweeters.
  12. kmile

    kmile Member

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    Thanks Cliff...Sounds very interesting. Problem is is don't think the will fin in 104/2.

    By "use them on top of your 104s" do you mean to connect them to the wires but leave them out of the speakers?

    Has anyone done anything like that in the past?

    Again, thank you all of you for your helpful input.


    -
  13. Cliff

    Cliff Active Member

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    Thats right. Just place the tweeter on top of the speaker (taped down or experiment something neater).

    This type of tweeter does not need a crossover so you can connect directly to the speaker terminals on the back.

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