+ Reply to Thread
Page 1 of 4 123 ... LastLast
Results 1 to 10 of 38

Thread: Kef 105/3 Reference Speakers - Bass Distortion

  1. #1
    Join Date: Feb 2016

    Location: Melksham, Wiltshire

    Posts: 726
    I'm Peter.

    Angry Kef 105/3 Reference Speakers - Bass Distortion

    Dear all,

    Can anybody out there assist or advise with the problem detailed below.

    I have a pair of Kef 105/3 Speakers and one of the speakers has developed a Bass problem. I can only describe this problem as, very low bass (in comparison with the other speaker) and is distorted.

    All the bass units have been re-foamed in the last few years and on limited inspection the units appear to be in perfect condition. I have also visually examined the crossover units and again I can see no damage, burning or bulging. However, I have not electrically tested the crossovers due to lack of expertise in this area.

    I really didn't want to pull these speakers apart due to the complex build configuration, but that may have to be an option to find the fault. I would of course, prefer a professional repair but at present cannot find anybody that can do a repair investigation. "Unless anybody on the forum can advise differently"

    At present, I am unsure as to whether there is a problem is with the Bass Unit/Units or something has gone wrong with a component on the crossover and really didn't want to pull the speaker units if this Is not the cause.

    So, if anybody can respond with either pearls of wisdom / advice or indeed a possible repairer that could help, it really would be much appreciated. You have my thanks in advance.

  2. #2
    Join Date: Feb 2013

    Location: W Lothian

    Posts: 99,005
    I'm Grant.

    Default

    Sure there are a few guys here who have worked on these so hope you get an answer. Kinda sounds like the driver to me
    Regards,
    Grant .... ؠ ......Don't be such a big girl's blouse

    I've said it before and I'll say it again: democracy simply-doesn't-work
    .... ..... ...... ...... ................... ..... ..... ..... ..... .....
    FIIO K7 BT, M11 PLUS, BTR7, KA5 - OPPO BDP-103D - PANASONIC UB450 - PANASONIC 4K ULTRA HD TV - PIXEL 6 - AVANTREE LR BLUETOOTH - 2* X600 SOUNDCORE - HEADPHONES INCLUDE, FIIO, NURAPHONES', FOCAL, OPPO, BOSE, CAMBRIDGE, BOWER & WILKINS, DEVIALET, MARSHALL, SONY, MITCHELL & JOHNSTON - 2*ZBOOK'S- MERCURY BD ROM, ROON, QOBUZ, TIDAL, PLEX, CYBERLINK, JRIVER - MULTI HDD'S -

    Oh my god! There's nothing wrong with the bidet is there?

    “Nothing discloses real character like the use of power. It is easy for the weak to be gentle. Most people can bear adversity. But if you wish to know what a man really is, give him power. This is the supreme test. It is the glory of Lincoln that, having almost absolute power, he never abused it, except on the side of mercy".

    “You see these dictators on their pedestals, surrounded by the bayonets of their soldiers and the truncheons of their police ... yet in their hearts there is unspoken fear. They are afraid of words and thoughts: words spoken abroad, thoughts stirring at home -- all the more powerful because forbidden -- terrify them. A little mouse of thought appears in the room, and even the mightiest potentates are thrown into panic.”

    "You don't have free will. You have the appearance of free will.”

    “There's a war out there, old friend. A world war. And it's not about who's got the most bullets. It's about who controls the information. What we see and hear, how we work, what we think... it's all about the information!”


    ***SMILE, BE HAPPY***

  3. #3
    Join Date: Feb 2016

    Location: Melksham, Wiltshire

    Posts: 726
    I'm Peter.

    Default

    Many thanks Grant, I do hope someone can help. Just got this feeling of tripedation and terror about removing these bass units.
    Regards Peter

  4. #4
    Join Date: Mar 2012

    Location: Gloucestershire

    Posts: 3,377
    I'm Paul.

    Default

    I've worked on many of these, had to pull them apart and also recapped crossovers. The issue could be a few things. The bass double coupled cavity arrangement contains a reinforcing rod which reduces acoustic distortion and transfers energy to cabinet walls which are a particle board designed to damp unwanted resonance. If the woofers were removed for refoaming and this rod wasn't properly torqued (it either isn't tight enough or has worked loose) or the drivers properly aligned, then it can lead to audible distortion on bass.

    The other obvious issue relates to the refoaming. I always supply a printout of a rub and buzz test which confirms that there is no voice coil rubbing in operation when I refoam drive units. Most other specialists don't because they satisfy themselves by pushing down on the centre of the drive unit but this is not always a reliable method. If the bass voice coils(s) are rubbing it will cause distortion.

    Finally, if the crossovers were not recapped, these are getting on in age, and every single pair that I have tested has had the specifications of the electrolytics used drift so they were miles out of spec. In these complex multi-pole crossover designs, it is pretty critical to match like for like to very tight tolerances, as specified by KEF on their data sheets (available with a little searching) otherwise system efficiency will drop and crossover points will drift increasing out of band phase distortion.

    Of the above, my money initially would be on the reinforcing bar not being to correct torque given the woofers were presumably properly refoamed.

    If you can get the bass unit in question out and send it to me, I can test if for you FOC if you cover the postage costs. That way, at least it narrows things down. That is after checking that the rod itself is adequately torqued down!

  5. #5
    Join Date: Feb 2013

    Location: W Lothian

    Posts: 99,005
    I'm Grant.

    Default

    Was going to say they use a bar. Lol. sealed bass box is it Paul?

    Paul is your man for these
    Regards,
    Grant .... ؠ ......Don't be such a big girl's blouse

    I've said it before and I'll say it again: democracy simply-doesn't-work
    .... ..... ...... ...... ................... ..... ..... ..... ..... .....
    FIIO K7 BT, M11 PLUS, BTR7, KA5 - OPPO BDP-103D - PANASONIC UB450 - PANASONIC 4K ULTRA HD TV - PIXEL 6 - AVANTREE LR BLUETOOTH - 2* X600 SOUNDCORE - HEADPHONES INCLUDE, FIIO, NURAPHONES', FOCAL, OPPO, BOSE, CAMBRIDGE, BOWER & WILKINS, DEVIALET, MARSHALL, SONY, MITCHELL & JOHNSTON - 2*ZBOOK'S- MERCURY BD ROM, ROON, QOBUZ, TIDAL, PLEX, CYBERLINK, JRIVER - MULTI HDD'S -

    Oh my god! There's nothing wrong with the bidet is there?

    “Nothing discloses real character like the use of power. It is easy for the weak to be gentle. Most people can bear adversity. But if you wish to know what a man really is, give him power. This is the supreme test. It is the glory of Lincoln that, having almost absolute power, he never abused it, except on the side of mercy".

    “You see these dictators on their pedestals, surrounded by the bayonets of their soldiers and the truncheons of their police ... yet in their hearts there is unspoken fear. They are afraid of words and thoughts: words spoken abroad, thoughts stirring at home -- all the more powerful because forbidden -- terrify them. A little mouse of thought appears in the room, and even the mightiest potentates are thrown into panic.”

    "You don't have free will. You have the appearance of free will.”

    “There's a war out there, old friend. A world war. And it's not about who's got the most bullets. It's about who controls the information. What we see and hear, how we work, what we think... it's all about the information!”


    ***SMILE, BE HAPPY***

  6. #6
    Join Date: Oct 2012

    Location: NE England

    Posts: 4,173
    I'm Jez.

    Default

    It's extremely unlikely to be the crossovers first of all. Have you tried swapping the channels from the amp to rule that out? (again this is unlikely.
    Is the tie rod between the bass units loose? What about the plastic ring in the port? is it loose and rattling?
    More info on the nature of the distortion would be useful!
    Arkless Electronics-Engineered to be better. Tel. 01670 530674 (after 1pm)

    Modded Thorens TD150, Audio Technica AT-1005 MkII, Technics EPC-300MC, Arkless Hybrid MC phono stage, Arkless passive pre, Arkless 50WPC Class A SS power amp, (or) Arkless modded Leak Stereo 20, Modded Kef Reference 105/3's
    ReVox PR99, Studer B62, Ferrograph Series 7, Tandberg TCD440, Hitachi FT-5500MkI, also FT-5500MkII
    Digital: Yamaha CDR-HD1500 (Digital Swiss army knife-CD recorder, player, hard drive, DAC and ADC in one), PC files via 24/96 sound card and SPDIF, modded Philips CD850, modded Philips CD104, modded DPA Little Bit DAC. Sennheiser HD580 cans with Arkless Headphone amp.
    Cables- free interconnects that come with CD players, mains leads from B&Q, dead kettles etc, extension leads from Tesco

  7. #7
    Join Date: May 2013

    Location: surrey, uk

    Posts: 82
    I'm richard.

    Default

    Can't give any advice as the obvious reasons have already been explained.

    I know someone who used to own these speakers, and all Kef Ref speakers demand high quality amplification. Therefore would be good to know what amp the OP is using with them -- and what volumes he plays at. Clipping is a killer for speakers.

    Might be worth calling Kef and seeking their advice.
    Leema Pulse MKI; Electrocompaniet PC-1; PMC TB2i; Denon TU-260 MKII; Pro-ject Xpression 1 with ClearAudio Classic Wood cartridge

  8. #8
    Join Date: Mar 2012

    Location: Gloucestershire

    Posts: 3,377
    I'm Paul.

    Default

    Quote Originally Posted by struth View Post
    Was going to say they use a bar. Lol. sealed bass box is it Paul?

    Paul is your man for these
    It's a coupled cavity bass design Grant, with the bottom cavity port loaded.

    As Jezz suggests, it's unlikely to be the X-overs (but those will still benefit from being re-capped as almost certainly are adrift by now) and more likely the coupling rod assembly.

    The other issue, on bass is that the driving amp may be clipping as despite the claims, these demand a fair amount of current, especially in the bass region.

  9. #9
    Join Date: Feb 2013

    Location: W Lothian

    Posts: 99,005
    I'm Grant.

    Default

    Quote Originally Posted by Reffc View Post
    It's a coupled cavity bass design Grant, with the bottom cavity port loaded.

    As Jezz suggests, it's unlikely to be the X-overs (but those will still benefit from being re-capped as almost certainly are adrift by now) and more likely the coupling rod assembly.

    The other issue, on bass is that the driving amp may be clipping as despite the claims, these demand a fair amount of current, especially in the bass region.
    Knew they were coupled. Thanks for clarification.
    Regards,
    Grant .... ؠ ......Don't be such a big girl's blouse

    I've said it before and I'll say it again: democracy simply-doesn't-work
    .... ..... ...... ...... ................... ..... ..... ..... ..... .....
    FIIO K7 BT, M11 PLUS, BTR7, KA5 - OPPO BDP-103D - PANASONIC UB450 - PANASONIC 4K ULTRA HD TV - PIXEL 6 - AVANTREE LR BLUETOOTH - 2* X600 SOUNDCORE - HEADPHONES INCLUDE, FIIO, NURAPHONES', FOCAL, OPPO, BOSE, CAMBRIDGE, BOWER & WILKINS, DEVIALET, MARSHALL, SONY, MITCHELL & JOHNSTON - 2*ZBOOK'S- MERCURY BD ROM, ROON, QOBUZ, TIDAL, PLEX, CYBERLINK, JRIVER - MULTI HDD'S -

    Oh my god! There's nothing wrong with the bidet is there?

    “Nothing discloses real character like the use of power. It is easy for the weak to be gentle. Most people can bear adversity. But if you wish to know what a man really is, give him power. This is the supreme test. It is the glory of Lincoln that, having almost absolute power, he never abused it, except on the side of mercy".

    “You see these dictators on their pedestals, surrounded by the bayonets of their soldiers and the truncheons of their police ... yet in their hearts there is unspoken fear. They are afraid of words and thoughts: words spoken abroad, thoughts stirring at home -- all the more powerful because forbidden -- terrify them. A little mouse of thought appears in the room, and even the mightiest potentates are thrown into panic.”

    "You don't have free will. You have the appearance of free will.”

    “There's a war out there, old friend. A world war. And it's not about who's got the most bullets. It's about who controls the information. What we see and hear, how we work, what we think... it's all about the information!”


    ***SMILE, BE HAPPY***

  10. #10
    Join Date: Feb 2016

    Location: Melksham, Wiltshire

    Posts: 726
    I'm Peter.

    Default

    Dear Paul, many thanks for all that information. (I am reasonably near and live in Melksham Wiltshire). Unfortunately, I feel very nervous about taking these speakers apart without some hard and fast instructions but don't feel confident at all.

    I had looked at the reinforcing bar for tightness and it does appear to be very tight but as you say perhaps not correctly aligned (although all sounded fine initially).

    Limited information from the previous owner confirmed that the re-foam was carried our by Wembley Audio (about three years ago) together with some re-caps to the crossovers but I don't have any real detail other than all the speakers look like new.

    I really do appreciate your offer to look ant the units, all I have to do now is to get the things out for you to check.

    At the moment I can't even figure how to get the front unit off as it seems theres' more than just the visible hex bolts that hold this on..... nervous, to say the least.

    I don't sUppose you would take up the mantle ? Obviously not for free and you do sound like a bit of an expert in these matters. (No pressure... but I had to ask)

    At least I'm a step nearer knowing what it might be and would love to take up your offer to look.

    Best Regards Peter

+ Reply to Thread
Page 1 of 4 123 ... LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •