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Current Market Price? JR149s

Discussion in 'classic' started by RobJ, May 10, 2018.

  1. Stunsworth

    Stunsworth pfm Member

    JMH was also also a Belt fan. I think he once wrote that he listened to his speakers with the drivers pointing away from him rather than towards him.

    Naturally in those days having a phone in the room ruined the sound.
     
  2. Tony L

    Tony L Administrator

    Wiring a tweeter “out of phase” is not at all unusual in many speaker designs as some crossover slopes shift phase by 180 degrees or more, plus in a conventional flat baffle wooden box the drivers are not time aligned as the bass unit motor is a inch or two behind the tweeter. The important thing when replacing or repairing a speaker is to get it back as it was designed.

    PS The classic alnico Tannoy dual concentrics (Silvers, Reds, Golds, HPDs etc) all have the treble and bass unit at opposite phase in order to time/phase-align the horn compression driver which is right at the very back of the huge magnet well behind the bass unit. It is rather more complex than that as there is a fairly compilated crossover to be factored-in with all its phase shifts, but at the most basic level for a positive input the bass unit moves backwards and the compression driver forward.
     
  3. Martyn Miles

    Martyn Miles Trade: MGM Audio

    Peter Belt wasn't all bad. I owned a pair of his PWB Electrostatic headphones. Very good they were, too.
     
  4. jfs

    jfs pfm Member

    Partly true, the T33 - SP1074 did not utilise ferrofluid, however the T33 - SP1191 ( developed for the 104/2 ) did utilise ferrofluid.
    With Kef it's always important to use the SP coding rather than speaker 'generic' name e.g. B200, B110, T33, etc. The T27 most definitely did not use ferrofluid.
     
  5. Martyn Miles

    Martyn Miles Trade: MGM Audio

    Is ferrofluid used universally these days ?
     
  6. davidsrsb

    davidsrsb pfm Member

    Less often now as people have got wise to its short lifetime. Many shops must have been caught out with it sticking in display stock.
     
  7. ToTo Man

    ToTo Man the band not the dog

    They can't be very good salespeople then if they are lumbered with stock of loudspeakers for so long that the ferrofluid used in the drive units hardens!
     
    Last edited: May 17, 2018
  8. davidsrsb

    davidsrsb pfm Member

  9. Martyn Miles

    Martyn Miles Trade: MGM Audio

    I don't have to worry about things like ferrofluid, thank goodness. My BC1s have lasted decades without it...
     
  10. RobJ

    RobJ pfm Member

    Great thread. My 149s haven't turned up yet and while I bought a JVC AX4 I made the mistake of testing it on my teenage daughters TD160/A60 system. It's got an MC cart and the MC setting on the AX4 really made a difference. Now they want the AX4 leaving the A60 for the system the 149s will go with! I believe that's not a bad match, it's a small room.

    I do have a couple of newbie questions;

    How easy is it to recap these things? I have little soldering experience but can turn my hand to most things. Do you need special solder? Or should I be paying someone to do that?

    Also, how can I test that the drivers are in spec? I've read Tonys 'revisiting the JR149' thread with interest but most was above my head. I don't mind purchasing additional equipment to test them if it's not too expensive. I'm really wanting to get them back to spec if possible and finding how far they are out would be the first step.
     
  11. Tony L

    Tony L Administrator

    It is really easy assuming you can solder. Buy the Falcon cap set linked upthread and my advice is work around one crossover at a time, one capacitor at a time as it is easier to make sure you are putting the right one in the right place. Loudspeaker caps are bipolar, so they don’t need to go in a particular way round. The crossover obviously needs to be removed, and assuming you have the same version as me it is an easy job - gently pull the white plastic connector up to release the cabling, undo the center bolt thing, and then give the crossover a gentle rotational jiggle as there is also Blu-Tac like stuff holding it down that will need to be freed before it can be removed. Just be gentle as you don’t want to crack anything. I’d also go fairly easy when desoldering so as not to over-heat the board as you don’t want to lift any tracks, though I had no issues at all.

    If they sound good and sound the same as one another I’d assume they were ok. If when panning pink noise or a good mono recording between them the sound markedly different you may well have an issue. I’d recap them first and set the tweeter balance pot on the crossover exactly mid-way in its travel (it has very likely been moved by someone over the years, though it might be worth noting where it was set, mine were up full for some reason!).

    Basically they should sound superb, mine surprise/shock pretty much everyone who hears them. If they sound thin, shouty, dull or whatever then you may have a problem.

    PS They like to be fairly close to a back wall on decent stands.
     
  12. davidsrsb

    davidsrsb pfm Member

    Measure the speakers with REW with a PC gooseneck microphone before you make any changes. The Left and Right should be matched.

    The original crossovers used 60/40 solder, so easy to work on.
     
  13. Tony L

    Tony L Administrator

    Yes, just use standard solder. I don’t like the lead-free junk available now so I’d recommend the old style 60/40 stuff. It is still available and as I do so little soldering I’m not going to make myself ill or anything. It just seems to flow far better.
     
    RobJ likes this.
  14. RobJ

    RobJ pfm Member

    That's great, many thanks. I'm going to enjoy this refurbishment.
     
  15. davidsrsb

    davidsrsb pfm Member

    I have never come across a safety problem with the reel type solder, even the ladies working on production lines using it 6 days a week.
    There seem to be more problems with lead free due to the higher temperature releasing more fumes from flux and plastics.
    There might be risks with solder paste, wear gloves handling that.
    If there are hazards with 60/40 solder, it is in the disposal, especially if incinerated, but my own suspicion is that the ban was just to be seen doing something. The organic lead in petrol is a completely different issue.
     
  16. Tony L

    Tony L Administrator

    The H&S line is inhalation of fumes carries some risk, there are guidelines that can be googled-up from all over the world. For hobbiests such as us I suspect it is of absolutely no concern (e.g. I probably only solder something every couple of months). I’d not want to work full-time on an assembly line using lead solder, lead poisoning is not fun. I’ve not found anything indicating a statistical risk factor though. I’m certainly not shifting to lead-free!
     
  17. Martyn Miles

    Martyn Miles Trade: MGM Audio

    I use Multicore solder from the late ‘80s, given to me by the Head of Electronics in the University Dept. where I
    worked. They had to go over to more environmentally friendly types.
    It flows beautifully. I wouldn’t want to use anything else.
     
  18. 337alant

    337alant Negatively Biased

    My JR-149s have a couple of stripped threads in the alloy face plate for the Bass driver 's.
    Any recommendations in the best repair method ?
    Should I just glue a nut on the back?
    Another question should the drivers have gaskets as mine didn't
    Alan
     
  19. Tony L

    Tony L Administrator

    I’d have thought gluing a nut on would be fine. They should have gaskets, the ones that actually come with the Kef units (at least mine did).
     

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