My new IRS Betas, and a few questions.

Discussion in 'Infinity Loudspeakers' started by dastro, May 17, 2018.

  1. dastro

    dastro New Member

    Messages:
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    I just picked up these one owner IRS Betas that are in fantastic condition. There isn't a nick or scuff to be found on any of the cabinets. They came in the original boxes and still have the original packaging, both sets of feet, Servo control, and all paperwork. The sound is beyond my expectations. At louder volumes, I've noticed a couple of things that need to be addressed, but at the price I paid I am not concerned.

    First, one of the woofers (non-servo) vibrates at louder volume. It may be a voice coil. Should I just replace it or try to have it serviced?

    Second, one of the EMIM/mid range units material seems to no longer be perfectly flat and at louder volumes you can see it vibrate. It sounds great, maybe a little louder than the other one but it can be adjusted with the controls.

    Lastly, both EMIT/rear tweets are partially taped over which results in very low output. I take it this was done by the previous owner. Any idea why? Too much treble wall bounce perhaps?

    Any advice would be greatly appreciated. IMG_2558.jpg IMG_2560.jpg IMG_2559.jpg IMG_2550.jpg IMG_2554.jpg IMG_2560.jpg
     
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  2. Silentnet

    Silentnet I like to keep my issues drawn... Subscriber

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    Just taped over? Not on the driver itself? Have you taken it off or are you concerned about damage?
     
  3. wlhd1610

    wlhd1610 Penny and her new friend Subscriber

    Messages:
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    There is a recent thread about factory applied scotch tape on some EMIT variations.
    I wouldn't touch it until you get some more advice.
    There are several akrs who rebuild the Watkins woofers also.

    Bob
     
  4. swechsler

    swechsler Frog Whisperer

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    I was going to say that the taped-over EMIT was done at the factory (they've done it on at least one other model, I forget which) but after looking more closely, I have my doubts - don't think they would have covered the EMIT logo. Surprisingly, I couldn't find a single picture on the web of the rear of the Betas other than the one you posted.

    Regarding the vibrating woofer, make sure the surround and dustcap are completely glued all the way around. Also remove the woofer and check the spider for the same thing. Luckily these woofers are still readily available on the used market (although repair is also a possibility, of course).

    It goes without saying that the L-EMIMs are pretty much impossible to obtain anywhere (they appear rarely on eBay at stratospheric prices). Take care of them.
     
    Last edited: May 17, 2018
  5. pauljh

    pauljh Active Member

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    The tape on the rear tweeter was probably part of the design. It shortens the length of the radiating line and widens the dispersion pattern. EMITs were normally installed vertically and had wide horizontal dispersion and limited vertical dispersion. When installed horizontally, they would have good vertical dispersion and bad horizontal dispersion. The tape wold improve the horizontal dispersion pattern.

    The UHF tweeter in the RS1 was modified this way at the factory.
     
    Last edited: May 17, 2018
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  6. dastro

    dastro New Member

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    I just found and bought an EMIM on eBay for $199, which doesn't seem bad. I guess it's time to start stock piling. Thanks for all the advice.
     

     

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  7. swechsler

    swechsler Frog Whisperer

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    The regular EMIMs are still pretty easy to find (although I'm not sure if they're all the same or if there's more than one version).
     
  8. StimpyWan

    StimpyWan AK Subscriber Subscriber

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    I'd check with Bill LeGall, at Millersound, about repairing the woofer. I'd ask him about the wrinkled EMIM too, as Bill is an Infinity guru. He has IRS-III's and IRS-V's, to prove it. Both of which he personally rebuilt.
     
  9. dastro

    dastro New Member

    Messages:
    19
    Thanks, I'll do that right now. The EMIM I just purchased I just realized has different lead spacing.
     
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  10. pauljh

    pauljh Active Member

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    Yes, the Betas used a newer EMIM. You probably can't use the earlier version.
     
  11. StimpyWan

    StimpyWan AK Subscriber Subscriber

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    Do they use the same diaphragms? Could they be swapped? Definitely, with the use of a jig.
     

     

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  12. StimpyWan

    StimpyWan AK Subscriber Subscriber

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  13. pauljh

    pauljh Active Member

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    The
    The spec sheets show the same part number for the EMIM diaphragm. Which is weird, as the diaphragm controls the spacing of the terminals. Evidently, the rev D EMIM differed only in case/magnet structure .
     
    Last edited: May 17, 2018
  14. okeeteekid

    okeeteekid Well-Known Member

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    Here are a few pics of the rear tweeter that I found, no tape on them but don't know if they all came like this, the one pair I auditioned a few years ago did not have any tape on it, I remember because one of the rear tweeters was blown. 9339-6.jpg IRS_Beta17.jpg
     
  15. pauljh

    pauljh Active Member

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    Location:
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    I looked around for some contemporary reviews that show the rear of the mid/high panels. I found one, and there wasn't any tape. So, I think you can feel safe trying it both ways. A previous owner may have been experimenting; it may be room specific, i.e. tamping down highs when the speakers were placed in front of windows.

    But regardless if this was done at the factory or not, what I said about dispersion was correct . :)
     
    Last edited: May 17, 2018
  16. slimpikkins

    slimpikkins Super Member

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    Looking at that rear tweeter are the traces hanging out of the dispersion slots? If so that may be the issue. You can swap out that diaphragm then try it with and without the tape.
    The Emim diaphragms can be swapped as well. The clam can be altered for the different position of the post. Issues I’ve seen with emims are: broken or wavy diaphragms, flaking magnets on the newer ones, the magnets setting crooked on the frames causing distortion. These are all discussed on this sight. For flaking magnets you can buy all new magnets on eBay and remove the old, clean the frames and glue the new ones on.
     

     

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  17. dastro

    dastro New Member

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    Thanks for the advice. Yes, there are traces hanging out of each rear tweeter. Is eBay the best source for replacement diaphragms? I purchased another EMIM assembly on ebay. It sounds like I have lots to learn.
     
  18. imral3

    imral3 Super Member

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    :eek2::eek2::eek2: Awesome and good luck!!!
     
  19. pauljh

    pauljh Active Member

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    Location:
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    EMITs are easy to fix:

    Quoting myself:

    490125 is the rectangular EMIT with the thick magnet structure. 490126 is the same except for a round faceplate. Later versions of 490125 were labled 902-5086. Later versions of 490126 were labled 902-5023.

    490123 is the rectangular EMIT with the thin magnet structure. As above, 490124 is the thin magnet structure with a round faceplate. Later versions of 490123 were labeled 902-2252. Later versions of 490124 were labeled 902-3082.

    They all use the same diaphragm.
     
  20. slimpikkins

    slimpikkins Super Member

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    ^^^Paul is right on.
    Getting the emims and emits apart require a simple jig to separate the clam with out the magnets clicking together and smashing the diaphragm between them. There are lots of threads with pictures. I just use a piece of wood and long finishing nails which can fit through two diagonal tapped holes on the emits and use the mounting holes (all four) on the emims. Emits you just remove two screws which are diagonal, place it over the nails, hold it down and remove the other two screws. Emims you just place the drivers mounting holes on your nails, hold it down and carefully remove the six outer screws. Do not remove the four inner screws as they hold the frames on to the clam.
    Btw great job buying those speakers. Congratulations!
    Jim
     
    Last edited: May 18, 2018

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