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Quantum Line Source database ~ QLS1

Discussion in 'Infinity Loudspeakers' started by jimreeves, Aug 12, 2011.

  1. jimreeves

    jimreeves Poopy & Me Subscriber

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    I'm no expert, but have archived a number of interesting links for the Infinity QLS1 that may be of some use if you get the chance to own a pair.

    If you come accross other links please add them! :thmbsp:

    The Quantum Line Source was Infinity's largest speaker of 1976, a 4-way 17 driver tower consisting of 8 front firing EMITs (Electro Magnetic Induction Tweeter) + 1 rear firing EMIT, 6 soft dome midrange drivers, 1 mid-bass coupler driver in a tube TL alignment and 1 Watkins 12" dual-drive woofer. According to Infinity's literature of the time, the QLS uses a phase-aligned passive crossover network (see the first link below) and is (was) capable of 18Hz to 32KHz +/- 3db response. Several versions were produced with black or veneer baffles, paper or poly Watkins woofer cones and possible variations of the Philips AD5060/W8 mid-bass coupler.

    The intent of this thread is to provide information for the enthusiast who has the opportunity to own and refurbish these fine speakers.

    [​IMG]

    Photo Courtesy Bobby Shred's QLS1 webpage

    Infinity-Classics.de Quantum Line Source website:
    http://www.infinity-classics.de/mod...ne-Source-QLS-1/body_quantum_line_source.html

    Bobby Shred's Quantum Line Source website:
    http://bobbyshred.baberuthband.co.uk/infinity/qls.html

    Cdfac's "Running a crossover rebuild parts list by ya"
    http://www.audiokarma.org/forums/showthread.php?t=215773

    Cdfac's "Keeping another pair of QLS1's alive"
    http://www.audiokarma.org/forums/showthread.php?t=166374

    Ken Boyd's "Best way to bi amp my QLS1's?"
    http://www.audiokarma.org/forums/showthread.php?t=269529

    Thedelihaus's "Watkins woofers, what's so special about them?"
    http://www.audiokarma.org/forums/showthread.php?t=115775

    Geoff727's "Watkins woofer white paper"
    http://www.audiokarma.org/forums/showthread.php?t=276032

    Banffskiing's "QLS1 restoration project"
    http://www.audiokarma.org/forums/showthread.php?t=71339

    Meridian's "Watkins woofers in the Quantum line"
    http://www.audiokarma.org/forums/showthread.php?t=87469

    JT45's "Help restoring QLS1's"
    http://www.audiokarma.org/forums/showthread.php?t=317580

    JT45's "Infinity QLS1 recapping?"
    http://www.audiokarma.org/forums/showthread.php?t=341905

    JT45's "Infinity QLS1 recapping with pictures!"
    http://www.audiokarma.org/forums/showthread.php?t=387573

    Bucky Badger's "Opinions on Infinity QLS speakers anyone?"
    http://www.audiokarma.org/forums/showthread.php?t=383963

    Kencat & Charivari's "EMIT tweeter diaphram repair how-to"
    http://www.audiokarma.org/forums/showthread.php?t=65571

    JT45's "EMIT repair with pictures!"
    http://www.audiokarma.org/forums/showthread.php?t=387976

    JT45's "cleaning those pesky pots on QLS1's"
    http://www.audiokarma.org/forums/showthread.php?t=385996

    JT45's "Infinity Quantum Midrange repair with pictures!"
    http://www.audiokarma.org/forums/showthread.php?t=398687

    Mid-Bass coupler AD5060/W8 specs
    http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=4320

    Link to Rick Cobb's foam surrounds for Watkins 12" woofers (no affilliation), recommended
    http://www.ebay.com/itm/BEST-Speake...pt=Vintage_Electronics_R2&hash=item519f4f259b
    or contact him at rcobbattampabay.rr.com with your needs
     
    Last edited: Nov 29, 2018

     

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  2. SicMan

    SicMan Fire up those speakers Subscriber

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    Good post Jim
     
  3. jimreeves

    jimreeves Poopy & Me Subscriber

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  4. tubed

    tubed Lunatic Member

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    Nice read about line source in addition to the "previous" article on magnetic planars.
    Kudos on organizing the QLS links!:thmbsp:
    Now I'm off to finish pulling(literally) the crossover boards out of my QLS:)
     
  5. goodolpg

    goodolpg Just an old fart trying to help. Subscriber

    Nice of you to put all those links together.:thmbsp:
    I wish I had a pair of QLS1's to put the info to use.
     
  6. jimreeves

    jimreeves Poopy & Me Subscriber

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  7. jt45

    jt45 AK Subscriber Subscriber

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    Outstanding jim ! they should make this a sticky.
    This will help alot of folks in the future, thanks a bunch.
     
  8. Arkay

    Arkay Lunatic Member

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    Thanks for posting this. I'm pleased to own QLS-2s, and kick myself sometimes for passing up on a pair of QLS-1s when I was just getting into vintage gear. If another pair of QLS-1s comes along, I'll upgrade! :yes: :D Much of the information applies to either/both models.
     
  9. jimreeves

    jimreeves Poopy & Me Subscriber

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    Added JT45's excellent threads on recapping and EMIT repairs with pictures. Thanks JT45!
     
  10. Bucky Badger

    Bucky Badger AK Subscriber Subscriber

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    As stated before, good job on pulling the links together and for all your info on these wonderful speakers.
     
  11. jimreeves

    jimreeves Poopy & Me Subscriber

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    Added JT45's "Cleaning those pesky pots on QLS1's", another great post JT!

    (you guys have to keep me 'posted' on posts so I can add them here!):)
     

     

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  12. wwiztab

    wwiztab Active Member

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    Help with inside cabinet dimensions

    I've waded through all the QLS1 links Jim has attached here and I can't find anything about interior dimensions of the cabinets. I'm actually going to build my own cabinets and want to make sure I get the correct space for the woofer. I imagine the mids and tweets were isolated from the woofer. Some inside pictures would help too.

    I would really like the same for Quantum 2's if possible. Not sure I have the room for QLS1's right now so I most likely will build Q2's. Eventually though I will build QLS1's.

    Thanks for any info.
     
    Bobbyd38 likes this.
  13. jimreeves

    jimreeves Poopy & Me Subscriber

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    The Infinity-Clasics site has the dimensions for all the Quantum series in centimeters...
    http://www.infinity-classics.de/models/Quantum-series-1976/index-Quantum.htm
    The left-hand column links take you to the various models.
    Just divide those dimensions by 2.54 for inches, multiply the 3 dimensions together, then divide by 1728 for square feet. The cabinets of my QLS1's have 1" thick walls so you'd want to subtract that from all dimensions for interior volume.
     
  14. wwiztab

    wwiztab Active Member

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    Location:
    Northern Colorado
    I just wanted to be sure the the woofer did use the entire cabinet.

    That's a very large amount of cubic feet for that woofer in the QLS1 compared to the Q2, 1.5, 2.5 and 4.5. What is the optimal amount of cubic feet for the Watkins woofer? In other words, which of the Infinity models cubic feet measurements should I use for best sound using the Watkins woofer?

    Since I am building these cabinets I can modify the design and still end up with a cabinet that looks like a QLS1 or Q2 but maximizes the performance and sound of the woofer.
     
  15. jimreeves

    jimreeves Poopy & Me Subscriber

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    Aside from the woofer basket, crossover and mid-bass coupler transmission line tube the Q1 cabinet is wide open, approximately 5 cubic feet interior. Mine are fully stuffed with fiberglass, which I understand makes the woofer 'see' a larger cabinet.
    I haven't seen a post by Bill Watkins that says what the optimum size enclosure is. I'm perfectly happy with the bass extension and control from my Q1's and I've read that Q2 owners are as well. So I would imagine either size would work fine, just adjust the dual drive circuit to match the size you choose.
     
  16. bobrown14

    bobrown14 Super Member

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    I think I read somewhere Bill suggested the Watkins woofer was best sounding with the QLS-III cab...

    Cheers,
    Bob
     
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  17. Ken Boyd

    Ken Boyd AK Subscriber Subscriber

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    I read that link on Line Source speakers and it helped explain it in an easy to understand explaination. But I wonder just where the rear drivers of the QLS line up might interfer with the concept of the line source design. Since in the explaination of the line source advantages it tells the story of confusing the ear by reflecting sounds from walls and floors. Since the QLS uses rear firing drivers for the EMIT and mid bass it kind of screws up the concept of a true line source. Mcintosh made some pretty nice line sources which do not use di-pole designs, I wonder if they sound better.
     
  18. jt45

    jt45 AK Subscriber Subscriber

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    I thought the rear Emit and Midbass coupler port were mainly to increase the depth of the soundsage, at least that's what Iv'e been told by someone who used to sell them.

    Of course they would set them up several feet out onto the room to Demo them. Ive never had the chance to hear mine set up set up that way in a dedicated room setup.
    I would think it could have a big impact on how the QLS1s sound considering their design. Quite frankly I think they really need a large space to open up. I just dont have a room big enough to do them justice.
     
  19. jimreeves

    jimreeves Poopy & Me Subscriber

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    I would imagine that the rear emit and mid-bass, out of phase as they are with the line source, add presence when the cabinets are set up correctly in the room. Like JT, it's difficult to set mine up properly, but I haven't noticed interference per se.
    Even so, I would think that a line source would be less effected by a "sorta di-pole" than a point source. Maybe?
     
  20. jimreeves

    jimreeves Poopy & Me Subscriber

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    Added current 5/25/12 link to Rick Cobb's excellent foam surrounds for refoaming Watkins woofers. It's essential to use the proper foams to preserve the LF response you expect from these woofers. Be sure to check with him if you're unsure which foams you'll need (the paper cone Watkins may require angled inner edge foams, the poly cones use flat edge foams). Just insert @ instead of at in the address above. Kits come with 2 foams, special glue and a 30Hz test tone CD for centering the voicecoil during glue up.
    No affilliation, just another satisfied customer!
     

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