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Quantum 5 pedestals: Dimensions?

Discussion in 'Infinity Loudspeakers' started by gustavpaula, Jun 29, 2018.

  1. gustavpaula

    gustavpaula New Member

    Messages:
    4
    Hello everyone. I have owned a pair of Quantum 5 for 20 years, they are lovely speakers, especially the EMIT tweeters. Because I don't have the original Infinity sheet metal pedestals, I had the speakers on tennis balls, bricks, whatsoever for years. Now, after refoaming (for the 2nd time) and restoring the electronics I decided I should put them on their proper pedestals.
    I tried to figure out the dimensions from the few photos I found on the Internet. But there is so much uncertainty left that I thought I should ask "the experts" for help.
    Here I am, hoping someone can help. Is anyone owning these pedestals willing to take a few measurements?
    I would need to know dimensions a, b and angles alpha and beta. And of course the thickness of the sheet metal.
    Once they are finished I will post pictures of them!
    Thank you.

    Regards,
    Gebhard
     

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  2. 7.62

    7.62 Gearhead Subscriber

    Messages:
    1,613
    Location:
    Las Vegas
    You surely like your 5's, while I don't have original stands and I'm no help for you I sent you a PM.
     
  3. goat67

    goat67 AK Subscriber Subscriber

    Messages:
    4,822
    Location:
    Twin Cities MN
  4. chef free

    chef free AK Subscriber Subscriber

    Messages:
    2,254
    Location:
    Hayward, Ca
    I have a pair of Qb with those stands. They are not strong enough. The speakers bounce on them, I can't imagine how they would sag under the weight of a Q5...
     
  5. goat67

    goat67 AK Subscriber Subscriber

    Messages:
    4,822
    Location:
    Twin Cities MN
    They work fine with the Q5s the speaker just does not lean back as they do when used on my QAs. They do "bounce" but only if you initiate it not under normal operation.
    So if you build them you can make sure they will handle the weight.
     
  6. gustavpaula

    gustavpaula New Member

    Messages:
    4
    Thank you everyone for your comments and help.
    I am also in contact with "elnaldo" who seems to be the only forum member who actually has the stands made to measurements provided by "goat67".
    I know that discussion about the thickness of the sheet metal has been going back and forth but as no one of those who own a pair of original stands took the effort to measure the thickness with a sliding caliper, the only thickness actually tested is 5 mm (because "elnaldo" made his 5 mm). He reported they do allow his Qb to slightly rock back and forth but do not "sag". I don't know about the weight and size of the Qb cabinets compared to the Q5s which weigh 20.5 kg. From "elnaldo"'s album http://audiokarma.org/forums/index.php?media/albums/another-infinity-back-to-rock.662/ they seem to have the same size and loudspeakers as the Q5.
    So, I used most of his dimensions and went for a 94° angle between foot and leg. That'll compensate for the Q5s weight.
    To be on the safe side, I also made a little test before deciding on the sheet metal thickness. The stands are 12" wide with the cabinet spreading over the complete width. I put together a "slice" with all original dimension which has 1/15 of the original width, i.e. a "stand" made from a 5 x 20 mm steel and a wooden board of the dimensions of a cabinet side. Weight of the board is 1/15" of the loudspeaker ( ~ 1.37 kg).
    IMG_20180714_105501770.jpg
    Sag is next to zero.
    goat67, I assume there is a slight issue with your Q5 stands.
    http://audiokarma.org/forums/index.php?attachments/q5_2-jpg.198546/
    From that picture it looks like the angle between foot and leg is just slighty above 90° but the issue seems to be that the angle between the cabinet underside and the leg is less than 90°. Maybe the connection between the speaker and the stand (3 screws) is loose or the stand is not fully seated on the speaker's back panel? Hard to tell from the pictures...
    The Q5 sales brochure (pic in my original post) clearly shows the Q5 leans backwards.

    And elnaldo's stands also make the speaker lean backwards:
    http://audiokarma.org/forums/index.php?media/stand_p1070043.12000/

    Anyway, thanks everyone.
     

     

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  7. gustavpaula

    gustavpaula New Member

    Messages:
    4
    Hello. The project is finished now and I wanted to let the forum know how everything worked out. Maybe this is of help for someone in the future also wishing to reproduce the original stands.

    It took a while to find a company willing to make the stands to my specifications. ;-)
    They finally turned out quite nice. I rounded the edges with a file and spray painted them in matte black over a base coat (usingspray cans).

    Elnaldo's drawing had some measurements different to what I came up with so I changed these:
    Infinity pedestal diagram.gif
    I think I got the upper part which screws to the cabinet pretty identical:
    Quantum 5 pedestal reproduction 2.jpg
    This is what it lots like overall. I tried to create the same perspective but wasn't too successful:
    Infinity Quantum 5 pedestal reproduction.jpg
    The tilt looks different but bear in mind the perspective is slightly different.
    Re. sheet metal thickness, I had made a few test in advance to see how much the stand would bend under load and chose 5 mm for the sheet metal (actually not too much choice anyway). Unloaded the angle between foot and leg is 5°, loaded is approx. 4°. When measured at the front of the cabinet, this means the distance to the foot changes from 29.3 cm to 28.8 mm. You can barely notice it.
    Quantum 5 pedestal reproduction 3.jpg
    So that's about it. Once again thank you to the forum and those that contributed. This was a fantastic experience about how people are willing to help each other across thousands of miles/kilometers without knowing each other. ;-))

    gustavpaula.
     
  8. goat67

    goat67 AK Subscriber Subscriber

    Messages:
    4,822
    Location:
    Twin Cities MN
    Those look nice. What is the measurements from the bottom front of the speaker to the floor and from the rear bottom of the speaker to the floor. I do not see it having the seam back lean as the brochure.
     
  9. gustavpaula

    gustavpaula New Member

    Messages:
    4
    Those measurements are 29 cm resp. 23.5 cm on the "better" of the two. "Better" because the two stands are not 100% identical even though the worker and myself tried hard but because of the manual process it is not possible to get all the angles identical to a tenth of a degree. And that sums up to the differences.
    I made another picture, this as good as it gets with my equipment. I noticed that I seem to have a slightly different version of Quantum 5 than is pictured on the official leaflet. The bass speaker baffles are not coated with the black shiny stuff and the grille seems to have a bigger distance to the front of the cabinet than on mine.
    Infinity Quantum 5 pedestal new.jpg
    And it is true, the tilt on the stands on the leaflet is more pronounced than on mine. I noticed that in advance but figured it would be impossible to reproduce the different tilt of the stand and the cabinet truthfully and I also wasn't sure whether that was intentional (given the fact that various photos on the Internet do not show this difference). So I decided that I would aim for the same tilt for the stand and the cabinet.
     

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