Replacing The Big Electrolytic Caps In Quantum 2

Discussion in 'Infinity Loudspeakers' started by MoreBeer, Dec 6, 2017.

  1. MoreBeer

    MoreBeer Money + Money =More Money

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    I rebuilt the crossovers in my Q2's and replaced everything except the two big electrolytic caps and the inductors. I also wound up keeping the old pots and just cleaning them as the new pots I found were a little big as a drop in without some mods. They old pots now work and spec fine.

    Upon testing, although the drivers are out of the cabs, connected but just sitting on top the cabs, I can tell the rebuild is going provide a huge improvement in sound. I also checked everything using many specific frequency tones generated from audacity with a small amp connected to a laptop and everything checks out. Tested the crossover points with a multimeter that can read Hz. I did find out some interesting things when doing this.

    Anyhow, I'd like to dump the old big electrolytic cans as well. Since identical replacements don't exist, I was thinking of using Bennic electrolytic caps. A stack using a 1000 and 100 for the 1100uf cap and a 500 and 200 for the 700uf cap. These are cheap, although they are new, and the new caps which replaced the old for the other drivers did make a big difference, even if the old caps did read close to spec.

    Any thoughts on this appreciated.
     
    Last edited: Dec 6, 2017
  2. ivandezande

    ivandezande Super Member

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    1,066
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    minnesota
    There's lot of opinions on replacing these special caps on this subforum, a lot of people think it won't do anything in terms of sound or that power handling won't be the same. I think for one, judging on how these caps measure once taken out, that it's well worth it, and the need to parallel the new caps actually helps the power handling case. Bennic looks good, you probably know but Parts Express has some good cheap electrolytic that I'm sure are rebadged Bennic's too. You could always toss a bypass Dayton poly on the stack too for good measure. Good luck, and I' sure whatever you do will be a great improvement.
     
  3. MoreBeer

    MoreBeer Money + Money =More Money

    Messages:
    359
    Location:
    New Jersey - "Gods Country"
    Although the old big electrolytic cans measured okay, I'm leaning towards replacing them. About the only thing I'm annoyed with is I was about to put the crossovers back in tonight and start work on refinishing the cabs. Not a major refinishing job...just a little steel wool here and there followed by Howard Restore-A-Finish (this stuff is good btw) and some polish.

    Oh well, what's a few more days. Plus the crummy $50 to replace the big cans will be worth it knowing that everything that could be bad or not possibly working properly is new.

    Total cost so far to rebuild-replace things along with these caps is about $450 and this includes new midrange and midbass drivers which sound dramatically better, cleaner and slightly louder than the 40 year-old original drivers. HUGE difference in the midbass driver...like night and day. Old driver sounded like mud next to the new one.

    I only used Bennic as a reference. I ordered all the crossover parts and assorted garbage from Parts Express. The only thing they didn't have was the 25 watt resistors. Not many sources for those although Madisound has them.
     
    Last edited: Dec 6, 2017
  4. slimpikkins

    slimpikkins Super Member

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    ^^^how about some pics. Which driver did you replace the mid bass with?
     
  5. MoreBeer

    MoreBeer Money + Money =More Money

    Messages:
    359
    Location:
    New Jersey - "Gods Country"
    I replaced the mids and midbass drivers with the following and both were a major improvement.

    Tang Band W4-656SC 4" Midbass Shielded Driver
    Dayton Audio DC50FA-8 Classic Series 2" Dome Midrange
     

    Attached Files:

  6. MoreBeer

    MoreBeer Money + Money =More Money

    Messages:
    359
    Location:
    New Jersey - "Gods Country"
    Cabs all cleaned up and refinished. Primarily scrubbing down with extra fine steel wool to smooth them out and to remove all the years of grime, stains, etc. This was followed by rubbing down twice with Howards mahogany wood finish restorer.

    Tomorrow will be giving them a deep polish and the cabs should look almost new. I even repaired the grill covers and replaced the plastic nubs which hold the grill cover in place with velcro. Those little plastic pins were basically gone. This weekend the drivers go in and I'll keep my fingers crossed they sound great again.

    cabs1.jpg
     
    Last edited: Dec 8, 2017
  7. slimpikkins

    slimpikkins Super Member

    Messages:
    1,535
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    Those cabinets are beautiful, nice work!
     
  8. Bucky Badger

    Bucky Badger For he knew not his hole from an ass in the ground Subscriber

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    I agree. Very nice job indeed.
     
  9. Rex81

    Rex81 AK Subscriber Subscriber

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    Just be sure to keep the original drivers around. In the event you want to sell them, you'll get more $$$ with the originals in place.
     
  10. MoreBeer

    MoreBeer Money + Money =More Money

    Messages:
    359
    Location:
    New Jersey - "Gods Country"
    Yes, I'm keeping the old drivers. Although not likely selling the Q2's, especially after all the work. Probably have at least 50 hours in these when factoring in everything. It was worth the effort...they both look and sound great now.
     
    Rex81 likes this.
  11. tubed

    tubed Lunatic Member

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    Ak'er extraordinaire Echoworks declares the big caps to be of very good quality.
    So at the time, I left them on the board of my Q2's but decided to stack some Bennics on the QLS-1s as those crossover boards looked like they went through Hurricane Harvey.
    I'm curious, was it touch and go as to how well the Dayton mids covered the square holes:idea:
    Picture 821.jpg
    Picture 2191.jpg
     
  12. AirCombatGuy

    AirCombatGuy New Member

    Messages:
    15
    Location:
    Hudson Valley NY
    Just curious if you replaced any of the wiring to the drivers. I was in my Q2's recently and was very surprised at how lightweight the wiring was, especially to the mid-bass coupler.
     
  13. MoreBeer

    MoreBeer Money + Money =More Money

    Messages:
    359
    Location:
    New Jersey - "Gods Country"
    I left the wiring. Internal speaker wiring, especially to the drivers other than the woofer carries very little current for a short distance. 20 gauge wire is fine for this. Even the woofer wiring can be left. No reason to change it unless its obviously bad for some reason.
     

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