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Stimpy

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  1. AR MGC-1

    in Acoustic Research

    Posted

    12 hours ago, Pete B said:

    I'm not sure if I've ever seen the XO schematic.

    You might ask Ken Kantor, or some of the experts on here.  Please post it if you

    find it.

    Unfortunately, I've read comments from Ken, where he no longer has crossover schematics either.  So, unobaitium, at this point, short of an MGC-1 owner tracing out the wiring?

  4. At 9 lower midrange reconed

    in Acoustic Research

    Posted

    1 hour ago, Kal87bmw said:

    Thanks for the help you guys  it’s nice to have this site  not sure how to post pictures but I’ll try

    Pictures will help, as I'm a little unclear as to what's been done to the LMR?  Were the 8" woofers really re-coned, or just refoamed, with incorrect surrounds?  And I would think the cloth surrounds should be replaced, as they won't exhibit the correct compliance, of proper foam surrounds.  Incorrect surrounds can easily be removed and replaced with the correct foams. 

  7. At 9 lower midrange reconed

    in Acoustic Research

    Posted

    13 minutes ago, DavidR said:

    From what I remember the difference is more cosmetic. The 200044 became the AR replacement for the 200028 and 200032.

    The 20028 mid had more ferrofluild, than the 200044 and 200032.  The 200028 had ferrofluid on both sides of the voice coil, while the 44 and 32 used fluid only on one side.  This slightly altered the resonance frequency, allowing the 44 and 32 to play lower in frequency, than the 28.  That allowed the 200044 and 200032 mids to better blend with the woofers, in a 3-way design.  Being a 4-way, the AR-9 didn't require the 200028 to respond as low, hence the higher resonance, and hopefully, better power handling, with more ferrofluid in the voice coil gap .

  9. AR Midrange 200032 modified as 200044

    in Acoustic Research

    Posted

    1 hour ago, Kal87bmw said:

    Will the 200044 work in the ar 9 even though there not correct I just got a pair of 9s and that’s what’s in there or should I try to find the 28s. Thanks for all the great insights 

    The 200044 domes will work fine in AR-9's.  The 9's, with their LMR woofer, don't require the UMR bandwidth, that's required for 91's, 92's, or 58S's.  So, you're good as is.

  10. AR 58s to AR 91 Board Swap

    in Acoustic Research

    Posted

    1 hour ago, lARrybody said:

    Now my banana plugs fit all the way in. The new switches have longer levers and a nicer throw.

    Very nice job.  Well done.  And I like those new binding posts too.  I use them on my refurb's.  Also, which switches did you use?  I'd like to try those.

    Thanks.

  11. AR 9. Basic re-capping advice.

    in Acoustic Research

    Posted

    I agree with David.  Give the new caps some playing time, in order to settle in.  At least 10 hours, before doing anything drastic.  After that, if you still aren't satisfied, if too bright, play with the level switches.  If still too bright, you can add series resistors to the new capacitors.  A half Ohm to start, would compensate for ESR.  Go higher, if needed.  But I wouldn't start with extreme resistance.  Be subtle.

    Now, if the speakers are somewhat opaque, not transparent enough, again, give them time.  Break in will help.  Also, the suggestion of adding bypass caps, is a good one.  Bypass capacitors can both increase resolution and help smooth the sound.  At least in my experience.  I like to use the Dayton film & foil caps too.  0.01 and 0.1 work well for the high and low range capacitors.  Cheap enough to try, without breaking the bank.

    Good luck.

  14. AR 9. Basic re-capping advice.

    in Acoustic Research

    Posted

    8 minutes ago, DavidR said:

    Yup and I will usually order from whom ever I need to to get what I need. PITA

    Yea, I do the same.  No need to cry about a few extra bucks for shipping.

    Hey, maybe I should start an eBay business, selling cap kits for vintage speakers.  Entry level priced, with NPE's, bang for the buck kits, with film on the series caps, and cost no object, with stuff I can't afford.  I wonder if they would sell?  :)

  16. AR 9. Basic re-capping advice.

    in Acoustic Research

    Posted

    All this cap talk, reminds me how frustrating capacitor hunting can be!  Regardless, if I want to use NPE or film, no one parts site seems to have all the correct values that I need.  At least in a single capacitor.  I can find a few caps at one site, another cap at a 2nd site, and a couple more at yet another site.  It makes me crazy, that I can't get everything I need for one store, without having to parallel caps together, to add to what I need.  So, it's either mix and match, or pay extra shipping from different sites?  Not a big deal, just annoying, I suppose?

  17. AR 9. Basic re-capping advice.

    in Acoustic Research

    Posted

    11 minutes ago, DavidR said:

    Series and Shunt are correct terms. The 30uF is after a coil that filters out most of the frequencies that are 'unwanted' for that driver. The 30 shunt cap doesn't see that much duty because of the coil and is there to shunt any 'leftover frequencies to ground.

    The 4 and 6 caps are wired in series and forms (I believe) a 2nd order electrical circuit offering more protection to the tweeter.

    My only concern was the 80uF cap voltage rating.

    The 4 and 6 caps, along with the tweeter inductor, form a 3rd order 18dB per octave crossover.  Much better tweeter power handling as a result.

  18. AR 9. Basic re-capping advice.

    in Acoustic Research

    Posted

    Wow.  That's a nice recap (no pun intended).  Well stated, and which proves that you have a better than "loose grasp" of the subject at hand.

    While I can't really address power handling, since I don't listen loud, I don't think you'll experience any issues.  Many of the vintage speakers that I've rebuilt, or seen rebuilt, used capacitors with a 50V rating.  Those held up for decades.  Also, power handling is an additive thing.  All components add to the speakers capabilities, including capacitors, inductors, resistors, and finally drivers.  So, don't worry too much about the E-Caps.  They're not the only part exposed to wattage.  And regardless how I feel about their published specs, I like and use E-Caps, and have never had any fail.

    Finally, speaking of E-Caps, you can also use Jantzen Audio Premium Elko caps.  E-Caps and Elko caps are made by the same manufacturer.  They should sound similar.  The Elko caps are available in some values different than E-Caps, which might help in the rebuild.  Parts Connexion sells both NPE brands.

    Good luck, and Thanks for the shout-out...!

    Stimpy

  19. AR 9. Basic re-capping advice.

    in Acoustic Research

    Posted

    On 11/15/2019 at 7:56 PM, ra.ra said:

    Stimpy, I'm a bit perplexed by this remark of yours.... but not the company's statement. If you've been in direct contact with Mundorf and their U.S. rep, exactly what type of response would inspire confidence for you? :unsure:

    Less politics, and more actual measurements, in this case, would inspire confidence.  Something showing peak power handling.  While component measurements don't describe sound quality, they would at least help demonstrate real-world wattage capacity.

  20. AR 9. Basic re-capping advice.

    in Acoustic Research

    Posted

    Concerning the Mundorf E-Cap voltages.  The E-Cap spec sheets don't disclose much info, but I've written Mundorf, and the U.S. Mundorf rep, concerning their voltage rating.  Both responded with basically the same comment, "to not worry about the voltage.  We've never experienced a blown E-Cap in the field".  Not a response to inspire confidence.  Though, I've used E-Caps without issue.  But, I also add 400V film & foil bypass caps, to any electrolytic I use, and I'm sure that adds some extra power handling capability.

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