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About genek

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  • Birthday 07/31/1953

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  1. First time I ever saw one of these was in a Marantz-branded speaker in the early 70s.
  2. genek

    A pair of AR-3 fell into my lap this week

    The solvents in nitrocellulose lacquer are the same ingredients used in many paint strippers. You definitely want to seal wood that you've stained, especially if you used a pigmented stain.
  3. genek


    A level control would probably be a good idea. How are you determining frequencies? Are you measuring, or just doing it by ear?
  4. genek

    Ar-3a Capacitor Advice

    CSP's focus is on repair and restoration. If you contemplated installing something in your vintage ARs knowing it was going to produce "differences in sound," and didn't make the necessary adjustments to compensate for those differences, we'd boot the discussion over to "Mods, Tweaks, and Upgrades to the Classics."
  5. genek

    AR-3s With Korina veneer!

    The long face that's in shadow in photo #2 looks stripey enough to be korina, but the tops don't. Could be that the photos are washed out or the tops have been sun bleached. The face frames just look like generic "blonde." Do we know if the korina cabinets had solid wood korina face frames, or did they use birch the same way they did for the pine cabs?
  6. genek

    Ar-3a Capacitor Advice

    In other news, the prize in The Amazing Randi's $1,000,000 audiophile speaker wire challenge has yet to be won, either.
  7. genek

    Ar-3a Capacitor Advice

    The biggest factors in capacitor longevity are how susceptible their dielectrics are to age and environment and how good a job their encapsulation does of holding back the effects of both. In the case of the Sprague Compulytics and the older oil-filled caps, their heavy-duty cans are as close to being bulletproof as you're going to find (I know from my past day job that some of them were actually designed to be bullet and explosion resistant). So it's pretty easy to see how they've preserved their contents better than wax, paper or plastic. Plastic film is less susceptible to age and environment than impregnated paper and the finished product is more stable and long-lived. But probably more importantly, capacitors using them are less expensive to manufacture and have a lower reject rate. They've dominated the capacitor market in general since the 1980s.
  8. genek


    Consider doing what Micro Acoustics did when they designed their add-on tweeter. Multiple capacitors and a switch to enable the selection of different crossover frequencies. The MS1 could be set to cross at 2500 or 5000 Hz. For this setup, I would suggest switching between 700 and 1400 Hz (which was the crossover frequency of the early 2ax with cloth surround woofer).
  9. genek


    Here are the response curves for the 2 and the 1ms (1ms on top). The 2 has a flat response up to about 1200Hz, after which response becomes more variable for the upper 800Hz of its operating range. The 1ms is relatively flat from about 700Hz up, and is rather jagged below that. I'd say your best crossover point would be somewhere in the 800-1200Hz range. The 4" woofer in the 1ms and the 4" mid in the 48 series are not the same P/N. The tweeters in the two models also have different P/Ns.
  10. genek


    The 10" woofer in the 2 is a more capable driver than the 4" woofer in the 1ms. If reducing driver stress is your goal, you'd be better off raising the high-pass filter frequency to take the load in the under-2000Hz range off the 1ms.
  11. genek


    Just take the values from the schematics for the 3a. The 3t and 3st were designed to duplicate the crossovers from the 3.
  12. genek


    If the 1ms is doing a good job with mids and highs, you'd be better off removing the jumpers to disconnect the original mids/tweeters and just use the 2s as woofers. Positioning the speakers vertically is producing a narrow vertical mid-frequency beam along the front axis of the speaker boxes because the cross-fired drivers were designed to be placed horizontally. The 1ms is a 8 ohm speaker with a bottom end somewhere around 85-90 Hz. Response becomes a bit ragged below 200 Hz. The 2 and 2a are 8 ohm speakers whose woofers cross to their upper drivers at 2000Hz. If you insert a 100mfd capacitor on the + lead to the 1ms, that will provide a high-pass filter that cuts off frequencies below 200Hz. If you're happy with the performance of the 10" woofer in the 2s, then just removing the jumper will roll them off at the original 2000Hz and no additional coil should be needed.
  13. genek

    Vintage AR2a with vinyl finish (year)?

    Definitely laminate, and no way original. You can soften contact cement with a heat gun, and dissolve what's left behind with acetone. Nasty stuff, and you'll probably never get it all off. Plan on having to bleach the hell out of it and coating with a matte lacquer if you want to approximate the bare pine look, or putting a new veneer or pigment-based finish on the wood after sanding. Also, good chance the reason it was covered in the first place is that the wood was trashed, so be prepared for that possibility.
  14. genek

    Using AR speakers in a home theater?

    Let's see where it goes. I might split it off into other speakers/electronics.
  15. genek

    Using AR speakers in a home theater?

    I still use the FM radio in my car (two presets, my local NPR and a classical station). At home, TuneIn on the Roku has pretty much obsoleted my tuners.