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About GlennW

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  • Birthday 02/21/1957

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    Wauwatosa, Wisconsin
  • Interests
    Electronics hobbyist, woodworking

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  1. Did you find? I have a single unused 206-0117 ADS tweeter. I have been saving it as a spare for my 1090s, but haven't needed yet, so could part with it. PM if desired.
  2. The mid looks ok. Early model used a Braun mid, that is what we see here. Tweeters don't look right.
  3. I recognize the tweeters, they are Motorola piezo-electric tweeters. They probably date from late 70s, when they were popular in sound reinforcement speakers as super-tweeters.
  4. Tolerance improves with multiples, don't remember the formula...
  5. Those capacitors look familiar. I made similar construction for AR3a capacitor replacement. The Madisound 10uF surplus capacitors are gone now, they will be missed.
  6. Congratulations on finding a vintage amplifier that you like. I did a quick Google search - SAE A202 looks very nice. A hum - is this hum that is heard through the speakers? Or hum that comes from the chassis of the amplifier? If hum is from chassis of the amplifier, probably not much can be done. Sometimes transformers have a mechanical vibration that is excited by the magnetic forces of the power conversion of the transformer. Replacing the transformer is a large expense and suitable replacement may be impossible to find. Best solution is having the amplifier behind a door so
  7. Do capacitors need periodic replacement? Depends on the type, and usage. Film capacitors such as are used in your crossovers have extremely long life. Unless operated beyond their rating, they should be fine practically forever. Electrolytic capacitors use a liquid between the foil. This type has more limited life. This life is also dependent on part quality, with well made parts lasting well past ten years, others perhaps not. I have seen failures of old electrolytic capacitors, but never film types. If the parts were stressed by operation beyond rating their life may be
  8. I do not recognize the blue cap. All of these are good quality film types. I would not replace them. 63 is the voltage rating, Caps are rated DC, AC rating is same or higher. Rating is testable only by destructive test.
  9. The DC rating of a capacitor would be the voltage level at which arcing would occur, and all the magic smoke would escape. A detailed analysis of speaker protection is done in Doug Self's book "Audio Amplifier Design Handbook". Some of his points: Series capacitor is large and expensive. A large electrolytic type has measurable distortion. This level is significant compared to distortion rating of a good amplifier. Fuses have to be operated close to their rating to provide meaningful speaker protection. Used close to their rating, fuses degrade and may have nuisance failur
  10. GlennW

    L1090s in the house

    Raining good vintage in Milwaukee area. Last year I was given AR3a, now I have picked up a pair ADS L1090 series 2 from Craigslist. The ADS are a bit rough - one blown midrange driver and a woofer that looks a bit dodgy but seems to be working ok. Not pretty either. Compared to the fine furniture look of my ADS L710, the black lacquer finish does not impress. But Richard So can rescue the drivers. And I plan on trying my hand with veneer when time permits. Nice to have a new project. At the moment I have substituted a mid from an L810, and they sound pretty good. Glenn
  11. I have completed AR 3a tweeter replacement with Vifa D19TD, and I am happy with the result. To fit the small tweeter, I made a 3/16" plywood donut. Crossover is series 2.9uF and 6 ohm and parallel the 16 ohm of the AR3a pot. The wiper wire of the pot was shifted to +, so crossover resistances are fixed. I always thought the AR front speaker connections were crude, but I now appreciate these are great for hobbyists. After installing the tweeters but leaving the front connections open, I tried various values of resistance and capacitance using various wire jumpers, clips and components
  12. Ra-Ra, Thank you for the link to discussion about AR finishing. It was interesting to read about the multilayer lacquer finishing process for the cherry finishes. I agree with your guess that my AR3a s are cherry. Unfortunately they are not gorgeous on all the faces, some faces have scratches and some chips, fortunately no damage to the wood. The advice in the linked discussion that the only way to refinish the film finishes is to strip and redo is daunting. I will try shellac sticks before I refinish. That may work and is reversible if it doesn't. Glenn
  13. All the labels are there. But no indication of the name of the finish.
  14. Last year I received a set of AR3a speakers. A good friend is a woodworker - and a neighbor gave him the speakers because they did not work and thought they would be a nice source of wood. I went though the Restoration manual. Comparison with the crossover photos and driver photos place the speakers as vintage 1969. My speakers have good woofers, surrounds were fine. The original owners had them serviced in their lives. On first play, the woofers were all that were heard. I rebuilt the crossovers, replacing the capacitors with new film types, the 150 microF unit with composite of N
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