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About Carlspeak

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  • Birthday 08/08/1943

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  1. AR-3a pot orientation

    I did a survey some years back in preparation for the introduction of the Super-Mod kit. The question was asked of 3a owners: "where do you have your pots set". I got a 1/2 dozen or so responses. Most said the the tweeter pot was maxed out and mid pot was set about mid way or a little higher. Certainly not a scientific sample size, but an indicator, at least, that the original 3a dome tweeters were showing their age and need some 'help' to balance the sound better. There was even a poster here who espoused bypassing the pot to eek out a dB or two more! :-)
  2. KLH Research 10 Series Model SCX-3a repair and recap

    No, never used those other caps. With regard to bypassing, I would discourage those who may blindly follow North Creek's methodology of cascading bypass caps. They sure must have sold a lot of caps with that sales pitch. :-)
  3. New AR3 mids?

    While I may have dabbled a bit with that MR from HIVI, I just don't recall and cannot find any records on my computer. Any evaluations may have been in preparation for the introduction of the 3a Super-Mod Kit. However, I ended up settling on a lovely marriage of a Seas H1262 midrange and H1189 tweeter. The Seas mid is a perfect drop in fit to the rabetted midrange hole in the baffle board. The down side to using this mid is that it's has an open back design and one must thus fabricate a small chamber to install on the backside of the BB. I used a 6 inch diameter X 5 inch long thick core material tube which I glued a 1/2 inch thick MDF plate to the back side of. That plate had a hole in the middle for a threaded rod I used to pull the tube up against the backside (after applying a generous amount of carpenter's glue around the face of the tube beforehand. Ran the mid wires up thru that hole then sealed it with caulking and lastly stuffed the chamber with polyester. Fun stuff to work out these 'fixes'. Below is the entire Super-Mod schematic with the H1262 portion clearly shown for those brave enough to take on using the Seas Mid.
  4. New AR3 mids?

    I can only wonder if the Speaker Exchange has somehow acquired the old ABtech Services business. Their story seems eerily similar. Prices high and parts on back order with no ETA. IF that's the case, then will what they get (eventually from China most likely) meet or even come close to AR OEM specs.
  5. KLH Research 10 Series Model SCX-3a repair and recap

    I generally use 0.1 uF. Can't remember using one in a woofer circuit. I just don't see the value. Voltage 250V or higher Definitely Film Foil. Dayton has a small selection of FF caps that are a very good value. The ones in the KLH xo's are 0.1 and 400V If you want to spend more money, get AudioCap Theta's. They were a favorite of the late Zilch. Some audiophiles swear by FF. The AudioCaps come in even uF values above 0.47uF, unlike many others. JBL was one of the first to start using them. I have some JBL xo's to upgrade that have what look like orange drop types. They are probably mylar. Jon Bau of Spica fame used similar bypass caps to JBL Snell used pF value orange drop type caps in the Model A crossover to help glue the NPE bundle to the board.
  6. KLH Research 10 Series Model SCX-3a repair and recap

    For me, bp caps are st'd practice when the uF value of the NPE is too large and costly to use a film cap.
  7. I received two slightly different crossovers recently from a customer. They were from the Research Ten series and had slightly different model numbers. Both had very bad Aetna-Polak 5 ohm rheostats in need of replacement and those pesky black caps with the red ends (see my cap test thread). I managed to find some 5 ohm 25W Rheostats of similar design and construction to Ohmites but at considerable savings from what the Ohmites cost today. Also replaced 10 ohm 5W resistors with 10W versions. There's also a 50uF NPE (replaced with a 0.1uF bypassed ERSE 50 uF) and a 25 uF NPE with a Dayton film cap. The only difference between the two xo's was the tweeter cap. The Model SCX-3A had a 2.5 uF cap and the model SCX-A had a 5 uF cap. Below is a pic of the face of the terminal board and the opposite side.
  8. Under the dustcap of a 3a woofer

    You've a mess there. AR3a voice coil formers are perforated with holes around the outside just above the windings to allow venting of heat. Unfortunately, the holes are in a single line and not staggered and thus the distance between the holes must provide the vertical strength component of the voice coil former. If the woofer is driven too hard, the back end of the voice coil bottoms out (read slams) against the steel top magnet plate. The force of that collision is absorbed up thru the former. Those lands between the holes can't absorb that shock and the former collapses like shown in your picture. At a minimum you'll need a new voice coil or a complete recone job. They are great speakers but do have their limitations with regard to overpowering them leading to your issue and also burnt out tweeters.
  9. Under the dustcap of a 3a woofer

    That 'piece of card' is part of the voice coil. Leave it be. I suggest you remove the paper towel pcs you used to raise up the cone, then insert your shims. They should provide enough friction to allow you to raise up the cone without having to insert the paper towels. Centering the coil MUST take precedence.
  10. I have AR-3a's!

    ON further thinking, I didn't explain why. The pictures display at a nice viewing size and, overly large pic files don't tend to fill up the host's server quicker.
  11. EPI 100 woofer relocation suggestion

    Is there a question there somewhere?
  12. That's surprising because the 58b mids look much less modern than the one's in the pics.
  13. I'm refoaming some 58Bs 4 inch mids. They look quite a bit different from the OP's pics.
  14. Spraying lacquer on the AR3's...big fail.....

    IMHO, spraying lacquer isn't something for the DIY'rs and for a number of reasons. The OP cited some that led to his 'fail', but other reasons are doing it safely. You're basically working in a highly explosive environment and special breathing apparatus must be used. I've been doing speaker resto's for over 10 yrs. and luckily haven't had a customer insist on a sprayed on lacquer finish. If one had, I would have taken the cabs to a professional to get it done.
  15. AR 3 toe in or not?

    Tax is an understatement unless for a pillow speaker. DJ said he doesn't turn the amp up too loud and really shouldn't because damage causing clipping from the amp could occur. The 3/4 in dome tweeters are highly sensitive to clipping.