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graham

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  1. and a couple more photos I forgot. The crossover inside the enclosure, and a picture of the finished speakers. One with the grill cloth off to show you how ugly the mortite looks, but the grill cloth hides it of course. I wish I had take a before image of the grubby grill cloth. It is like new now.
  2. I have just built two of Dave Smith's March 2010 AR4X crossovers (drawing and a schematic PDF a couple of posts back). The pair of AR4X I got from auction for $10 back in 2006, and they have sat in my basement since then. One of the Tweeters was blown and in March 2006 forum member RoyC got me a replacement in trade for some other old AR tweeters that wouldn't fit. If you are still here - thanks RoyC I am finally using that tweeter. AR4X with the blown tweeter was serial number FX227334. The woofer had a Black paper cone with cloth surrounds, it had black gauze each side of the magnet and had 4X 2748 137 6903D stamped on it. It was stuffed with Rockwool. It had the usual Brick 20uf wax capacitor and a number 5 coil inductor. The blown tweeter was dated Jan 31 1969. AR4X with the working tweeter unfortunately had the serial number paper peeled or ripped off. The woofer had a Brown paper cone with cloth surrounds but the sides of the magnet had brown paper tape sealing them. I believe this tape was original from the factory as it had the date JAN 31 1969 stamped on the paper ( see photos). It also was stuffed with Rockwool and had the same large 20uf brick wax capacitor and a number 5 coil inductor. The tweeter had the date Jan 28 1969 stamped on it. It is a mystery to me why one woofer had a black cone, and the other a brown cone? If only the 2nd serial number was there !. I soldered up the components according to the schematic. I built the crossovers outside the enclosures on 4" x 8" x 3/8" board which I then placed into the enclosure and screwed on top of the old board alongside the Input contacts and AETNA POLLACK Pot hole. One problem I hit was that in the new position for the crossover, the original wires on the Tweeter and Woofer were not quite long enough. I disconnected the speaker wires from the Woofer Tweeter and obtained new wires that were slightly longer. Of course the new wires had to be in the original blue, red, green, yellow colors. I dragged out of my basement an ancient tower PC that I had been meaning to scrap, it had a good supply of 18 AWG wire in red, blue, yellow going to the power transformer. The old PC power cord yielded another length in green. (see photos). Is 18 AWG thick enough ? it works great. Checkout the photo showing the solder and paste I used - out of an auction box, probably from the 1960's too. Solder had a 49c woolco sticker on it!. The pots had a few faint bits of green on the wires inside. I cleaned up with salt water and a toothbrush, then after thorough washing and drying, used 000 grade steel wool on the contacts, then a spray with MG chemicals Nu-Trol control cleaner. I used Mortite to seal the back of the Pots when I reinstalled. I used Mortite to seal the tweeter and woofer cutouts. ( see photos), On this forum I had read about the 11oz mini-packs of fiberglass from Walmart. I picked up two packs. Unrolled they are 4' ft. long 16" wide. I ripped them into 4 12" x 16" pieces. 16" is just about the inside length of the AR4x. One piece full length on right side, one on the left side. one piece in half to the back of the crossover under the tweeter, the remaining piece in middle front under the woofer. I used the 000 steel wool on the cabinets, to which I then applied Bri-Wax. The speaker grill cloths had a grimy appearance, but I thought I would have a go at cleaning them before resorting to buying new material. I unscrewed the one ARX badge remaining, then took the grills still on the frames to the sink. I had warm water flowing from the tap, wetted, gave a couple of squirts of dish soap, then very lightly used a nylon scrubbing brush. After about a minute each, I thoroughly rinsed them off, then took the to dry in the sun. They look great. Well, they are back to a clean tweedy beige look of the late 1960's. Could almost pass for new. These 49 year old speakers are now alive again. They sound magnificent. That crossover design of Dave Smith's works like a charm. I am playing Jazz on them now. The saxophone and trumpets are clear and ringing - Stan Getz knew how to blow a horn. Yes I am using CD's ! It seemed that the sound got more and more 'body' after about CD number 2 was played . I am now 3 days into using them for a couple of hours a day, and they are unbelievable. Here are the photos - comments appreciated... On the crossovers, the Blue, Red, Yellow, Green wires of course will go to the Woofer and Tweeter. The Orange goes off to #1 negative amplifier input. The white goes off to #2 positive amplifier input. Many thanks to Speaker Dave and RoyC for their contributions
  3. Hi Dave,    I see you were last on this classic speaker pages on 21 Mar 2016,  I hope you are still a member? I was looking at the AR4X crossover design in thread number 5815 posted 2nd April 2010,   a couple of questions,  what is the crossover frequency that this design is expecting to apply to the standard AR4x woofer / tweeter?  Also, I have a couple of silk dome tweeters with FS:800HZ  impedance: 8 Ohm DCR:5.9ohm sensitivity: 90db power:50W frequency: 1K~~20KHZ recommend crossover point:>2.5 K       Would these work with that design and regular AR4X cloth woofers? What would have to be done to change the design to allow a crossover point of >2.5K. 

    Thanks

    Graham

     

  4. Thanks for the schematic Dave, and more thanks to RoyC for plugging it into a computer. If anyone has sourced the parts could they share the details of suppliers and prices please? the extra 0.10mH air coil inductor - parts-express have 14/15/18/20 gauge - which is best ? also what is the source for an iron core inductor of 0.25mH / 250uH ? part-express don't go down that low.
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