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Jeff_C

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  1. Was one of the photos laterally inverted? His ring may be a clue.
  2. If you replace like with like, having little knowledge of capacitors will not be a drawback. From your picture I think I can read (upside down) that the top capacitor has a value of 20MFD (20 microFarads) and 50V (Volts). They will be NPE (non-polar electrolytic), so you cannot solder them the wrong way round. If you replace with 100V caps that will not hurt, but it would be wise not to replace with a lesser Voltage rating than 50. If you are unable to source exact values as replacements then note that a 15MFD and a 5MFD wired in parallel will result in capacitance of 15+5 = 20MFD as required. I cannot read the values on the other cap. [Capacitors (in typical speakers) have values given in microFarads (sometimes written µF). It was common practice for capacitors to be marked as MFD or mFd either for machinery difficulty to produce the µ symbol print on the casing or for other manufacturer specific reasons.]
  3. I replaced my caps with Alcaps tighter tolerance NPE caps from Falcon Acoustics. Personally I would not fit more exotic/expensive caps, but do the reading up about caps. I've been very pleased with the Alcaps. I think it is worth paying just a little bit extra for tighter tolerance caps if they have them available. If you are handy with a soldering iron I would replace the caps yourself. What's the point of having some tech guy do them (at some cost presumably) when you may be waiting quite a while to hear them in spec with suitable fixed or replacement tweeters? Especially when you picked them up at a song. Most of my enjoyment came from from knowing I fixed them myself.
  4. I don't know much about the M50, but couldn't help noticing the Jim Rogers JR149, with foam speaker cover in wonderful condition.
  5. Reza may already be aware that Falcon Acoustics is a good place in the UK to order capacitors. ClarityCap Solen & Alcap capacitors, audio components for loudspeaker crossovers. (falconacoustics.co.uk)
  6. Your comments are noted @DavidR. It is a good thing for Elsdon to have as much information from members as is available. Another tip I can offer is to have some of those wooden metal sprung clothes pegs available to clamp the surround to the speaker basket to keep the surround in place as the glue sets. He has probably seen the pegs in videos that he may have watched but I thought it would be a good idea to mention it again here.
  7. I have re-checked Elsdon's photo' of the woofer cone. The "silicone" appears to me to be a bead surrounding the cone applied during manufacture by AR. (on mine it was a double bead). The bead(s) peels away fairly easily in long threads if you ease it away carefully. It is elastic, and nowhere near as stubborn as the glue remnants I had to deal with on the cone's edge. (For info' I think those bead(s) were applied at the factory to reduce sound wave diffractions at the cone's edge - others may may know more about this). It is a thing that will be almost impossible to replace with a DIY repair. If Elsdon decides to buy foam surrounds from the Netherlands I can reassure him that the glue that they can also provide is the proper white milky rubber glue which turns transparent when set. As for one of Kent's other main points about "shimming", that is probably the better way to go, but for us novices it is rather daunting cutting away the dust cover such that it can be reused afterwards. Also I would say that shimming would be much more important way to go about a repair on larger 10 inch and 12 inch woofers. Elsdon will have to decide which way he wants to do it.
  8. I re-foamed and re-capped my speakers which had 8 inch woofers several years ago. If you are reasonably handy at DIY stuff, and take reasonable care in preparation, you should be able to do the repair yourself. I am in Birmingham UK so had limited access to replacement foam surrounds like yourself. The grain on your speakers resembles mine which are also in teak veneer. Here's an extract from my thread asking for help. I thoroughly cleaned the speaker basket of foam and glue with a box cutter work-knife and sandpaper. I removed most of the foam and glue from the paper cone by carefully pulling it away with fingers. I removed the stubborn remnants of glue from the cone's edge by gently digging away and pulling at it with my thumb nail, while supporting the underside of the cone with my index finger. I decided to glue the new surround to the cone edge first. I brushed the glue onto both the cone edge and the back of the foam surround where they would make contact. While the glue was curing/setting, I tried to get the surround nice and concentric, and kept pressing the new surround to the cone edge to ensure a good seal as the glue set. I then got the computer and amplifier set up so all would be ready to deliver a 30Hz test tone to the speaker. I then brushed a layer of glue to the speaker basket and the back of the foam surround where they would make contact. I pressed the foam surround into place while trying to keep it nice and concentric. Within ten minutes of doing this I connected the speaker up to the amplifier. I set the computer software to play the 30Hz test tone repeatedly. I started with the volume fairly low but turned it up until I could see the cone vibrating and could hear the bass tone. (On the first woofer I tackled) I heard a sort of low frequency buzzing / flapping sound. I was able to gently manoevre the foam surround until the flapping sound stopped. There was no need to completely remove the new surround and the manipulation was very minimal. I stopped the test tone and gently pressed on the surround edge and speaker basket to get a good seal as the glue dried. I played the test tone again to ensure that I was still getting a clean tone with no flapping. I stopped the test tone and gently pressed on the surround edge and speaker basket to get a good seal until the glue dried. With the second woofer there was a clean test tone at the outset. I suggest you watch some YouTube videos of similar repairs. Try and find repairs of similar paper coned units because although the process is the same I imagine polypropylene cones are different to scrape glue from. Here is a link to the full thread, where you may pick up other tips and avoid pitfalls, but I am sure there are many other threads to guide you through this repair. Good luck with your repair. Refoaming AR16 speakers - help needed - Acoustic Research - The Classic Speaker Pages Discussion Forums There is a shop in the Netherlands which can provide surrounds and glue for your AR-7 Foam surround to repair Acoustic Research AR7 woofer (speakerrepairshop.nl)
  9. NB this is an untested suggestion but if no better solution presents itself should be worth giving it a go. I would try super glue "Loctite Super Glue All Plastics" should work well. Use one of those dispensers with a thin pipette so you can run a trail of glue along (and into) the crack.
  10. Any idea of the timeline when this rental plan was offered? Dealers here in the UK have been offering home trials for a few decades but usually the dealer offers up their own demo pair and I have always declined home trials because I would feel a bit guilty if the trial (or trials) failed to win the dealer a sale from me. Home trials of equipment funded by the manufacturer with pick up from local dealer seems a more workable arrangement IMO.
  11. For those living in Europe, this supplier comes recommended. I have used them in the past. Your foams are shown in this link with proper white water based speaker glue lower down the page. I took advantage of buying 3 at the discounted price in case I messed up, but even as a complete novice at this I only needed 2. http://speakerrepairshop.nl/index.php?item=foam-ring-_10-inch_-for-acoustic-research-ar5-woofer&action=article&group_id=10000033&aid=945&lang=en#.Wd3lHLpFycw
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