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AR-3a : How am I lookin?

Discussion in 'Speakers' started by drfous, Mar 13, 2017.

  1. onplane

    onplane What! No Wake???

    Messages:
    2,016
    Location:
    Rochester, NY
    Problem with these 3a's (and I am the original owner of a set) is voicing. That is (as you have mentioned these are East Coast speakers) there is a significant "roll off" of high frequencies. Attached is AR's published frequency curve for the 3a's with the pots full ON.

    The "muffled sound" on these was so bad, I rarely listened to them. That changed nine years ago, when I by-passed both pots and bi-amped. By passing the tweeter pot gets you an additional 1 to 2 dB, so you are going in the right direction. Unfortunately, it's still not enough. To get more, I added a padding resistor (2 ohms 25 watts) to the mid driver xover. This brings the tweeter and mid in balance, but puts the mid way behind the woofer. In short, this makes the 3a's more bass heavy - East Coast.

    That's where passive bi-amping comes into play. By having separate amps, one devoted solely to the power hungry woofers and another midpower amp for the high frequency drivers, I can adjust "voice" by applying more power to the respective halves. In short, if I want West Coast speakers, I just apply more power to the high frequency side. More important, however, I can easily bring the mids/tweeters back into ideal balance with the woofers.

    As I said earlier, I did this 9 years ago and today I listen to my bi-amp 3a's almost daily.

    Regards,
    Jerry
     

    Attached Files:

    drfous likes this.
  2. drfous

    drfous AK Subscriber Subscriber

    Messages:
    91
    Location:
    Scottsdale, AZ
    Opened the 1st one up to see what's what.
     

    Attached Files:

  3. GD70

    GD70 AK Subscriber Subscriber

    Messages:
    10,686
    Location:
    Northern Westchester Co, NY
    Well, it's all original. The pots look good externally, but you'll meet to pop the retaining wire clips and inspect the interiors. Caps are an easy swap.
     
  4. drfous

    drfous AK Subscriber Subscriber

    Messages:
    91
    Location:
    Scottsdale, AZ
    Thanks for the tips, Jerry

    I may end up going that way, but I'm going to get them back up to "spec" as much as possible first and see how that goes.
     
  5. drfous

    drfous AK Subscriber Subscriber

    Messages:
    91
    Location:
    Scottsdale, AZ
    Opened one up.
     

    Attached Files:

  6. GD70

    GD70 AK Subscriber Subscriber

    Messages:
    10,686
    Location:
    Northern Westchester Co, NY
    Not too bad. Hope the remaining three are like that. Notice the pitting and uneven surface along the edge where the wiper makes contact. If you have a Dremel, use a sanding disk to smooth the surface. Test it and if good, apply dielectric grease to the disk surfaces and wire coils to help prevent any future corroding.
     
    Last edited: Mar 17, 2017
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  7. drfous

    drfous AK Subscriber Subscriber

    Messages:
    91
    Location:
    Scottsdale, AZ
    Really can't say how much I appreciate the help!
     
  8. GD70

    GD70 AK Subscriber Subscriber

    Messages:
    10,686
    Location:
    Northern Westchester Co, NY
    You bet!
     
  9. drfous

    drfous AK Subscriber Subscriber

    Messages:
    91
    Location:
    Scottsdale, AZ
  10. GD70

    GD70 AK Subscriber Subscriber

    Messages:
    10,686
    Location:
    Northern Westchester Co, NY
    I referred to the same thread on my first 3's restoration. Excellent resource.
    I'm sitting listening to my 3's listening to some Sade live recordings and they are fantastic!
     
  11. drfous

    drfous AK Subscriber Subscriber

    Messages:
    91
    Location:
    Scottsdale, AZ
    Well I guess the eyes are going. Once I got them out of the vinegar/salt bath and started to shine them up on the dremel one of the wipers has a missing "hump" on the rectangular end. Corroded through.

    I hit it with some solder (probably too much). Assuming I can get the hump size right, is this a lasting fix? Or move on to replacement?

    Thx
     
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  12. GD70

    GD70 AK Subscriber Subscriber

    Messages:
    10,686
    Location:
    Northern Westchester Co, NY
    Solder
    Solder hump should be fine as long as you're not constantly turning the pot back and forth and wearing it down. I've had to do this on several of my own.
     
  13. drfous

    drfous AK Subscriber Subscriber

    Messages:
    91
    Location:
    Scottsdale, AZ
    Cool. I pretty much just set them to neutral and forget about it.
     
  14. drfous

    drfous AK Subscriber Subscriber

    Messages:
    91
    Location:
    Scottsdale, AZ
    Speaker #2. One of the knobs for the pots was glued on. Broken shaft. I need to find a replacement.
     

    Attached Files:

    Last edited: Mar 19, 2017
  15. GD70

    GD70 AK Subscriber Subscriber

    Messages:
    10,686
    Location:
    Northern Westchester Co, NY
    Shoot me a conversation with your address info. I have a spare knob I can throw in an envelope to you.
    See that white powder on the woofer magnet? Don't breath that stuff in! Wipe it off with a damp paper towel asap! Nasty stuff!
     
    drfous likes this.
  16. drfous

    drfous AK Subscriber Subscriber

    Messages:
    91
    Location:
    Scottsdale, AZ
    Appreciate the offer.

    I think the knob is okay. The red shaft was broken. They glued the broken top end of the shaft into the well of the knob and then glued the whole knob onto the remaining shaft. When I loosened the set screw the knob wouldn't come off. So I pried it off. That left the broken end in the well. I managed to chip it out. I need to find the red shaft. There's a guy on fleebay with a set of pretty corroded looking pots. I messaged him to see if he'd part out one of the shafts.

    I was wondering what that white stuff was. I wiped it down. Thx!
     
  17. GD70

    GD70 AK Subscriber Subscriber

    Messages:
    10,686
    Location:
    Northern Westchester Co, NY
    The red shaft is what I meant. If you want it let me know.
     
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  18. drfous

    drfous AK Subscriber Subscriber

    Messages:
    91
    Location:
    Scottsdale, AZ
    In the pot restoration thread he uses silicon spray to prevent/lesson the chance of future corrosion issues. Is that a better option than the Deoxit Fader Lube? Just wondering why that option. Thx
     
  19. Drugolf

    Drugolf AK Subscriber Subscriber

    Messages:
    2,677
    Location:
    Boise
    Dielectric grease will be good.
    Did you order up some new weatherstripping tape type driver sealant yet for when you re-install the woofers? Key step. Parts Express stuff is good. You can also use the current version of the mortite that you can get at home improvement stores - duct sealant putty stuff.
     
  20. drfous

    drfous AK Subscriber Subscriber

    Messages:
    91
    Location:
    Scottsdale, AZ
    I ordered up the 3M calk from Amazon.

    I thought I had some dielectric grease, but couldn't track it down. I'll probably go that route.

    Thx
     

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