10 replies to this topic

[Wing Nut]

Hi all,

My son and I are attempting to restore a set of AR-4x speakers as a way for both us to learn a bit more about speaker repair as a hobby and are looking for help with the project. My experience with speakers is limited to replacing the surrounds on a couple of sets and my knowledge of electronics is even more lmited.

The reasons for restoring this particular set are easy enough:

1. We want to do the project together.
2. They seem like a pretty simple design as opposed to a set of Infinity Quantums or something like that.
3. While they're a great line of speakers, we don't have a lot invested in them ($10) and if we trash them, it won't be an Earth Shattering loss. If we succeed, he'll have a great pair of speakers for his room.
4. They're here and available.

So far, I have removed the speakers from the boxes and started to clean the boxes up with some Restore-a-finsh, but that is about it.

I am also curious where the AR-4x falls in the AR line. Some people seem to love them, but more seem to think they're the AR red-headed stepchild.

Any thoughts on this would be helpful...

Kevin

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[ligs]

One question. The woofers do not seem to be identical? The one on the left has a foam surround?

[Wing Nut]

The left one has no surround...

[JKent]

Nice find.
The one on the right has some open seams. Force some Hide glue in there and clamp.
Does the one on the right have a cloth surround or is it foam? If cloth, has it been coated with something?
The grilles should of course be re-covered. If you want to keep the cost low, go to Michael's and look for linen in the cross stitch section. Get a 40% off coupon in your local paper if you're lucky.
The nicest and most authentic linen is available from 1-2-3 Stitch but it's expensive. Refer to the AR3a Restoration guide (which is full of good guidance for your 4x project).
Replace the pots with cheap L-pads from PE or Madisound.
Replace the stock 20uF cap. OK to leave it in place. Just wire in a new 20uF film cap. You could use 2 10uF "surplus" caps from Madisound wired in parallel.

Kent

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[Wing Nut]

The woofer on the right has cloth surrounds, but someone did a half assed job of repairing them. It's some kind of glue...

[JKent]

The woofer on the right has cloth surrounds, but someone did a half assed job of repairing them. It's some kind of glue...

So, probably the best bet is to remove that surround then install new foam on both woofers. See Carl's post here: http://www.classicsp...t=0 He had to remove screwed-up cloth surrounds.
Best source for re-foam kit is MSound (ebay seller moonlistener).
I should mention: Not everyone agrees on replacing pots with L-pads. You could certainly try cleaning the pots. But L-pads are cheap and effective.
Kent

[pb8000]

I just restored AR4x's. When I received them the tweeters were cheap replacements ( I knew that from the ebay pix) and not working. I bought the PE phenolic ring tweeters but softened them with a cap and coil. Since I was into it I also replaced the stock 20uf cap. I tried to clean the pots with no success, so I went with the PE L-pad and a resistor. My listening is classical vinyl and so far I very pleased with the sound. As JKent and Carl suggested to me the phenolic tweeters need to be softened and set in the middle of their range or lower. The resistor on the L-pad and the cap and coil before the tweeter seemed to do it. I previously restored my AR 5's and used the 1-2-3 stitch lambswool 18 count linen and I was very happy with it. Looks like the original. So, as the AR4x's came without grills I ordered the same cloth from 1-2-3 stitch today for them.

[JKent]

Can you share details on the cap and coil? I believe the PE tweeters can also be improved a bit by the application of Roy's surround sealer around the edge to damp it some. If your 4x's (or any of your speakers) have cloth-surround woofers, it would be worthwhile investing in a bottle of the stuff.
Kent

[pb8000]

I'll be at my vacation home where the restored 4X's are later this week. I have the order receipt for the PE cap. and coil there and will post the precise info. then.

[pb8000]

Okay - I replaced the stock cap. with a polypropylene 20uf 250v cap. (PE part 027-436. I replaced the pot with a PE 15W L-Pad (PE part 260-248) with a 25 Ohm resistor (PE part 004-25) across tabs 1 & 2 (as per RoyC’s diagram). I then added a 12uf 250v poly. cap (PE part 027-430) between the L-Pad and new tweeter (Phenolic ring 8 Ohm)(PE part 270-252) with a .25 mH air coil inductor coil (PE part 255-214). I wired the coil parallel to the tweeter with one wire going to ground (terminal 1).

I kept the tweeter wired as per stock - reversed polarity to the woofer -(i.e. positive from L-pad to neg. term. on tweeter). Also, I set the L-pad at the middle position. Going higher or lower did not sound right. I do not find the new tweeter harsh at all. I think it has the AR sound. I can’t say anything about the often talked about 1200 hz hump because I have no equipment to measure it. But I like how it sounds

[RoyC]

Okay - I replaced the stock cap. with a polypropylene 20uf 250v cap. (PE part 027-436. I replaced the pot with a PE 15W L-Pad (PE part 260-248) with a 25 Ohm resistor (PE part 004-25) across tabs 1 & 2 (as per RoyC’s diagram). I then added a 12uf 250v poly. cap (PE part 027-430) between the L-Pad and new tweeter (Phenolic ring 8 Ohm)(PE part 270-252) with a .25 mH air coil inductor coil (PE part 255-214). I wired the coil parallel to the tweeter with one wire going to ground (terminal 1).

I kept the tweeter wired as per stock - reversed polarity to the woofer -(i.e. positive from L-pad to neg. term. on tweeter). Also, I set the L-pad at the middle position. Going higher or lower did not sound right. I do not find the new tweeter harsh at all. I think it has the AR sound. I can’t say anything about the often talked about 1200 hz hump because I have no equipment to measure it. But I like how it sounds

For the record, it is not necessary to use the 25 ohm resistor with the l-pad when implementing alternative crossovers. The only purpose of the added resistor is to prevent the new 8 ohm l-pad from affecting the behavior of the *original* drivers. If modern replacement drivers with internal crossover changes are in the mix, the l-pad can be used as is. If no crossover changes are made, the 25 ohm resistor can be used when there is a possibility of returning to all original drivers at a later date.

Roy