AR 4X Dust Cap Question

[Bauhausler]

I don't think that's an Lpad. It looks like a 20 Ohm pot. There's a big difference.

Mine looks like rock wool too. I guess AR used the cheapest stuff they could get on these - or both ours were at a time with the yellow FG wasn't available.

Someone put what look like 20 OHM l-PADS in mine. Now I don't know what to do. I have a couple of old Aetna-Pollak's from my other AR projects I could clean up and put in there. I'd hate to use $15 Ohmites on the 4X's. And 20 OHM is closer to 16 so maybe these L-Pads are OK as far as effects on crosseover freq or midrange forwardness. Heck maybe they do the opposite as far as the midrange effect. :scratch2:

Also see 2 "Dimie" 10 OHM caps in each. Are these any good?

The seal on the woofer wasn't great so I think fixing that up will increase performance and I'll re-seat the tweeter as well.

Here are some more pics:

 

[shacky]

Figured a way to straighten out the bent tweeter flange. Put the tweeter in cab backwards and tighten screws

 

[motorstereo]

That's one way to get it done shacky. How about some fender washers to hold it flat?
I just finished up my 4x's and I've been listening to them non stop for a couple of days now. Have to "break in" that new cap. So far I'm quite pleased with all the mods.

 

[shacky]

That's one way to get it done shacky. How about some fender washers to hold it flat?
I just finished up my 4x's and I've been listening to them non stop for a couple of days now. Have to "break in" that new cap. So far I'm quite pleased with all the mods.

That sounds like a good idea. I was just putting the drivers in a safe place as my granddaughter is fond of pushing in dustcaps if out in the open. Then decided tightening might be a good idea and viola.

Glad to hear you like them. I'm planning to leave the newer caps as is - PO tested them for ESR and they measure well. But I think I'll replace the pots with 8 OHM L-Pads with 25w resistors as it's a known option. I'll measure these pots when I take one out for evaluation though.

Looks like my stuffing is FG so it'll go back in. Will try to make run to Post Office for quick weight for reference.

 

[shacky]

Decided to take the 20 OHM pots out to check their readings. They are pots (reading across 2 outer tabs stays constant):

20 OHM Pots
1-2 constant 21.4Ohms
B-1 21.4 - 0.8

Here are previous measurements I've taken. I haven't measured 8 OHM L-Pads with 25 W resistor between 1-2.

Originals
1-2 constant 15.5 Ohm throughout range
B-1 15.6 to 0.3

Mem Cors
1-2 constant 15.6 Ohm thoughout range
B-1 15.3 to 0.2

L-Pads
1-2 (infinity all the way) Just off full 40.7 to 8.4
B-1 (infinity all the way) just off full 40.2 to 0.2

So will the 20 OHM pots lower the crossover freq to tweeter? :scratch2: I'm thinking of using 2 originals out of my AR 3a project to make these 4X's correct. What do you think?

 

[shacky]

Just cleaned up a pair or original pots. Measurements much like my previous post:

1-2 15.2 OHM constant
B-1 15.3 - 0.3 Ohm

These seem to be working well so I'll use them. Need to find some rubber washers as I used the ones from these with Ohmite replacements on my 3a's.

 

[shacky]

I put the 4X's back together today. After a little confusion about which tweeter wires went where I'm all set. Took a lot of care resealing the two drivers and making sure all contacts are clean. I rewired tweeter as the wires were too short to work with comfortably.

I sprayed the old pots with faderlube after sanding away any crud with a Dremel. I looked at buying Dielectric Grease but it was $21 at my local hardware store.

Here are some pictures:

 

[gkimeng]

I sprayed the old pots with faderlube after sanding away any crud with a Dremel. I looked at buying Dielectric Grease but it was $21 at my local hardware store.

That seems cheap enough to me if it helps stave off having to go into a speaker for a few more years. $21 wouldn't even pay for a half hour of my working time.

I keep a bunch of these around. One tube is just the right amount to fill up two pots.

http://store.caig.com/s.nl/it.A/id.2494/.f

 

[HepcatWilly]

I have a few ARs that have that screen-like dustcap. More than one pair, anyway.

 

[shacky]

Thanks for the tips on grease! I'll have to grab some to have on hand.

These little speakers are incredible! No wonder they got such good reviews at the time. Sure they are rolled off compared to higher end models but these sound fantastic.

I'm amazed at the bass - but guess I shoudn't be as they are AR's.

 

[motorstereo]

Nice job on the restoration shacky. They do have an amazing amount of bass for such little guys don't they. My restored 4x's are sitting silent in a corner simply because my wife prefers the black grillcloth of my epi100's on her kitchen set up. I really need to put them in some other set up and break in that new cap. Have you noticed any difference in the sound of yours as you get more playing time on them?

 

[shacky]

Thanks Motor!

The caps in mine were in there when I got them so they're already broken in. Biggest change in mine are better seal - the putty had dried an was crack when I got them. Then the correct pots truing up crossover and some new wiring to the tweeters.

Nice improvements though They just sound more like AR's which I like.

I like EPI too. Have a pair of 202's that need some attention though I recapped them as well.

 

[shacky]

Motor - is that a Roadstar in your avatar?

 

[motorstereo]

No shacky that's a 2053cc Kawasaki Vulcan. More torque than my old ass knows what to do with for sure. It's still fun though to burn the rear tire in 3rd gear with the wife on the back. Maybe someday I'll grow up.
My beautiful looking 4x's might be sitting for a long long time now it seems. I just now walked in the door with a pair of infinity kappas 5.1s 3 way bookshelf speakers from the flea market. I don't want this thread to get moved so I won't mention any prices. It isn't looking too good for my epi 100's either. Looks like there'll be a shoot out coming up here in the very near future.

 

[shacky]

Good luck with the Infinity's. I've only heard Infinity's in other people's homes or stores.

My 4X's aren't going to get a lot of living room time. I have the Klipsch Forte's hooked up to my Eico and the AR 3a's to my Sui. But I am appreciating the 4X for what they are. A great small speaker that is very musical. On the proverbial deserted island one would be fortunate indeed to have them :yes:

BTW - I have a Road Star. Like it a lot but the rear suspension isn't great for two up. Just put a progressive spring on before storing for winter. We'll see if it makes it more palatable for the Mrs. I'll bet that Kawi rides very nice :tresbon:

 

[shacky]

I took the old wax caps out. Figured these can use all the internal cabinet space they can get.

And close up of tweeter:

 

[ke4mcl]

ventillation for the voice coil. allows woofer to pump air past coils.

 

[motorstereo]

I had the same wax caps in mine to shacky. I couldn't believe the size of them and thought they were quite unusual. I thought about taking mine out but it looked like it would be more hassle than it was worth. I'm really going to try hard to keep and use the 4x's. They really have that vintage appeal to me.
Very nice bike the Roadstar. Is yours the 1700cc version?

 

[gkimeng]

I took the old wax caps out. Figured these can use all the internal cabinet space they can get.

Do you have access to a capacitance meter? It'd be interesting to see how they measure.

 

[EddyR]

Ventilated dust caps are very common. Many AR's had them. They aid cooling.
Also many of the early AR-2 and 4's had those pots. They work fine and don't corrode. Factory must have run out of the one that are seen most of the time and used those. I had one set of early AR-3 that had those pots and the were original.
Ed