Which caps for AR4X's?

[Guest orionkc]

I read somewhere that the crossovers (20uf) could be exchanged for a (10uf). The ones in my set are a big blue sprague 20uf. They are not very open compared to the AR3's that I just recapped. I have an extra set of Kimber Kaps 6.0uf leftover from another project and was wondering what would happen if I put those in the 4X's?

Thanks,

Rick

[johnieo]

I have an extra set of Kimber Kaps

>6.0uf leftover from another project and was wondering what

>would happen if I put those in the 4X's?

>

Rick, you would seriously affect the speaker's performance if you reduced the capacitance--it would greatly increase the crossover frequency.

The correct capacitor value is 20 uF. Try replacing it with a new unit (or parallel smaller ones if available in your scrap box).

Electrolitic capacitors drift over the years due to seal leakage. (See date code YYWW for the year and week of manufacture.) First C increases as the electrolyte concentration changes, then C finally drops to essentially zero, after the electrolyte has completely evaporated. The quality of the hermetic seal varied greatly with the manufacturing firm and that's one reason why some are no longer in business!

If you have not already done so, you might consider taking the 16-Ohm level control potentiometer apart and cleaning its contact surfaces. They often become corroded. Retain the stuffing, and replace exact weight removed. Under no circumstances should you consider "bypassing" the potentiometer -- e.g. removing it from the circuit -- it is part of the crossover network. If you haven't checked the potentiometer, I'll bet coffee it's the first order problem. It was with some of mine; however, replacing the capacitor also made major improvements to the speaker's performance. Great speaker, worth restoring properly!

Cheers,

[RoyC]

Rick,

Changing the cap's original value and/or type is not going to bring the 4x any closer to the "open" character of the AR-3. Among other things, the dome drivers of the AR-3 provide greater dispersion.

As John suggests, replacing the original cap with one of the same value is the first and most prudent thing to do. I also second John's comment regarding the pots. The original level control or an electrical equivalent is required to maintain the original AR sound.

Roy

[Guest orionkc]

Thanks for the reply John

My version of the AR4X is in the Birch Finish. The caps are blue sprague compulytic (sp?) 20uf. When I removed the woofer I was pleased to find that the insulation was the yellow fiberglass instead of the rock wool. The pots function perfectly and show no sign of corrosion. The serial numbers were 1000 numbers apart. One of the woofers was cloth and the other was foam which was shot. I picked up a pair of the older woofers that had the criss cross design on the cone and will replace with those so that they have matching woofers. The tweets are the newer version without the mesh covering which I assume were in first generation AR4X. I will order some new 20uf caps and give it a go and will report back. This is the auction I won showing the woofers that I will install.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...28405&rd=1&rd=1

Will the new caps give the AR4X's new life and open the mids and highs?

Any comments on the difference in the various generations of woofers and tweeters that were used in the 4X's?

Here are some pics of my AR3s and AR4X's.

http://profile.imageshack.us/user/orionkc/

Thanks,

Rick

[JKent]

Great buy on those drivers Rick! I'm curious about the "hot cross buns" pattern on the woofers. I have a pair of KLH 33s with that pattern. Think it was to add damping to the woofer. But I have not come across it on my 3 pair of 4x's. Good luck with your restoration. You have some good advice from John and Roy--both have given me expert guidance with my restorations.

btw--I put Zen caps in my first AR4x restoration (John's recommendation), but they are no longer available and were pretty expensive. My next restoration will use Carlis (Roy's recommendation) from Madisound. Clean those pots! It's not hard, just takes patience and elbow grease. Use a little deoxit or electrolytic grease to keep them working.

Good luck!

[johnieo]

I picked up a pair of the

>older woofers that had the criss cross design on the cone and

>will replace with those so that they have matching woofers.

>The tweets are the newer version without the mesh covering

>which I assume were in first generation AR4X.

Rick:

Something is wrong here. You claim to have AR-4x -- could you tell me their serial numbers, please? What is the date code on the Compulytic?

The photo of the ebay auction shows AR-4 woofers (cross hatched damping) and AR-4 mesh-covered tweeters. The AR-4 is NOT the same as the AR-4x. The woofers will work fine in the AR-4x -- I have checked that with Tom Tyson -- but the tweeters will not. You might resell them as AR-4 tweeters, someone may want them. Becareful what you see on e-Bay as sellers do not always know what they are selling.

If you had a cross-hatched woofer, and a foam woofer, then someone has replaced both woofers from an original set of AR-4x. AR-4x never used foam-surround woofers. The tweeter driver in the 4x is a one-inch dome tweeter. If you do not know what it looks like, I can send you a photo.

Cheers -- I hope!

[johnieo]

Rick:

Attached is a photo illustrating both speakers. Tom Tyson sent me the AR-4 photo; the 4x is copied from AR literature.

Three added comments regarding speakers pairs with widely differing serial numbers:

---AR modified the woofers many times in both 4 and 4x -- smooth cones, ribbed cones, cones with cross-hatched damping, yellow cloth, black cloth ... The style is not the major issue, but all surounds were cloth. Check the surrounds for flexibility- I have seen some that have become stiff with age; it raises the woofer's free-air resonant frequency.

---AR changed the crossover frequency from 1,400- to 1,200-Hz somewhere between June 68 (s.n. 175,xxx) and Jan 69 (s.n. 225,xxx). The earlier units can be identified by the number "4" inductor (0.88 mH), whereas the later units used the AR number "5" inductor (1.187 mH).

---At about the same time, AR reduced the stuffing weight from 18 oz yellow fiberglass to 12 oz. This increased the Q factor of the speaker from about 0.5 to about 0.7.

Bottom line: you will want a matched pair!

[johnieo]

>driver in the 4x is a one-inch dome tweeter.

Sorry, I meant to say cone tweeter.

[Guest orionkc]

Serial numbers are 380725 and 390851.

The one with the bad woofer which I still have which has no cloth or foam. It has something written on the back of the woofer but is not ledgible.

The serial number on this speaker is 390851

Capacitor is a Large Blue Sprague that reads from the top to the bottom

Sprague

Compulytic

32D5345

AR/34/2761

Edit

Speaker No 2 Serial #380725

Capacitor is a Large Silver Metallic that reads from the top to the bottom

Sprague

Compulytic

32D5345

20MFD VNR

-10%+10% CAP TO

7147L

Woofer on the back of this one is ledgible it reads

4X2748H

137 7145

Woofers also have white foam circular gasket instead of caulk.

Tweeters are 1" Cone on both speakers

Hope this helps. I am going to go ahead and open up the other speaker now and report back on this thread.

My thinking regarding the foam or cloth was that since the serial numbers are so close together (1126) there may have been a change or possibly someone put in a woofer from an AR4XA?

I thought it unusual that one would have cloth and the other foam.

I also found this link regarding AR4X's...Don't know how accurate this information is.

http://www.soriaudio.com/zboard/view.php?i...vintage&no=3123

Regards,

Rick

[dynaco_dan]

Hi there;

I have AR-4X's, not AR-4's, with both foam and cloth surrounds.

The link to ebay shows the, hot cross bun woofer cones, but the tweeters are not AR-4X's.

These are the AR CTS tweeters less the fiberglass full front muffler.

Unless my glasses need cleaning again.

I just now went up to see John's jpg of the AR-4 and AR-4X speakers.

I have not ever seen an introductory photo of the AR-4 speaker before, if that is an intro photo.

I have only ever seen the CTS 3 1/2" cone completely covered w/fiberglass and with the screen cover.

This is also the AR-2AX mid driver and AR-2X tweeter as well.

Perhaps the AR-4 with the partial tweeter fiberglass surround was an earlier prototype.

Nice to see heavy speaker cables for the AR-3A's.

[Guest orionkc]

>Hi there;

>

>I have AR-4X's, not AR-4's, with both foam and cloth

>surrounds.

>

>The link to ebay shows the, hot cross bun woofer cones, but

>the tweeters are not AR-4X's.

>

>These are the AR CTS tweeters less the fiberglass full front

>muffler.

>

>Unless my glasses need cleaning again.

>

>I just now went up to see John's jpg of the AR-4 and AR-4X

>speakers.

>

>I have not ever seen an introductory photo of the AR-4 speaker

>before, if that is an intro photo.

>

>I have only ever seen the CTS 3 1/2" cone completely

>covered w/fiberglass and with the screen cover.

>

>This is also the AR-2AX mid driver and AR-2X tweeter as well.

>

>Perhaps the AR-4 with the partial tweeter fiberglass surround

>was an earlier prototype.

>

>Nice to see heavy speaker cables for the AR-3A's.

Thanks Vern...they are AR3's. Speaker wire was a tight fit on the binding posts...LOL....Anybody know where I can find some of the number "3"'s?

I saw a set of them go for $66 on eprey. Oh well......

[johnieo]

>Serial numbers are 380725 and 390851.

>

>The serial number on this speaker is 390851

>Speaker No 2 Serial #380725

>Sprague

>7147L

>

>Woofer on the back of this one is ledgible it reads

>4X2748H

>137 7145

>Woofers also have white foam circular gasket instead of

>caulk.

Rick: The Sprague mfg date (47th week of 1971) and the woofer mfg date (45th week of 1971 in plant #137) is consistent with my serial number data set. My highest serial number is 363,970 and its woofer was mfg 8th week of 1971. In line with your serial numbers above. Yes, by that date, the putty gasket was replaced with foam.

So, both of your cabinets/tweeters are late model -- toward the end of production, with no recorded differences I know of in that serial number range. Both will have #5 coils and 12 oz yellow fiberglass. Neither of your woofers was original. By then they were all ribbed cone woofers. The cross hatched woofer comes from a much earlier era; it was used in the (1964) AR-4. The AR-4xa was mfg in 1973-74 and used a 1.25-in. cone tweeter; certainly not a ten-year-old woofer! AR called the tweeter used in the 4x a "2.5-in. cone tweeter." The tweeter in your e-bay purchase were from AR-4. When you receive them, look for the mfg. dates. In that era AR ink stamped them with month, day, year.

Keep the woofers if they are compliant and sound good; sell the AR-4 tweeters. All is not lost, as you already own a pair of AR-4x tweeters. It is an excellent speaker!

Perhaps someone else knows: was the AR-4 tweeter also used in any of the AR-2 series? If so, potentially more bidders.

Cheers,

[RoyC]

Rick,

Attached is a photo of an AR-6 8" woofer dated May 1972. Notice the deteriorating foam surround. It may be possible that some foam surround AR woofers found there way into later AR-4x's with higher serial numbers. Your numbers are among the highest I have seen.

Roy

[dynaco_dan]

>>Hi there;

>>

>>I have AR-4X's, not AR-4's, with both foam and cloth

>>surrounds.

>>

>>The link to ebay shows the, hot cross bun woofer cones,

>but

>>the tweeters are not AR-4X's.

>>

>>These are the AR CTS tweeters less the fiberglass full

>front

>>muffler.

>>

>>Unless my glasses need cleaning again.

>>

>>I just now went up to see John's jpg of the AR-4 and

>AR-4X

>>speakers.

>>

>>I have not ever seen an introductory photo of the AR-4

>speaker

>>before, if that is an intro photo.

>>

>>I have only ever seen the CTS 3 1/2" cone completely

>>covered w/fiberglass and with the screen cover.

>>

>>This is also the AR-2AX mid driver and AR-2X tweeter as

>well.

>>

>>Perhaps the AR-4 with the partial tweeter fiberglass

>surround

>>was an earlier prototype.

>>

>>Nice to see heavy speaker cables for the AR-3A's.

>

>Thanks Vern...they are AR3's. Speaker wire was a tight fit on

>the binding posts...LOL....Anybody know where I can find some

>of the number "3"'s?

>I saw a set of them go for $66 on eprey. Oh well......

>

Hi Rick;

I just came back again and another link, in Korean?

It wasn't there when I posted?

I now have seen at least 6 different woofers used by the AR-4 series of speakers.

Makes ones shake their head when buying as to which ones you'll get and will they be matched.

Perhaps you have a Radio Shack near you.

Buy loop, hook or u style solder connectors.

Just wrapping a loop at the wires end and soldering together will give you a strong loop which which fit the threaded screw.

Loose bare stranded wires can un-twist and touch each other and cause a short as well as slip from under the fingernut/washer.

Today, most amplifiers can probably rely on self protection, othewise the amp may self destruct, if shorted, if not fused.

Do you have speaker fuses installed?

If not, goto, "OTHER" forum, goto "fast blow fuses", for a reading and reference session.

[johnieo]

Roy:

The cross-hatched woofer from the AR-6 that you show is rather different from the one used in the AR-4. However, as you note, it might have been used in some very late serial numbered 4x unis. In any event, I would choose to use all cloth-surround woofers and not mess with the foam units.

The AR-4 woofer had a number of variants, including one with a yellow colored cloth surround as shown in Rick's e-bay purchase. It works as well as the other units in my opinion. AR was constantly changing the damping, but they all seem to work.

Cheers,

[JKent]

funny how these threads are strung together. I made my hot cross buns observation before all the helpful info from John. You still got a deal on the drivers. 2 woofers you can use and 2 tweets to sell. Heck, you may even come out ahead! ;-)

Kent

[RoyC]

John,

I've done some swapping of 4x and 6 woofers and found them to sound more alike than different. My observations are that the original AR-6 woofer has a slightly heavier magnet (about 3 oz), and somewhat more sensitivity. The 4x and 6 woofers were both used in cabinets of similar volume along with 11 to 12 ounces of the later type of fiberglass. The AR-4 woofers I have seen also had heavier magnets than that of the 4x. Anyway, I believe an AR-6 woofer would work fine in a later 4x cabinet.

Regarding Rick's cloth surround AR-4 woofers, I agree that they should work very well in the 4x. If they are in as good shape as the photo indicates, they were a bargain! The cloth surround alnicos are still wonderful, reliable performers, and using them (thankfully) takes the foam replacement variables out of the equation. I also agree that matching the woofers is the most important consideration.

Roy

[RoyC]

...correction...the AR-6 woofer magnet is closer to 6oz heavier than the 4x woofer. It is also about 1/4" deeper.

The 1977 parts catalog still listed the AR-6 woofer separately (at $4 more than the 4x woofer), so they were probably never used interchangeably during the years the 4x and 6 were being manufactured.

In the 1979 catalog the AR 8" woofer was listed as a "universal replacement" for those models.

Roy

[dynaco_dan]

Hi there;

There is a pair of AR-4's with, "hot cross bun" woofers, with full fiberglass covered tweeters on ebay as I write.

The green one is probably for St Patricks Day.

[Guest orionkc]

>Hi there;

>

>There is a pair of AR-4's with, "hot cross bun"

>woofers, with full fiberglass covered tweeters on ebay as I

>write.

>

>The green one is probably for St Patricks Day

Those are the woofers I am going to install. I did take some tacky glue and dilute it with water and applied a good coat around the surrounds. Hope that was OK...Ordered some Clarity Caps from Madisound shown here:

http://www.madisound.com/catalog/product_i...roducts_id=8158

Cant' wait to hear them with the new caps. The 30+ year old Spragues have in all likely hood worn out their welcome...Will work on the finish a little and should have myself a pretty decent pair of 4X's...

To all who have recapped before and after impressions would be appreciated.

[dynaco_dan]

>

>Those are the woofers I am going to install. I did take some

>tacky glue and dilute it with water and applied a good coat

>around the surrounds. Hope that was OK.

Where did you get the advice to use, diluted with water tacky glue, on the cloth surrounds?

[Guest orionkc]

I did some more research before I applied the tacky glue and found out in some threads here that Armorall (2 coats in 24 hours) was one way to treat the surrounds. My surrounds aren't leaking just needed to have something applied that will keep them from drying out. This is what I did on my AR3's and 4X's. I think I read the tacky glue fix at AK...Glad I came over here and did some more research...

[dynaco_dan]

>I did some more research before I applied the tacky glue and

>found out in some threads here that Armorall (2 coats in 24

>hours) was one way to treat the surrounds. My surrounds aren't

>leaking just needed to have something applied that will keep

>them from drying out. This is what I did on my AR3's and 4X's.

>I think I read the tacky glue fix at AK...Glad I came over

>here and did some more research...

Hi again;

What pray tell is AK, please?

You had me squirming when you mentioned, "tack glue", to be honest with you.

Pardon my ignorance of the product and the results.

I've been running off at the mouth, as much as possible with using the Armorall 2 coats over a two day period technique.

Ditto with fusing and larger cables.

I am certain that the originator of using Armorall was Tom Tyson, but I cannot say 100% for sure.

He may have been told or read it somewhere.

I stand corrected, if I am wrong on that point.

At least Armorall is the same all over North America and does not need thinning or any additives to apply.

In theory we should all have the same outcome with it.

We need something to sometimes coat the cloth surrounds with if needed, by that I mean if never done before or a set was just bought and needed it, not on a regular basis.

It should be not harmful to the surrounds, not negatively affecting the sound, to a noticeable degree at least, readily available, at least at a reasonable price and quantity, consistant results and without a lot of skill required to apply.

With a few other treatments, waterdowned or thinned, unless we all know the exact amount, a few may go too far in an application and YOWZER, a ruined surround.

I have yet to read that Armorall is not one of the correct solution's or has done any harm, as in degrade the sound or deteriorate a single surround.

I can only comment on original AR and KLH cloth surrounds, this may apply to other cloth surrounds as well.

Another option would be that someone starts making cloth surrounds.

I don't see any present manufacturer running out and killing their foam surround repeat sales every 5 - 10 - 15 years.

It would need to be a rebel or an upstart company.

About 10 or so years ago I bought something from, I believe California.

I talked to the man's wife and she said that he was trying to make older style rubberized cloth surrounds, copy's of the originals.

I lost that information long ago.

I did buy, from ebay, a few rubber surrounds several years ago, probably among my very first purchases.

They were 10 and 12 inchers.

These are new, as in not used, rubber (neoprene) surrounds, probably overstock from a manufacturer, perhaps in Britain or Europe.

I emailed the seller numerous times requesting what other sizes were available, never ever received a reply and never saw them for sale again.

When I worked here at the local Dynaco warantee depot, I used to save the rubber surrounds from the Dynaco A-25's that were destroyed.

I had several hundred rubber surrounds at home, why I don't know.

We had several cartons of Dynaco A-25 aluminum woofer baskets.

They all were dumpstered many years ago, sadly.

[Guest orionkc]

I got the new 20uf clarity caps in yesterday and after a long day I started my restoration project about 11:00 P.M. Got the first one completed and it sounds perfect. I also replaced the woofers with the ones I got from an auction. 1st speaker functions perfectly.

The tweeter isn't working on the second speaker after replacing the cap,

cleaning the pots, installing the woofer and sealing. I hooked it up and no highs...The woofer is working as it should. Pots are OK as they were working perfectly with the old Sprague Caps. I loosened the tweeter and put a small load on it and it works if I bypass the crossover and just put power directly to the tweeter. I don't get any sound from the tweeter if I put power to the pot (green) that goes to the tweeter and the common blue. I thought I might have dislodged something but checked all connections and they are good. Anybody know what I could have done or what the fix might be for this problem?

I did the 2nd speaker just like the 1st. I cut the wires to the cap, 1 blue and the other green. wired the cap with the blue and the green, soldered and capped with twist cap.

Any possibility I might have a bad cap? Help!!

My kids have a track meet today and I will be back this afternoon. Maybe I will have a little clarity after a long, hot day in the sun...LOL

Any advice would be appreciated.

Thanks,

Rick

[bmz]

I am planning to do a recap of my ar4x using mundorfs m supreme. Their closest value is 22uf 250v. Thinking this  cap is expensive, it should sound good and probably better than most. I would appreciate your thoughts on this. Thanks.