Australian AR6's resto

[ReggaeBen]

Ahh...so I'm back to work on my next little project, this time my Aussie 6's.  They'd been playing fine and are in great shape already to begin with therefore I wouldn't expect I'll need to spend a great deal of time on this job.

Plans for these include -  

*replace the original tweeters for a pair of later model fero cooled (200014-3).

*Boston Acoustics filled fillet surrounds.

*Recap with a pair of big russian oil caps that I decided to try.

*Fibreglass fill instead of the rockwool.

*Bypass the inductor and cap/resistor setup found in this model for the later version that runs the woofer at full range and the tweeter cap to 6uf.

*Try out Howards restor a finish (neutral) on the cabs.

That's about it I figure but I welcome any more suggestions on this as I'm still fairly new to speaker resto's.

Okay... now what's been done,

One woofer had a clicking noise when pushed in that was bothering me a bit, I thought It may have suffered from bottoming out at some point and there could be damage to the VC.  So curiosity got the better of me and I decided to remove the cone from the basket, very carefully of course!  With the aid of acetone and a very potent product called MEK (methyl ethyl ketone) I softend the glue holding the spider to the basket, then used a utility blade to work it up slow and steadily. Bingo, cone now was separated.  After inspection of the VC and gap I couldn't see any damage or anything to cause the noise, but what I did find was that the placement of the magnet was not square with the basket or pole "plate?" thus leaving me to think that as the VC lowers down it then gets drawn by the magnetic field to one side and hits someplace in the gap. As I can't see it doing this and Its not at precisely the same point each time, I can only say that what I'm hearing is that grabbing noise when a magnet has pulled something in. Anyhow moving ahead, since I can't see damage and couldn't detect any sonic issue I guess without breaking the speaker down even further then I'll resemble it next.  

I was lucky enough to find a Sprague compulytic can in the first cab but not so in the second, the first speaker was slightly clearer sounding that the other and this could likely be why. 

I'll keep up with posting my progress as I go along and hope this help with others that are working on the same speakers or similar models.  

Later all

Ben

 

[ra.ra]

Hey Ben, maybe this time we can drum up a few more voices to contribute to this AR-6 thread. That's a nice-looking pair of speakers you've got there.

Funny that this topic should come up now - - just last week I began a project on a very similar pair of AR-6's, also with Crossover (B). This pair belongs to a friend, and in the pic attached you see his pair sitting on my identical pair that I rescued and restored a few years ago. In fact, this foursome is a group of siblings separated at birth, circa 1974 - - my serial numbers are 40071 and 40253, while his are 39899 and 40265 - - and drivers indicate the same week of production. Both pairs are real walnut veneer (his are nicer!) with Norwood labels proclaiming "walnut grained" (note: not "oiled walnut"). Our plan is to conduct a very minimal restoration: check cap values, clean switches, re-foam woofers, freshen cabinets and grilles, polish badges. We can already tell that the original tweeters in these are still superb. 

Also attached for discussion are the two relevant schematics: the current version (B) and your proposed version (C). Although I am very curious, I have no experience with version (C), which I think was first identified in this forum by KlausDK from Denmark.

Before diving in, you may want to review these two threads first. They reinforce the notion that each of the three crossover variations is specific to the particular drivers (especially woofer) used in each version of AR-6, and that a mix-n-match assembly might result in performance results that do not meet your expectations. 

http://www.classicspeakerpages.net/IP.Board/index.php?/topic/7566-ar-6-crossover-comparison/

http://www.classicspeakerpages.net/IP.Board/index.php?/topic/1687-ar-6-crossover/&

I love to see successful hybrids constructed, but my advice is to travel at your own risk. I'm curious what type of cap you found inside the second cabinet, and also just wanted to note that the multi-color stuffing in your speakers is not rockwool, but is some type of poly fill found in many Euro AR's from this era. I think it probably works fine, but the two pairs that I've shown here do contain densely packed fiberglass fill. 

 

 

 

[ReggaeBen]

Thanks as always ra.ra, your knowledge shared here is invaluable, particularly so regarding the AR6. Do you have any new threads open on your current projects?

I hadn't read the first thread but had the second, seems that there is some preference to the the simplified crossover but also the "B" version as are mine.  Going by recommendations on CSP to take your time with the work and also that mine are already correct B versions then I will keep them as such. 

To answer your question about the second capacitor, its the Industrial Royalitic long life, I'll post pics of all measured caps shortly.

Regarding the tweeter change, my reasoning is that I bought a pair of the FF cooled tweets to put into use and then as to have spares on hand. The pair in these cabs will most likely go into replace my other pair of early model 6's as they both have pushed in dimples and one presents a little harshness at higher volumes. Then there will still remain two spares for the future. 

Will the FF cooled be compatible with the 10uf cap in the "B" version crossover?  My thinking is, yes.

Perhaps it's only that they aren't as popular as their bigger siblings or that there's just less folk who own and listen to them, but whatever the case is these are an astonishing litte speaker!

Cheers

Ben

[ra.ra]

On 8/25/2018 at 12:03 AM, ReggaeBen said:

I hadn't read the first thread but had the second....

Regarding those two threads, it seems to me that both kcbluesman and KlausDK were unimpressed with different versions of the AR-6 when the various crossovers were paired with non-original drivers. In kcbluesman's instance, he tried the simpler "C" crossover with "B" drivers and did not like the results; and in the KlausDK situation, he found that the early "A" version, when used with square ferrite woofers rather than the original hugh magnet alnico woofers, was inferior to the stock "C" version employing universal woofer and no coil. From my own experience and the comments of others, this leads me to believe that each version of the AR-6 is a terrific loudspeaker in and of itself, but once you begin a mix-n-match between versions, the unique assembly of components becomes compromised and then all bets are off. 

Three pics here are just for interest regarding the pair of AR-6 version B that my friend and I are working on - - first pic shows commencement of cleaning up old woofer, and pics 2 and 3 show crossovers with different brands of tweeter capacitors. 

[ra.ra]

On 8/25/2018 at 12:03 AM, ReggaeBen said:

Regarding the tweeter change.......Will the FF cooled be compatible with the 10uf cap in the "B" version crossover?  My thinking is, yes.

This is the interesting question and where others may be able to help out better than me. I am sure you can get that 014-3 tweeter to work just fine, but there are at least a couple things to keep in mind. First, using a rear-wired tweeter with the large diameter magnet may require some minimal cabinet modifications similar to what is shown here.  For my first pair of AR-6's (version A), I had to abandon some mismatched and damaged tweeters and I opted to install a pair of more recent AR tweeters - - these shown are the 038-0 tweeter which I believe has greater sensitivity and power handling. I completely abandoned the original rear-front tweeter terminals.  

To me, the 014  tweeter is a somewhat curious driver because it was used in several two-way speaker models in different configurations and with different test measurements. According to the Library drawings at least, there were dash one (-1), dash two (-2), and dash three (-3) suffixes which followed the 200014 designation. Dash one and two were used in the MST/1 speaker with a 10uF cap and had DCR measurement of 10 ohms (this surprised me). Dash three was used in the AR-17, AR-18 and AR-7x with a cap value of 6uF and DCR measurement was reported at 4.5 ohms. I have one very good 200014-3 tweeter (date 1979) in front of me right now and it shows DCR of about 5.3 ohms. See portion of drawing attached.

I think the central question is: For your AR-6 application, what is the correct cap value when replacing with a different tweeter? Is it 10uF or is it 6uF.... or is it something else? Perhaps you can experiment and help to establish some best guidelines. In my case shown here, I stayed with a 10uF cap and the speakers sound great, but I have long wondered if maybe a different cap value for the 038 tweeter might result in an even more satisfactory performance. 

[ReggaeBen]

I'm onboard with the whole mix and match issue now too ra.ra, thank you. Now that when someone tries googling "best AR6 crossover" they should be led to this and see that they are all the best ?

Tonight was spent on measuring the components in the crossovers and all drivers I have. Here is what I've found-

Cabinet A 

Woofer- 6.0 Ohm

Tweeter- 4.4 Ohm

10uf Sprague Compulytic - 11.76 uf, 0.19 ESR

24 uf Industrial cap has been replaced with an "ME" brand 22 uf 100v - 24.09 uf, 0.31 ESR

10 Ohm resistor - 10.03 Ohm

Cabinet B

Woofer- 5.9 Ohm

Tweeter- 4.4 Ohm

10 uf Industrial Royalitic - 17.6 uf, 0.50 ESR

24 uf Industrial Royalitic - 33.40 uf, 3.0 ESR!

10 Ohm resistor - 10.02 Ohm

 

200014-3 tweeters from AR17

4.7 and 4.9 Ohm

Spare 200014-3 tweeter with pushed in cone - 4.7 Ohm. 

I've notched out one of tweeter openings to fit the new tweeter already and something to watch for was that the new tweeter didn't line up exactly with the holes, probably a bit of tolerance in the production process. So the t nut had to come out, the hole slightly made larger and then the t nut could be re fitted and sealed with glue.

How did you rewire in the new rear wired tweeters? Did you simply snip the existing green and yellow wires from the inside of the baffle and connect with new spade connections then fit? 

With your friends 6's have non matching caps as too do mine and seeing that I don't think I'll be trying to source another Sprague cap, would you like to have mine? 

Ben

 

 

 

 

[ReggaeBen]

Okay so spent last night refitting the cone into the basket. I took care cleaning the bottom masonite ring and the spider before applying the Gorilla Grip epoxy glue.  Once the glue was laid down I fitted the cone and lined up where the lead wires line up with the terminal, then working delicately I fitted the shims.  The glue was good in the fact it didn't go off too fast, giving me time to raise and lower the cone a couple of times, remove and refit the shims just to make sure all was settling in nicely. The glue took about 30 mins before it didn't need anymore pressing down around the edges.  

Moving on to this morning, I checked the re-glue and all good.  I now stared to fit the Boston Acoustics filled fillet surround.  I let the glue get tacky first which helped a lot because, man..are these tricky to fit!! I had to just keep on pushing inward to my pencil line until the glue held it all in place, a bit nerve racking as its not something you want to make a mistake on.  I continued the outermost edge in the normal fashion without issues. 

The best part is that the mysterious clicking noise has disappeared, happy about that.  

Caps used were PE ltyhic 10+12 uf that measured 24 uf and bypassed with Dayton FF 0.1 uf that was polarity tested using a scope. ESR measured 0.24 Ohm.

Second woffer next up. 

Ben

 

 

 

[ReggaeBen]

Second woofer recaped and cleaned off much of the glue, just awaiting the surround now.  I'll take on that tomorrow as It's late here Down Under..

[lARrybody]

I use little silver tick marks with a depth gauge to make sure I have the new surround centered on the cone. You can use the appropriate color sharpie to disguise them afterwords.

 

[ReggaeBen]

Great way of doing it LARrybody, I figured of doing it the same way too, just measured the inner lip of foam and used that measurement. You'll see I favored green on the one completed!

[ReggaeBen]

Been working to get these finished sooner rather than later, to many projects to complete..

Found something on the schematic that doesn't quite look right, think it's only a small error but if the case can someone please confirm? 

The yellow wire goes directly from the negative hookup to the negative connection on the tweeter, as is the case on my crossover but here it is marked by a +.  I am changing to rear wired tweeters this is how I spotted it.

To try out something different, I made the tweeter cap up with what I only have left, a "captail" of sorts..

PE Lytic 4 uf x2

Russian k40y PIO .22 uf

Dayton FF 0.1 uf

All measured up a tad under 9 uf , ESR 0.24.  They at least will drift upwards no doubt.

If it works out alright then good, but I'll likely go with something more tried and true, just don't have many new caps left.

Peace 

[ra.ra]

Hey, thanks for all the updates - - your pics and descriptions are excellent and it's good to have the measurement data as well. About the DCR measurements, it seems to me that all your readings for two woofers and both sets of tweeters look good; same result for resistors (no surprise!). Of interest to me is seeing how far off original values the Royalitic caps have drifted - - I have these same 24uF caps and am now convinced I should confirm their accuracy. Also of interest is the blue 10uF Sprague Compulytic - - generally, these are considered to retain their original values very well, but yours is already measuring almost 18% higher than stated value, so this also suggests that these caps should generally be confirmed as well. And while your generous offer is much appreciated, it would not be worth shipping one used cap all the way from Australia, and besides, it is not measuring well to begin with. But thank you nonetheless.

Am surprised to hear that your tweeter T-nut required re-positioning; and yes, for my rear-wired tweets, I simply snipped the original wiring to the external terminals and connected green and yellow directly to (new) tweeter's rear terminals.

On your woofers, you did a fine job with the prep work cleaning them up, and I'm pleased to hear you got that one back together with good results. I don't think an epoxy was required for spider re-attachment, but if its now working fine, you've done well, and it can barely be seen that the dust caps were ever removed. Nice job on the foam installation, too, but now you know why I tend to prefer the easier fitting Bose foams with the full roll profile. Woofer caps look fine, I suppose, but I'm curious why you didn't start out with a 12+12 if trying to match an original 24uF? Also, if this assembly required four components as your does, I'd probably think about removing this from the woofer magnet/basket and re-locating to the cabinet interior - - - reason being, with this much added volume, it can become a challenge to fit the woofer back into the cabinet opening. 

Just one side note - - from this early ad for the AR-6, you can see that even the original tweeters have a silicone substance in the voice coil gap to address power handling issues.

(Edit: anyone ever seen the AR-6 in rosewood veneer or "soft white" finish?)

[ra.ra]

On 9/1/2018 at 3:32 AM, ReggaeBen said:

Found something on the schematic that doesn't quite look right....

Hmmm....... very good point, and I cannot remember if this has been discussed before in this forum. It is not unusual for some AR speaker drivers to sometimes be wired with reverse polarity, but I am drawing a blank on this one. I will try to look into the two similar pairs of AR-6's here to see if I can add any further observations. One other minor thing about that schematic B: don't know if it makes any difference, but it looks like the coil is shown on the wrong side of the woofer - - - compare with crossover pic attached. Also, I wanted to include here this great diagram that RLowe provided to help me better understand the operation of the switch. 

[ReggaeBen]

Hi all,

Some really useful information being shown here to add to the AR6 resources.  I've now been listening to the speakers for the past few days and they're sounding very impressive! At this stage they are not fully finished as I'm going on holiday and wanted to get them to this point for when I come back home.  I was a little nervous about how these would turn out with the cap arrangements but I can honestly say they they work well. Even in the pre amp stage in my Marantz I fitted those Russian PIO caps to good effect, they add realism to the sound.

For using a 10+12 uf instead of 12+12 was to aim for 24 uf as all of these lytics measured on the higher side, when it came to the mounting I just attached them where the originals had been, there were no issues when it came to refitting the woofer. 

When stuffing the cabs with 16oz new fibreglass (originally was purple poly fill) I sat the cabs side by side with the weighed fill in bags. Then slowly started filling from the top a section at a time while watching and feeling for consistency between the two. Even weighing the bags some more to try get this close as I could to each other, took a little extra time but I feel is important.

Oh, and I had been mislead by some of those last cap measurements, I used the reading off my el cheapo ESR meter and not the Fluke. The sprauge reads 10.7 uf so is still in spec, the others are out of spec, but not quite as high as first posted. The ESR meter seems to measure resistors the same as the Fluke so hopefully all my ESR have been okay. I'll keep onto that cap ra.ra, postage may be something like 20 bux, I'll find out anyway next I'm at the post office and pm you.

Now there is a little issue,  when I boxed them up I found them to be very air tight, like when I push the come down there is resistance and they come back rather slowly. I used the black caulk on both the tweeter and woofer, I like it for the cost factor but it can be frustrating at times so I'll start using foam next.

Any tips on getting the seal correct? And yes, I also understand it's to be an acoustic seal, not air. One seems a little bit fimer than the other and I had to adjust my ballance pot to get an even db reading from the pair at the woofers.

Really like those old AR brochure adds, it's great to have a hobby with nostalgic appeal too. 

Cheers

 

 

 

[ra.ra]

On 9/8/2018 at 3:27 AM, ReggaeBen said:

I was a little nervous about how these would turn out with the cap arrangements....

Good to hear that this worked out well for you - - it's important to have some personal fun with these restoration projects. Your speakers look great, and thanks for the update on the 10uF Sprague Compulytic measurements. Did you happen to re-measure the 24uF Royalitic cap with the Fluke? In my current AR-6 project (still in progress), we replaced the caps with a semi-generic 10uF film cap (pic attached shows wire nut connections for easy cap replacement), and even without stuffing or tight seals on the drivers, the speakers sound very good already in primary test run.  

On 9/8/2018 at 3:27 AM, ReggaeBen said:

When stuffing the cabs with 16oz new fibreglass.....

I have made no weight measurements, but jeepers..... these AR-6 cabs are surely stuffed tight and full with gobs of FG.

On 9/1/2018 at 3:32 AM, ReggaeBen said:

The yellow wire goes directly from the negative hookup to the negative connection on the tweeter...

Good eye.....my closer look confirms your statement - - - put another way, in each of four AR-6 (B) speaker cabinets, I have found the positive (+) terminal of the tweeter to be connected to the green wire, which ultimately connects with the 2 (+) terminal on the rear of the cabinet.

On 9/8/2018 at 3:27 AM, ReggaeBen said:

Really like those old AR brochure ads....

And here are two more...

[ra.ra]

This may have been brought up before, but I cannot recall a satisfactory response, so I'll stick it in this thread. I've been curious why the AR-6 is the only model which has its woofer purposely misaligned from the N-S centerline of the front baffle board ........ any thoughts?