AR-9 / AR-90 Crossover Re-capping Adventure

[AR surround]

Well, I had been warned by many here that my beloved 38 year old AR-9's would eventually need to have their crossovers recapped.  I was listening to a quadraphonic SACD on my system (The AR-90's are the front speakers and the AR-9's are the surrounds) when I noticed reduced output from the right rear AR-9.   I immediately stopped playing the music and used a white noise test tone on the speaker.   The tweeter not only had reduced output but was crackling away.   Miraculously, I was pleased to discover upon re-capping that the tweeter DID NOT BLOW.   Perhaps these tweeters are very robust, or perhaps the bass-free rear channels of the quadraphonic SACD saved it, or maybe I just dodged a bullet.

Anyway, I replaced all of the upper range capacitors.   The three smallest capacitors are Dayton PMPC (1%); the 30uF and 40uF caps are Dayton DMPC (5%); the 24uF cap is a Solen (5%) and the 80uF cap was replaced with a Jantzen 82uF (5%).   I used Dayton or Janzen wherever possible as I understand that the Solens sound a bit brighter based on what I've read in these pages.

I sent the old Callen capacitors, except for one of the 6uF units, to my cousin for measurement.   The results are shown in the attached diagram:

- One 6uF cap was off by 400%.   This is the one that probably had failed and caused the immediate problem with the tweeter.

- Both 30uF caps were way off by over 40%.

- All the 4uF and 8uF caps still measured very close to their ratings.

- The 24uF, 40uF and 80uF caps were in the range of 20% or less than nameplate.  Given that both of the the 80uF caps were very close to each other at +15%, I suspect that they have always been that way.

It is interesting to note that the AR-9's now sound somewhat clearer the the AR-90's but the 90's sound a tad sweeter.   The AR-90's are a bit more forgiving and sound better with crappy source material while the AR-9's are more revealing and sound better with great sounding source material.

Regardless, the upper range crossovers of the AR-90's will get redone next month as doing so is inevitable.

Much thanks to all of you who provided input on this site regarding recapping these speakers.  It was very helpful.

AR Surround

 

[DavidR]

Nice recap. I've used the Dayton 1% and 5% and find them OK but not great. I have found that Parts Express will send me matched pairs. I don't believe they measure them, as they say they don't offer matching, but they must all run close. I'm getting ready to recap my 90's but recently had hand surgery and waiting for more flexibility and for my brother in-law to give me a hand taking them down to my workshop. I too bought a Jantzen 82uF CrossCap for the LMR series cap. I like the fit and finish. I found a 24uF cap in a pair of AR speakers that measured 40.4uF.

 

[DavidDru]

Excellent recap of your recap!   Congrats.

[Stimpy]

Crap!  This just further highlights the fact that I need to get off my butt and recap my 90s!  Plus, these findings, concerning the caps drifting so out of spec, are scaring me, making me afraid to even play my speakers, until after they've been recapped.  I definitely don't want to blow any drivers, as replacement parts are scarce and expensive.

Also, to the OP, why the 90s in front, while the 9s are used as surrounds?  Just curious?

Thanks, and nice job on the recap!!!

[DavidR]

Stimpy, Have you decided on caps yet?

Are you doing any resistors?

[Stimpy]

On 1/5/2017 at 7:29 PM, DavidR said:

Stimpy, Have you decided on caps yet?

Are you doing any resistors?

Yea, I'll do resistors when I do the recap.  I might even slightly shift the toggle switch values too, so the changes are a bit more subtle. 

As to what brand(s) of caps to use, no, I haven't decided.  I'm still torturing myself.  But, I really want to try the Mundorf EVO Oil caps.  I want to try something 'better' than Dayton poly caps.  I guess to see what the 90s are really capable of?  Plus, I still occasionally do some audio mastering, and use the 90s as a 2nd reference.  As such, I don't mind spending more for caps, if they'll help with the resolution and balance of the 90s.  Hopefully, it'll help with hearing the changes in mastering?

[DavidR]

Most of the caps I've chosen are Dayton. I got 1% for the smaller values and 5% for the others. The 80uF is a 82uF (81.6 and 81.8) Jantzen CrossCap, the 350uF are Solen 200 +150 caps. I got lucky as many of my caps are matched (by chance) or very close to matched.

I decided to look into Mills resistors as Sonicraft is having a sale. All added up its still over $130. I re-read what Roy wrote about replacing them nilly-willy with expensive ones. I've never found an AR resistor to be very far off so I decided to go with Roy's logic. I will donate the money to a worthy charity as it will do more good.

You may find it difficult to find suitable values in the EVO line. Good Luck.

 

[ar_pro]

David, any chance of a comparison of the AR-90 with the new 350uF woofer cap(s) against the one with its original electrolytic still in place?

 

[DavidR]

I suppose I could A/B the first recapped speaker vs the original. I will also take a look at what the original cap measures before doing anything.

What are you looking for?

Not sure when I can get to them as I recently had hand surgery and am working towards more flexibility, sensation and strength. I will also need my brother inlaw to help me lug them down to my workshop and then back upstairs.

[ar_pro]

Ouch. Forget that I mentioned it; hand surgery is no fun, and you don't want to be tempted to do anything that might set back your recuperation. One "simple" surgery on my left thumb was enough to make me subsequently ignore, and live with three fractured fingers and a collateral ligament rupture on my right little finger. Hand surgery? No. Thank. You. Seriously, get well soon, and be careful!

I've become curious about the big electrolytic caps in the AR-90 and the AR-9; with the first round of re-builds - figure '95 to 2010 - many were reluctant to replace the woofer caps, and I'm wondering what sort of condition they're in, after nearly 4 decades. After you've healed up, it would be interesting to learn of their measurements and any sort of audible difference against the new poly replacements.

[DavidR]

My hand is doing very well thank you. I had a very good surgeon and I'm ahead of schedule. Using it helps in the healing process but I do have limits. I have a case of Viking disease in my R-hand.

I will post my before and after cap readings.

[AR surround]

15 hours ago, Stimpy said:

...Also, to the OP, why the 90s in front, while the 9s are used as surrounds?  Just curious?...
 

Out of curiosity, and some strange desire to haul 130 lb and 90 lb speakers around the room, I swapped the 9s with the 90s.   I was stunned that the sound field was significantly better with this configuration, so I've kept it that way.   I surmise that I've gotten these improved results because:

1. The upper range drivers of the 90s are now at ear level.

2. The upper range drivers of the 9s as the surround speakers are now above ear level.   When I used the the 90s as surrounds, they were essentially firing into the back of the couch.  Also, it has been my experience that the high range drivers of surround speakers sound better when placed above the listener.

3. Because the 90s are lower and smaller (and have higher WAF), I was able to pull the 90s further away from the rear walls and toe them in.   This affords a better angle between the speakers and listening position.   Also, although these speakers are intended to be placed against the wall, I have gotten better results with them pulled well away from any walls...specifically I've perceived better depth to the sound field.

BTW, I just finished doing the same recap on the 90s yesterday.   I'll have some comments on that soon.

[Stimpy]

29 minutes ago, DavidR said:

My hand is doing very well. I had a very good surgeon and I'm ahead of schedule. Using it helps in the healing process but I do have limits. I have a case of Viking disease in my R-hand.

I will post my before and after cap readings.

Glad to hear that you're healing properly!  But, "Viking disease"???  Does that mean you have little horns growing out of your hand, and that you go into a berserker rage if a LP skips???  (Sorry). 

[Stimpy]

7 minutes ago, AR surround said:

Out of curiosity, and some strange desire to haul 130 lb and 90 lb speakers around the room, I swapped the 9s with the 90s.   I was stunned that the sound field was significantly better with this configuration, so I've kept it that way.   I surmise that I've gotten these improved results because:

1. The upper range drivers of the 90s are now at ear level.

2. The upper range drivers of the 9s as the surround speakers are now above ear level.   When I used the the 90s as surrounds, they were essentially firing into the back of the couch.  Also, it has been my experience that the high range drivers of surround speakers sound better when placed above the listener.

3. Because the 90s are lower and smaller (and have higher WAF), I was able to pull the 90s further away from the rear walls and toe them in.   This affords a better angle between the speakers and listening position.   Also, although these speakers are intended to be placed against the wall, I have gotten better results with them pulled well away from any walls...specifically I've perceived better depth to the sound field.

BTW, I just finished doing the same recap on the 90s yesterday.   I'll have some comments on that soon.

Thanks!  That makes perfect sense.  Plus, I look forward to your comments concerning the recap of your 90s.  Should be fun! 

[DavidR]

2 hours ago, Stimpy said:

Glad to hear that you're healing properly!  But, "Viking disease"???  Does that mean you have little horns growing out of your hand, and that you go into a berserker rage if a LP skips???  (Sorry). 

Viking disease is a slang term for Dupuytren's Contracture as it is most prevalent in people of northern European decent and is believed to be spread by the Vikings. Horns depicted on metal helmets is not accurate as authentic Viking wear.

[Stimpy]

3 minutes ago, DavidR said:

Viking disease is a slang term for Dupuytren's Contracture as it is most prevalent in people of northern European decent and is believed to be spread by the Vikings. Horns depicted on metal helmets is not accurate as authentic Viking wear.

Thanks.  Sounds like a very inconvenient illness.  I wouldn't want any of my fingers incapacitated or disabled.  Especially since I use my hands for micro-assembly work, on a daily basis.  As such, I truly hope that your surgery was 100% successful...!  

And Thanks for setting me straight concerning Vikings!  Too much Robert E. Howard (and Frank Frazetta) as a kid, I guess?  

[DavidR]

Thanks. My knuckle is very sore and stiff; but my finger is straight. It's hereditary and my mom has it in the same finger and hand. She, like her whole family, is left handed so she never did anything about it and she can barely move it now. It can come back and probably will. It progressed VERY fast from the time I discovered a lump in my palm last February.

On to audio.................

[AR surround]

I finished the AR90 re-capping project and had the original capacitors tested.   I used the same caps for the AR90's as used in the AR9's cap replacement project.  The test results for the AR90 caps are included in the table below as well as those for the AR9's.   My observations based on the combined AR90 and AR9 listening tests are as follows:

1. Highs are definitely cleaner.  On many remastered CD's with over-equalized treble, the highs no longer sound as "smeared" especially with the AR90's.

2. The speakers exhibit a bit more detail.

3. But where the overall system shines is in multi-channel modes.   The  AR9's and AR90's sound totally integrated.  They sounded pretty well matched before the re-cap project, but are even better now.   I would suspect that this result is due to having identical capacitors in both pairs of speakers.    Note that several of the original capacitors in the AR90's were from different manufacturers than those used in the AR9's...The AR9's had all Callins while the 90's had Callins, Unicon and a third brand.

4. The sound field in multichannel modes seems more open and airy.

5. I perceive the system to have just a tad more dynamic range.   Perhaps the very low ESR of the polypropylene capacitors has increased the overall speaker sensitivity a touch?

I am truly enjoying the fruits of this recap project.   I wish that I had done it sooner.   The results are truly good value for the money at about $75 per speaker.

 

[DavidR]

That yellow 6uF cap may have been a mylar cap. I've seen some pics online with those installed on later models where the unicons have been used.

Happy to hear you are enjoying the new sound.

[DavidR]

[Stimpy]

20 hours ago, AR surround said:

I finished the AR90 re-capping project and had the original capacitors tested.   I used the same caps for the AR90's as used in the AR9's cap replacement project.  The test results for the AR90 caps are included in the table below as well as those for the AR9's.   My observations based on the combined AR90 and AR9 listening tests are as follows:

1. Highs are definitely cleaner.  On many remastered CD's with over-equalized treble, the highs no longer sound as "smeared" especially with the AR90's.

2. The speakers exhibit a bit more detail.

3. But where the overall system shines is in multi-channel modes.   The  AR9's and AR90's sound totally integrated.  They sounded pretty well matched before the re-cap project, but are even better now.   I would suspect that this result is due to having identical capacitors in both pairs of speakers.    Note that several of the original capacitors in the AR90's were from different manufacturers than those used in the AR9's...The AR9's had all Callins while the 90's had Callins, Unicon and a third brand.

4. The sound field in multichannel modes seems more open and airy.

5. I perceive the system to have just a tad more dynamic range.   Perhaps the very low ESR of the polypropylene capacitors has increased the overall speaker sensitivity a touch?

I am truly enjoying the fruits of this recap project.   I wish that I had done it sooner.   The results are truly good value for the money at about $75 per speaker.

 

Awesome.  Glad to hear that the 90s have been recapped, and that the results were worthwhile.  Plus, it isn't surprising that the matched speakers sound even better for surround.  I was always a firm believer in matching all speakers, and that it helped create a more cohesive sound field.  So, it sounds like you had similar experiences.

Now, the results of the capacitor testing; not good.  Some extreme findings!  While I shouldn't be surprised that the values had drifted so far out of nominal, I was still shocked with the actual values reported.  No wonder you wanted to recap, and no wonder you were scared that you'd blown a tweeter.  Easy to do, with values drifted that far out.

[AR surround]

DavidR and Stimpy, thanks for your comments.   From the recent posts in the "Capacitor Myths" thread regarding the 350uF capacitor in the AR90:  DavidR noted that it is simply a shunt capacitor that routes high frequencies to ground.  So Stimpy recommended using NPE's with a small poly as a bypass.   What size "small" bypass cap would you recommend for this application?  Thanks.

[Stimpy]

8 hours ago, AR surround said:

DavidR and Stimpy, thanks for your comments.   From the recent posts in the "Capacitor Myths" thread regarding the 350uF capacitor in the AR90:  DavidR noted that it is simply a shunt capacitor that routes high frequencies to ground.  So Stimpy recommended using NPE's with a small poly as a bypass.   What size "small" bypass cap would you recommend for this application?  Thanks.

Film and Foil capacitors are typically what's used for a bypass.  They're supposed to sound even better than poly caps, so that's why they're used paralleled with a poly.  But, for the 350uF NPE cap, you could use a 1.0uF poly, or a 0.1uF film and foil.  Either would be fine.  Some people use both for dual bypass capacitors.  Though, each bypass cap is supposed to have a higher voltage rating, as they're added.  Why, I'm not sure.  So, NPE's for the 350, usually at 100v, then a 1.0 250v poly, then a 0.1 400v F&F - If you want to go nuts, and confuse yourself!

Parts Express sells their Dayton F&F 0.1uF cap for around $0.99.  So, not a huge cash outlay.  I've used the 0.1uF F&F caps, and like what I've heard.  Good luck!

[DavidDru]

AR Surround, thanks for all the detailed accounting of your effort.  Like Stimpy, I have been keeping a recap of my 9's in teh que for a little while now.  I too want to spend appropriately on caps and also like the EVO's as an option.  Does make making the order a little more difficult if you know what I mean ($).

 

You said you sent the caps to your cousin to test.  What equipment did he use?

 

Also, good additional input from David and Stimpy throughout.  David, hope the hand heals up well.  But, Vikings without horns just doesn't do it for me.  Too cool not to be authentic.  If I could get away with wearing horns, I would.

[AR surround]

I forgot to mention in my listening tests that I keep the tweeter, midrange and lower midrange switches at -3dB on both the AR90's and AR9's.    But that was my preference even before the recap.  Hopefully, that extra 3dB of headroom on the tweeter will come in handy as my ears age.

David, I don't know what specific piece of equipment my cousin used to test the caps but I know it was one of those plain vanilla capacitor testers...nothing sophisticated like Carl has described.