AR 9 Crossover Rebuild

[brianw]

Several months ago I was fortunate enough to acquire a pair of AR 9 Speakers in excellent condition with the exception of surrounds.   These were a one owner speaker, came with the original boxes, original sales receipt and two sets of manuals and all the brochures.   I have had the surrounds professionally replaced and all speakers tested.   The cabinets are close to new showroom condition.  

So I have read a lot about the crossovers, both on this site and talked to many local audio pro's about wanting to replace the capacitors and the one resistor in the upper mid range circuit.  
It seems a lot of discussion about capacitor brands and types, changes in sound and so on.   Solen capacitors make things brighter, others debating electrolytic versus PMPC. So not a pro at audio and just like to indulge and enjoy. Although some background in electronics and a passion for audio, I need some help with this one.

My question is I don't have a problem with a bit brighter or more open, my goal though is to just replace capacitors and bring the AR 9 speakers and components back to factory specification, and if there is a added bonus using newer components that handle things better better that is great.

So I guess I am looking for some advice for capacitor replacements.
Upper & Lower Mids and Tweeter.

4 uF  PMPC   x 2     
6 uF  PMPC   x 2
8 uF  PMPC   x 2
24 uF  Electro   x 2
30 uF  Electro  x 2
40 uF Electro   x 2
80 Uf Electro   x 2

Thank in advance to anyone who can start to point me in the right direction or even a complete parts list, brands, values and were to purchase. I have heard I can spend a few bucks,  a few hundred or the skies the limit. 

I will post some pictures as soon as I figure if I can upload pictures here.

Brian

 

 

 

 

 

 

 

[Stimpy]

While I may be in the minority, I believe in at least using poly caps for the high pass, series capacitors.  Those are:

4 uF  PMPC   x 2     
6 uF  PMPC   x 2
8 uF  PMPC   x 2
24 uF  Electro   x 2
30 uF  Electro  x 2
40 uF Electro   x 2
80 uF Electro   x 2

The series capacitors will have the biggest impact on sound quality (IMHO), since they are wired in a direct line to the drivers.  So, when I recapped my AR90's, that's what I did.  Plus, it's a 'little' cheaper that way, as you can use NPE caps for the shunt values.

As to brands, who knows???  There's such a wide variety available, that it can get very confusing as to what to use.  But, I'll just mention a few brands that should at least sound good.  I wouldn't hesitate to try any of the following:  the Parts Express Dayton brand, 5% and 1%.  Clarity Cap, with I feel the ESA/CSA line offering a good balance of performance and price, SoniCaps, Mundorf, Audyn Q4 and Plus, or Jantzen Cross Cap and Superior.  Personally, my main choices would be Mundorf, SoniCap, or Clarity Cap.  I used Mundorf EVO Oil and Supremes on my 90's.  To me, they sound very good.  Clean and clear, with good presence and soundstage depth.  I just acquired a nice pair of AR58s speakers yesterday, and will be looking at those same 3 brands again, when I recap the 58s pair soon.

Oh yea, I got Mills resistors for the in-circuit resistors.  Why not?

Congratulations and good luck.

P.S. Don't be afraid to use all NPE capacitors, if that is what your budget dictates.  They work fine, and I've done it too.  But, when using solely NPE's in a crossover, I've always added bypass capacitors.  Usually Dayton Film and Foil bypass caps.  Basically, I believe they help improve the sound of the NPE by opening up the sound a bit, and they have helped eliminate vocal "S" distortion and spittiness, that I sometimes hear, with them.

[Stimpy]

There's several places where you can buy capacitors.  I've used all of these, without issue:

Sonic Craft

Parts Express

Parts Connexion

Madisound

One thing that irritated me when trying to decide on which brand of capacitors to use; no one single brand of capacitor seemed to have all of the values that I needed.  At least in a single capacitor value.  So, you'll probably have to parallel a couple of capacitors together here and there, to get to the required values you need.  And that's a touchy subject too, and how you should do it?  Some feel it best to use 2 equal capacitors, like two 12uF's for the 24uF.  That you shouldn't use a 22uF + a 2uF.  This can cause phase issues, since the unequal sized caps will have different discharge rates.  Again, I don't know.  Maybe someone smarted than me can answer that?

[AR surround]

Brian,

My experience in recapping both of my AR9 and AR90 speakers (among others) is that the choice of the 24uF UMR capacitor can make the most difference in the performance of the speaker.   I went through five iterations on that 24uF cap:

Solen 24uF

Solen 24uF + 0.10uF F&F bypass cap

Jantzen Fastcap 22uF + 2.2 uF

Mundorf E-Cap 22uF + 2.2uF

Mundorf E-Cap 22uF + 2.2uF + 0.01uF F&F bypass.  

The Solens were a disaster even with the bypass caps.  The Jantzens were better but still on the harsh side.  The Mundorf E-Caps (electrolytics) were the best and performed even better after adding the F&F bypass.   I did not try the Jantzens with F&F bypass caps.  I probably should have given it a shot as I used the Jantzens with F&F bypass on the dome midrange of an AR915 with successful results.

The whole adventure is in these two threads:

http://www.classicspeakerpages.net/IP.Board/index.php?/topic/9406-ar90-crossover-recapping-taming-the-umr/

http://www.classicspeakerpages.net/IP.Board/index.php?/topic/9293-ar-9-ar-90-crossover-re-capping-adventure/&

 

[Stimpy]

On 10/20/2017 at 10:13 AM, AR surround said:

The Solens were a disaster even with the bypass caps.  The Jantzens were better but still on the harsh side.  The Mundorf E-Caps (electrolytics) were the best and performed even better after adding the F&F bypass.   I did not try the Jantzens with F&F bypass caps.  I probably should have given it a shot as I used the Jantzens with F&F bypass on the dome midrange of an AR915 with successful results.

Did you start a thread on your AR915's?  I picked up my AR58S speakers last night, and definitely liked what I've heard through them so far.  I'm very pleasantly surprised, in fact.  The 12" woofer blends seamlessly with the dome mid.  Which I frankly didn't expect.  So, that's got my little brain in gear again, considering a recap.   So, just curious, as we PM back and forth so much, I tend to forget where we've discussed our various AR's.   I wanted to find what you used for the 915's, as a guide.

Thanks.

 

[harry398]

Congrats on your 58s Stimpy.

 

Brian, I also own are among others.

My advice, decide how much you want to spend and experiment.

In the end, j prefer Npe for ease,expense and most of all........Smooth sound.  Don't overlook the inexpensive caps.  They work. 

I put all Npe caps in my ari, with a few polystyrene on the tweternal circuit since I didn't order proper caps in Npe (I had spare polys) so I installed them

I do like running .01 bypass on all caps on miss and tweeters.

That's my simple approach.   Don't over think it 

[Stimpy]

59 minutes ago, harry398 said:

Congrats on your 58s Stimpy.

 

Thanks!   The 58s's are impressive so far.  I'll play around with them, this weekend, and tweak their positioning.  They should be fun.  

They're in pretty good shape as well.  The previous owner refoamed them, a couple of years back.  He did a good job.   The owner was also kind enough to hold them for me.  He had one other offer, but that guy wanted to part them out, which neither of us wanted.  The PO was 'upgrading' to a pair of Paradigm Reference Studio 40 V.2 speakers.  The Paradigms looked nice, but I didn't get to hear them.  I'll be happy with the AR's...! 

[harry398]

Should have nice low end.......

I have a set of 58bxi.  GREAT BASS!!!   

nice mids and tweeters on the  's model.

 

Enjoy 

[AR surround]

2 hours ago, Stimpy said:

Did you start a thread on your AR915's?  I picked up my AR58S speakers last night, and definitely liked what I've heard through them so far.  I'm very pleasantly surprised, in fact.  The 12" woofer blends seamlessly with the dome mid.  Which I frankly didn't expect.  So, that's got my little brain in gear again, consider a recap.   So, just curious, as we PM back and forth so much, I tend to forget where we've discussed our various AR's.   I wanted to find what you used for the 915's, as a guide.

Thanks.

 

Stimpy,

Here is the thread on recapping the AR915:

http://www.classicspeakerpages.net/IP.Board/index.php?/topic/9578-ar915-crossover-help/&tab=comments#comment-114663

 

[Stimpy]

Thanks...!!!     Now I remember.  I even commented in the thread!  It sad to get old, and not remember things anymore...!  

[brianw]

Wow.  First I just have to say thank you to Stimpy, AR Sound and harry398 for you amazingly quick response and helping out with this issue. 

So talked to my audio professional at Sound Hounds Victoria BC after reading your posts.  He is in agreement with the Mundorf capacitors. They have a range of quality levels and he suggested low to mid range as the quality of new components today will still be many times better than when the speakers were built and designed.  My biggest criteria will be keeping the speakers as close to specification as they were designed.

Going to also change out the 7 resistors, as the new resistors available will be cleaner in the signal path I am told.

The location of the AR 9 is going to get changed to a larger room along with all the other gear. As you can see the side firing woofers currently have no room but they still shake the house when a low note is present. About the only thing left to do is the crossovers And some finishing up of the re-finishing. 

The AR 91's beside them will also be getting the crossovers updated.

 

[brianw]

And with these two units completed the hunt will be on for my next AR purchase.  

Side note:  The speakers were being driven by a Bryston 250 WPC, (into 8 Ohms),  power Amp. I shipped the Amplifier to Bryston for a complete check over since they have a 20 year warranty.   While it was gone a substitute Rotel 985 MK II 5 channel was put in place, 100 WPC.  My conclusion, they need the headroom and power. And have to say that the Bryston amp has much more clarity and openness with the AR 9 speakers.  

[Stimpy]

As a side note, Jeff at Sonic Craft (maker of SoniCaps), recommended the use of the Mundorf capacitors in my AR90 update.  That made an impression on me, as Jeff could have easily suggested I use his own brand of caps, but he didn't.  So, that made me feel the Mundorf line of products would be worthy of my use. 

Also Brian, Parts Connexion is in Canada.  That may make them easier for you to purchase through? 

Now, which Mundorf caps?  They make quite a range of product to choose from.  That doesn't make it easy to decide on what to use? 

[brianw]

HI Stimpy

You are so right, quite a product range. I am investigating that right now. Thanks for the tip on Parts Connexion, that will definitely make it easier as far a shipping and of course the dollar exchange rate etc.  Once I arrive at the correct parts I will post what I propose to use.   

Going to talk with the Audio engineer at Sound Hounds Victoria, they have the highest reputation, they are also the ones who did the surrounds on both speaker systems. 

Thanks again

 

[Stimpy]

Hi Brian,

Thanks for the reply.  That sounds really interesting about Sound Hounds Victoria.  I'm definitely curious as to what their recommendations will be?  Please keep us updated when you hear back from them.

Also, here's the thread where Jeff and I discussed my AR90 recap.  Further into the thread, Jeff provides a list of capacitors of what he suggested.  Maybe this will help too?

http://www.audiocircle.com/index.php?topic=142236.0

Happy reading!

 

 

 

[lARrybody]

5 hours ago, brianw said:

Going to also change out the 7 resistors, as the new resistors available will be cleaner in the signal path I am told.

 

11 hours ago, Stimpy said:

Oh yea, I got Mills resistors for the in-circuit resistors.  Why not?

Just a question about replacing the resistors.I see on the AR9 schematic that the seven resistors are rated at 22 watts.  Would using the Mills 12 watt resistors as replacements be of any concern. Finding 22 watt non inductive wire round resistors may be a challenge.

[ligs]

You can double the wattage by either connecting two resistors in series or in parallel. Just remember use two resistors and each is 1/2  of the target value in series. In parallel, you need two resistors and each is  2x the value of the target. 

[Stimpy]

21 minutes ago, larrybody said:

 

Just a question about replacing the resistors.I see on the AR9 schematic that the seven resistors are rated at 22 watts.  Would using the Mills 12 watt resistors as replacements be of any concern. Finding 22 watt non inductive wire round resistors may be a challenge.

The Mills resistors are rated at a 10X power rating into 5 second peaks.  So, I wouldn't worry.  But, to be sure, I paralleled two resistors, at double resistance each, for a 240 watt peak power handling capability.  . I'm not sure why, as I never listen at that wattage.  And again, I only did that for the 2 resistors that are in circuit.  I left the leveling resistors as is, as I run my 90s flat.

[brianw]

With my electronics background, if we could not find the correct wattage for a replacement part going over is not a bad thing as long as the value was correct and you have the space.  Better to reserve than not enough just match the value.   Same with Caps, right value and if the wattage is over it's usually not a problem.  

I have a Bryston power AMP 4B that does 250 watts into 8 ohm, or 350 + into 4 ohm.  I listen at usually lower volumes but the AMP has the reserve and never has to get near to clipping and usually is cold to lukewarm, hence a easy long life.  So if we have the additional power rating it won't hurt and no warm or hot resistors if you do decide to turn it up you have the headroom.   

QUOTE from,   http://www.dummies.com/programming/electronics/components/electronics-components-resistor-power-ratings/

For example, if a 100 Ω resistor will have 3 V across it, you can calculate that 30 mA of current will flow through the resistor by dividing the voltage by the resistance 3V ÷ 100 Ω = 0.03 A, which is 30 mA).

Once you know the voltage and the current, you can calculate the power that will be dissipated by the resistor by using the power formula:

P = I V

Thus, the power dissipated by the resistor will be just 0.09 W, well under the maximum that can be handled by a 1/4 W (0.25 W) resistor. (A 1/8 W resistor should be able to handle this amount of power too, but it’s always better to err on the large side when it comes to power ratings.)

[brianw]

The original goal was to retain the original design and sound of the AR 9 Speakers.  In doing so a lot of research and a lot of talking to some very prominent people in audio.  My main contact who has designed, redesigned and upgraded hundreds of crossovers over his career had a fair amount of input. And has a lot of professional experience with AR vintage product restoration.  

So to keep it simple we will be matching values as they were originally, using same or higher voltages. For the Tweeter and Upper Mid Range, it will be all  MunDorf Oil Capacitors.  The Lower Mid Range will use Axon True Cap,  (cost was prohibitive to use EVO Oil on these large capacitor values).

Given delivery and my own time we will see just how things progress.  

 

 

[brianw]

Correction --  For the Tweeter and Upper Mid Range, it will be all  MunDorf EVO  Oil Capacitors.

[Stimpy]

3 hours ago, brianw said:

Correction --  For the Tweeter and Upper Mid Range, it will be all  MunDorf EVO  Oil Capacitors.

Hurray!!!  I used the Mundorf EVO Oils too.  Though, I went nuts and used the EVO Oils on all 4 series caps.  .  Plus, I wiggled in a Mundorf Supreme or 2 as well, where I could.  I think it was a 3.9 Oil and a 2.2 Supreme, for the 6uF, and a 22 Oil and another 2.2 Supreme for the 24.  I wouldn't have spent for the Supremes, but I found 4 used, at a very good price.  Far less than half.  Someone upgrading to Jupiter caps, and trying to recoup a bit of the cost of those monsters!  

So, as before, I want to hear your impressions, after the upgrade!  I need affirmation.  I spent more than I wanted.  Though, I don't regret it, as I feel the AR's are deserving of the quality of the parts and the expense!  

And in all their glory.  My AR90 crossovers. 

[Stimpy]

Up next.  And I already used a vacuum to suck out that dust cap!

 

[brianw]

Stimpy !!!     NIce pair of 58's .  Look to be in great shape.    I decided to go against the Mundorf supreme, part cost, part not going overboard.  And wanting to keep the flahship AR 9 as close as possible to it's design.  I am on the lookout for another pair of AR 9's,  AR90's,  Ar 9 LS,  or AR 9 LSi. to set aside for my next restoration project. 

In the meantime will be doing some very minor cabinet touch ups and a second coat of oil.  

 

 

 

 

 

 

[brianw]

So my other question is does anyone have any comments about the ferrofluid used in the tweeter and upper mid range of any of the AR speakers ? 

I have heard many stories and many that say it is still intact unless someone abused and over powered the speakers.