My AR-9 Capacitor Recap/Upgrade Project

[fedeleluigi]

On 12/4/2020 at 4:21 AM, r_laski said:

I'm posting this AR9 crossover schematic and picture to show there is a second 1.37mH (6) coil in the Upper MidRange (UMR). It is the one to the right in the picture. One (outside) wire is connected to the 24uF cap and 0.2mH coil. The other (inside) wire is connected to the upper black (-) binding post. The other 1.37mH (6) coil is on the lower left corner. One wire (outside) is connected to the 0.2mH coil, orange wire to UMR (+), and 8uF cap. The other wire (inside) is connected to the 6 Ohm resistor, as shown in the schematic (resistor not in the picture).

In 2009 mluong303 wrote about the same mistake on the CSP schematic and the correction that you reported. 

https://community.classicspeakerpages.net/topic/5317-ar9-crossover-parts-verification/?do=findComment&comment=78769

 

 

 

Contrary to AR9 schematic in the CSP library, the AR90 schematic (original engineering drawing) is correct concerning this point. It also has the 8uF capacitor instead of the 6uF (on the CSP schematic) in parallel with the upper midrange. On the AR90, the HR, UMR and LMR are connected out of phase with respect to the woofers. 

Here  a little inconsistency in the original AR90 schematic is reported (with respect to the crossover assembly).

 

 

[fedeleluigi]

If any member has the engineering drawings (possibly not resized) of the AR9-90 schematic and crossover assembly, please post them. If the files are too large to be embedded here, please post me a PM.

Unfortunately, it seems that they are not  present in the AR Drawings   except that of the AR90 crossover assembly.

[fedeleluigi]

Today, thanks to web.archive.org I was able to find some AR engineering drawings which unfortunately are neither present in the CSP AR-Drawings nor in other pages of this site but were present in some pages of the old site (Arsenal.net).

For those who want to download them (as long as they are downloadable) the link is the following: http://web.archive.org/web/20040604022548/http://www.arsenal.net/speakers/ar/ar.htm

So, on web.archive.org I could find the original drawing of the AR-9 crossover assembly, the AR-90 crossover schematic (it has a much better resolution than that of the new site)  and other interesting files. Unfortunately, I could not find the original technical drawing of the AR-9 crossover schematic.

[Pete B]

@fedeleluigi  There are several posts in this thread with the AR-9 xo schematic, is that one redrawn,

and the one you are looking for an original from AR?  I can look on my 10 year old computer where I

probably downloaded it.  On the other hand if the redrawn one is easier to read I might have just

kept that one.

[NJtechguy]

On 9/1/2021 at 5:37 PM, r_laski said:

NJtechguy, the capacitors in AR90 and AR9 crossovers are very similar. Stimpy’s reply to your post has excellent information and recommendations. AR Surround also has excellent recommendations on capacitor combinations.

 

Since you posted on my thread, I will give my recommendation, based on my recent AR9 recap project. To keep cost reasonable, use MDL NPE capacitors for the 350mF woofer capacitor. I would use ClarityCap poly film caps for all the other capacitors. I use different series of ClarityCap capacitors  for series (inline) and parallel (shunt) capacitors.

 

4mF (series) ClarityCap CSA (2) 2.0mF 630VDC connected in parallel.

 

6mf (series) ClarityCap CSA (2) 3.0mF 250VDC connected in parallel

 

8mF (parallel) ClarityCap PX 4.7mF and 3.3mF 250VDC connected in parallel

 

24mF (series) ClarityCap CSA (2) 12.0mF 250VDC connected in parallel

 

30mF (parallel) ClarityCap PX 30mF 250VDC

 

40mF (parallel) ClarityCap PX 40mF 250VDC

 

80mF (series) ClarityCap (2) PX 40mF 250 VDC connected in parallel

 

I use ClarityCap PX for the 80mf series cap to keep total cost within budget. If cost was no object, I would parallel ClarityCap CSA 47mF and 33mF 250 VDC caps.

 

All of these are available from Parts Connection.

 

You can reduce cost by using single “close” cap values 3.9mF, 5.6mF, 8.2mF, and 22mF depending on how particular you are to matching designed cap values precisely.

 

I add small value film bypass caps to the AR9 woofer caps. If you decide to add bypass caps these are a matter of personal preference as to what you use.

R_Laski,  

Thank you so so much for your feed back (as well as the others that provided info). I was tied up for the past 6 weeks but now ready to move forward. I was deciphering your parts list for the ClarityCaps and was confused in a few areas but think I have it right.

1) I assume the list of parts is for one complete crossover upgrade (one AR Speaker cabinet). Therefore I would double up on the parts to complete 2 AR90 speaker cabinets. 

2) In each line item you mix the words "series" and "parallel" in the same sentence, which confuses me.  example: 24mF (series) ClarityCap CSA (2) 12.0mF 250VDC connected in parallel.  To me, I would think I need to just wire two 12mF together in parallel to make 24mF. So whats the "series' for?   

Finally, please review the parts list I assembled in PartsConnexion shopping cart (the 4.7mF and 2mF caps are out of stock right now and listed as $0, but I would order them when it comes in stock or elsewhere) and let me know if this is complete for 2 AR90 cabinets.

 

 

Many thanks!!!

 

[Stimpy]

20 hours ago, NJtechguy said:

R_Laski,  

Thank you so so much for your feed back (as well as the others that provided info). I was tied up for the past 6 weeks but now ready to move forward. I was deciphering your parts list for the ClarityCaps and was confused in a few areas but think I have it right.

1) I assume the list of parts is for one complete crossover upgrade (one AR Speaker cabinet). Therefore I would double up on the parts to complete 2 AR90 speaker cabinets. 

2) In each line item you mix the words "series" and "parallel" in the same sentence, which confuses me.  example: 24mF (series) ClarityCap CSA (2) 12.0mF 250VDC connected in parallel.  To me, I would think I need to just wire two 12mF together in parallel to make 24mF. So whats the "series' for?   

Finally, please review the parts list I assembled in PartsConnexion shopping cart (the 4.7mF and 2mF caps are out of stock right now and listed as $0, but I would order them when it comes in stock or elsewhere) and let me know if this is complete for 2 AR90 cabinets.

 

 

Many thanks!!!

 

The parts list looks good.  But, don't forget the 350uF Capacitor on the woofer.  These should do it.

MDL 100 X 2

MDL 150

As to "series" and "parallel", don't be confused.  The 4, 6, 24, and 80 capacitors are all series capacitors, as they're wired directly in the circuit part to their respective drivers.  Now, since you have to combine caps, to add to the needed values, they are wired in parallel, to correctly add together.  Then, the parallel bundle is wired up where it's used.  The actual "parallel" caps, in the schematic, are shunt capacitors, since they are wired to ground.

Now, you can also order ClarityCaps through Madisound.  They look to have your missing caps in stock.

Good luck!

[r_laski]

8 hours ago, Stimpy said:

The parts list looks good.  But, don't forget the 350uF Capacitor on the woofer.  These should do it.

MDL 100 X 2

MDL 150

As to "series" and "parallel", don't be confused.  The 4, 6, 24, and 80 capacitors are all series capacitors, as they're wired directly in the circuit part to their respective drivers.  Now, since you have to combine caps, to add to the needed values, they are wired in parallel, to correctly add together.  Then, the parallel bundle is wired up where it's used.  The actual "parallel" caps, in the schematic, are shunt capacitors, since they are wired to ground.

Now, you can also order ClarityCaps through Madisound.  They look to have your missing caps in stock.

Good luck!

What Stimpy said about my use of "series" and "parallel" is correct. Thanks Stimpy! Look at the crossover schematic and you can see to what we are referring. Along these lines, since the 8uF cap is a parallel (shunt) cap I used and recommend 4.7 and 3.3 Clarity PX caps instead of Clarity CSA. They are in stock at Parts Connexion. The quantity ordered for each capacitor is correct to complete 2 AR90 crossovers. I would order the 2uF caps from Madisound. No telling when they will be back in stock at Parts Connexion.

MDL electrolytic caps are available from Parts Connexion (look under Jantzen Audio in Electrolytic caps brands list) and Madisound.  Stimpy's recommended combination for the woofer crossover is a good one. You would order (4) 100uF caps and (2) 150uF caps for 2 AR90 woofer crossovers if you go with the recommended combination.

Check the condition of the 6 Ohm resistor in the upper mid-range and 1 Ohm resistor in the woofer crossover. If the resistor looks charred or if it is glued to the board and the glue is dark or black I would replace them and do not glue them to the board but have them elevated above the board. These get hot during use and need to be elevated to help dissipate heat.

Good luck with you project! Be sure to post pictures and listening impressions.

[Stimpy]

Thanks @r_laski, I appreciate the kind words.  😃

 

 

[DavidR]

Why not use a 200uF + 150uF ?

 

[r_laski]

6 hours ago, DavidR said:

Why not use a 200uF + 150uF ?

I got my NPE caps from Parts Express for my 90s.

A 200uF + 150uF is another good combination. Maybe better, because you only need two of each cap for a pair of AR90s. 200uF MDL non-polar electrolytic (NPE) cap is not available from Parts Connexion. Both 150uF and 200uF NPE caps are available from Madisound and Parts Express. Parts Express NPE caps are made by MDL, just without the brand name stenciled on them. If you are going to buy Clarity Cap 2uF caps from Madisound you can also get the MDL caps there. Saves on shipping costs.

I buy parts from Parts Express as well. I ordered some 220uF caps from them when they were out of stock elsewhere. My issue with them, as well as other suppliers, is if I have a small, inexpensive order, (like 4 caps) their shipping cost can be twice or more the total cost of the items purchased. If possible, I try to limit the number of suppliers I order from because of this. I try to find enough items I need to purchase to get free shipping. I also live in one of the states that US online retailers have to collect sales tax on my purchases from them. Another addition to my costs.

NJtechguy, One more recommendation - pay the fee to have Parts Connexion match the capacitors for you. It's worth it.

[DavidR]

1 hour ago, r_laski said:

................ Parts Express NPE caps are made by MDL,..............

I don't think so. They sure don't test the same on my Agilent cap meter. The Parts Express test the best vs MDL and Bennic. Other companies (like Meniscus Audio) sell those and they are known as Black Beauty.

I've complained about the Parts Express 220uF NPE caps. It seems to be the only cap that does not measure close. They are within tolerance but most of the large caps are 1 or 2uF away from stated value vs like 15uF for the 220uF cap.

I concur about Parts Connextion and their matching. No one else comes close.

[fedeleluigi]

On 10/1/2021 at 3:12 PM, Pete B said:

@fedeleluigi  There are several posts in this thread with the AR-9 xo schematic, is that one redrawn,

and the one you are looking for an original from AR?  I can look on my 10 year old computer where I

probably downloaded it.  On the other hand if the redrawn one is easier to read I might have just

kept that one.

Thank you Pete,

at the moment I only miss the original AR drawing of the AR-9 crossover schematic. But, probably, it has never been posted on CSP. However, If you have it please post it.

Thank you

 

I corrected the AR-9 schematic present in the CSP library:

 

 

[Shacky]

Wow what a great project!!!  Still considering recap of my 9’s.  Will use your plan if and when I do.

[JKent]

On 2/5/2020 at 3:46 PM, r_laski said:

I actually purchased Mundorf 22uF and 1uF ECaps (couldn't find a 2uF) for the 24uF UMR and was going to experiment with them. However, when I measured new 22uF ECaps they measured 23.8/23.9. That’s almost 9% over rated value. It should be no more than +/- 5%.

I had the same experience when I rebuilt the crossovers in my Snells. Decided to give ECaps a try, since they had been recommended by some here. Mine are all about 10% over. Probably not audible but I expected better. IIRC Dayton electrolytics are usually spot on and cost less. No more ECaps for me.

YMMV

[JKent]

On 2/5/2020 at 3:46 PM, r_laski said:

There is one thing I wish someone would research about bypassing. Is there a formula for an optimum ratio of bypass capacitor value to “primary” crossover capacitor value?  I’ve seen the recommendations for .01uF up to a certain capacitor value and 0.1uF above that. I’m not sure how much affect a 0.1uF capacitor has on a 2500uF or 470uf capacitor. Not going to remove them, just something to ponder.

Here's an old paper from North Creek

the art of bypassing.pdf

[DavidR]

Not sure the pdf link is working. All I get is a blank screen.

North Creek was owned and started by George E. Short III. He made several lines of capacitors including the bypass caps and a line of speakers. I'm told they were very good caps. He was an audio engineer at Acoustic Research for a period of time.

[Stimpy]

Here's a repost of the North Creek file.  Hope it works...!

the art of bypassing.pdf

[DavidR]

Thanks for the try Stimpy...............same issue. I was able to download it to my laptop and was able to view it.

My turn ...

 

G.Short BYPASS white paper.docx

[DavidR]

12 hours ago, JKent said:

I had the same experience when I rebuilt the crossovers in my Snells. Decided to give ECaps a try, since they had been recommended by some here. Mine are all about 10% over. Probably not audible but I expected better. IIRC Dayton electrolytics are usually spot on and cost less. No more ECaps for me.

Did you test them at 1000 Hz ?

You can also request a matched pair for a $1

My LCR always matches what they write for a value on the bag within a tenth of a uF.

[JKent]

I tested them with my B&K Precision 810C Capacitance Meter. The caps "match" pretty closely, all 10% above rated value. As I said, YMMV but I'm not a fan.

[RoyC]

2 hours ago, JKent said:

I tested them with my B&K Precision 810C Capacitance Meter. The caps "match" pretty closely, all 10% above rated value. As I said, YMMV but I'm not a fan.

There seems to be a bit of mythology forming around the Mundorf cap. My experience and measurements have never shown it to be superior to similar decent npe caps (such as those offered by Parts Express, Bennic, and MDL). On the other hand, the now-defunct Erse npe cap did prove to be clearly inferior.

[DavidR]

10 hours ago, JKent said:

I tested them with my B&K Precision 810C Capacitance Meter. The caps "match" pretty closely, all 10% above rated value. As I said, YMMV but I'm not a fan.

Not what I asked. What frequency did you use when doing the test?

If you want send them to me and I can measure them and label them and send them back to you free of charge. PM me if interested.

Also, if they are 10% high then P.C. will correct the problem. So will Mundorf - free of charge.

[DavidR]

I looked up the manual for your unit on the B&K website.

Here is a screen shot and the reason for why they measure high - pre-selected test frequency is too low >>>

[AR surround]

On 8/7/2023 at 9:33 AM, JKent said:

I had the same experience when I rebuilt the crossovers in my Snells. Decided to give ECaps a try, since they had been recommended by some here. Mine are all about 10% over. Probably not audible but I expected better. IIRC Dayton electrolytics are usually spot on and cost less. No more ECaps for me.

YMMV

Sorry that the ECaps didn't work out for you, Kent.  Perhaps I should have mentioned that I paid $1 per capacitor for precision matching by Sonic Craft.  But that was over six years ago now.  I bundled the 22uF and 2.2uF caps for the UMR on my AR9's and AR90's.  I found the packing slip this morning with the measurements:

 

[Stimpy]

12 hours ago, DavidR said:

Not what I asked. What frequency did you use when doing the test?

If you want send them to me and I can measure them and label them and send them back to you free of charge. PM me if interested.

Also, if they are 10% high then P.C. will correct the problem. So will Mundorf - free of charge.

 

Parts Connexion just changed their website.  It's now Audio-Connexion.  The new site isn't as easy to navigate, and it's more geared to audio equipment, and not parts.  Parts Connexion now requires clicking on a link, within Audio-Connexion...!  The PC site has been "updated" too, and not for the better.  But, at least the same parts brands are there, they just take a little more effort to find...!

 

Edit:  The new AC/PC site is very buggy.  I can't even log into my existing account, to double-check the details of a previous parts order...!