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

[Stimpy]

8 minutes ago, DavidR said:

LOL. At least I have my caps in-hand. Which may not be a good thing at this point.

You been holding out on me?  What gives?    Which capacitors did you order?  

[DavidR]

Well, with the positive results of recapping my AR91s I thought I'd do my 90s. Below is a spreadsheet of what I have gathered for that project. However, I am a bit concerned about getting speakers that are too bright and/or harsh. The crossover circuits are different in the 90 vs the 91 and I'm worried this may give me different results.

Any comments and/or recommendations ?

I picked up the 25uF Clarity at half price on clearance - otherwise I wouldn't have bothered. I thought it would be a better cap than the Erse Pulse-X - If I can get it to fit.

AR90 Cap values - Copy.pdf

[Carlspeak]

For those contemplating their recap projects, I just want to say that there is no one correct combination of cap type that will please all listeners. We all hear differently and our listening environments are yet another HUGE variable. That is why AR included adjustments in the HP circuits. First, the Aetna-Polak rheostats and later, switches. The rheostats were ideal because they provided continuous adjustment, whereas the switches were limited to incremental adjustments. 

So, take your best guess on what to buy, do the recap and give the speakers some time for you to adjust to them because they will most surely sound different - hopefully better. Your listening taste will dictate what tweaks may be required to 'voice' them to suit your particular situation.

[Stimpy]

20 minutes ago, DavidR said:

Well, with the positive results of recapping my AR91s I thought I'd do my 90s. Below is a spreadsheet of what I have gathered for that project. However, I am a bit concerned about getting speakers that are too bright and/or harsh. The crossover circuits are different in the 90 vs the 91 and I'm worried this may give me different results.

Any comments and/or recommendations ?

I picked up the 25uF Clarity at half price on clearance - otherwise I wouldn't have bothered. I thought it would be a better cap than the Erse Pulse-X - If I can get it to fit.

AR90 Cap values - Copy.pdf

 

Thanks for the spread sheet, with the measurements.  It's nice to see that all of the replacement capacitors measure so well, and were well balanced to one another.  Plus, I most definitely look forward to your listening impressions after the recap.  Especially how you like the ClarityCaps, and the Solen's in the bass circuit.  And if you think they "sound" better? 

Oh yea, any plans to test the Pulse X caps against the Clarity's, on the UMR?  Inquiring minds want to know!  

  

[Carlspeak]

I agree with using Solens in shunt circuits where large uF values are needed and film is a priority.

[DavidR]

@Stimpy: If I can get the Clarity to fit I will NOT be trying the Erse. If I use the Erse I will put one of the Vishay 1837 10nF caps in parallel to it. (I have no idea if they will do what Tony Gee says but they are only 99 cents each). I only want to open them up once and be done with it. Not sure if I should add any resistors in series to the new caps in the UMR and tweeter (thoughts people).

The Clarity and Solens came from Parts ConnXion and they only charge a dollar to match caps. They screwed up on the Solens. They were supposed to match a 150 and 200 to get 350uF value. They matched the 150 to each other and 200 as well. They were willing to correct the issue but I would have had to pay for shipping back. I decided to live with it. The closeness of the Dayton caps was pure luck.

I don't expect to hear any difference with the shunt caps in the bass. I will, however, measure the old cans and see how close they are.

Here is a link to my AR91 re-cap thread: AR91 re-cap

At first I had a bit of brightness with some music/sources. I played hours of pink noise as Carl suggested. I'm not sure if that helped or the fact I went from an Emotiva XPA-2 G2 amp to an Emotiva SA-250 amp. The XPA-2 was somewhat forward (out in front) with the upper mid and treble.

 

[RoyC]

11 hours ago, DavidR said:

The Clarity and Solens came from Parts ConnXion and they only charge a dollar to match caps. They screwed up on the Solens. They were supposed to match a 150 and 200 to get 350uF value. They matched the 150 to each other and 200 as well. They were willing to correct the issue but I would have had to pay for shipping back. I decided to live with it. The closeness of the Dayton caps was pure luck.

David,

You didn't luck out with the Daytons. Most 5% Dayton caps are very close to 1%. It is unusual to find any of them more than 2% beyond stated value. Heck, the meters they used to match them may have greater tolerances...and are likely measuring at only one frequency.

Roy

 

[RoyC]

On 1/22/2017 at 9:06 AM, DavidR said:

Wow

I opened one up and its full of what appeared to be polyethylene (plastic) film. My limited experience in this area led me to believe they were some early type of film cap.

Hey David,

Well, you motivated me to tear into some caps, as I found a red and black AR cap in the stash. Attached are photos of it, as well as several other new npe's after dissection. I also included photos of a dissected AR "wax block" cap from an AR-5.

Every capacitor below is an electrolytic capacitor. Aluminum foil and/or aluminum oxide deposited on film (the film you saw) is in every one of them. What makes them "electroytic" is the oily liquid or semi-liquid electrolyte impregnated paper rolled up with it. (The paper in the old wax block actually has a petroleum odor and is rolled up with a thicker foil.) As better electrolytes were developed and manufacturing techniques became more precise, npe's became smaller. Note that the use of foil and oxide film in these caps does not make any of them a "film and foil" capacitor, which is a type of film cap. Film caps are dry...no electrolyte.

Btw, after looking at the innards, I concur that Erse are not the best npe's to use. Even though I've been able to verify that they measure (just) within stated spec at 1000hz, they are smaller, and their construction does not inspire confidence.

So while you guys debate the unmeasurable "nuances" of various brands of film caps, or by-pass film capacitors, make sure to keep in mind the very measurable differences of the original (as well as new) npe capacitors. If after a re-cap, a tweeter or mid is sounding too bright or harsh (compared to before) it is extremely unlikely to be due to the brand of film cap, or due to a missing by-pass cap. It is simply due to the removal of up to an ohm of resistance in the circuit, as well as differences in npe behavior at varying frequencies.

I'm not saying not to use film caps. I use them often...and it is fun to experiment and speculate. Most people are happy with the outcome. It just makes me smile to read discussions about Clarity vs Solen vs Dayton vs whatever film caps, given the greater variables to consider in 40 year old speakers.

Roy

 

[DavidR]

9 hours ago, RoyC said:

David,

You didn't luck out with the Daytons. Most 5% Dayton caps are very close to 1%. It is unusual to find any of them more than 2% beyond stated value. Heck, the meters they used to match them may have greater tolerances...and are likely measuring at only one frequency.

Roy

 

What I meant by "lucked out" was that they were matched. Parts Express does not offer matching - I've asked. So the fact I got caps that had the same value was by chance.

[DavidDru]

Thanks for doing that Roy.  Was hoping you would actually after it was discussed above.  And now all know what those were.

So the typical black with red top caps in many of our AR's are NPE's.  Correct?

What are the big metal callins cans?

Also, have folks found some high quality audio grade NPE's?

[DavidR]

9 minutes ago, DavidDru said:

Thanks for doing that Roy.  Was hoping you would actually after it was discussed above.  And now all know what those were.

So the typical black with red top caps in many of our AR's are NPE's.  Correct?

What are the big metal callins cans?

Also, have folks found some high quality audio grade NPE's?

David, 5th post up from the bottom of page 4 I posted that the black caps with red ends are in fact electrolytic. I found this out by reading a pdf Kent posted on Callins caps. The big cans are also electrolytic.

[Carlspeak]

The big caps might be Sprague Compulytics. They will be appropriately labeled. If so, my testing has shown they drift very little from spec. after 30 years. I again refer you to the 'good,bad & ugly' thread where I discussed the Sprague caps in another post.

You can save a lot of money if you retain the Sprague caps (if you indeed have those) and not let lytic-bias get the best of you.  :-)

 

 

[Stimpy]

12 minutes ago, Carlspeak said:

The big caps might be Sprague Compulytics. They will be appropriately labeled. If so, my testing has shown they drift very little from spec. after 30 years. I again refer you to the 'good,bad & ugly' thread where I discussed the Sprague caps in another post.

You can save a lot of money if you retain the Sprague caps (if you indeed have those) and not let lytic-bias get the best of you.  :-)

 

 

I wish we could get a Sticky for The Good, the Band, and the Ugly.  Plus Capacitor Myths as well.  It might make things easier...  

[DavidDru]

Here is the bottom board in my AR9's with the large metal Callins cans.

My guess is that being encased in metal, these would have a much better chance of not drying out over time.  But that is just me trying to apply some logic.  The smallest of them (the one in the foreground) I can't tell from teh photo.  There is one of those up on the top board too along with the 4 black and red NPE's.

[DavidR]

The metal one up top is the 24uF (series cap for the UMR) and I had one in my 91's that measured over 40uF; the other measured 29.1uF.

Madisound sells Bennic NPE caps. You could get (2) 1000uF + (1) 500uF for the 2500 and (2) 165uF + (1) 140uF for the 470uF cap.

[RoyC]

3 hours ago, DavidR said:

What I meant by "lucked out" was that they were matched. Parts Express does not offer matching - I've asked. So the fact I got caps that had the same value was by chance.

...and what I am saying is that they would likely have been "matched" anyway. It is really not necessary to have "matching" done with these. It is typical for them to be that close. They don't vary....and if they do, the tolerances are so tight you will never know the difference.

Roy

 

[DavidR]

5 minutes ago, RoyC said:

...and what I am saying is that would likely have been "matched" anyway. It is really not necessary to have "matching" done with these. It is typical for them to be that close. They don't vary....and if they do, the tolerances are so tight you will never know the difference.

Roy

 

I totally agree with this on the Dayton caps. It matches (pun) my experiences.

[Carlspeak]

Having low tolerance resistors in your XO's is just as important, if not more so, than having 'matched' caps. It's the main reason I opt for Mills 1% resistors when doing a XO resto or upgrade even if the original cement 5 or 10% resistors may still be fine.

[DavidR]

That's a big expense Carl. You need 2 of each (dbl value) in parallel to get the necessary wattage. Do you use the Mills or the Vishay-Mills? and What do you think of the MoX resistors in comparison?

Would you describe it as a subtle or remarkable difference in SQ ?

[JKent]

I like Mouser A LOT. Always great service and zillions of parts. Here are some 25w wire wound resistors in values 2, 3, 4 & 5 ohms at 1% tolerance. I think those are the values for the AR-9.

So prices each would be:

• 2 ohm $2.77
• 3 ohm $2.77
• 4 ohm $2.77
• 5 ohm $2.81

http://www.mouser.com/Passive-Components/Resistors/Wirewound-Resistors/Wirewound-Resistors-Chassis-Mount/_/N-7fx9gZscv7?P=1z0wo4tZ1z0wn9mZ1z0srt3Z1z0vnvfZ1z0vpm5Z1z0srtsZ1z0we4uZ1z0wljoZ1z0x737Z1z0x77jZ1z0x74hZ1z0x70qZ1z0wn7yZ1z0x88n&Ns=Pricing|0

[RoyC]

26 minutes ago, Carlspeak said:

Having low tolerance resistors in your XO's is just as important, if not more so, than having 'matched' caps. It's the main reason I opt for Mills 1% resistors when doing a XO resto or upgrade even if the original cement 5 or 10% resistors may still be fine.

The old resistors and new sandcast/cement type do not vary much (typically much less than 5%, if at all), and I leave them in if they are not damaged. In older AR's, the pots and drivers' voice coils often vary by 10% +/-, not to mention their mechanical differences. I seriously doubt high end resistors will be noticed as any kind of upgrade in these speakers. Then again, I don't believe "matched" film caps will be noticed either. There are way too many other variables in play for this to be any kind of priority.

Roy

[RoyC]

2 hours ago, DavidDru said:

Here is the bottom board in my AR9's with the large metal Callins cans.

My guess is that being encased in metal, these would have a much better chance of not drying out over time.  But that is just me trying to apply some logic.  The smallest of them (the one in the foreground) I can't tell from teh photo.  There is one of those up on the top board too along with the 4 black and red NPE's.

 David,

AR used 3 different brands of the large can type capacitors...Sprague ("Compulytic"), Industrial Condenser ("Royalytic"), and Callins, as seen in your photo. The nature of their construction, with only one end cap, suggests they would be more resistant to drying out. I measured many of them prior to my work with Larry/Vintage AR, as well as those found in his repair/restoration work in recent years. They all have held up pretty well compared to other types of capacitors, with Sprague being the best, and Callins being the worst. It could be the vents (see the round disc between the terminals) were sealed better in Spragues. Larry tests the caps, but always leaves the cans in place if they are within 10% of spec.

Roy

[RoyC]

3 hours ago, DavidDru said:

Thanks for doing that Roy.  Was hoping you would actually after it was discussed above.  And now all know what those were.

So the typical black with red top caps in many of our AR's are NPE's.  Correct?

Also, have folks found some high quality audio grade NPE's?

Yes, it has been firmly established the red and black caps are NPE's. As I mentioned earlier in this thread, the only AR speaker I have ever seen with a film cap is the 4uf mylar tweeter cap found in the AR 303 manufactured in the 90's.

Regarding high quality NPE's, Bret Thiel, one of the AR-3a restoration guide contributors, acquired some high quality European NPE's for an AR-9 restoration a number of years ago. I don't know anything about them, but he used them to replace the film caps he initially used. 

Roy

[DavidDru]

2 hours ago, RoyC said:

Yes, it has been firmly established the red and black caps are NPE's. As I mentioned earlier in this thread, the only AR speaker I have ever seen with a film cap is the 4uf mylar tweeter cap found in the AR 303 manufactured in the 90's.

Regarding high quality NPE's, Bret Thiel, one of the AR-3a restoration guide contributors, acquired some high quality European NPE's for an AR-9 restoration a number of years ago. I don't know anything about them, but he used them to replace the film caps he initially used. 

Roy

Finding some good audio grade NPE's beyond what Erse and Parts Express offer would be fantastic.  I will hunt some more.  I have found a few here and there but not in very many values.  I emailed the folks at Partsconnexion to see what they have to offer.  Couldn't tell on their web site very well.  If you do just the black and reds in the AR9 you need  4, 6, 8, 24 and 40 values.

Not to open another can of worms but I was reading another recap thread on guys discussing Celestion Dittons and they were suggesting when combining 2 values to get a desires value of cap that you should always strive to get 2 of the same values if at all possible.  So there's that too.

[JKent]

4 hours ago, DavidDru said:

another recap thread on guys discussing Celestion Dittons and they were suggesting when combining 2 values to get a desires value of cap that you should always strive to get 2 of the same values if at all possible.

the word that springs to mind is "malarky." Or "hooey." Take your pick