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

[RoyC]

15 hours ago, AR surround said:

Thanks gentlemen.   Since the Dayton F&F bypass caps are so cheap, I'll get a bunch of them the next time I place an order.   Perhaps I'll bypass the tweeter caps as well as the UMR caps.  I'll stock up on resistors too.

Debating brands of film capacitors intended to replace original electroytic caps in 40+/- year old speakers is absurd. As stated above, all of the components of a system have an effect on the outcome. This does not mean, however, that using expensive film capacitors will improve a design previously based on capacitors having different characteristics. If we were designing a system from the ground up today using high end capacitors with minimal ESR, and low DF, etc, later replacing those film caps with electrolytic caps would be detrimental to the sound of our new design. Well, It works both ways.

You are more likely to bring the sound back in line with your expectations with some well placed series resistors, or the replacement of the new film caps with electrolytic caps. "By-pass caps", which, in my opinion, are dubious in terms of benefit, will just lower series resistance (ESR) a bit more than it already is...which is already much lower than it originally was due to your new film caps. You are not the first person to be disappointed by the replacement of the original electrolytic capacitors with film caps in an old speaker.  A more subtle option would be to try some polyester/mylar film capacitors, which provide a bit more series resistance than polypropylene caps.

Perhaps some original components were chosen by the design engineers based on cost or lack of something more sophisticated at the time, BUT these successful speakers were engineered and voiced around these components, and swapping one crossover component for something with different characteristics is not automatically an "upgrade", regardless of cost or superior construction. 

For the record, Ken Kantor has stated that a capacitor "burns in" within a few seconds of its initial usage. A person adapts to any changes in the sound much more than any changes taking place in the capacitor. He also believes using film caps to replace electrolytic capacitors in classic/vintage speakers designed around electrolytic caps is a waste of money, and can yield inferior results.

Roy

[Jeff_C]

15 hours ago, Carlspeak said:

Clarity Cap in the UK did a comprehensive study of mechanical resonances in audio Capacitors 7 years ago (link to study summary below) which led to the development of their MR series. The solution was improved winding technology which the Germans have also adopted. Only they haven't made a marketing campaign out of it..

http://www.partsconnexion.com/t/claritycap/Reseach_Summary.pdf

I fiddled with some caps years ago and found some of them emitted a sound when connected in series with an 8 ohm dummy load and driven by a function generator tied to an amplifier. It didn't take too many volts of input to get some caps to literally 'sing'. 

OK I have to admit I was wrong about this, but mainly because I overlooked mechanical resonances. I have only skim read the Clarity Caps paper, but it is interesting that they had to take a new line of approach after a panel of ordinary listeners failed to give them any meaningful and useable results in ABX tests. They then moved on to using a panel of skilled/trained/critical listeners and even then around 10% thought the sound was worse, about 30% thought it was the same, and about 60% thought it was better. So yes statistically they have proven something, but it is not overwhelming, night and day differences for your average Joe.

I agree with RoyC that it seems of dubious worth using expensive speciality caps to replace electrolytics in vintage speakers which were designed using electrolytics. Replacing like with like will replicate more accurately the electrical measurements of the original cap thereby maintaining the system's original sound

[JKent]

8 hours ago, RoyC said:

using film caps to replace electrolytic capacitors in classic/vintage speakers designed around electrolytic caps is a waste of money, and can yield inferior results.

When I started doing this stuff our friend John O'Hanlon (and Roy) provided a lot of guidance. John, being an EE, knows more about the science than any of us and it was his recommendation to use film caps, not for "better sound" but because 'lytics only last a couple of decades or so. His thinking was that if you want to pass your beloved AR-3a's down to your grandchildren you should build them to last.

I never claimed to have "golden ears" but to me the "sound" of capacitors is a bit like the "sound" of stupid-expensive speaker cables. There are SO many more variables, such as room acoustics or--in the case of our beloved classics--the deterioration of various mechanical components in the speaker, that it all seems a bit silly (full disclosure: I'll admit to having installed bypass caps from time to time but I'm convinced there was no benefit).

I'll continue to use film caps for their longevity but my preference will always be for inexpensive mylar. I like the price of Carli, or the long-gone "surplus" caps, or "gum drops" and Roy makes the only scientific argument I've heard: The higher ESR of Mylar is closer to the ESR of the original 'lytics.

YMMV

Kent

[DavidR]

<edit>?

[Stimpy]

12 hours ago, DavidR said:

@DavidDru and @Stimpy I'm curious what you two are leaning towards for caps in the tweeter and UMR series caps. It seems that to go from the 'everyday' MKP caps to the next step up in film caps it gets expensive; especially because  you need to start paralleling caps to get the correct value for the 6uF.

I'm still undecided.  While I know anything would be better than the 35+ year old NPE's in there now, I just can't bring myself to not consider every option.  Stupid, but there ya' go.  I've even recapped other speakers using Bennic NPE's bypassed with Dayton F&F caps, and liked the results!  More presence, with much more palpable imaging.  A smoother sound too, while more detailed.  My wife heard the differences as well, without me telling her what I had done.

Also, I was just reading this old thread, on an AR9 recap, that has been interesting.  Could be worth a look too?

AR9 Recap

Another good cap thread.

AR9 Recap #2

One thing I've done is make a list of caps and prices.  A list of values and their prices, from most of the major brands of caps.  Maybe it'll help in making a decision?  Of them all, the Dayton (Bennic) 5%, the Erse Pulse X, and the Audyn Q4 caps seem the most economical.  Those and the Axon caps on sale at Parts Connexion.  Really good pricing on those.

Axon

My AR90 Cap lists. 

TWEETER 4.0uF        
    01) DAYTON 5% - 2.19
    02) AUDYN Cap Q4 (3.9) - 2.29
    03) ERSE PULSE X 400 - 2.67
    04) SOLEN (3.9) - 3.89
    05) DAYTON 1% - $3.97
    06) JANTZEN CROSSCAP (3.9) - 4.18
    07) JANTZEN STANDARD-Z (3.9) - 4.25
    08) CLARITYCAP PX (3.9) - 4.65
    09) MUNDORF MCAP MKP (3.9) - 5.54
    10) CLARITYCAP ESA 250 (3.9) - 8.60
    11) SONICAP GEN1 - 11.98
    12) MUNDORF MCAP EVO OIL (3.9) - 12.40

TWEETER 6.0uF
    01) DAYTON 5% (5.6) - 2.87
    02) AUDYN Cap Q4 (5.6) - 2.99
    03) ERSE PULSE X 400 - 3.25
    04) SOLEN (5.6) - 4.53
    05) DAYTON 1% (5.6) - $4.64
    06) JANTZEN CROSSCAP (5.6) - 5.42    
    07) JANTZEN STANDARD-Z  (5.6) - 6.15
    08) CLARITYCAP PX - 6.20
    09) MUNDORF MCAP MKP (5.6) - 6.23
    10) CLARITYCAP ESA 250 (5.6) - 10.30  
    11) MUNDORF MCAP EVO OIL (5.6) - 13.50   
    12) SONICAP GEN1 - 15.25    
    13) AUDYN PLUS (5.6) - 21.22

UMR 24.0uF
    01) DAYTON 5% (12+12) - 5.24 ea.    
    02) ERSE PULSE X 400 - 8.56
    03) AUDYN Cap Q4 (22) - 8.57
    04) DAYTON 1% (12+12) - $8.87 ea.
    05) JANTZEN CROSSCAP (22) - 9.99
    06) MUNDORF MCAP MKP (22) - 15.13
    07) CLARITYCAP PX (22) - 16.40  
    08) JANTZEN STANDARD-Z  (22) - 22.35    
    09) CLARITYCAP ESA 250 (22) - 24.60
    10) MUNDORF MCAP EVO OIL (22) - 29.55
    11) CLARITYCAP ESA 630 - 31.55 (on sale at Parts Connexion)  ***
    12) SONICAP GEN1 - 36.05

*** This might be a good replacement for the Solen discussed earlier.   Very warm sounding...!

LMR 80.0uF
    01) BENNIC NPE  - 1.98
    02) Mundorf E-Cap NPE  (82.0) - 8.39
    03) Dayton 5% (40+40)  - 9.39 ea.
    04) AUDYN Q4 (82.0) - 19.62
    05) ERSE PULSE X 400 (82.0) - 21.21
    06) DAYTON 1% (40+40) - 22.07 ea.
    07) JANTZEN CROSSCAP (82.0) - 28.35
    08) CLARITYCAP PX (82.0) - 43.10
    09) MUNDORF MCAP MKP (82.0) - 48.46

The 4.0, 6.0, 24.0, and 80.0uF capacitors are the high pass caps in series with the drivers.  They're the most critical values where sound quality is concerned.  Spend your money there.  The 8.0, 30.0, 40.0, and 350.0 (on my 90s) are all parallel caps that shunt to ground, and don't affect sound to the extent the series capacitors do.  Use NPE's for those.  Or the poly Axon caps on sale wouldn't be too expensive.

Parts Express, Parts Connexion, Sonic Craft, and Madisound are all good places to shop for capacitors.

Parts Express

Parts Connexion

Sonic Craft

Madisound

Hope this helps...???  

 

 

    

 

 

[Stimpy]

1 hour ago, DavidR said:

The 4, 6, 8 and 40uF caps are not electrolytic caps and it would seem no one is quite sure what type of film cap they are. Do you still recommend using mylars to replace those?

I still think that they were NPE's.  Just maybe a higher quality NPE, that was available at that time.

Of the various capacitor manufacturers around now, not many are building poly, mylar and NPE's.  Maybe only Bennic and Erse.  Of the 2, Erse has the widest range of values, that would work for our AR's.

Erse Capacitors

You could use a mix and match of any of the 3 types, as budget allowed.  But IMO, the 24uF cap, used on the UMR dome, is the most critical value in the speaker.  Spend the most for that one...!

Edit - Just looked at the Erse PE-X mylar caps.  They only have the 4, 6, and 8 caps in exact values.  The other values either aren't available, or need to be ordered in multiples.  

[DavidR]

Stimpy, if you take one of those black with red ends caps apart you will see It is not an NPE. The film looks like polyethylene.

[Carlspeak]

15 hours ago, AR surround said:

Regarding Carl's response to my thoughts that the 24uF Solen might be responsible for the brightness in the UMR:  Carl, do you have any suggestions as to how I might tone it down a bit?  Add a resistor?  Bypass cap?  Rip it out and replace with electrolytic, or another brand of polyprop?   Thanks.

Sorry for the late response.

You can add a 0.3 ohm resistor in series with the Solen or revert back to a lytic which won't be the end of the world despite the bias so many recappers have against replacing a lytic with a lytic. If you use good quality audio grade lytics like those sold thru speaker parts suppliers, you'll be fine for many years to come..

[Stimpy]

5 minutes ago, DavidR said:

Stimpy, if you take one of those black with red ends caps apart you will see It is not an NPE. The film looks like polyethylene.

Wow.  Thanks.  I did not realize that.  I never knew they were anything other than NPE's.  I 'thought' that even Ken Kantor mentioned that they were NPE's?  But, then again, I've never taken one apart!  Good work!  

[Carlspeak]

13 hours ago, Stimpy said:

I've no direct experience with Solen caps (yet), so take my comments as such; I only know from what I've read in forums and in reviews.  As such, Solens are reported as being bright, and better suited as being used in electronics, and not for speaker crossovers.  However, it's also said that Solen caps can be improved in sound quality by adding a bypass cap.  I've used bypass caps, and never heard any issues with using them.  The Vishay capacitor is said to work very well for this.

Vishay

Parts Express also has a line of Film & Foil bypass capacitors, which I've used and liked.

Dayton F&F

Both brands are cheap enough that you could buy a few of each and compare...!  

Good luck, and let us know how they work out, if you try the bypass caps.

Give the bypasses a try, although I don't think they will dampen the brightness significantly. I use bypass caps on lytics mostly. 

[Stimpy]

4 minutes ago, Carlspeak said:

Sorry for the late response.

You can add a 0.3 ohm resistor in series with the Solen or revert back to a lytic which won't be the end of the world despite the bias so many recappers have against replacing a lytic with a lytic. If you use good quality audio grade lytics like those sold thru speaker parts suppliers, you'll be fine for many years to come..

Now why did you want and go and do that!  Inject logic and reason back into the equation!!!  Shame on you.  

[Carlspeak]

5 hours ago, Jeff_C said:

OK I have to admit I was wrong about this, but mainly because I overlooked mechanical resonances. I have only skim read the Clarity Caps paper, but it is interesting that they had to take a new line of approach after a panel of ordinary listeners failed to give them any meaningful and useable results in ABX tests. They then moved on to using a panel of skilled/trained/critical listeners and even then around 10% thought the sound was worse, about 30% thought it was the same, and about 60% thought it was better. So yes statistically they have proven something, but it is not overwhelming, night and day differences for your average Joe.

I agree with RoyC that it seems of dubious worth using expensive speciality caps to replace electrolytics in vintage speakers which were designed using electrolytics. Replacing like with like will replicate more accurately the electrical measurements of the original cap thereby maintaining the system's original sound

I agree with RoyC as well about using expensive caps in vintage speakers. But how do you define expensive? That's a relative term for all of us. I've recapped many crossovers professionally for a number of customers that brought a broad range of vintages to me. I always used proportionate judgement in cap choices commensurate with the vintage and overall quality of the speaker. I certainly wouldn't suggest to a customer my installing Duelund foil caps in a vintage Sears speaker for example. There are some good quality caps that are not much more expensive that the most economical ones out there if you look. 

[Carlspeak]

5 hours ago, Jeff_C said:

OK I have to admit I was wrong about this, but mainly because I overlooked mechanical resonances. I have only skim read the Clarity Caps paper, but it is interesting that they had to take a new line of approach after a panel of ordinary listeners failed to give them any meaningful and useable results in ABX tests. They then moved on to using a panel of skilled/trained/critical listeners and even then around 10% thought the sound was worse, about 30% thought it was the same, and about 60% thought it was better. So yes statistically they have proven something, but it is not overwhelming, night and day differences for your average Joe.

 

About the CC study, the first panel of general listeners did well telling the difference between a lytic and a film cap, but when CC removed lytics from the study to focus on film caps with and without construction improvement that addressed the mech. resonances, the differences were much more subtle. So, the panel was upgraded to trained listeners who, in the end came up with the results Jeff_C quoted. The differences are not overwhelming, but significant enough to  entice audiophiles and cap lovers to spring for the much higher priced MR series when that was introduced. You see, cap differences alone are indeed very subtle within construction types. So, doing a DBT with Dayton film caps compared to say, Solens or Audyn or Jantzen caps will be difficult without a group of trained listeners. The differences are not night and day. They never were.

Cap pricing follows the law of diminishing returns. You can spend a lot more for eeking out a very small perceived improvement in sound. But isn't that the case for most audio gear?  :-)

[DavidR]

Here's a quote from Ken Kantor from an AK thread:

" ……... are you saying that all caps sound the same?

Of course not. That would be just as unjustified as saying, "All caps sound different."

What I am trying to get across is that the "sound" of a cap is all about how it interacts with the circuit around it.

In circuit X, Cap A might sound brighter than Cap B.

In circuit Y, Cap B might sound brighter than Cap A.

In circuit Z, Cap A might be audibly indistinguishable from Cap B.

This is obvious from measurements, and it is easy to hear if one takes the time to set up the listening test.

-k "

[Carlspeak]

What Ken is quoted is obvious from the get go. Circuit type is critical. However, I think the discussion here is about 1, maybe 2 circuits.

Don't forget, Tony Gee of HHMHIFI uses the same pair of reference speakers to test all his caps; or so he claims. With that constant, he then removes all other variables other than the fact he knows what he's testing from having acquired the caps and installed them himself. So, certainly not pure science and heavily weighted toward subjectivity and influence of the price and size of the cap to affect his scores. 

[Jeff_C]

18 hours ago, Carlspeak said:

About the CC study, the first panel of general listeners did well telling the difference between a lytic and a film cap, but when CC removed lytics from the study to focus on film caps with and without construction improvement that addressed the mech. resonances, the differences were much more subtle. So, the panel was upgraded to trained listeners who, in the end came up with the results Jeff_C quoted...

That is not what I read. Have another look at the first paragraph on page 9 of the document.

 "We empanelled fourteen volunteer listeners, comprised of University students and staff. As a group the panel found the testing difficult and tiring, and gave no usable outcome.  Most were unable to distinguish electrolytic from film capacitors, and were similarly unable to distinguish between film capacitors of varying resonance."

That quote refers to the ABX testing. I remain in the dark whether the next round of subjective AB testing for the film cap construction (using skilled listeners) was even blind, but am happy to assume that it was.

[RoyC]

On 1/21/2017 at 9:39 AM, Stimpy said:

You could use a mix and match of any of the 3 types, as budget allowed.  But IMO, the 24uF cap, used on the UMR dome, is the most critical value in the speaker.  Spend the most for that one...!

You are implying "spending the most" for the 24uf cap will somehow make the speaker sound "better". I disagree.. In my opinion, it doesn't matter if a film capacitor costs $2 or $200. It simply may not work as well as a relatively inexpensive electrolytic in some designs originally voiced around capacitors with higher ESR.

Using parallel caps to build a desired value is not a bad thing, but it will lower ESR as well.

AR did not use film caps in any of the "classic" speakers, and the AR-3a Limited introduced around 1990 had all electrolytic capacitors. The later AR 303 has only one small mylar tweeter cap in the crossover.

Imo, folks willing to spend crazy dollars for "high end" capacitors should redirect their money into purchasing a high quality capacitor meter, and learn how to use it. It is a much more satisfying way to participate in this hobby than to speculate on other people's speculations.

Roy

 

 

[DavidDru]

Carl, Roy,

Do/did engineers measure and therefore incorporate values other than ohm when designing the speakers originally?  Did they say "oh, I want a cap with an ESR of this"?  Did the designers actually voice the speakers around ESR at that time, or was it what it was?

And I guess I still wonder, is it the measurements that impact SQ or is is the material the cap is made of?

 

[Aadams]

I am not trying to influence opinions with this post but I do have 2 questions.  If today's caps had been available when the AR9 was designed which caps would, in your opinion, have been specified by the designers?  Also, which of todays caps most closely conform to what was originally specified?

Adams

[frankmarsi]

1 hour ago, RoyC said:

You are implying "spending the most" for the 24uf cap will somehow make the speaker sound "better". I disagree.. In my opinion, it doesn't matter if a film capacitor costs $2 or $200. It simply may not work as well as a relatively inexpensive electrolytic in some designs originally voiced around capacitors with higher ESR.

Using parallel caps to build a desired value is not a bad thing, but it will lower ESR as well.

AR never used film caps in any of the classic speakers. Even the AR-3a Limited introduced around 1990 had all electrolytic capacitors, and the later AR 303 has only one small mylar tweeter cap in the crossover.

Imo, folks willing to spend crazy dollars for "high end" capacitors should redirect their money into purchasing a high quality capacitor meter, and learn how to use it. It is a much more satisfying way to participate in this hobby than to speculate on other people's speculations.

Roy

 

 

You go Roy!

[Stimpy]

1 hour ago, RoyC said:

You are implying "spending the most" for the 24uf cap will somehow make the speaker sound "better". I disagree.. In my opinion, it doesn't matter if a film capacitor costs $2 or $200. It simply may not work as well as a relatively inexpensive electrolytic in some designs originally voiced around capacitors with higher ESR.

Using parallel caps to build a desired value is not a bad thing, but it will lower ESR as well.

AR never used film caps in any of the classic speakers. Even the AR-3a Limited introduced around 1990 had all electrolytic capacitors, and the later AR 303 has only one small mylar tweeter cap in the crossover.

Imo, folks willing to spend crazy dollars for "high end" capacitors should redirect their money into purchasing a high quality capacitor meter, and learn how to use it. It is a much more satisfying way to participate in this hobby than to speculate on other people's speculations.

Roy

 

 

If one believes that capacitors 'don't' sound the same, I suppose what I said makes sense.  If not, never mind.  NPE's are all that anyone will ever need!

[RoyC]

18 minutes ago, Aadams said:

I am not trying to influence opinions with this post but I do have 2 questions.  If today's caps had been available when the AR9 was designed which caps would, in your opinion, have been specified by the designers?  Also, which of todays caps most closely conform to what was originally specified?

Adams

Adams,

Today's audio grade npe (non-polar electrolytic) capacitors conform most closely to the original capacitors of the vast majority of mainstream speakers. Bennic and Parts Express are two good sources for them. Erse is another source, but these caps tend to be smaller in size and vary more from stated spec. It should be noted that all electrolytic caps not only have higher ESR than film caps, but behave differently beyond the label's typically stated value at 1000hz. If a crossover is designed around a npe, a replacement film cap will change some things, and vice versa. It is a matter of degree and personal preference as to whether the changes are for the better or worse.

Film capacitors have been available for a long time, but have been used rather sparingly, and are usually found as the less costly mylar type in a tweeter circuit. A company building a state of the art speaker today would likely use film caps. The highest quality caps I've personally seen in a mainstream crossover was a Dynaudio system with Solen polypropylene caps. (Hard to believe, as they are so much "brighter" than other film caps...more internet baloney .)

David, The characteristics of individual components (even the drivers themselves) available to a manufacturer are factored into the overall design goals. I seriously doubt something like ESR of a capacitor is considered, as long it is of the required construction quality and meets any cost considerations. Once the component becomes part of the overall design and response goals, however, replacing that component with one of different characteristics can be an issue. The most obvious example is attempting to drop in a driver, regardless of cost, to replace an original. A state of the art $300 midrange may be great in a modern system designed around it, but is not likely to sound very good as a replacement in an old AR speaker.

Roy
 

[RoyC]

2 hours ago, Stimpy said:

If one believes that capacitors 'don't' sound the same, I suppose what I said makes sense.  If not, never mind.  NPE's are all that anyone will ever need!

Film caps are different than NPE's...but debating the "sound" differences between brands of film caps in vintage speakers is futile and irrelevant relative to other variables. On the other hand, some people armed with nothing more than calibrated hearing have a need to believe. This is not a problem for me as long as their opinions are not stated or quoted as facts in an audio forum dedicated to repair and restoration advice.

Roy

[DavidR]

4 hours ago, Carlspeak said:

What Ken is quoted is obvious from the get go. Circuit type is critical. However, I think the discussion here is about 1, maybe 2 circuits.

Don't forget, Tony Gee of HHMHIFI uses the same pair of reference speakers to test all his caps; or so he claims. With that constant, he then removes all other variables other than the fact he knows what he's testing from having acquired the caps and installed them himself. So, certainly not pure science and heavily weighted toward subjectivity and influence of the price and size of the cap to affect his scores. 

Carl (and others),

What do you think of Tony's descriptions of the different caps he's auditioned? Even Michael Jantzen has said this to me in an email:

"For series connected caps  on the mid-range section and especially for the tweeter section, Super caps (like our Superior, Silver & SilverGold) makes a hearable difference, but even here, we are talking about small nuances and it will also depend on the other equipment in your setup, the media you play, type of music etc.

As with all things audio, it is always a personal preference in sound and also a question of investment versus gained performance."

 

I'm sure that with my age, lots of loud music when younger and 40 years spent mostly in manufacturing I wouldn't hear much difference.

[RoyC]

5 hours ago, DavidR said:

Carl (and others),

What do you think of Tony's descriptions of the different caps he's auditioned? Even Michael Jantzen has said this to me in an email:

"For series connected caps  on the mid-range section and especially for the tweeter section, Super caps (like our Superior, Silver & SilverGold) makes a hearable difference, but even here, we are talking about small nuances and it will also depend on the other equipment in your setup, the media you play, type of music etc.

As with all things audio, it is always a personal preference in sound and also a question of investment versus gained performance."

 

I'm sure that with my age, lots of loud music when younger and 40 years spent mostly in manufacturing I wouldn't hear much difference.

Hi David,

"Different" is not always an improvement.  As Carl mentioned above, placing a small resistor in series with a cap can make an audible difference. I agree with the statement regarding personal preference. 

Some years ago I replaced the caps in a pair of Celestion speakers with new film caps. The owner had been reading internet forum threads suggesting the necessity of replacing original crossover capacitors, and "upgrading" them with film capacitors. Having two pairs of these speakers, the owner said the re-capped speaker now had a harsh upper midrange, and preferred his pair with the original electrolytics in them. (The original electrolytic caps in all 4 speakers measured within 10% of stated value with ESR of nearly an ohm.) Placing a .82 ohm resistor in line with the new film cap brought the speakers back to the sound he preferred, and he decided to leave the original caps in the other pair. Automatically replacing caps without measuring the originals is not always the best course of action, especially if the owner of the speaker is satisfied with the sound as is. I've been measuring old capacitors for lots of years, and continue to find many more in spec than not.

Roy