To Recap or not AR91

[uarnutz]

I just acquired a set of AR 91 that are in very nice shape. Just a quick coat of oil and they will look like new. I just had a chance to crack them open for an inspection and possible recap. I found that all the caps are Unicon (made in Japan). Are these OEM? What has been users experience with these in terms of longevity and sound quality? Worth replacing? ( I do not have a capacitance tester)

[Stimpy]

My AR58S speakers came stock with Unicon caps.  The sound quality was still very acceptable.  Actually, very dynamic in tone.  I did a recap, for safety's sake, but truth be told, the Unicon's were equivelent to the poly caps I used.  It would take boutique level capacitors to better the stock caps, IMO.

Oh, the Callins capacitors in my AR90's, were horrible before a recap.  Rolled off, muted, and distorted.  The AR58S Unicon's exhibited none of those issues.

Good luck.

[uarnutz]

5 minutes ago, Stimpy said:

My AR58S speakers came stock with Unicon caps.  The sound quality was still very acceptable.  Actually, very dynamic in tone.  I did a recap, for safety's sake, but truth be told, the Unicon's were equivelent to the poly caps I used.  It would take boutique level capacitors to better the stock caps, IMO.

Good luck.

That's kind of what I expected to hear. In fact, I had bought new caps before I even knew what was in there. I probably would not have done so if I had known. The one thing that may be worth it is that 24mfd cap based on these forums. Replacing with a Munsdorf e-cap has been an improvement for some.

[Stimpy]

25 minutes ago, uarnutz said:

That's kind of what I expected to hear. In fact, I had bought new caps before I even knew what was in there. I probably would not have done so if I had known. The one thing that may be worth it is that 24mfd cap based on these forums. Replacing with a Munsdorf e-cap has been an improvement for some.

I am definitely a fan of Mundorf caps.  Their E-Caps too.  But, hang onto what you've ordered, and when you feel there's a true need for an upgrade, you'll have the parts at hand.

[Stimpy]

Also, don't discount the use of bypass capacitors.  A small value (0.10 or 0.01uF) poly film cap, in parallel with the NPE, can really open up and improve the sound of the electrolytic capacitors.  They've been mentioned here, and aren't expensive.  The Dayton film & foil bypass caps, that I use, are around a $1.00 each.  Very affordable to try.

[uarnutz]

2 hours ago, Stimpy said:

Also, don't discount the use of bypass capacitors.  A small value (0.10 or 0.01uF) poly film cap, in parallel with the NPE, can really open up and improve the sound of the electrolytic capacitors.  They've been mentioned here, and aren't expensive.  The Dayton film & foil bypass caps, that I use, are around a $1.00 each.  Very affordable to try.

Thanks. Bypass caps will be part of my next PE order.

[Markolone]

I just bought a pair of AR91s in excellent condition, and would like to replace the old caps.

I've read all the posts in the Forum, paying particular attention to the comments regarding the replacement of the midrange capacitor (better NPE to not change the original design too much?)

Before ordering the material, I ask you for an opinion.

 

Capacity	Brand	Model	Price	Note	Qty	Total Price tot
4 uF	Mundorf	Mcap 3.9uF  250V	5.49 €	polypropylene	2	10.98 €
8 uF	Mundorf	Mcap 8.2uF  250V	6.49 €	polypropylene	2	12.98 €
24 uF	Mundorf	NPE 22uF  100V	2.49 €	add 2uF	2	4.98 €
40 uF	Mundorf	NPE 22uF  100V	2.49 €	2 x total capacity of 44uF	4	9.96 €
100 uF	Mundorf	NPE 100uF  100V	4.99 €		2	9.98 €
BYPASS	Mundorf	Mcap 2.2uF 250V	5.19 €	polypropylene to bypass midrange	2	10.38 €
	Mundorf	Mcap 0.1uF 250V	5.29 €	polypropylene to bypass woofer	4	21.16 €
						80.42 €
						88 $

 

[AR surround]

Markolone,

Those 2.2uF Mcaps as the "bypass" caps on the midrange are not Film and Foil caps as @Stimpyis referring to in his above post.  You might want to add a 2.2uF NPE to the 22uf NPE on the midrange and then use a 0.1 uF Film and Foil bypass cap.   I'm not saying that the combination that you have won't sound OK, but I know for certain that the 22uF NPE + 2.2uF NPE + 0.1uF F&F bypass combination does work.

Also consider adding 0.1uF film and foil bypass caps across the 4uF and 8uF Mcaps IF for some reason you don't like the result of just using the MCaps in those positions.

While the film and foil bypass caps may not be necessary on the large shunt capacitors, you might as well add them if you plan on buying the Dayton F&F bypass caps as they are inexpensive.

[Markolone]

Thanks for the clarification. I mistakenly thought that as a bypass they were also fine in poly

I have to review my shopping list!

[AR surround]

6 hours ago, Markolone said:

Thanks for the clarification. I mistakenly thought that as a bypass they were also fine in poly

I have to review my shopping list!

Technically, one could use a poly as a bypass capacitor across an NPE, but I've never tried it.   The theory of adding a bypass cap across a main cap is that the circuit will take on some of the characteristics of the bypass cap.   The 2.2uF poly as a bypass across a 22uF NPE that you have suggested seems like a rather large value for a bypass cap.   @Stimpy, myself and others have used low value (0.01uF and 0.10uF) Film and Foil bypass caps across both NPE's and Poly caps with excellent results.   Film & Foil caps are relatively expensive, so the thought is to add a small value Film & Foil cap to get the most bang for the buck.

 

[DavidR]

I first ran across this in PS Audio's Paul McGowan Question & Answer video on YT - "Why do capacitors sound different"

[AR surround]

12 hours ago, DavidR said:

I first ran across this in PS Audio's Paul McGowan Question & Answer video on YT - "Why do capacitors sound different"

Here is the video that you are referencing.   He briefly talks about using bypass caps at about 8:15 into it.

 

[Markolone]

Based on your feedbacks I reviewed my shopping list,  including and option for the 24uF cap.

The idea is to test two different solutions about the 24uF cap, then select the best one.  The cost of this test is quite low.

Your opinions will be appreciated.

[AR surround]

I am curious to hear your opinion on the two options for the 24uF position after you try them out.   On both of my AR9 and AR90 recaps, I ended up with Mundorf ECaps (22uF + 2.2 uF) plus the F&F bypass.    All previous tests yielded very unacceptable results.   However, for my AR915 (same as an AR91) center channel speaker, I have Jantzen Cross-Caps 5% MKP with 0.01uF F&F bypass caps.  I haven't found the need to change those out to NPE's.

[Markolone]

I'm also curious to compare the different results.  The annoyance will be having to reassemble the woofer for each test, risking doing some damage. 

Now I put the order of the capacitors and as soon as possible I'll tell you the outcome 🙂

[AR surround]

22 hours ago, Markolone said:

I'm also curious to compare the different results.  The annoyance will be having to reassemble the woofer for each test, risking doing some damage. 

Now I put the order of the capacitors and as soon as possible I'll tell you the outcome 🙂

Perhaps you might want to recap one of each speaker with each option installed?  Then you can compare them side by side to check for obvious audible differences.   Of course, it would make sense to listen and then swap speaker locations to ensure that room interactions are not biasing the result.

Another suggestion is to check the results using both recordings of the highest sound quality and those to which you mostly listen.   It is my opinion that a speaker that only sounds good playing the highest quality recordings is useless if it is unlistenable with 90% of everything else.

[DavidR]

15 minutes ago, AR surround said:

Perhaps you might want to recap one of each speaker with each option installed?  Then you can compare them side by side to check for obvious audible differences. 

Great idea. I did this with my 91s.

Keep in mind the circuitry in the 91 midrange is different than the 90 and 9 UMR and is less 'finicky' .

[Markolone]

I was thinking of doing the following:

• 1st step: I replace the capacitors on the first speaker in the version with Mcap on the midrange and I compare the result with the other speaker and with the pair of my old AR35bx which I'm currently using to compare performance
• 2nd step: I replace the capacitors on the second speaker in the version with Ecap on the midrange and I compare the result as above.

For the tests I will select songs that I know well and are well recorded, such as: "you and your friends" by Dire Straits. Classical music to highlight the separation of instruments in full orchestras, etc.

Regarding the bypass, I plan to apply it to everyone immediately, but I don't rule out doing a final test with and without a bypass.

[Stimpy]

1 hour ago, Markolone said:

I was thinking of doing the following:

• 1st step: I replace the capacitors on the first speaker in the version with Mcap on the midrange and I compare the result with the other speaker and with the pair of my old AR35bx which I'm currently using to compare performance
• 2nd step: I replace the capacitors on the second speaker in the version with Ecap on the midrange and I compare the result as above.

For the tests I will select songs that I know well and are well recorded, such as: "you and your friends" by Dire Straits. Classical music to highlight the separation of instruments in full orchestras, etc.

Regarding the bypass, I plan to apply it to everyone immediately, but I don't rule out doing a final test with and without a bypass.

I like bypass capacitors too.  I use them on all values, series and shunt caps.  Bypass caps seem to smooth out the sound, while still Improving detail retrieval.

Oh, HiFi Collective and Falcon Acoustics, both in the UK, are good sources of capacitors.  They could be useful for future projects.

Good luck.

 

[DavidR]

16 hours ago, Stimpy said:

HiFi Collective and Falcon Acoustics, both in the UK, are good sources of capacitors. 

I'd like to try some of the Alcap npe. I think I'll inquire about overseas shipping costs.

[Stimpy]

25 minutes ago, DavidR said:

I'd like to try some of the Alcap npe. I think I'll inquire about overseas shipping costs.

Alcaps come in some good AR values; with 6, 8, 30, 40, and 80uF caps.  If you eventually try some, I'd love to hear about your impressions.  

[DavidR]

On 4/23/2023 at 9:53 AM, Stimpy said:

Alcaps come in some good AR values; with 6, 8, 30, 40, and 80uF caps.  If you eventually try some, I'd love to hear about your impressions.

Getting harder to find the AR cap values used. The 6 is now a 5.7; the 8 is now an 8.2; the 30 is 31 and/or 33; and the 80 is 82.

I'll let you know if I get some and what I think. Of course it will be my opinion.

[Markolone]

Finally I received the capacitors. I state that for the mid I only ordered the ECAP version.

As for the assembly, it was not easy for two reasons:

 - the sound-absorbing material is also stuck in the upper part and I avoided removing it

- the components were drowned in an adhesive part as shown in the photo

 

 

I worked only on one speaker replacing one capacitor at a time and measured the capacitance of both the old and new before installing. The table summarizes the values. I also took the opportunity to check the functionality of the switches, because the variation from 0dB to -6dB is barely perceptible. Electrically everything is fine.

 

 

And now let's move on to the outcome of the tests, performed with different musical genres.

I encountered a strange situation that I did not expect. There is a perceptible difference between the two speakers, I would say in the mid range but I don't know which of the two versions to prefer. After several listens I'm tempted to say it sounded better before, but we're talking details. I tried to switch the position of the speakers thinking of a difference due to the environment, but it was not that. I'm a bit perplexed. The tolerance of the capacitors may have changed the bandwidth, and perhaps my ear prefers the old frequency response.

Before modifying the second speaker, I will carry out further tests.

 

 

[Aadams]

27 minutes ago, Markolone said:

I encountered a strange situation that I did not expect. There is a perceptible difference between the two speakers, I would say in the mid range but I don't know which of the two versions to prefer. After several listens I'm tempted to say it sounded better before, but we're talking details. I tried to switch the position of the speakers thinking of a difference due to the environment, but it was not that. I'm a bit perplexed. The tolerance of the capacitors may have changed the bandwidth, and perhaps my ear prefers the old frequency response.

Before modifying the second speaker, I will carry out further tests.

This has my interest.  Two questions. Do you use an equalizer?  What kind of recordings?

[Markolone]

1 minute ago, Aadams said:

This has my interest.  Two questions. Do you use an equalizer?  What kind of recordings?

Usually I leave the control flat and I use only the loudness control.

About the recording I'm using CD's