Latest aquisition - AR91s

[DavidR]

I got my new binding posts from Madisound. Good and Bad news:

The Good: They are gold plated brass, can accept a bigger wire thru the post hole, the screw portion is the same size as the original so using existing/original terminals should be easy.

The Bad: They still don't accept the full length of my BFA Banana plugs. They accept more than the originals though.

[DavidR]

I have done quite a lot more reading on crossover cap replacement since beginning this thread. Several threads here on CSP, a few on AudioKarma and general ones on the internet. The most helpful were two by Carlspeak and one on AudioKarma titled 'Are boutique caps Worth it in a Crossover'. Understandably it got off topic but it was all good info. Even Ken Kantor posted several responses. However, the most useful threads and posts were from Carlspeak: 'Capacitors: the GOOD, the BAD & the UGLY' and 'What type of capacitors should I put in my AR-90s?; as well as Pete B's 'Capacitor Myths'. I think the most interesting fact was comments (from Carl, I believe) that the old Sprauge caps had ESR values very close to today's film caps.

I am now thinking along the lines of the following:

• 4uF Tweeter series cap: Dayton 4uF 250V 1% precision
  
• 8uF Mid parallel/shunt cap: Dayton 8.2uF 250V 1% precision
  
• 24uf Mid series cap: Dayton 25uF 250V 1% precision
  
• 40uF Woofer shunt cap: Dayton 40uF 250V 5%
  
• 100uF Woofer shunt cap: Dayton 100uF 250V 5%
  

[DavidR]

<EDIT>

I some how ended up with a double post.

[DavidR]

Its been a while since I had time for these speakers. Too many life problems. However, I finally got around to refoaming the woofers and decided to give them a listen.

I also installed new gold plated binding posts (5th pic).

I found mold under the dust caps of each woofer (4th pic). Anyone else ever run across this?

Woofer re-edged (2nd pic)

Made some gaskets from craft foam (3rd pic)

I'm going to try them as fronts in my HT system for a month and then install the Dayton caps I got for them.

After I had the first speaker completed I lugged it upstairs to my son's room and put it in place of one of the TSW610s I rebuilt for him. I set the stereo tuner to mono. I was not able to hear a big difference; althou I thought the 610s sounded better/fuller. Pretty much the only discernible difference was in the mid-range driver. The AR91 mid was better. I'm not convinced the craft foam has made a good seal so I'm hauling them back down to the basement and installing the new caps and when I place the woofers back in I'm going to use double sided sticky foam tape.

[DavidR]

Well, doing the caps in place wasn't as bad/hard as I thought it would be. It took a while as I took my time. There were two solder points that were awkward to do without (almost) burning myself or melting a wire. Now I'm just waiting for the sealing tape for the woofer.

[ra.ra]

Really nice work, David. The re-foams look terrific, and the homemade gaskets look sharp and clean, but if you feel they are not properly sealing, try some simple and inexpensive rope caulk. It may be the "messy+wet" option opposed to the "clean+dry" foam gaskets, but it rarely fails if distributed properly. Cap replacement looks great and I love the pic of the original caps. Just curious - - - what did you do about the mold under the dust caps? At the least, I would've tried to abate with an alcohol cotton swab.

[DavidR]

Thank you ra-ra for your kind words. The re-foam went OK. Again I owe Roy C a big thanks for encouragement and tips. I was worried about messing up on paper cones. I don't think the surrounds I used were perfectly round.

I ordered some sticky tape from Parts Express that is made for sealing drivers. I just felt the bass wasn't as good as it should have been. I also sealed with silicone caulk around the xover board. I really expected the 91s to stand out over the TSW610s even with the original caps but they did not.

On the mold I first used a vacuum and then a cotton swab with isopropanol.

Doing the caps in place took patience. Most of the solder points were easy and a few were a b__tch. Pretty sure I have no cold solder joints. Some of the splices look over done but when you have a light hanging over the hole, your head, and two hands with a tool or two you take what you can get.

I wrote down all the cap values for the new caps and the old. When I finish up the 2nd speaker I'll post those. Almost all the old ones were over 10% on the high side. The new PP Daytons are all very close; even the 5% were within 1%.

[DavidR]

DONE and PLAYING nicely.

I finished up the second speaker today.

Here are the old and new cap values in a pdf attached.

Attached a pic of the foam/gasket tape.

AR91 cap values.pdf

[DavidR]

< UPDATE >

Occasionally I will rotate my 91s into my office system replacing the 90s. I had recapped the 91s using all Dayton polypro caps and found I liked the detail and clarity BUT always found that after about 1/2 hour they'd get under my skin and I couldn't listen anymore - Listener Fatigue - despite having the level contour switches in the -3dB position. Recently I mentioned this to our Member AR Surround who had his own recap adventure with his AR9 and 90 speakers. He suggested I put some Dayton Film and Foil 0.01uF bypass caps on the tweeter and mid series caps. I happened to have a pair in my drawer as well as some Vishay 1837 0.01uF caps.

So I hauled one of the 91's down to the basement (smashed my finger between the door and the speaker in the process) and installed the bypass caps. A Dayton 0.01uF F&F on the tweeter 4uF cap and a Vishay on the 25uF Dayton for the midrange driver. What a PITA ! Very difficult to wrap the leads while working in the cabinet. It was even worse soldering. I was able to get them sufficiently soldered BUT not the type of work I like to do.

I then hauled the 91 back up the stairs and put them both into my reference system for an A/B test. First impression was that the speaker with the bypass caps was duller. Certainly it didn't seem as loud. After some time I got down on the floor and put my ear up to each driver in each cabinet. I now realized what was going on. The non-bypassed speaker has brightness and glare; it was gone from the bypassed speaker. Detail and clarity was actually better in the bypassed speaker.

I then lugged the other speaker down to my workshop and installed the bypass caps in that speaker. Back into the system and put both level control switches to 0dB. WOW!!!!

The music still has all the clarity and detail...........more detail. The music has more depth and smoothness. A cymbal isnt a chrishhhhhh but rather a nice tishhhhhhh. So happy I did that.

I don't know what the bypass caps actually do (electrically) but they do it well.

Pictures are before soldering and permanently gluing down with hotmelt:

[AR surround]

6 hours ago, DavidR said:

...Recently I mentioned this to our Member AR Surround who had his own recap adventure with his AR9 and 90 speakers. He suggested I put some Dayton Film and Foil 0.01uF bypass caps on the tweeter and mid series caps...

To give credit where it is due, it was Stimpy who saved the day by suggesting that I install the Dayton F&F bypass caps in my AR9's and 90's.

[DavidR]

1 hour ago, AR surround said:

To give credit where it is due, it was Stimpy who saved the day by suggesting that I install the Dayton F&F bypass caps in my AR9's and 90's.

Thanks Stimpy !

[ar_pro]

An excellent low-cost tweak!

David, how are the level-control switches on your AR-91's? Any intermittence or static?

[DavidR]

15 minutes ago, ar_pro said:

David, how are the level-control switches on your AR-91's? Any intermittence or static?

None that I've noticed. However, I'm now on 0dB. I did have an issue with one of my AR90 switches. It was 'stuck' on a -3dB setting. I just worked it back and forth. They have always been very stiff to operate.

[Stimpy]

This sux.  Everyone enjoying their freshly recapped AR's, and mine are still sitting.  The crossovers from my 90s were pulled and recapped, but the refinishing of the cabinets has really slowed the rebuild process.  Refinishing isn't something that I had much experiencing with, and I'm taking it very slowly.  I definitely don't want to damage or destroy anything.  But, I'll get there.  Soon I hope, as I really want to hear the results of my recap!

Oh yea, DavidR and AR surround, You're Welcome.  Plus, I'm very happy to hear that my advice helped, and the speakers are performing nicely.  Awesome.

[ar_pro]

On 5/30/2017 at 4:14 PM, DavidR said:

None that I've noticed. However, I'm now on 0dB. I did have an issue with one of my AR90 switches. It was 'stuck' on a -3dB setting. I just worked it back and forth. They have always been very stiff to operate.

David - the AR-90/91 switches are usually very precise, but even they are getting old, right?

The switches in the AR-9 have been an issue for at least 20 years, and can definitely have an effect like the one you've described, which made me wonder about the switches in your '91.

[DavidR]

The switches in the 91 move quite freely.

2 hours ago, ar_pro said:

David - the AR-90/91 switches are usually very precise, but even they are getting old, right?

Yup and not as old as I am and I'm not as 'precise' as I used to be.

[DavidR]

I decided to try some higher quality caps in the series position of my AR91's (4 and 24uF caps). I know many say there is no difference in caps but I wanted to see (hear) for myself.  I picked up some Clarity ESA 25uF at half price and CSA 3.9uF. I also picked up some AudioCap Theta and Cornell-Dublier 940C to use as bypass caps. I have found that bypass caps cut glare, harshness and brightness some find in poly caps.

I got the two Clarity caps soldered up today. Clarity CSA 3.9uF + AudioCap Theta 0.1uF bypass on the tweeter and a Clarity ESA 25uF + Cornell-Dublier 940C 0.01uF bypass that replaced Dayton 1% 4.0uF + Dayton FF 0.01uF bypass and a Dayton 1% 25uF + Vishay 1837 0.01uF bypass.

I did an A/B test with the AR91's. First impression was that there really is not much difference. The Dayton speaker was a bit 'brighter'. My son listened and picked the speaker with the Daytons as better. He did not know which speaker had been capped with the Clarity. He also said there was very little difference.

<LATER> a 2nd listen with my go to album 'Tom Cat' by Tom Scott and the L.A. Express. Still only marginal difference. The Clarity capped speaker did exhibit a blacker background. No white noise mixed in. Dead, silence in the background. Its actually preferred but can seem like something is missing at first. That's why the Dayton speaker seems brighter.

I had always thought I heard a 'ringing' noise very prevalent with this album using the 91's with poly caps; especially with electric piano passages. It was not present with the Clarity speaker. All in all very slight improvements. Good thing I got the 25uF Claritys at half price. YMMV

[AR surround]

David,

- Do you think that the addition of the Dayton 0.01uF F&F bypass caps to the Dayton PMPC caps made a bigger difference than going from that setup to the Clarity Caps?

- Do you conjecture that one could tell the difference between the two setups without the ability to A/B them at equal volume levels?

[DavidR]

(1) Yes

(2) Maybe some could and some could not.

[Stimpy]

This thread started on June 10th 2014.  It was last updated, March 26th 2018.  I made my first comments about my AR90's being recapped on May 31st 2017.  So, my 90's have been in the works for roughly 10 months.  David's 91's have been evolving for approximately 45 months.  That gives me 35 months, give or take, to complete the cabinet refinish, and reassemble the speakers.  At least, if I follow David's timeline?  No pressure, and no complaints from the peanut gallery then!  . I just hope that's enough time???  

[Stimpy]

Oh yea, I'm glad to hear that the Clarity's sounded nice on the 91's.  I guess I should have used bypass caps on my Clarity's, on my 58S speakers, from the start.  They didn't play nice at first for me.  Adding bypasses helped me too.  And I still need to try those C-D 940C caps.  I suppose I need more speakers?  For scientific purposes!  

[DavidR]

Actually I bought the Clarity ESA for my AR90's but decided to use Mundorf ECap-70 NPEs on the tweeter and mid after hearing about AR Surround's issues. That left me with a dust collector.

Sadly no startling revelations with the cap upgrade. They cost quite a bit more than Daytons AND they are not the top of the line which are cost prohibitive for me.

[valkyrie]

A question on the AR-91 crossover - in specific how do the attenuation switches work?   The schematic does NOT show a direct connection from the -6 dB setting to the resistor pack.  I assume that with the -6 dB setting BOTH resistors are in series with the signal.  While with the -3 dB setting only the 2.5 ohm resistor is in series with the signal?    I hate to make "assumptions" - can anybody out there clarify this for me?

Second; what kind of switch is being used?  Would that be a three-throw, triple throw?  Never heard of such an animal.  Can anybody tell me how that switch is qualified in the nomenclature of "switches"?  Or even better - who sells such a switch?  I have 91s and a set of 9s and would like to replace the attenuation switches on the 9s with a style similar to the 91s.  

Thanks for your assistance.

[ra.ra]

I am pretty sure that is known as a SPDT (single pole, double throw) toggle switch, and the switch positions are described as On-Off-On. The 0dB position bypasses the resistors; -6dB position engages both resistors for 4.0 ohms; and it looks to me like the -3dB engages only the 1.5 ohm resistor.

https://www.parts-express.com/spdt-medium-duty-toggle-switch-center-off--060-552

[ar_pro]

valkyrie -  Where do you plan to locate the three replacement switches?

The original switches on the AR-9 are soldered directly onto the switch board assembly, which is then held in place against the front panel by the nuts & washers on the 3 switches.