New member with AR90's

[Joel]

I've been lurking here for a while, so I thought I would introduce myself. In my teenage years I was pretty heavily into hi-fi. In 1980 I purchased my present setup- a JVC AX5 integrated amp and a pair of AR-90's. I still have the original receipt for the speakers, bought at the Sony Sound center in Minneapolis for $950/pair.

I used to listen to them regularly until the late 80's and had a kid. Not being able to listen at night and a volume, I drifted away from using the equipment for many years. The speakers just sat unused in our living room until a year ago. My daughter moved out to go to college a few years ago, so I decided to use her room the setup my stereo again.

Of course the surrounds were rotted out, but I had them re-foamed locally and I think they sound pretty good. I am thinking that recapping them should be next. I've spent countless hours on the forum reading about it and I think I can handle doing it. My biggest question is the 350 cap. This cap alone will double the cost of the project so I am looking for advice on how to keep the costs down. Alternatively, could I just replace the others and do the 350's later?

Thanks.

-Joe

[JKent]

Hi Joel and welcome

Two options that I can think of:

1. Leave the 350s. They are "probably" OK. Are they big aluminum cans? Probably still good.

2. Replace the 350s with electrolytics.

You can use Bennic electrolytics from Madisound. They don't come in 350uF so use a 250 + a 100. Cost per speaker: $6.90.

Parts Express has those values, too. $5.06 per speaker. Don't know what brand they are.

Best bet may be Erseaudio. They have 350uF NPEs for $2.73 each.

http://www.erseaudio...P10-05-350-0-PB

They also sell good film caps for the other values you'll need. I can't make out the schematic in the Library so don't know the other values, but I just finished an AR 91 restoration. Probably a similar (but smaller) beast.

Kent

[rrcrain]

Most any good cap will work. TO be honest, I'm not convinced the boutique caps are really any better but I've also refused to spend the money on them to find out for myself.

I used Solen Poly caps when I recapped my AR90s. Other people have used different caps with excellent results with this speaker. All reported a major (dare I say massive?) improvement in the sound.

Some claim you should install a small value bypass cap no greater than 1% of the value of the cap being bypassed. No opinion, never tried it myself.

I did replace the 350 uf caps and as recommended in the previous post, I used a 250 and 100 uf cap in parallel. This did make the bass quite a bit tighter. All of the old caps technically measured in spec capacitance wise but did have high leakage.

The old coils are not "perfect lay" or "Litz wound" but they are good quality and can stay.

For me, recapping changed the sound so much I discovered I had a dead upper midrange. Prior to recapping, you absolutely couldn't tell it was dead by comparing it to the other speaker.

[Joel]

Thanks Kent and Richard,

I was wondering about the cheaper electrolytics. What am I losing by going to a cap that is that much cheaper? Would they sound the same, but lose longevity? I am going to use Solen for all but the 350.

I followed the thread on Richards recap, and learned more than I probably wanted to know. I am hoping that just changing the caps will make me satisfied without going through some of the exotic changes that other have done.

I haven't opened mine up yet to look at the crossovers. If they come out easily, that may be the best way to work on them. How difficult is it to put them back in? Should it be screwed, or stapled? What about using glue?

Thanks.

-Joel

[Joel]

Is this the correct list of caps needed for the AR90:

4, 6, 8, 24, 30, 40, 80, 350

Madisound doesn't list a 24 for solen, so should I use two 12's?

Anything missing?

-Joel

[Robert_S]

I haven't opened mine up yet to look at the crossovers. If they come out easily, that may be the best way to work on them. How difficult is it to put them back in? Should it be screwed, or stapled? What about using glue?

Thanks.

-Joel

Hello,

If you haven't already found these, the following topic/post contains information and links that may prove useful to you for the tasks ahead:

http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=4174&view=findpost&p=72384

Cheers,

Robert_S

[JKent]

I was wondering about the cheaper electrolytics. What am I losing by going to a cap that is that much cheaper? Would they sound the same, but lose longevity? I am going to use Solen for all but the 350.

I haven't opened mine up yet to look at the crossovers. If they come out easily, that may be the best way to work on them. How difficult is it to put them back in? Should it be screwed, or stapled? What about using glue?

Re: Electrolytics. Yes. The only thing you are sacrificing is longevity. Electrolytics may last 20 or 30 years (or longer). Film caps last "forever." Take a look at the AR3a restoration guide in the Library here. Lots of useful info that applies to all speaker restorations.

Re: Your cap list: Take a look at the nice pdf attached to post #38 here:

http://www.classicsp...384

And yes, you can use two 12s to make 24. Or combine ANY values that add up to 24 (20 + 4 for example). Or just use a 25uF. That's close enough.

As far as removing the crossovers, assuming that they are similar in construction to the AR91, they will be attached to Masonite boards that are glued AND stapled, with about a million staples. And the 90s have FOUR boards according to what I've read (or is it 2 per speaker?) You can remove the boards by prying all around the perimeter to loosen the board from the glue without breaking it. Prying as many staples as possible out first is the way to go. Get under each with an awl or similar, then pull with pliers. A pain. And FIRST trace the outline of the board so you know exactly where to put it back.

To reattach, first drill holes around the perimeter of each board, maybe 3/4" apart. Use an adhesive with some body, to fill any gaps and avoid air leaks" RTV, latex caulk, Liquid Nails etc. should all work. Then attach the board by driving screws through all those holes you drilled.

Or just leave the boards in place and work on them through the woofer hole.

Here's a thread on "to remove or not", with conflicting opinions pro & con:

http://www.classicsp...?showtopic=1554

Kent

[rrcrain]

The speakers have 2 boards each. The bass section is on the bottom of the speaker. Removing the boards is a relatively simple matter since the glue is pretty well dried out. I'm far sighted and need the distance to see what I'm doing so I removed the boards.

The caps in the bass section of my crossovers were some of the worse leakage wise.

[Joel]

I looked inside the speakers. It is far less space in there than I thought. I don't think there is any way I can do this with the crossovers in place. I just hope I don't damage anything getting them out. The bottom crossover is far more accessible so I should be able to do that on in place.

I am going to order the caps next week, I'll let you know how it goes.

-Joe

The speakers have 2 boards each. The bass section is on the bottom of the speaker. Removing the boards is a relatively simple matter since the glue is pretty well dried out. I'm far sighted and need the distance to see what I'm doing so I removed the boards.

The caps in the bass section of my crossovers were some of the worse leakage wise.

[JKent]

I am going to order the caps next week, I'll let you know how it goes.

Solens are fine, but you're buying a lot of caps. Here's a comparison of Solen vs Erse:

uF Solen PulseX PEx

4 3.05 2.73 (3.9uF) 1.23

6 3.65 2.31 2.09 (5+1)

8 4.85 4.22 (8.2uF) 2.12

24 9.90 (25uF) 8.56 4.00 (25Uf)

30 11.25 10.09 5.64 (27+3)

40 13.95 12.16 (39uF) 6.21 (39Uf)

80 23.65 18.10 (82uF) 10.00 (2X39)

And as I mentioned, Erse has 350uF electrolytics.

Kent

well, the columns don't line up but I think you get the idea. PEx caps are very good, very inexpensive. PulseX caps are premium caps and still less than Solens. Some of the Erse values are slightly off--no big deal. They are close enough.

[Joel]

What should the voltage be on the caps? Also, why don't the values have to match exactly? Is it because of the margin of error in the original design/

-Joel

[JKent]

What should the voltage be on the caps? Also, why don't the values have to match exactly? Is it because of the margin of error in the original design/

-Joel

Voltage is not a big deal. I think the originals were 50 volts. New mylars are 150 volts. Various polys are 250, 400, some higher. Unless an engineer in the group wants to tell me something I don't know (entirely possible), ANY film cap will have sufficient voltage.

The thread Robert_S linked to is very interesting. Here's a quote from Roy (a guy who really knows a lot about crossovers): I have liked mylar film capacitors for restorations because they a have bit more Equivalent Series Resistance than polys, making them act somewhat more like original electrolytic capacitors, with the durability of film capacitors.

So another choice would be the Carli capacitors sold by Madisound. Very inexpensive. They only go up to 20uF though, so you would have to connect a few in parallel for some of the higher values.

Pete said he does not prefer the Carlis because they are 10% tolerance, but when I have measured them (at least the ones I bought) they were pretty well spot on.

That brings us to why the values don't have to match. You can easily go +/- 10% and be considered within spec. In fact, for at least some caps, -10%/+75% is considered within spec! Plus 75%! Substituting a 25 for a 24, or a 39 for a 40 is so close it doesn't matter. You CERTAINLY would never hear it!

I can understand not wanting to go for "cheap" caps on such high end speakers. And if you are planning to keep them, why not go for the gusto? I used Erse PulseX caps in my AR91s. AFAIK they are at least as good as Solen and cost less. Another nice cap that won't break the bank, although they DO cost a bit more than Solen is Clarity Cap PX (sold by Madisound). I actually used one Clarity Cap in my 91s, only because I had some on hand, which brings up another point: The caps don't all have to match.

IMHO, Carli Caps have an advantage over Solen because they are much cheaper and are more "authentic" due to their higher ESR. Erse caps have an advantage because they are "premium" caps at a low price. Clarity Caps are extremely well built, although audio snobs do not think of the PX series as "premium." And Dayton (the house brand, I think, from Parts Express) are perfectly good caps, probably comparable to Solen.

Just to make you crazy, here's another thing to consider: "some" audiophiles extol the virtues of "bypass caps" on the tweeter caps and possibly on the upper-mid caps. That would be the 4, 6, 8 & 24uF caps if I'm reading the diagram right. The bypass cap would be a very low value, like 0.01uF up to maybe 0.47uF for the higher value caps. The bypass caps are usually high quality, high voltage. PE has 400 volt Daytons that they sell as bypass caps, Madisound has some 0.33uF 850v GE caps or 0.1uF 630v Bennic caps that they don't call bypass but could serve that purpose. Some people think it's snake oil. Others swear by them. I'm pretty much on the snake oil side but HAVE used them, only because I figured "for a buck apiece, why not give it a try?"

Post #7 here shows my AR91 crossover rebuild: http://www.classicsp...?showtopic=6565 The black caps are Erse, the blue one is Clarity. I contradict myself, because I added a 0.1 cap to the 3.9 to bring it up to 4.0. This is partly because I had some 0.1 caps on hand, so why not? It was also because the 0.1 Jantzen is high quality and may serve as a bypass. AND I used 1.0uF EPCOS caps (yellow) in parallel with the Erse 39 to bring it up to 40. Again, only because I have a box full of caps on hand. Totally unnecessary. OTOH, the Clarity is a 25uF, used to replace the original 24uF. Really--it's close enough.

Hope this isn't getting too convoluted.

Kent

[Joel]

I just took a look at erseaudio.com. Several of the pulsex sizes are on backorder, as well as the Electrolytic 350. Does anyone else sell them?

-Joel

[JKent]

I just took a look at erseaudio.com. Several of the pulsex sizes are on backorder, as well as the Electrolytic 350. Does anyone else sell them?

-Joel

Bummer. Well, you could contact them and ask about the ETA. Or build up the caps by combining smaller values in parallel, like 150+200, or 330+20, whatever. Doesn't matter as long as the values add up to about 350. Same goes for the PulseX. Or, use PEx. Or go back to the offerings from Madisound: Solen, Carli, Clarity. Or PartsExpress: Dayton or Solen. Both Mad and PE have NPEs.

Pete has recommended this outfit. Not sure how you order from them though

http://www.zalytron.com/caps.html

He has also recommended this outfit:

http://meniscusaudio.com/capacitors-pulsex-polypropylene-c-101_104.html

Try a google search for Erse Pulsex capacitors. A few companies sell them.

Kent

[michiganpat]

check meniscus audio

www.meniscusaudio.com

that's where I get a lot of my caps from, since they're local.

also, personally, I only go for poly caps for values under ~30uf or so.

using a 6.2uf vs. an original 6uf cap, or a 24vs. a 25 are within spec of the originals, and would only alter the crossover point by a few hertz, so that's why a lot of guys say "good enough"

[soundminded]

My experience recapping my AR9s a few years ago was that it was easy to leave the boards alone and cut off the old caps as close to the cap body as possible. I simply soldered the new caps to what was left from the leads of the old ones and secured them with tape or wire wraps. I put enough tape around the exposed leads so that there will never be a short circuit. I used the least expensive NPCs from Parts Express. I think they were 100 volts which is adequate. Higher voltage is of no benefit, the speaker will never see 100 volts. If it does, there'll be far more to worry about than the caps. I did not replace the two large aluminum cans in the woofer circuit. I won't use expensive caps unless and until someone demonstrates that they sound both different and better. Anecdotal stories that aren't backed up with evidence that can stand up to peer review scrutiny holds no water for me especially in this industry. It has more snake oil in it than a snake pit.

BTW, I only found one of the old caps that tested out of spec but that was sufficient to justify the effort especially since I had the woofers and LMRs out for refoaming anyway. Needless to say I'm pleased with the results. If I have to do it again in 20 or 30 years, so be it.

[JKent]

check meniscus audio www.meniscusaudio.com that's where I get a lot of my caps from, since they're local. also, personally, I only go for poly caps for values under ~30uf or so.

using a 6.2uf vs. an original 6uf cap, or a 24vs. a 25 are within spec of the originals, and would only alter the crossover point by a few hertz, so that's why a lot of guys say "good enough"

http://meniscusaudio...tors-c-101.html

4uF (3.9 Solen $3.10)(3.9 PulseX 2.67)(3.9 Sonicap $10)

6uF (6.2 Solen $3.65)(6.2 PulseX 3.17)

8uF (8.2 Solen $4.90)(8.2 PulseX 4.27)

24uF (25 Solen 9.95)(2 x 12 PulseX $10)

30 (30 Solen 11.30) (2 x 15 PulseX 12.80)

40 (40 Solen 14.00)(33 + 6 NPE $2.10)

80 (80 Solen 23.70)(80 Mars NPE 2.47)

350 (200+150 Solen $93) (200 Bennic NPE + 150 Erse NPE $8.33)

If I were doing it, buying from Meniscus, I'd use PulseX for the 4 (3.9), 6 (6.2), 8 (8.2) and 24 (two 12s). Solen for the 30. Either Solen or two NPEs for the 40. NPE for the 80 and 350.

YMMV

Kent

[Joel]

I would think there would be more room to work inside a AR9 because of the bigger woofer hole. There is a brace in the way of the top of the crossover board that makes if very difficult to see past. I hope the boards come out easily, but I will find out in a couple of weeks.

-Joel

My experience recapping my AR9s a few years ago was that it was easy to leave the boards alone and cut off the old caps as close to the cap body as possible. I simply soldered the new caps to what was left from the leads of the old ones and secured them with tape or wire wraps. I put enough tape around the exposed leads so that there will never be a short circuit.

[Joel]

I just got my caps in the mail today. I've got a mixture of Solen and Pulsex, along with electrolytic for the 350 (100 +250).

I was surprised at the size of the electrolytics- they are much smaller than the original 350. My originals are in a tin can.

Is there a direction for the caps? For the 250-100- I just solder the leads together, then to the crossover?

Also, some of the caps are, for example- 80uf, then the other is labeled 80,000uf. Are they both the same?

I am going to dig into this next week. I'll post how it goes.

-Joel

[JKent]

I just got my caps in the mail today. I've got a mixture of Solen and Pulsex, along with electrolytic for the 350 (100 +250). I was surprised at the size of the electrolytics- they are much smaller than the original 350. My originals are in a tin can.

Is there a direction for the caps? For the 250-100- I just solder the leads together, then to the crossover? Also, some of the caps are, for example- 80uf, then the other is labeled 80,000uf. Are they both the same?

Yes--modern electrolytics are much smaller than the old ones. Some guys keep the old ones for that reason, but I think new is probably better. No direction for non-polar (NPE or film) caps. Yes--just arrange them side-by-side (parallel) and solder the leads together.

80,000uF??????? Maybe post a photo.

Kent

Oh, I see. The Solen is marked 80,00uF That is European for 80.00uF which is indeed 80uF

whew!

[Joel]

I just finished the job on one speakers. I worked on the crossover in place, so that make it a bit easier.

I started to work on the second speaker, but I've run into a problem. One of the heads of the screws holding in the woofers is stripped, so I can't get the screw loose. Any suggestions on getting the screw out?

-Joel

-------------------

Never mind- I got the screw out. On to the next speaker.

-Joel

[michiganpat]

on my AR18's, I had a problem, where some of the stuffing of the speakers got jammed in the threads as I was unscrewing it, and stripped the T-nut that the screw threads into. I can think of 2 options for you.

1) what I did-- drilled the head off of the screw, and after extracting the remainder of the screw, I then glued in the T nut, and found a new screw....

2) since you have another hole opposite of the first (assuming the stripped screw is on the 10"), get someone to go in on the other side and hold the spinning t-nut with some vice grips....

[rrcrain]

Most likely, this is not a stripped screw or nut. AR used an insert of sorts with a threaded hole. most likely, the three teeth or barbs on the back side of the insert have pulled free of the cabinet allowing the insert to rotate with the screw. This has the appearance of being stripped but can be overcome by either of 2 methods.

1. If you can remove the other woofer, reach inside the cabinet and push the insert back into the cabinet and hole in place while removing the screw.

2. Get a fine tip flat screw driver and slide under the screw head. This should engage the barbs sufficiently to keep it from rotating with the screw.

My advise is based on personal experience with the AR90.

[Joel]

Thanks for the advice on the screw. I used a square drive screw driver and got enough grip to get it out.

I finished the other speaker last night- so the job is done.

I worked through the woofer holes. I was pretty easy to reach all the caps once the speaker was laying on its back. I had to buy a better soldering iron and I practiced on scrap wire before I started. A 40 watt iron from Radio Shack worked really well. My older 30 watt wasn't enough.

I ended up using PulseX for 8.2, 6.2 and 3.9. Solens for 25, 30, 40 and 80. A combination of 100 and 250 for the electrolytic.

How do they sound? I haven't spent much time listening to them yet, but they sound "clearer" to me now. There is better separation in the upper range. I'm sure I will get a better opinion when I have time to sit down and listed to some familiar material.

Thanks everyone for all the help.

-Joel