Acoustic Research AR90 Recap - Basic Xover Questions?

[StimpyWan]

Hey,

I hope someone can help with my crossover questions? Specifically, I have original Acoustic Research AR90's, bought directly from the AR factory, when I once worked at a Teledyne company. They're in very good shape. I've refoamed the woofers and the lower midranges. But, the cabinets need a bit of a clean-up, and I'd like to recap the crossovers, being that the speakers are around 35 years old.

Now, my questions. Are certain crossover caps more important in regards to sound than others? Series caps more important than parallel? Tweeters, over mids, over woofers? I want to use decent parts, but I am admittedly on a tight budget. I want to change what counts, using the best that I can afford, and the rest with 'good enough', if there's little sonic impact? Lot's of NPE caps in my 4-way 90's: 4, 6, 8, 24, 40, 30, 80, & 350uf, so I want to budget my money where it'll make the most difference. I'll attach the crossover schematic, for illustration.

Oh yea, the 4, 6, 24, and 80uf caps are the caps wired in series to the drivers. Are they the most important? And should I use only capacitors of the same brand, for consistency in sound? I've looked at Dayton, Audyn, Jantzen, Sonicap Gen 1, Mundorf MCap EVO, and others, but these seem to get consistently good reviews, and aren't 'too' expensive. But, I've been driving myself crazy, and just need some guidance, and a 2nd opinion, just to make sure that I'm not over thinking this!

Thanks for any suggestions!

Stimpy

 

[Binkman]

greetings;

looks good to me to try to replace with orig. or near values. can always adapt or adjust. keep electrolytic if orig design, poly's can come in later if needed and plenty out there for mids or tweets. think this is keeper.

 

[bobschneider]

I'd use poly caps on the domes, and good quality non-polar electrolytics on the lower mids and woofers. For the 80uF cap on the lower mid, I'd parallel a small value poly with the electrolytic, which should give most of the sonic benefits of a poly cap without the huge cost of a poly cap that big. When paralleling caps, the values add - a 75uF electrolytic in parallel with a 5uF poly cap is a combined 80uF cap.

You can also use the paralleling approach when you need a value you can't find.

 

[StimpyWan]

Thanks Bob,

Good sound advice. I should listen to it. I even have that exact combination of components saved in a Parts Express Cart. I even used a NPE/Poly recap on a set of my planar ribbon hybrid speakers and it sounded great. So, I don't know why I keep second-guessing myself over this simple recap? Maybe because my AR's were my 1st serious set of speakers, and I want to do them justice? Maybe I'm just getting senile? If so, maybe I'll soon forget that I own the AR's, and then they won't need a recap!

Later.

 

[StimpyWan]

I'm still contemplating which capacitors to use in my AR90 recap. While I could recap pretty cheaply using NPEs, I really want to try film caps. So, to try and gain some clarity to my decision, I emailed a couple of different cap vendors for advise. One vendor suggested ClarityCap PX caps, or Mundorf M-Cap MKP caps. Both good suggestions. However, another vendor supplied a very detailed response. As such, I thought I'd share it, for any interest parties. Some very good suggestions, but not cheap. Especially considering these were suggestions for a 'tight budget'! Still, I really appreciated both reply's!

"High-pass:

Mills MRA-5 resistors: http://www.soniccraft.com/index.php/mills-watt-c-29_53_62

4uF G1/200VDC: http://www.soniccraft.com/product_info.php/gen-sonicap-uf-200vdc-p-429

6uF Dynamicap E/210V: http://www.soniccraft.com/product_info.php/dynamicap-6uf-210vdc-p-155

Upper mid:

Mills MRA-10 resistors: http://www.soniccraft.com/index.php/mills-10-watt-c-29_53_295

22uF Supreme: http://www.soniccraft.com/product_info.php/mundorf-supreme-22uf-600vdc-p-4213 If you are concerned about trimming it up, this would be the most economical match: http://www.soniccraft.com/product_info.php/kimber-kap-22uf-200vdc-p-4650

8uF G1/200VDC: http://www.soniccraft.com/product_info.php/gen-sonicap-uf-200vdc-p-446

6.8uF + 33uF Ecap: http://www.soniccraft.com/product_info.php/mundorf-cap-plain-68uf-70vdc-50vac-p-4076 + http://www.soniccraft.com/product_info.php/mundorf-cap-plain-33uf-70vdc-50vac-p-4078

Mills MRA-5 for the RLC network resistor: http://www.soniccraft.com/product_info.php/60-ohm-mills-mra-p-564

Lower mid:

5 Ohm parallel a pair of these: http://www.soniccraft.com/product_info.php/10-ohm-mills-mra-10-p-3609

3 Ohm parallel a pair of these: http://www.soniccraft.com/product_info.php/ohm-mills-mra-12-p-687

33uF + 47uF EVO Oil: http://www.soniccraft.com/product_info.php/mundorf-mcap-evo-oil-33uf-450vdc-p-4163 + http://www.soniccraft.com/product_info.php/mundorf-mcap-evo-oil-47uf-350vdc-p-4167

Low value 33uF EVO Oil: http://www.soniccraft.com/product_info.php/mundorf-mcap-evo-oil-33uf-450vdc-p-4163

Low-pass:

350uF Ecap: http://www.soniccraft.com/product_info.php/mundorf-cap-plain-82uf-50vdc-35vac-p-4073 + http://www.soniccraft.com/product_info.php/mundorf-cap-raw-270uf-63vdc-23vac-p-4065

1 Ohm resistor: http://www.soniccraft.com/product_info.php/ohm-mills-mra-12-p-696"

Enjoy.

 

[elnaldo]

What I'd do, with a limited budget, is to buy Clarity caps PX for the tweeters (no affiliation ),electrolytic with a film bypass for the 25 uf on the mid, and just electrolytic for the rest. If you have some extra $$, I'd spend them in a film capacitor in series with the mid, that 25uF.

I don't think you need film bypasses on the other caps, or "quality looks and technical style". I'd save some $ on the look or the style.

Dayton 5% film caps are always well regarded too. Check those too, don't think they are "cheap". lot of people uses them with success, you'll read just good things about them.

 

[StimpyWan]

What I'd do, with a limited budget, is to buy Clarity caps PX for the tweeters (no affiliation ),electrolytic with a film bypass for the 25 uf on the mid, and just electrolytic for the rest. If you have some extra $$, I'd spend them in a film capacitor in series with the mid, that 25uF.

I don't think you need film bypasses on the other caps, or "quality looks and technical style". I'd save some $ on the look or the style.

Dayton 5% film caps are always well regarded too. Check those too, don't think they are "cheap". lot of people uses them with success, you'll read just good things about them.

I agree. I'm definitely thinking ClarityCaps for the tweeter, maybe a Mundorf of some type, for the UMR, and Dayton or Audyn Q4's (the Audyn's are generally cheaper than the Dayton's) for the lower mid. Then, bypassed NPEs for everything else. I guess pretty much anything would sound better than the 40 year old caps in there now!

 

[elnaldo]

I' d use film caps in series with the drivers, tweeters and higher mids, not on shunt capacitors, or other networks.

 

[Smallies]

Clarity has different models/costs to make life easy and to spare you of stupid Daytons (5% lol). Blast money into the caps and screw the resistors you won't feel cheated at all.

 

[StimpyWan]

I' d use film caps in series with the drivers, tweeters and higher mids, not on shunt capacitors, or other networks.

That's my plan. Though unfortunately, only 2 of the 8 caps are true shunt capacitors; 4 are the high pass series caps, and 2 of the parallel caps are in circuit. That only leaves the 30uF and 350uF caps as viable NPE candidates. And, I found a 350uF poly film motor run cap, that I might use on the woofer. Only 12 bucks, so why not? I've read other accounts of motor caps working out well. I 'might' try it too.

 

[StimpyWan]

Clarity has different models/costs to make life easy and to spare you of stupid Daytons (5% lol). Blast money into the caps and screw the resistors you won't feel cheated at all.

Any favorite ClarityCaps, or are they all good? Also, just curious, why "stupid Dayton's"? I truly want to avoid unworthy parts, so if you have any experience with different brands, I'd love to hear your opinions! My feeling is, just because you can't measure it, doesn't mean that it isn't audible. So, I'm open to personal experiences, concerning upgrades!

 

[elnaldo]

That's my plan. Though unfortunately, only 2 of the 8 caps are true shunt capacitors; 4 are the high pass series caps, and 2 of the parallel caps are in circuit. That only leaves the 30uF and 350uF caps as viable NPE candidates. And, I found a 350uF poly film motor run cap, that I might use on the woofer. Only 12 bucks, so why not? I've read other accounts of motor caps working out well. I 'might' try it too.

I'd use film caps only in the tweeter, and the 24uF in the upper mid-range. Or, electrolytic with a film by-pass on that 24uF. You could use film for the 8 uF too, but all the other large capacitors, just stay with electrolyitcs. The "problem" with electrolytics is their performance at high frecuencies, but in all those positions, the high freqs are already filtered by inductors. And the original crossover uses electrolytics. That's my idea...

I've got Clarity caps PX because they were cheaper then other series, but you can use daytons too. I don't see aproblem with that. I´ve used Epcos "motor run" capacitors in many projects, up to 30uF , they are very good quality caps.

 

[StimpyWan]

I'd use film caps only in the tweeter, and the 24uF in the upper mid-range. Or, electrolytic with a film by-pass on that 24uF. You could use film for the 8 uF too, but all the other large capacitors, just stay with electrolyitcs. The "problem" with electrolytics is their performance at high frecuencies, but in all those positions, the high freqs are already filtered by inductors. And the original crossover uses electrolytics. That's my idea...

I've got Clarity caps PX because they were cheaper then other series, but you can use daytons too. I don't see aproblem with that. I´ve used Epcos "motor run" capacitors in many projects, up to 30uF , they are very good quality caps.

Thanks for the info. That helps.

My 'plan' is a ClarityCap ESA for the 4.0, an Audyn Plus cap in the 6.0, a ClarityCap PX for the 8.0, Mundorf EVO Oil for the 24.0, and an Audyn Q4 for the 80.0. Everything else is still up for debate. I already have some 0.1 Auricaps, and some Russian 0.01 PIO caps, to try as bypass caps too. Should be fun, even if it takes a while to get everything else bought and ordered.

 

[elnaldo]

It's not my $$, but I wouldn't buy an expensive capacitor for the 8 uf and the 80uf.

 

[StimpyWan]

It's not my $$, but I wouldn't buy an expensive capacitor for the 8 uf and the 80uf.

I agree that the 8.0uF 'might' not be critical. But, my only reservation is that both the 8.0 and the 40.0 parts are parallel caps in circuit to the upper dome. They do not shunt directly to ground, and 'could' benefit from better quality parts.

As to the 80.0uF cap, it is a series high pass cap for the lower midrange. That LMR driver covers from 200Hz to 1200KHz. So, to me that is a critical cap. Since I can pick up an Audyn Q4 cap for around $20 bucks, I want to use a poly, and feel it is worth the cost. Time will tell! Otherwise, keep the comments coming. I appreciate all feedback.