RoyC Posted March 21, 2019 Report Share Posted March 21, 2019 1 hour ago, Stimpy said: Almost forgot - I just picked up a single AR92, for use as a center speaker. It's been recapped with Mundorf E-Cap NPE's. Sticking closer to stock, as another experiment. So, my front set up is AR58S - AR92 - AR58S. The 58S with film caps, and the 92's with NPE's. And these 3 speakers do not sound alike. Same mids and tweeters, but a very different presentation. I wonder why? Different drivers, age of drivers, damping material, speaker position, associated electronics, other crossover components, ESR, along with known differences between npe cap and film cap behavior at frequency extremes. Btw, I also agree with Ken regarding crossover capacitor "break -in". It happens in the first few seconds of use. After that your ears are "breaking in" to the new arrangement. The 3a used electrolytic caps. Roy Link to comment Share on other sites More sharing options...
ra.ra Posted March 22, 2019 Report Share Posted March 22, 2019 10 hours ago, swayzeeee said: I really opened up a can of worms, didn't I? We've all been cooped up with cabin fever all winter, so it's perfectly normal that we emerge from our dens with a little growling feistiness. Your previous projects have been of interest to me, so I want to throw in my $0.02 here. We all love our music, and restoring old speakers can provide great satisfaction and pride of ownership, but ........ at what price? About the capacitors - - - yikes! - - - it is indeed a big, dark, scary world out there. In other threads, I have openly outted myself as something of a cheap b*st*rd within this hobby, so I am very inclined to align myself with your "el cheapo route". Always remind yourself of what was used in the original circuit configuration...... and then ask: Will throwing dollars at your project provide superior results above and beyond the original performance? I cannot be convinced that there is good reason to pay dearly for a 150uF parallel film cap in the woofer circuit; and likewise, spending $100 for special tweeter caps seems to me like chasing unicorns. Do these type of profligate decisions result in excellent performance? Yeah, probably they do. Do they represent prudent cost-benefit choices? Nope, definitely not in my world, but your opinion and situation may be different from mine. Back to the two cents I promised: I have no doubt you'd love these speakers if you used all new electrolytics in your re-cap effort - - just like the original engineers specified. Nonetheless, these 3/4" dome tweeters are known to have diminished output over 45 years, and theoretically it can be argued that using a film cap for this application may provide a slightly increased HF output due to the film cap's lesser resistance. Also, the tweeter caps are small values and will not be costly even if you do purchase a film/poly type. Capacitors are important components in these circuits - - no doubt about that - - but I almost feel like your attention would be better focused on assessing the quality of the aged drivers and those "quite corroded" pots. Woofers might very well benefit from a re-foam or re-doping, and you should confirm that both mids and tweets are properly functioning. At the very least, the pots will require a full cleanse and re-hab. If not restorable, you'll need to find suitable replacement components. How 'bout posting some pics of these TLC 3a's? Link to comment Share on other sites More sharing options...
RoyC Posted March 22, 2019 Report Share Posted March 22, 2019 3 hours ago, ra.ra said: and theoretically it can be argued that using a film cap for this application may provide a slightly increased HF output due to the film cap's lesser resistance. Also, the tweeter caps are small values and will not be costly even if you do purchase a film/poly type. Agreed, ra.ra. I really don't have a problem with the use of film caps in general, if for no other reason than longevity. The 3a level controls and driver condition are easily the most significant variables. AR pots sometimes vary by as much as 2 ohms. Photos and serial numbers would be helpful. Roy Link to comment Share on other sites More sharing options...
ra.ra Posted March 22, 2019 Report Share Posted March 22, 2019 1 hour ago, RoyC said: I really don't have a problem with the use of film caps in general, if for no other reason than longevity. The 3a level controls and driver condition are easily the most significant variables. About film caps.....yep, I've learned at least this much from you, Roy, and your advocacy for simple and affordable replacement components has greatly helped to shape my own philosophy about sensible vintage speaker restorations. Even more so, my own experiences have confirmed that aged drivers often have significant variation, and I always appreciate when you try to drive this particular issue in these restoration discussions. Aside from this issue of capacitor ESR (re: film vs. NPE), fancy caps alone will never re-establish the diminished performance of an old and fading driver. Not dissimilarly, the adjustable controls require equal scrutiny as critical components in these circuits, and as time marches on, I'll admit that I am finding it harder to maintain confidence with these original AR pots. This is somewhat rhetorical and mostly navel-gazing, but this issue of film capacitor longevity still puzzles me a bit. Even if the robust build quality, physical size, and increased voltage ratings of contemporary film caps far exceeds the dinky little electrolytics found in many vintage speaker crossovers, where is the data to make these kind of blanket statements that seem to have become "conventional wisdom"? Albeit the Sprague Compulytics are not "dinky" or "little", but many of these seem to have retained their original values after nearly fifty (50) years. Comparatively, just where does the timeline begin to show that film caps have superior longevity? Just when did film caps debut in speaker crossovers, and where is the discussion that many (or all?) of them are still consistent performers 50 years hence? Link to comment Share on other sites More sharing options...
genek Posted March 22, 2019 Report Share Posted March 22, 2019 The biggest factors in capacitor longevity are how susceptible their dielectrics are to age and environment and how good a job their encapsulation does of holding back the effects of both. In the case of the Sprague Compulytics and the older oil-filled caps, their heavy-duty cans are as close to being bulletproof as you're going to find (I know from my past day job that some of them were actually designed to be bullet and explosion resistant). So it's pretty easy to see how they've preserved their contents better than wax, paper or plastic. Plastic film is less susceptible to age and environment than impregnated paper and the finished product is more stable and long-lived. But probably more importantly, capacitors using them are less expensive to manufacture and have a lower reject rate. They've dominated the capacitor market in general since the 1980s. Link to comment Share on other sites More sharing options...
swayzeeee Posted March 22, 2019 Author Report Share Posted March 22, 2019 21 hours ago, ra.ra said: How 'bout posting some pics of these TLC 3a's? Pics? Sure... These popped up my local CL for a (very) small fraction of what they're normally listed for on eBay. There weren't any pictures of the drivers on the listing but they were only 10 minutes away so I called the guy and made an appointment to see them right away. Well, first I studied all the driver pictures in the restoration guide. Lesson learned from my AR-4x experience, I guess. ☹️Anyway, the asking price was low enough that if they looked original, I'd scoop them up even if there were "issues". The drivers looked original, as far as I could tell the woofers are either the A.2 or A.3, as listed in the guide, the mid looks like the A.12 and the tweeter like the A.19. Do I have that right? They all seem to work and sound good. When I opened them up at home, the date marked on the back of the woofer is from Feb or March of 1972. The serial numbers have me a bit perplexed... The sheets taped to the back of the cabinet indicate 7055 and 7057. That seems low for 1972... The guy I bought them from was a little bit of a tinkerer. He re-foamed the woofers and replaced the pots with L-Pads. Luckily, he saved the original pots and still had them. I asked him if he'd ever heard of this site and if he'd seen the restoration guide...no. He put in 16 Ohm L-Pads, which are not correct, I gather. I'm gonna see what I can do to clean up the original pots this weekend. They're not too much worse than the ones that were in my 4x's and those cleaned up pretty nicely. If I can get them to work, I'd like to use them. Otherwise, I guess I would get some 8 Ohm L-Pads and 25 Ohm resistors, as recommended in the restoration guide. For the caps, I bought Solen polys for the 8 and the 50 and an NPE for the 150, all on sale at Parts Connexion. The existing caps might well test within spec when I pull them out... I just figure as long as I have them open, I'll take care of everything at once... Link to comment Share on other sites More sharing options...
DavidR Posted March 23, 2019 Report Share Posted March 23, 2019 Hendrix wrote " Now if 6 turned out to be 9 " But what if an 8 turned out to be a 6 ? Link to comment Share on other sites More sharing options...
lARrybody Posted March 23, 2019 Report Share Posted March 23, 2019 2 hours ago, swayzeeee said: The serial numbers have me a bit perplexed... The sheets taped to the back of the cabinet indicate 7055 and 7057. That seems low for 1972.. Those serial numbers may be right. My 1970 3a's have serial numbers in the 27XXX range. I earlier stated that I was planning on using Dayton polys for the 150uf and 50uf caps. I also have the option of using these matched Mundorf ecaps instead. What do you guys think. Film or bypassed NPE's. Link to comment Share on other sites More sharing options...
lARrybody Posted March 23, 2019 Report Share Posted March 23, 2019 Just checked my October 1973 3a's and here are their numbers. Link to comment Share on other sites More sharing options...
DavidR Posted March 23, 2019 Report Share Posted March 23, 2019 9 minutes ago, lARrybody said: I earlier stated that I was planning on using Dayton polys for the 150uf and 50uf caps. I also have the option of using these matched Mundorf ecaps instead. What do you guys think. Film or bypassed NPE's. I used Mundorf ECap70 on my 10Pi but used the Vishay 1837 0.01uF bypass on the two series caps. They sound wonderful. As good as my 91s with the Clarity CSA + AudioCap Theta 0.01uF FF caps on the series caps. But I run the 10Pi on a 60wpc tube amp and the 91s on a 500wpc Class AB Studio Reference amp. Link to comment Share on other sites More sharing options...
ra.ra Posted March 23, 2019 Report Share Posted March 23, 2019 2 hours ago, swayzeeee said: Pics? Sure... Those speakers look pretty good and appear to have been well cared for ('cept for that one mismatched screw on the woofer). Despite the neat re-foam installation, it looks like at least one of the woofer foams may have been one of those slice-n-dice affairs where an ill-fitting foam is cut and spliced to "fit" a smaller diameter. How would you describe the tweeter output? As David has already intimated, that tweeter cap should be a 6uF and not an 8uF. Also, the "international" stamp on the paper label is a bit curious. IMO, good call using 150uF NPE cap for woofer circuit. 2 hours ago, DavidR said: Hendrix wrote " Now if 6 turned out to be 9 " That's pretty funny....I appreciate the reference. Axis: Bold as Love. Link to comment Share on other sites More sharing options...
ra.ra Posted March 23, 2019 Report Share Posted March 23, 2019 1 hour ago, lARrybody said: Just checked my October 1973 3a's Larry, the drivers might well have 10/73 date codes, but it looks like your speakers were assembled in seventh week of '74. 1 hour ago, lARrybody said: What do you guys think. Film or bypassed NPE's. You've got a full inventory of very good caps there - - - two choices! - - - so one suggestion would be to try two (or more) temporary set-ups using alligator clips to find what suits your own preferences best. Start with Daytons in channel A; and Mundorf/Theta in channel B. Link to comment Share on other sites More sharing options...
RoyC Posted March 23, 2019 Report Share Posted March 23, 2019 4 hours ago, swayzeeee said: The serial numbers have me a bit perplexed... The sheets taped to the back of the cabinet indicate 7055 and 7057. That seems low for 1972... swayzeeee, The cabinet serial numbers are definitely not in keeping with a 1972 manufacture date...more like late '67 or '68. The drivers, capacitors, and fiberglass, however, are indeed of early 70's vintage...and the cabinets themselves appear to be later than what the serial numbers would indicate. I believe a clue to the inconsistency is the note stamped on the cabinet label, "International Guarantee Packed Separately". I have never seen this on any AR-3a cabinet before. I'm thinking these may have been manufactured for export in 1972. The serial numbers are consistent with the few European built AR-3a's I have seen from the early 70's. 3a's manufactured in Europe had a different cabinet design and different serial number sequence. Perhaps this was part of a special order for someone overseas who wanted US cabinets. Whatever the case may be, they appear to be fine specimens. -The first thing I would do is confirm the number on the spool and/or measure the value of the large inductors serving the woofers. If all crossover components are from 1972, these will be #9/2.85mh coils. If you have converted cabinets from the late 60's they will be #7/1.88mh coils, which would need to be changed to be made appropriate for your foam surround/ferrite magnet woofers. -The woofer re-foam work looks funky. -The L-pads should be replaced. -At least one (blue), probably both, of the large capacitors (50uf and 150uf) are the excellent Spragues mentioned earlier in this thread. -The block cap is 6uf. There may be some repeat info above. Apologies to ra.ra who posted while I was typing. Roy Link to comment Share on other sites More sharing options...
DavidR Posted March 23, 2019 Report Share Posted March 23, 2019 8 minutes ago, RoyC said: -The woofer re-foam work looks funky. If you look at the surround roll at the 10 o'clock position it looks spliced but I'm unable to see the splice in either the inner or outer lip. The picture gets fuzzy when I enlarge it too much. Link to comment Share on other sites More sharing options...
RoyC Posted March 23, 2019 Report Share Posted March 23, 2019 31 minutes ago, ra.ra said: Larry, the drivers might well have 10/73 date codes, but it looks like your speakers were assembled in seventh week of '74. Ra.ra is right on the money! 10/73 is actually the date of the label iteration. It is the one found on later AR-3a's. Roy Link to comment Share on other sites More sharing options...
swayzeeee Posted March 23, 2019 Author Report Share Posted March 23, 2019 11 hours ago, DavidR said: Hendrix wrote " Now if 6 turned out to be 9 " But what if an 8 turned out to be a 6 ? Thanks for checking my math. ? It was a typo... I ordered a 3.3 and a 2.7 to run in parallel. 8 hours ago, RoyC said: If all crossover components are from 1972, these will be #9/2.85mh coils. Thanks... I checked and they are #9 coils. It's interesting that these might be special order exports from 1972. At least there's a really good hypothesis for why the serial numbers don't match the vintage of the components. I'm gonna work on those pots today. Hopefully I can get them cleaned up and get rid of those L-pads. Link to comment Share on other sites More sharing options...
DavidDru Posted March 23, 2019 Report Share Posted March 23, 2019 First time checking in here to CSP in a while and it feels like I never was away. Love me some caps debate. Cool. Use whatever you want. Good catch by RoyC on the surround there. Roy keeping his eye on the ball. I'd reorient the coils too. Link to comment Share on other sites More sharing options...
genek Posted March 23, 2019 Report Share Posted March 23, 2019 52 minutes ago, DavidDru said: First time checking in here to CSP in a while and it feels like I never was away. In other news, the prize in The Amazing Randi's $1,000,000 audiophile speaker wire challenge has yet to be won, either. Link to comment Share on other sites More sharing options...
ar_pro Posted March 24, 2019 Report Share Posted March 24, 2019 On 3/22/2019 at 10:42 PM, ra.ra said: That's pretty funny....I appreciate the reference. Axis: Bold as Love. "I'm gonna' wave my freak flag high...." Analogue Productions will be releasing an UHQR deluxe vinyl edition of "Axis" in April: https://store.acousticsounds.com/d/130940/The_Jimi_Hendrix_Experience-Axis_Bold_As_Love-UHQR_Vinyl_Record I've been enjoying the 2010 remaster on Sony for years, but I'm thinking about ordering one of these boxes. "Are You Experienced" is still my favorite - I put it right there with "Kind Of Blue", "Time Out", and "A Love Supreme" for breakthrough instrumentation. I could listen to any of them a thousand times. Link to comment Share on other sites More sharing options...
Pete B Posted March 24, 2019 Report Share Posted March 24, 2019 On 3/22/2019 at 12:22 AM, ra.ra said: About film caps.....yep, I've learned at least this much from you, Roy, and your advocacy for simple and affordable replacement components has greatly helped to shape my own philosophy about sensible vintage speaker restorations. Even more so, my own experiences have confirmed that aged drivers often have significant variation, and I always appreciate when you try to drive this particular issue in these restoration discussions. Aside from this issue of capacitor ESR (re: film vs. NPE), fancy caps alone will never re-establish the diminished performance of an old and fading driver. Not dissimilarly, the adjustable controls require equal scrutiny as critical components in these circuits, and as time marches on, I'll admit that I am finding it harder to maintain confidence with these original AR pots. This is somewhat rhetorical and mostly navel-gazing, but this issue of film capacitor longevity still puzzles me a bit. Even if the robust build quality, physical size, and increased voltage ratings of contemporary film caps far exceeds the dinky little electrolytics found in many vintage speaker crossovers, where is the data to make these kind of blanket statements that seem to have become "conventional wisdom"? Albeit the Sprague Compulytics are not "dinky" or "little", but many of these seem to have retained their original values after nearly fifty (50) years. Comparatively, just where does the timeline begin to show that film caps have superior longevity? Just when did film caps debut in speaker crossovers, and where is the discussion that many (or all?) of them are still consistent performers 50 years hence? Hi Robert, nice chatting at Frankenfest today. Film caps are fabricated out of metal foil and plastic there is no chemical paste to dry out and degrade over time. It is the nature of the beast. Military electronics guidelines suggest disposing of new spare electrolytics after 10 years on the shelf. We've discussed this before: http://www.classicspeakerpages.net/IP.Board/index.php?/topic/9255-smaller-advent-woofer/&page=2 Link to comment Share on other sites More sharing options...
Aadams Posted March 24, 2019 Report Share Posted March 24, 2019 5 hours ago, Pete B said: We've discussed this before: The cap topic has been opened many times over the years with the only conclusive advice, from experts BTW, being to replace like with like to maintain the original sound or install film/poly for longevity. While there are some among us who can hear a difference in caps , we are also told that the influence of caps on sound is much less than the influence of potentiometers (wide band tone controls) and driver condition. When it is said some caps sound cold, while others sound warm or sweet or less strident or faster, it reminds me of cartridge debates and esoteric reviews of active electronics. It seems to me this is about coloration of sound which can be done with speaker placement, tone controls and equalizers much more easily. Just my two cents. Adams Link to comment Share on other sites More sharing options...
fran604g Posted March 24, 2019 Report Share Posted March 24, 2019 On 3/22/2019 at 10:59 PM, ra.ra said: Larry, the drivers might well have 10/73 date codes, but it looks like your speakers were assembled in seventh week of '74. Ra.ra, Not to pirate the OP, but are the driver date codes listed somewhere on the forum for us to use? I don't think I've seen a cypher before. Sorry if this has already been discussed elsewhere, I searched but haven't found an obvious post. -Fran Link to comment Share on other sites More sharing options...
DavidR Posted March 24, 2019 Report Share Posted March 24, 2019 On 3/21/2019 at 1:35 PM, RoyC said: Let's confuse him by warning him off those potentially "horrible" Dayton film capacitors in favor of "warmer" Clarity capacitors. As I said, silly. Roy, where did I say the Clarity caps had a warm sound? That was another member, not me. I made a comment that they didn't exhibit glare and brightness that the Daytons did and thus were a better cap for that situation. Yes, I could hear the difference in an AB test and so could someone who didn't know what was different in the xover. I also mentioned the speakers no longer got under my skin after just 20 minutes of listening. Link to comment Share on other sites More sharing options...
ra.ra Posted March 24, 2019 Report Share Posted March 24, 2019 2 hours ago, fran604g said: Not to pirate the OP, but are the driver date codes listed somewhere on the forum for us to use? Hi Fran. To my knowledge there is no such list, and not all drivers or cabinets have consistent identification markings. Several of the more experienced members here are able to make estimates of production dates based on serial numbers, but the most accurate confirmation of dating is from specific notations found somewhere on your speakers. In the case of Larry's AR-3a tag shown, RoyC has correctly noted the printing date of the label - - which says 10/73 (likewise, I have similar labels for some AR-6's that say 6/74) - - but the ink stamp ending in "74 07" indicates that AR-3a speaker s/n 87147 was assembled the seventh week of 1974. Inside that speaker, it would be very likely that one or more of the drivers might have its own date stamp suggesting the driver was assembled at some point in late 1973, since the drivers need to pass inspection at some point before the full speaker gets assembled from its many parts. In the attached pic, for example, you can see two types of date stamps found on drivers. The 014-3 tweeter (center) has a separate ink stamp (8th week, 1979) on the rear of the magnet; while the 038-0 tweeter (right) has the date code (28th week, 1981) clearly printed in red on its sticker tag. The tweeter on the left is very difficult to read and this is sometimes the case, unfortunately. I can think of three other places where date evidence might be found. Sometimes an ink stamp can be seen on the early wax block capacitors. Also, many of the robust Sprague can capacitors have date notations printed on them. And last, once in awhile the cabinet maker will leave his own personal mark inside a cabinet side panel near the woofer opening. Link to comment Share on other sites More sharing options...
fran604g Posted March 24, 2019 Report Share Posted March 24, 2019 Thank you, Ra.ra, your explanation is perfect. I was hoping it was something as simple, but didn't want to guess. -Fran Link to comment Share on other sites More sharing options...
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