RoyC

Nah, just a little slap on the woofer.

Since you asked...No! You had a chance to hear the AR sound of the era and let it go. I'm not sure what you mean by having had your "vintage fix" without having actually listened to them. They were a steal. You could have easily turned them around later for a profit after acquiring some experience with them, which could then have been used toward something "higher up the food chain". You are in the wrong forum to have asked that question. I should add that AR-3's typically costing 10 to 20 times as much as this deal often need additional work just to get them to sound as good as a humble pair of relatively easily restored AR-4x's. Roy

I agree with Larry as well. Even if the cabinets are the larger AR-2/2a/2ax/5 size, they are not likely to be AR-5's unless the unique "AR-5" badge had been replaced on all of the speakers with the type used on earlier models (ie AR-1, AR-2/2a, and AR-3). Roy

I've been repairing AR-3 mids for Vintage AR for the past year or so, and I'm convinced there are very few AR-3 mids operating within spec these days. The white coating over the voice coil gap has been hardened, or nearly hardened, on literally every mid (around 30 to date) I have seen, restricting the movement of the dome. The white coating was originally a white grease-like material, which can sometimes be found in its original state under the "crust". Roy

I'm with you regarding the original pots, David. Grinding away at a crusty green pot only to end up with a compromised component with a limited lifespan is silly, imo. Actually AR began using a 15w 15ohm replacement pot (see attached photos) physically identical to a modern 15 watt 8 ohm L-pad in the 80's. It was made in Japan and very reliable. I run across them occasionally, and often find them to still be functional. In the AR-3a Limited in the early 90's, AR used conventional 15 watt 8 ohm L-pads with a slight crossover adjustment. The AP pots were a weak link from the very beginning, and I replace them with 8 ohm L-pads (with or without a 25 ohm parallel resistor) at every opportunity, and I have little doubt AR would be using them today. Frankly, I only retain original pots if they are in excellent condition to begin with, and only in restorations/repairs for people who value "authenticity" over function and long term reliability. Roy

20oz of new fiberglass will work fine, regardless of era. Polyester has different characterisitics and should not be used in the same quantities as fiberglass. I don't recommend using it in the 3a. Roy

I was able to resolve the Fs issue with a different (more compliant) spider. The kit's surround, which is is the preferred version, is neatly pre-attached to the cone...so all good there. The voice coil has about 1/2 ohm greater dcr and slightly higher inductance...not too bad. Unfortunately, the cone itself is less than half the weight, and much stiffer than the original cone. For folks debating differences in such things as capacitors, level controls, and amps, the resulting response difference between the re-coned woofer and any version of the original woofer is much more significant than these concerns. Otoh, for those who simply want to get their speakers working it is really the only option next to finding a decent original woofer. It should be noted that the kit will only fit the foam surround version of the AR 12 inch woofer basket, not the cloth surround version. Roy

That is my primary concern. The LST is much better in this area, and generally more balanced through the entire spectrum.

I'm just responding to your question "Hey I am just asking" with an opinion. Your plan could very well sound great, but based on my experience it still won't sound "like" a pair of LST's. Imo, the 3a does not sound enough like an LST to begin with, despite the similarities and your conjecture. The transformer's influence, and multiple tweeters/mids/one woofer array are simply different in character. Roy

Other than the number of higher frequency drivers, the LST's variable transformer settings are significantly different than the 3a's simple pot adjustments. These settings affect the woofer as well as the mids and tweeters. To me, the LST is a much cleaner sounding speaker than the 3a, and multiplying the number of AR-3a's would only enhance the less desirable aspects of the 3a relative to the LST. 4 woofers vs 2 would present differences from the start...not to mention the insanely low impedance of 2 AR-3a's per side (two amps would be needed). Roy

Ah, you are a patient man, Carl. I will be very interested in your findings. Roy

Carl and ra.ra, Just happened to see this thread. I'm willing to bet the "filled fillet" Boston Acoustic foam serves the same purpose. It adds extra foam instead of glue to the edge, and fills in the crease. Roy

The unfiltered response differences between the AR-3a type tweeter and the AR-11 type tweeter are essentially the same as they are between the 3a tweeter and any modern dome tweeter. It has more to do with the very unique construction of the 3a type tweeter than anything else. AR manufactured the 3a type tweeter to have a very limited excursion, which mechanically, naturally, and relatively steeply, rolled off the response into lower frequencies beginning at very high frequencies, with a simple series capacitor crossover. This approach also affected the overall sensitivity of the 3a type tweeter....and pushing it hard would often result in burning it out. The later AR-11 type tweeter, like most modern dome tweeters, has a much more compliant suspension and much greater excursion. In spite of a similar size magnet to the 3a tweeter, the unfiltered overall output is significantly greater than the 3a tweeter. This "modern" construction, however, results in increased output into lower frequencies...so in order to cross the AR-11 type tweeter over at around the same (quite high) frequency as the AR-3a, a parallel inductor was used in the AR-11/10pi (and later models) to more steeply roll it off into lower frequencies. Regardless of the use of ferro fluid, the unfiltered mechnical characterisitics of these tweeters must be taken into consideration. It is often overlooked, especially when trying to find suitable modern replacement drivers, and in many crossover discussions. Roger...There were some great woofers with rubber surrounds used in acoustic suspension speakers, but they were MUCH more compliant than today's rubber replacement surrounds. Unfortunately, all of the replacement rubber surrounds I have seen being sold today are too thick and not compliant enough (by alot) to use with old AR speakers. They are meant for ported, typically automotive, speakers and "subwoofers". It would ruin a perfectly good AR woofer to glue one of these things to it. Otoh, I have adapted some excellent old Avid woofers with very compliant rubber surrounds to AR speakers in the past. (AR was foam crazy on many levels, imo...but that is a discussion for another time. ) Roy

Msound (John Mcpeak) used to sell the appropriate foam, but I would ask him before ordering. msound@shentel.net. "Vintage AR" definitely sells it. Last I checked, Simply Speakers does not sell the preferred version. The earlier tweeters do not have ferro fluid, are favored by many, and are hard to come by. Not having old ferro fluid to potentially gum up the vc gap is probably an advantage these days. There was originally foam on the faceplate of the AR-11 type tweeter, which has decomposed by now. Felt diffraction rings are often used to replace it. Roy

I have never seen a modern rubber surround replacement compliant enough for an AR, or any other classic acoustic suspension speaker...nor have I seen one that would fit the AR 12 inch woofer. Are you sure it is not foam? Perhaps post a photo... Due to non-standard dimensions there are only two foam replacement surrounds available for the AR 12 inch woofer, and these are very specific to the woofer. The best one is more compliant and has a slightly larger roll than the other. It is also very dark grey in color. The early AR-11 and 10pi used a tan dome tweeter. The later tweeter had a dark dome and ferro fluid in the voice coil gap. Roy

Welcome to CSP, baski, Here are my answers to your questions, but I'm fairly certain others may have different opinions: Do I need expensive caps. If not which is cheap and neutral sounding Caps?No...Non-polar electrolytics will work fine and are very inexpensive. Parts Express, Madisound, and Erse are all good places to find them.If you desire to use film caps, steer clear of the high priced variety. The best brands of film caps to use from the above sources are Dayton polypropylene, Carli mylar, and Erse polyester. When I removed the woofer, I saw a cheesecloth lookalike covering the fiberglass stuffing. Is that normal? As a matter of fact, cloth was in mint condition.I have never seen a KLH speaker without that cloth behind the woofer. Save it and use it again. Sealant for woofer from Roy.. He says it will not dry. Will it accumulate dust?My sealant remains tacky, but dust collection is not an issue. Since I removed the Woofer to access the X-over, What sealant to use as caulking?Black sealant caulk or foam gasket tape (my preference) from Parts Express works very well. Duct seal from Lowes or Home Depot also works satisfactorily. Avoid plumbers putty (too soft). Is it blasphemous to change the speaker binding post with banana plugs attached in the picture? There is no functional or performance reason to do so... unnecessary work, imo. If you want to re-sell them someday, don't do it. Is it real wood or veneer? If it is veneer, Can I sand it? If I can sand it, how deep I can go.It is veneer...It can be sanded. Be careful. Jkent mentioned about Vishay cap for bypass. How it is Wired? And what is the advantage?By-pass caps are not necessary....unnecessary work, imo. These speakers were designed, and earned their reputation, with ordinary non-polar electrolytic capacitors. You will not "improve" them with by-pass caps. Good luck with your project. Roy

I do not see any reason to replace the caps. "If it ain't broke..." Roy

Red, The last pair of Smaller Advents I opened up had original green tweeters and your crossover, which would be consistent with Doug's comments. Roy

Hi Rex, I also thought the 24's sounded quite good. Interestingly, I just re-capped a pair of KLH 20's and found a similar situation. These had a single 8uf cap as the entire crossover, yet others I've worked on have had the 8uf cap as well as an additional 2X2uf cap. Roy

I did find an AK thread and a schematic. Along with the larger 8uf cap, it also shows a 3 ohm resistor on the tweeter not found in the simple crossover version. The added 16uf cap is in series with a parallel woofer inductor. I would go one way or the other, but would not combine the two crossover versions. Roy

Don't know for sure about KLH, but AR and KLH owned the lions share of the speaker business in those days. I think Kent has it figured out. It is possible the serial number sequence differs between the two versions. Do you have a schematic for the other crossover? Roy

I'm pretty sure KLH speakers were sequential for each model. AR speakers of that era certainly were. The poorest selling model, the AR-5, sold around 50,000, which was reflected by the serial numbers. Other AR models, such as the AR-4x, sold around 400,000, with cabinet serial numbers showing same. Roy

No dates on the woofers. The serial numbers on the rear of the cabinets are 020872 and 020873. Roy

Coincidentally, I've just been given a pair of KLH 24's to check out for Ebay's "Vintage AR". The crossover cap in each cabinet is a dual 2uf npe wired in parallel to produce a total of 4uf. They are not out of spec by much, but I will replace them with single 4uf film caps. See photo of crossover with original cap... Roy

Hey John, I'm sure they were only manufactured with foam surrounds. There are certainly no flat surrounds available, so any replacement will have a roll. The use of shims in the voice coil gap will provide friction, and allow the cone to be set at the correct height when replacing any surround.. Roy