Andre_Db66 Posted January 27 Report Share Posted January 27 Hello everyone, 😁 My name is Andre and i live in Holland. I just became a member of this forum because lately i have been busy acquiring and refurbishing AR speakers. This occurred after someone introduced me to the wonderful A3a which set in motion my curiosity toward other models. (Maybe there is another place or way to introduce myself, i am mostly about vintage, and have a nice collection of amps, speakers and such. Point the way plz) By now i have found a set of SRT 380, 2 sets of AR6, one set being in the 300 range of ser # with alnico woofers. I had to take apart the tweeter with one as the coil was good but the external wires had broken off within the unit. Also i found 2 sets of AR3a with improved badges yet an old style keramic filter and one with the AR11 type filter. (Amazing to see all the inconsistencies) in the first set i velieve there are also tonegem woofers so possibly these are Frankensteins. Another lucky find was a set of wel preserved and refurbished LST. My next and latest acquisition is a set of LST2 which had a peculiar mix of tweeters and made me choose for the HiVi Q1r option, which triggered me to want to join this forum, rather than being a silent reader. The tweeter alternative was thought out for the AR3a as far as i have concluded, please correct me gently if i am mistaken. The HiVi tweeter has an impedance of 6R, and originally 3 were placed parallel in the system. That adds up to 2R and i dont think that can be right. I have ordered 6 0.05mH inductor coils 1mm and 6 3uF BP caps. How should i proceed? Simply place this all accordingly eg 1 of each per tweeter? I am very much in the dark here. Before i joined, i could only find a sketch of schematic, which seems to have 1 tweeter out of phase. I am not sure about this. When i measured this setup though, i found it adds up to 4R. Please anyone?? PS The tweeters are up for sale in case anyone is wondering. There is a date on one 1972. They have not yet all been extracted but there seem to be at least 2 different kinds. Also a type with felt on the front. Look forward to replies Cheers Quote Link to comment Share on other sites More sharing options...
Andre_Db66 Posted January 28 Author Report Share Posted January 28 Quote Link to comment Share on other sites More sharing options...
Andre_Db66 Posted January 28 Author Report Share Posted January 28 Gear in picture above JBL 2226 - 2405 - 2426 - 3105 - 3110a AR 3A - AR LST - AR LST 2 Monitor Audio Studio 2 SL 1700MK2 - X555ES - PMD 321 - DC300A MK2 - PHILIPS 280 - DSP 260 - DATEQ HPA600 - CROWN K2 - METRUM HEX NOS DAC - FR3 SU. Icon Audio MB845 INTERLINK AudioQuest and vandenHul AudioQuest Rocket 33 There is also an 18 inch sub with RCF driver in the middle. This is my HT setup in the living room. Quote Link to comment Share on other sites More sharing options...
RoyC Posted January 28 Report Share Posted January 28 Welcome to the forum, Andre. That is an impressive stack of equipment. The LST-2 tweeters are indeed wired in parallel. If you are using Hi-Vi tweeters you only need 1 inductor per cabinet, wired in parallel across the entire tweeter array. Additionally, the original crossover capacitor value should be reduced for the LST-2. If your tweeters are all original AR tweeters, the preferable approach would be to have them rebuilt. Roy Quote Link to comment Share on other sites More sharing options...
Andre_Db66 Posted January 28 Author Report Share Posted January 28 Thank you for replying RoyC... It is a small portion of my gear. I will post some pictures of my other equipment as well. My hobby comprises CD player refurbishment and modfication ( DAC mod with Revox/Philips chipset), amplifier refurbishment, building speakers (the JBL i designed and built myself), building tube (pre)amps, obviously now also refurbishment of AR speakers. I love all types of speakers and am not confined to one brand or type. More specific, i like closed, bass reflex, backloaded horn, open baffle, electrostatic , transmissionline, dual concentric, MFB, braodband, modern and vintage alike. To name a few things i own, Quad, Beovox, AR, KEF, Rogers, JBL, Philips MFB, B&W, Elac, Monitor Audio, MACH, Tannoy, Dynacord, without being specific about model types and such about 35 sets all together. I like good quality music, regardless if it is vinyl, CD, Youtube, or MP3/FLAC and i am convinced that recording studios mostly dictate which gear i prefer to listen to rather than to stick to one media type as the ultimate and perfecting only one set. That in my book is impossible. Quad never used impressive interlinks or was never consistent in parts which they used. It came as it was available. The concept dictated the outcome, not materials. I taste the same woth AR speakers, that is for sure. Inconsistencies with materials but always the same outcome, a wonderful sound and a definitive stamp, that is a character trait of AR speakers. Just like Quad for example. Excelence in design rather than the best of the best materials. This is why i did not hesitate to take for granted that the HiVi tweeter mod would be more than fine in the LST2. To seek the near impossible replacement of the originals and paying top dollar would seem outta my league and absurd. I found someone asking 160 each for the tweeters so i decided to buy all 6 for 180. Coming to my obvious question, assuming the 12uF is the tweeter cap, what size would be recommended? I have 2 sprague 20UF from a set of AR2x unused. Would that be good? I can say about the speakers i have that the AR 6 seem to have yet another crossover type i had not seen in schematic before. Someone here had a version with only a cap and no inductors. The other 2 schematics is the Alnico verzion without piggyback cap and resistor yet 2 coils and cap. And the obvious ceramic magnet schematic. My Alnico version has no piggyback, a 10uF cap and the bass coil. Thats it. All original. Serial # 330 and roundabouts... too lazy to look it up. Very early cabinets anyway. So that is different as i had not come across before.... As mentioned earlier, my 3a impr, possibly Frankenstein edition, has an old style XO which does not concurr with the impr being the latest version before AR11... correct me if im wrong. Cheers Quote Link to comment Share on other sites More sharing options...
Andre_Db66 Posted January 28 Author Report Share Posted January 28 Sorry Roy, i missed the word reduce in your advice... so given i have 6 x 3uF coming my way i can make this 3,6 or 9uF per side in series with the tweeter lineup? Quote Link to comment Share on other sites More sharing options...
rjr513 Posted January 29 Report Share Posted January 29 Here's AR-LST2 schematic with added components for tweeter mod using hi-vi tweeters or you could remove the original capacitor and replace with a 4uf capacitor Quote Link to comment Share on other sites More sharing options...
rjr513 Posted January 29 Report Share Posted January 29 imo if the original tweeters are in the cabinets for both speakers I would highly recommend you having them refurbished if your looking to retain close to original sound qualities Quote Link to comment Share on other sites More sharing options...
Andre_Db66 Posted January 29 Author Report Share Posted January 29 Thank you for this. What is approximately the effect of lowering to 4uF and adding 0.05mH for the xo point? If i had all original yet some broken tweeters in my cabinets i would go the refurbish route. I have bought them with AR38s woofers, original xo and mids and at least 2 kinds of different tweetrs. I saw 1972 at least on one of them. I can always revert to this but for now i have already purchased the HiVi and the caps and coils are arriving soon. Besides, there is noone here in the vicinity with the skillset and knowlegde to rebuild these tweeters. Aside from being very costly. When the cabinets are playing again and i am satisfied it could be ill never look back. I will definitely post pictures of the tweeters and reaort to this forum for info and perhaps aid on the topic of rebuilding. It will have to be shipped to the USA and back so i dont know if that is an option for me. We pay taxes over goods coming from abroad... That wil be a matter of originality over functionality.... Cheers Quote Link to comment Share on other sites More sharing options...
rjr513 Posted January 29 Report Share Posted January 29 44 minutes ago, Andre_Db66 said: What is approximately the effect of lowering to 4uF and adding 0.05mH for the xo point? goal is to get as close as possible to the original tonal balance from the Hi-Vi tweeters,in comparison to the AR Originals by altering the Crossover point for the tweeter,the Hi-Vi tweeters tend to extend into the mid freq range which tends to make the LST2 very harsh in the high end Quote Link to comment Share on other sites More sharing options...
RoyC Posted January 29 Report Share Posted January 29 The mechanical properties of the HiVi tweeters are different than the original tweeters. As Ron mentioned above, they have a very different frequency response without the added inductor. Some years ago after a fair amount of experimentation I ended up replacing the original 12uf capacitors with 5uf capacitors. It was for a "Vintage_AR" customer who was happy with the result. Since then Larry has been using that capacitor value for his HiVi/LST-2 kits with no complaints. No measurements were done, but subjectively it fit in very well with the (many) other AR models we had in the shop. Roy Quote Link to comment Share on other sites More sharing options...
Andre_Db66 Posted January 29 Author Report Share Posted January 29 Fair enough... Would it be conclusive to say that the best for me to do is order a set of 5uF caps? I have a set of untouched 3a's improved with 4 coils and could simply use at least 4 x 3uF here, so they have not been ordered in vain. The coils i need only 2 instead of 6, alas, they are made for the order and 4 shall render useless unfortunately. I had obviously sound checked the first lst2 and encountered that harshness first hand but have my hands tied as i am waiting for the ordered parts. Quite frankly i enjoy very much the cleaned up look of the lst 2 without the nasty wires on front panel. ( it is the exact thing that kept me away from AR in the first place for ever.) I always assumed someone had tried to fix something there in a very ugly way. Recently, i had a Thorens with SME upgrade for sale and an adcom 555 amp. Someone was very interested and insisted on bringing his own speakers for a trial. They were AR3a and i welcomed him with open arms as i had never heard any AR's. The next thing is text book history in my opinion as i have been buying all the models that fit the desription ever since... 😁 Quite soon after this i heard a set of Quad 2 tube monos on a set of SRT 380 and was amazed... Next came about the first 3a with impr badge. Little did i know of the 3a history and they had been refurbished. (Caps and a very ugly manner of pot removal) I corrected this with lpads and last week i cannabalized a set of 2x for exchange of the B38s woofer in my LST2. I am waiting for cork 3mm thick to make a ring underneath the foam edge as that was originally there like the ar3a' woofers. I also removed 1 lpad each as i obtained 2 original pots. My main goal was the woofers though. The AR6 is a true diamond and in a small room possibly the best AR i have heard. It does exactly what the 3a does in a bigger room making the latter unnecessary. The stage, the lows and highs are ultra deep and sweet, and a very natural timbre... With my first set i read up on the coil less schematic and wanted to try this so i decided it was time for a cheap pair. And this is when i stumbled upon the very early alnico version with 1 broken tweeter which i fixed, and the set of Frankenstein LST 2. 2 diff types of tweeters, somehow none working when fired up and the 38s woofers. They look very pretty though and most definitely needed a better destination. So i took it uoon myself to clean them up and not being scared of stepping away from originality and preferring functionality and in this case also esthetic improvement i went down the HiVi road thinking if some people are more than satisfied using them for 3a purposes i would be too with the lst2. Only snag so far is i didnt expect them to be too small for the holes to fit properly... but that is just woodwork troubles. I will show more of my gear in photos later. Cheers everyone... Quote Link to comment Share on other sites More sharing options...
Andre_Db66 Posted January 29 Author Report Share Posted January 29 My attempt to save the original tweeter of my precious alnico very early AR6 Playing nicely now, driven by this beauty Icon Audio Stereo 300 pp300b Btw my 845MB 100 watt pp drive the LST wonderfully. I can also say that the Crown DC300a is up to the job. I must admit though that with crazy db levels it tend to make a light show io wise. Then again i have had the yamaha M2 in clipping mode with the 3a. It is worth 2 x 240w pch 🤣 so who mentioned powerhungry??? Cheers everyone... Quote Link to comment Share on other sites More sharing options...
Andre_Db66 Posted January 29 Author Report Share Posted January 29 First 3 tweets removed so far... Anyone? Cheers y'all Quote Link to comment Share on other sites More sharing options...
RoyC Posted January 29 Report Share Posted January 29 The tweeters in your photo are from 3 different eras. The top, lower impedance tweeter is obviously a later replacement from 1976. It would have been used in the 3a or LST (not LST-2). The bottom one is a later (1974) specimen as well. The middle tweeter from 1972 has the red mark ("5') indicating it is a higher impedance tweeter used in the AR-5 and LST-2. Given the situation it is a good idea to replace them all with one type of tweeter. Any capacitor value between 4uf and 6uf should bring your LST-2's within easy tweaking distance of the original sound. You might as well use the capacitors you have available to begin with. Quote Link to comment Share on other sites More sharing options...
Andre_Db66 Posted January 29 Author Report Share Posted January 29 OK so i can place 6 or 9 and simply listen to what sounds best. Adding 6uFwill amount to 4uF, 9uF will amount to 5,143uF and removing 12uF and simply 6uF is also possible. About the elevated edge below the foam of the woofer and spider, what is the purpose and if the spider is elevated should i replace it on the chassis below the foam also? Quote Link to comment Share on other sites More sharing options...
RoyC Posted January 30 Report Share Posted January 30 4 hours ago, Andre_Db66 said: OK so i can place 6 or 9 and simply listen to what sounds best. Adding 6uFwill amount to 4uF, 9uF will amount to 5,143uF and removing 12uF and simply 6uF is also possible. About the elevated edge below the foam of the woofer and spider, what is the purpose and if the spider is elevated should i replace it on the chassis below the foam also? -I would simply replace the existing 12uf cap with your new (3+3) 6uf cap. -Do not remove the surround and spider mounting rings! They provide the proper elevation and dimensions. Quote Link to comment Share on other sites More sharing options...
Andre_Db66 Posted January 30 Author Report Share Posted January 30 Ok so i was right in the assumption. I ordered 3mm cork to make the rings. The 2x woofers had been (butchered) refoamed and my deduction was that the chassis ring had been removed. Some people, when refurbishing do more damage than good unfortunately... Thank you Roy Quote Link to comment Share on other sites More sharing options...
Andre_Db66 Posted January 30 Author Report Share Posted January 30 The next lot... It would seem there is even more than 3 different kinds Quote Link to comment Share on other sites More sharing options...
Andre_Db66 Posted January 30 Author Report Share Posted January 30 Is there any info on how many oz of glasswool need to be placed in the lst2 cabinet? And the AR6? And the LST? I bought a big roll of yello glasswool and just finished placing 20 oz in the first set of AR3a. It was filled with cotton and changed the sound signature significantly. So... Any difference in AR3a and the improved version with regard to this? Quote Link to comment Share on other sites More sharing options...
RoyC Posted January 30 Report Share Posted January 30 1 hour ago, Andre_Db66 said: Is there any info on how many oz of glasswool need to be placed in the lst2 cabinet? And the AR6? And the LST? I bought a big roll of yello glasswool and just finished placing 20 oz in the first set of AR3a. It was filled with cotton and changed the sound signature significantly. So... Any difference in AR3a and the improved version with regard to this? 20 oz of fiberglass will work fine for the LST and LST-2, and 8 oz for the 6. The earliest version of the 6 contained closer to 11oz. The 3a only used fiberglass. Later AR models with the same woofer utilized smaller amounts (vs fiberglass) of audio grade polyester...which is more dense than that found in a fabric shop. From a sonic perspective fiberglass is the safest choice when restoring old acoustic suspension speakers. Quote Link to comment Share on other sites More sharing options...
Andre_Db66 Posted January 31 Author Report Share Posted January 31 Thank you yet again for the very useful information. This one is near finish. Only waiting for the xo parts. Wonderful bass... Quote Link to comment Share on other sites More sharing options...
Andre_Db66 Posted February 21 Author Report Share Posted February 21 Hip hip hurah... I have gathered the correct tweeters when i bought the 2ax remains yesterday. Luckily i had not sold any of the others yet, so i have now 4 with outer connection and 2 with inner. The latter are the same so will make a nice clean faceplate for the lst2 as i place 1 on each side in the front panel. I have bought all the other stuff which is unfortunate, but the 4 2ax speakers were only 10€. The sprague 12uF measure fine so i can start rebuilding the LST-2 to original standard. Off to the hardware store for some materials and start the new quest... Quote Link to comment Share on other sites More sharing options...
Andre_Db66 Posted February 27 Author Report Share Posted February 27 I have a problem with the bass. The speakers are supposedly finished but there is a big difference in how one handles bass as opposed to the other. One woofer reaches its xmax very quickly and is moving a lot as though it is trying to reproduce frequencies it cannot, whereas the other woofer doesnt doe that. I have exchanged them and the problem stays in the same cabinet. What is exactly responsible for the excursion excess? The "good" cabinet can take a lot more power from the amp, the other seems to explode and reach bottoming out dangerously... Anyone? Quote Link to comment Share on other sites More sharing options...
Aadams Posted February 27 Report Share Posted February 27 I would check for a serious cabinet leak as first step. Typing on phone is pia. Quote Link to comment Share on other sites More sharing options...
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