Aadams Posted July 16, 2018 Report Share Posted July 16, 2018 We seem to be at a low in topic generation. Given AR as the focus, the universe of topics is limited but this may be a new one in the sense that it has been hinted but never explicitly explored. Question: What is the likelihood of a ¾” AR3a, 5, or LST tweeter installed new in in 1974, which has worked without failure to today, is still operating to at least 80% of its designed output? Given that most 3a and 5 owners set the tweeter control to max, and according to Mr Allison flat response in the tweeter range requires an additional 5 db boost, it seems that any drop off from 100% performance would mean a TOTL classic AR does not sound at all they way it should. My conclusion: The likelihood is very low that 45 to 50 year old AR tweeters are even operating at 50%. This means if you want your 3as, LSTs or 5s to sound very near original you should have the tweeters rebuilt or install HIVIs. The route you choose really depends on budget and listening preferences. Feel free to change my mind. Adams Link to comment Share on other sites More sharing options...
AR surround Posted July 16, 2018 Report Share Posted July 16, 2018 What about those bloody capacitors again? Replacing the high-ESR Callins with late-model low-ESR NPEs or Polys changes the whole equation. The perceived dull sounding original tweeters might then sound "as original" with a cap replacement. It wouldn't make sense, to me anyway, to put money into the tweeters without also dealing with the suspect Callins caps. So I guess I would try one step at at time...Replace the caps first and then decide on a tweeter rebuild/replacement. Link to comment Share on other sites More sharing options...
Steve F Posted July 16, 2018 Report Share Posted July 16, 2018 You better be ready to defend the statement about “Allison” himself saying that the 3a needed 5dB more tweeter output for flat response. There are many fanatical AR defenders here who are going to jump on any criticism of the 3a as sacrilege and imply that its performance was essentially perfect in its day and if functioning at factory-designed level today, would still be among the very best speakers available anywhere in the world. In fact, AR’s own system curves of the 3a’s own drivers shows that on-axis, the 3a tweeter is down at least 5 dB from the woofer. Off-axis, the reduction in level compared to the woofer is even more, of course. Full credit to AR for publishing such honest and accurate curves, both the technical specs curves of the individual drivers overlaid into a system curve and the Berkovitz-Allison curves done for the AES paper on listening rooms. Both show the tweeter down 5dB. Even the Technical Paper on the 3a , which has a “full system” response (not individual drivers), says that the amplifier’s treble control needs to be advanced to 2:00 for flat response. AR's own curves show exactly why the 3a sounded the way it did— powerful bass with very low THD, widely-dispersed mid and HF, reticent overall tonal character. A total lack of harshness. Advance the treble control to 2:00—about a 3-4 dB increase for most amps—and the 3a sounded incredible. Play it too loud with that tonal adjustment and you blew the tweeter. Today’s hard paper ¾” tweeters? Likely down another 3-5dB from factory level, at best. That’s my WAG. I’d have them rebuilt by Chris, not go the HiVi route. Something about that original ¾” tweeter that’s just so nice. Steve F. Link to comment Share on other sites More sharing options...
Aadams Posted July 16, 2018 Author Report Share Posted July 16, 2018 19 minutes ago, AR surround said: Replacing the high-ESR Callins with late-model low-ESR NPEs or Polys changes the whole equation. The classics that I have seen have all had Sprague or Chicago Industrial.......no Callins. 10 minutes ago, Steve F said: You better be ready to defend the statement about “Allison” himself saying that the 3a needed 5dB more tweeter output for flat response. I was working from memory and probably conflated the graphs and the Allison document. Adams Link to comment Share on other sites More sharing options...
lARrybody Posted July 16, 2018 Report Share Posted July 16, 2018 Aside from there being damage to the voice coil or the dome, wouldn't much of the derogation of the original tweeters have to do with the suspension material. Even if you had NOS AR3a tweeters they would be prone to suspension derogation just because of time and atmospheric exposure. I have a set of untouched 1970 AR3a speakers and the tweeters sound fine to me. Of course my high frequency hearing ability has to be degraded from age. I was talking to my friend Lakecat at the Midwest Audio Fest Saturday and he has a pair of original AR3a tweeters that Chris1 rebuilt for him and is very much impressed with their performance. This may be the way to go to bring these old tweeters back to near if not original condition. Link to comment Share on other sites More sharing options...
DavidR Posted July 16, 2018 Report Share Posted July 16, 2018 2 hours ago, Aadams said: This means if you want your 3as, LSTs or 5s to sound very near original you should have the tweeters rebuilt or install HIVIs. Could someone please post a picture of these and where to source them. Thank you. Link to comment Share on other sites More sharing options...
Aadams Posted July 16, 2018 Author Report Share Posted July 16, 2018 Full disclosure: I started this thread with goal of consolidating the current best options for 3a tweeter replacement. I recently had working AR5 tweeters rebuilt. The difference is astonishing. Someone recently, on this forum, mentioned how they remember AR5s sounding holographic. That post came to mind when I reconnected my AR5s. My 3as have unmolested working tweeters that have decent output when using the cardboard tube test, but I know now they are deficient. The only practical way to restore the sound that Roy Allison intended us to hear is a rebuilt tweeter. I am sure the HIVI works well but I am doubtful you will get that “holographic” sound from recordings that were or are engineered to convey an original large soundstage. If you don’t listen to those types of recordings, then you will probably never hear the difference. The 3a, LST, and AR5 were the only mass produced AR speakers capable of this kind of sound. Nothing after. I cannot hear above 12khz, maybe lower now, but I hear just fine at 5Khz where the crossover blends between the mid and tweeter. At the crossover frequency both units should have approximately the same output with the controls set to max. If not, your original tweeter is ailing. Adams Link to comment Share on other sites More sharing options...
AR surround Posted July 16, 2018 Report Share Posted July 16, 2018 Aadams: Regarding AR5s sounding "holographic," what is meant by this term? Is it the effect that I get with my AR9's (pulled well away from the walls) where it seems that the sound stage is wrapping around? The other day I was listening to a recording and thought that I had set up the system for faux surround sound. I was at least three minutes into the first track when I realized that only the front AR9's were playing. Quite astounding. My cousin has my original AR5's. I will be visiting him later this year. I will have to listen to my first AR babies...haven't heard them in almost 40 years. Link to comment Share on other sites More sharing options...
DavidR Posted July 16, 2018 Report Share Posted July 16, 2018 1 hour ago, Aadams said: I recently had working AR5 tweeters rebuilt. Who rebuilt them for you? Link to comment Share on other sites More sharing options...
Aadams Posted July 16, 2018 Author Report Share Posted July 16, 2018 I used “Holographic” because it is the only single word I could think of to describe the sound but that word implies a 3d effect and that is not accurate IMO. However, in my experience the effect you heard on your AR9s sounds similar except with the 3a, LST, or 5 the size of the listening area would be much larger and probably would not require any toe in of the speakers. Hearing the difference also depends on how the recording was engineered IMO. If it was created in a studio, you may not hear the difference. Anything recorded in complete live performance and engineered with the objective of recreating the live venue sound will easily convey the difference. This is not imaging or an enveloping sound field. It is more akin to sitting in an audience and changing the volume according to which seat row you prefer. I have AR9s to which I listen frequently, but the 9 does not present a recording in the same way a properly working Allison era classic can do above 500hz or so. Until now I have felt fortunate to have good working original tweeters in my 3as. I knew my 5 tweeters were ailing but was flabbergasted at the difference after the rebuild. Now I wonder what I am missing with the 3as. 1 hour ago, DavidR said: Who rebuilt them for you? CSP handle is Chris1this1 Adams Link to comment Share on other sites More sharing options...
Pete B Posted July 16, 2018 Report Share Posted July 16, 2018 It really helps to have a modern reference to compare a vintage design agaist before and after changes, or to measure them. Link to comment Share on other sites More sharing options...
Aadams Posted July 16, 2018 Author Report Share Posted July 16, 2018 1 minute ago, Pete B said: It really helps to have a modern reference to compare a vintage design agaist before and after changes, or to measure them. If you are talking about individual drivers I have no way of doing that. If you are referring to entire speaker systems that is how I discovered the need for more tweeter output. As for measurement I only have my ears which are slowly failing. Link to comment Share on other sites More sharing options...
Pete B Posted July 16, 2018 Report Share Posted July 16, 2018 What speaker did you compare against, many are voiced far too bright in my opinion. Link to comment Share on other sites More sharing options...
DavidR Posted July 16, 2018 Report Share Posted July 16, 2018 2 hours ago, Aadams said: 3 hours ago, DavidR said: Who rebuilt them for you? CSP handle is Chris1this1 Adams Thank you. I had contacted him regarding my 10Pi tweeter #2000011-1 and he does not do those. I was unaware that the AR5 used the 'egg shell' dome tweeter. Link to comment Share on other sites More sharing options...
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