ReliaBill Engineer Posted March 18 Report Share Posted March 18 Ok. Maybe a place for Replacement Replacements? Mods to Replacements? You want me to start the “Mod To Replacement 4x Tweeter”? Quote Link to comment Share on other sites More sharing options...
ReliaBill Engineer Posted March 18 Report Share Posted March 18 1 hour ago, Aadams said: No reason to be shy. If you can credibly restore failed AR5/AR3a/11 midranges for a reasonable fee you will get interest. Well, it wouldn’t fit under a “restore”, to the AR purists. Not using an AR dome, and not an AR voice coil would make it a Mod, no? Quote Link to comment Share on other sites More sharing options...
Aadams Posted March 18 Report Share Posted March 18 16 minutes ago, ReliaBill Engineer said: Ok. Maybe a place for Replacement Replacements? Mods to Replacements? You want me to start the “Mod To Replacement 4x Tweeter”? Your project is interesting. I would say, just take your project to conclusion and the admin will know in the end whether or not it is an MT thread. Quote Link to comment Share on other sites More sharing options...
Aadams Posted March 18 Report Share Posted March 18 13 minutes ago, ReliaBill Engineer said: Well, it wouldn’t fit under a “restore”, to the AR purists. Not using an AR dome, and not an AR voice coil would make it a Mod, no? Just make it perform and appear correctly. None of the rebuilt dome tweeters you hear about have original coils. Some of them are custom wound for application as either 4 or 8 ohm as specified by the buyer. Some tweeter domes are original some domes are aftermarket. Midranges could be a bit different. Nobody restores them. Quote Link to comment Share on other sites More sharing options...
RoyC Posted March 18 Report Share Posted March 18 11 hours ago, ReliaBill Engineer said: There’s more going on in this tweeter than you realize. First, RoyC said this PRT has a sound similar to the 4x AR tweeter, but some find it more harsh. Thats why RoyC’s attempt to tame this PRT failed. He added his dope to the existing dope. Adding dope to a surround that is already too stiff won’t accomplish anything. I see this one is still going. 🙄 Bill, As I mentioned some posts ago in this thread I did mention that the 4x tweeter is "more compliant"...so in that regard, I agree with what you are trying to accomplish with the PRT tweeter. It rolls off more quickly than the original, yet is apparently more sensitive in the upper frequencies. The 4x's crossover exacerbates the issue. The result can be a subjectively aggressive character in the upper mid/lower high frequencies....most noticeable as the volume is increased. As I mentioned before, some people prefer this to the original character. Unlike what you seem to believe, I don't think its behavior as a drop-in replacement for the 4x tweeter is an indictment of the PRT tweeter as a whole. For the record, I did not add anything to the PRT's "surround". Some material was added to the paper cone to add some mass and try to reduce its upper mid sensitivity, which it did slightly...but I was fully aware that it was never going to make it sound the same as the original tweeter. Knowing that most people were accepting of the PRT tweeter, it was a simple attempt to make it a bit more friendly to my ear, and others who were not satisfied with it. It should be noted that the original tweeter had a similar treatment to the cone's perimeter, which is where I got the idea. Attached is a photo of a nasty old specimen showing where it was applied. Most 4x tweeters had various amounts of it on the cone. It should also be noted that the 4x tweeter has a larger cone along with the softer suspension. Your modifications to the tweeter appear to be thoughtful and neatly done, and I'll be interested in the outcome if they are practical for others to implement or acquire should they prove effective. "What I failed to effectively communicate to RoyC is that if these sound good in my Polks, they’ll also sound good in the 4X, or in any speaker, regardless of the crossover." You haven't failed to "communicate" anything to me. You just haven't convinced me. Roy Quote Link to comment Share on other sites More sharing options...
ReliaBill Engineer Posted March 19 Report Share Posted March 19 A smooth tweeter is a smooth tweeter. No “extreme” aberrations in the FR and a smooth, well controlled impedence curve, makes designing a crossover a breeze. I saw how much work Speaker Dave put into the 4x tweeter XO in an attempt to tame its response. (In combination with the woofer.) It would have been easier if the tweeter had a smoother FR response, don’t you think? My experience says “yes!” The mention of dome tweeters was only to illustrate a point. Not so much to state definitively the merits of one over the other. Pistonic motion was the point of the comparison I was making. Unconstrained (but damped) motion of a tweeter cone/dome provides the best chance for smooth FR output. Im still in the process of documenting my work on this tweeter. I haven’t even solidified my own process, yet alone listened to final results. So of course I haven’t provided any instructions to the readers. But in the end, it should be up to the readers to decide if they want to try it themselves, no? I think so. Yet already it seems a judgement has been made about the merits of doing this, and its level of complexity. Prejudged, if you will. I’ll finish this tweeter, then mount it for audition, and do some critical listening. I’ll compare it to the untouched unit. If it passes that test, I’ll have it tested with plotted results, mine and the original. I think that’s fair. BTW: I’m no quack. I’ve been doing this kind of work for many years. I was a product and equipment design engineer, engineering manager for 6 companies. Now as a reliability engineer for NASA SLS, it is my job to identify root causes of failures and non-comformance, predict and quantify failures, as well as design solutions. It’s very challenging in aerospace vehicles. But with audio components, a certain artistic flair helps. Quote Link to comment Share on other sites More sharing options...
RoyC Posted March 19 Report Share Posted March 19 11 hours ago, ReliaBill Engineer said: "A smooth tweeter is a smooth tweeter....... Not so much to state definitively the merits of one over the other. Pistonic motion was the point of the comparison I was making. Unconstrained (but damped) motion of a tweeter cone/dome provides the best chance for smooth FR output." You started that part of the conversation by telling us about AR's use of inferior cone-type tweeters, and conjecture as to why AR did what it did with the 2ax mid and 4x tweeter (along with other generalizations and suppositions about AR designs). Too bad so many speaker companies and their design engineers didn't have access to "smooth" tweeters over the decades. Why not just recommend your favorite dome tweeter instead of rebuilding an inferior cone replacement tweeter with which you have no experience to be adapted to a speaker system you have never owned and have no access to? It would likely be easier for someone to make cabinet changes than to rebuild a less than desirable new replacement tweeter. Personally, I would be more inclined to investigate the driver PeteB (many credentials, btw) mentioned earlier in this thread if that were the case. ...Yet already it seems a judgement has been made about the merits of doing this, and its level of complexity. Prejudged, if you will. Perhaps, but most likely based on your participation in this forum to this point. Most people arrive here seeking advice on the restoration, not modification, of classic speakers (AR in this case) or to offer experience in that regard. You pretty much started out by finding fault with the design of a pair of 2ax's, which apparently was your only experience with AR speakers. You installed a pair of new dome mids and pronounced them superior based on your years of critical listening. Was that meant to establish credibility with a forum comprised of AR speaker enthusiasts? "...I’ll finish this tweeter, then mount it for audition, and do some critical listening. I’ll compare it to the untouched unit. If it passes that test, I’ll have it tested with plotted results, mine and the original. I think that’s fair." Yup, in a Polk system. This will tell AR-4x owners how to modify the 4x crossover to work with the 4x woofer, woofer inductor, and extra large 4x tweeter capacitor....after they rebuild it. I'm sure everybody knows by now you have an engineering background. That and your audio hobby doesn't place you in a special category. Actual audio design engineers, including a former AR speaker engineer and other audio professionals have contributed much useful data and insight to this forum over the years. I'm sure you saw some of this in the SpeakerDave 4x replacement tweeter thread you cited. One prominent forum member actually owns the entire archive of AR engineering drawings and notes. Despite some of my comments, I am still interested, if not curious, as to how the tweeter turns out. I do agree that a softer suspension and increased excursion could bring it closer to the original. Roy Quote Link to comment Share on other sites More sharing options...
ReliaBill Engineer Posted March 19 Report Share Posted March 19 I think you’re being a bit too defensive, RoyC. The reasons I decided to experiment with this tweeter were already stated. But to recap, here are my reasons: Quote Link to comment Share on other sites More sharing options...
JKent Posted March 19 Report Share Posted March 19 9 hours ago, RoyC said: I would be more inclined to investigate the driver PeteB (many credentials, btw) mentioned earlier in this thread I was wondering why no one picked up on that. Pete has mentioned good subs for other drivers in the past and it looks to me like an adapter plate could be made, even without a 3D printer. Maybe I should add a couple to my next Mouser order. Anyone plan to investigate? Quote Link to comment Share on other sites More sharing options...
meta_noia_fot Posted March 19 Report Share Posted March 19 I would be interested in this. I have a pair of 4x with the tweeters from Vintage AR. I was showing my wife this and we think we could get an adapter done. This is beyond my abilities alone but she’s a trained theater tech and has helped me with projects on here in the past. I also have a turntable part I’d like to get 3D scanned so I could kill two birds there. For evaluation, what do you seasoned vets use to compare the tweeters and get quantifiable results? Quote Link to comment Share on other sites More sharing options...
ReliaBill Engineer Posted March 19 Report Share Posted March 19 4 hours ago, JKent said: I was wondering why no one picked up on that. Pete has mentioned good subs for other drivers in the past and it looks to me like an adapter plate could be made, even without a 3D printer. Maybe I should add a couple to my next Mouser order. Anyone plan to investigate? I looked at that one, plus many more. Just based on appearance, they are very obviously not AR. There are a few paper cone tweeters that look a lot like the AR tweeter, but they all require pretty major mounting mods. I was going off of RoyC’s comments about the PRT sounding similar and not requiring major mods to mount in the baffle. Quote Link to comment Share on other sites More sharing options...
ReliaBill Engineer Posted March 19 Report Share Posted March 19 I’ve been trying to find comparison FR and impedance plots of the PRT vs an original AR tweeter for the 4x. I either overlooked it, or I just can’t find it. Anyone know where they are? Quote Link to comment Share on other sites More sharing options...
ReliaBill Engineer Posted March 20 Report Share Posted March 20 FWIW…. I just bought a pair of 4x speakers. All intact, never worked on. So now we’ll see…. Supposedly both woofers work, tweeters intact, but may or may not work. Prime for repairing the originals (if required), and testing and comparing these PRTs. Quote Link to comment Share on other sites More sharing options...
ReliaBill Engineer Posted March 20 Report Share Posted March 20 I’m a bit more than surprised…. These PRTs have been offered up as “replacements” and “temporary replacements” for many years for the AR 4x tweeters. But yet, nowhere have I been able to find a representative FR and impedance plot for them. How is that possible? Again, if I’ve overlooked it, I apologize in advance. The AR tweeter FR plot: Quote Link to comment Share on other sites More sharing options...
genek Posted March 20 Report Share Posted March 20 As far as I can recall, the people saying the PRT is a good replacement for AR-4s are usually the same people trying to sell them. The consensus here is that the only thing they really have going for them is that they fit in the cabinet. But the fact that nobody trying to sell these seems to have ever put a FR graph for them up may in itself be telling. Quote Link to comment Share on other sites More sharing options...
ReliaBill Engineer Posted March 20 Report Share Posted March 20 I decide to move my efforts over to the Mods and Tweaks section. I would hate to fail and keep posting in here. Plus, it really doesn’t belong here. Quote Link to comment Share on other sites More sharing options...
RoyC Posted March 20 Report Share Posted March 20 On 3/19/2024 at 10:27 AM, ReliaBill Engineer said: I think you’re being a bit too defensive, RoyC. Whatever... I believe there were measurements posted way back when SpeakerDave, carlspeak, (and others?) were recommending crossover changes. The bottom line is the recommendations apparently did provide a smoother system response, but I'm not aware of anyone who implemented them. The crossover change was not just a simple tweeter capacitor swap, and the primary issue was a peak in the upper midrange response of the PRT. I also seem to recall the availability of other PRT tweeters at the time with similar, but somewhat different, response characteristics. To Gene's point...I just had a conversation with "Vintage_AR" (Larry Lagace), and told him about this thread. He just laughed and said he sells "lots of them" and has never had a return or a complaint. I then went to the Parts Express website. Here is the description: "At last, a faithful reproduction of the classic "phenolic ring" tweeter developed by CTS and used by Marantz, Altec, Martin, Acoustic Research and many others." ...where it gets decent reviews. Low cost and ease of installation has obviously made this a popular way to repair the 4x, especially since used original 4x tweeters have become very scarce. Roy PS Hmmm...In case it isn't clear, I have never had any involvement in the sale of this tweeter (modified or otherwise). Quote Link to comment Share on other sites More sharing options...
ReliaBill Engineer Posted March 20 Report Share Posted March 20 How much easier would SpeakerDave’s crossover have been if the response anomaly wasn’t there? That’s all I’m saying. And what if the PRT sounded more like the original AR tweeter? I certainly understand the “If it ain’t broke, don’t fix it!” proverb. But to me, it’s “broke”. I thought you might encourage the attempt. Guess not. So is the following an attempt to shame me somehow?? Reaching over the fence to get some type of agreement or “consensus”? Is that what we do in here? “To Gene's point...I just had a conversation with "Vintage_AR" (Larry Lagace), and told him about this thread. He just laughed and said he sells "lots of them" and has never had a return or a complaint. I then wentto the Parts Express website. Here is the description:” And the above doesn’t agree with the below very well: ”This tweeter is certainly not a perfect replacement, especially when used in a pair next to an original. Unfortunately, there are really no other "drop-in" options. There was some experimentation with crossover changes for this tweeter mentioned in the forum quite a few years ago, but I'm not aware ofanyone who implemented any of the suggestions.” Selling “lots of them” doesn’t mean it’s the better option. It means it’s a convenient, “viable” option. Looking at prices of AR-4x pairs with the PRTs installed seems to drop the asking price considerably. Of course, it means the pair isn’t all original; and there are plenty of comments about the PRT being a compromise. But I see no reason for my attempts to be disparaged, any more than SpeakerDave’s work to be. Quote Link to comment Share on other sites More sharing options...
RoyC Posted March 21 Report Share Posted March 21 5 hours ago, ReliaBill Engineer said: How much easier would SpeakerDave’s crossover have been if the response anomaly wasn’t there? That’s all I’m saying. And what if the PRT sounded more like the original AR tweeter? I certainly understand the “If it ain’t broke, don’t fix it!” proverb. But to me, it’s “broke”. I thought you might encourage the attempt. Guess not. So is the following an attempt to shame me somehow?? Reaching over the fence to get some type of agreement or “consensus”? Is that what we do in here? “To Gene's point...I just had a conversation with "Vintage_AR" (Larry Lagace), and told him about this thread. He just laughed and said he sells "lots of them" and has never had a return or a complaint. I then wentto the Parts Express website. Here is the description:” And the above doesn’t agree with the below very well: ”This tweeter is certainly not a perfect replacement, especially when used in a pair next to an original. Unfortunately, there are really no other "drop-in" options. There was some experimentation with crossover changes for this tweeter mentioned in the forum quite a few years ago, but I'm not aware ofanyone who implemented any of the suggestions.” Selling “lots of them” doesn’t mean it’s the better option. It means it’s a convenient, “viable” option. Looking at prices of AR-4x pairs with the PRTs installed seems to drop the asking price considerably. Of course, it means the pair isn’t all original; and there are plenty of comments about the PRT being a compromise. But I see no reason for my attempts to be disparaged, any more than SpeakerDave’s work to be. Yow...Now who is being "defensive"?! None of that post was meant to be a justification for you (or anyone else) to not work with the tweeter! If you take another look, you will see that the second part was information pertinent to Gene's (correct) assumption that there is no other data from the sellers of the tweeter...despite its obvious popularity. I was not defending the tweeter, and it was not a criticism, implied or otherwise, of your project. SpeakerDave and Carl Richards were redesigning the 4x crossover with actual measurement equipment and calculations when the PRT tweeter was first introduced. They even had AR speakers to work with...imagine that! It was very credible work from guys with professional experience in the audio field. Unfortunately, like your project, it was only of some interest to us geeks. Since that time the PRT tweeter has become established as a popular replacement, like it or not. You are just late to the party with far fewer tools. Carry on, it will be entertaining if nothing else. Quote Link to comment Share on other sites More sharing options...
genek Posted March 21 Report Share Posted March 21 Response also depends on context. The brand name forums of this site are devoted to the history, care and restoration of original speakers and sound. A discussion of how to adapt a non-original driver to replicate the sound of a now unobtainable original part will usually generate some interest and positive reactions. Starting out with a mission to "improve" originals with redesigns because you think original was somehow lacking may get interest and positive reactions in Mods and Tweaks, but is unlikely to here. Imagine you modded a 1920s art deco cocktail bar to add a beer keg tap and a margarita machine. There would probably be people who would think it was a cool project, but you would be unlikely to find them in a forum devoted to art deco antiques. Quote Link to comment Share on other sites More sharing options...
ReliaBill Engineer Posted March 21 Report Share Posted March 21 10 hours ago, RoyC said: Yow...Now who is being "defensive"?! None of that post was meant to be a justification for you (or anyone else) to not work with the tweeter! If you take another look, you will see that the second part was information pertinent to Gene's (correct) assumption that there is no other data from the sellers of the tweeter...despite its obvious popularity. I was not defending the tweeter, and it was not a criticism, implied or otherwise, of your project. SpeakerDave and Carl Richards were redesigning the 4x crossover with actual measurement equipment and calculations when the PRT tweeter was first introduced. They even had AR speakers to work with...imagine that! It was very credible work from guys with professional experience in the audio field. Unfortunately, like your project, it was only of some interest to us geeks. Since that time the PRT tweeter has become established as a popular replacement, like it or not. You are just late to the party with far fewer tools. Carry on, it will be entertaining if nothing else. Nothing defensive in my post at all. Just me scratching my head at your very negative comments. Quote Link to comment Share on other sites More sharing options...
ReliaBill Engineer Posted March 21 Report Share Posted March 21 1 hour ago, genek said: Response also depends on context. The brand name forums of this site are devoted to the history, care and restoration of original speakers and sound. A discussion of how to adapt a non-original driver to replicate the sound of a now unobtainable original part will usually generate some interest and positive reactions. Starting out with a mission to "improve" originals with redesigns because you think original was somehow lacking may get interest and positive reactions in Mods and Tweaks, but is unlikely to here. Imagine you modded a 1920s art deco cocktail bar to add a beer keg tap and a margarita machine. There would probably be people who would think it was a cool project, but you would be unlikely to find them in a forum devoted to art deco antiques. I already started a thread in Mods and Tweaks yesterday. I guess you didn’t see it. I never said I was setting out to “improve an original” tweeter. Where did that come from?? I said I was working on improving the PRT. Go back and read my posts and see the pics. Nowhere do I show or comment about improving an original AR 4x tweeter! SMH Quote Link to comment Share on other sites More sharing options...
genek Posted March 21 Report Share Posted March 21 The question is whether you are trying to improve the PRT by making it sound like the original AR tweeter or to make it sound "better" than the original. This is the key to determining whether to post here or in Mods and Tweaks. Quote Link to comment Share on other sites More sharing options...
RoyC Posted March 21 Report Share Posted March 21 20 minutes ago, genek said: The question is whether you are trying to improve the PRT by making it sound like the original AR tweeter or to make it sound "better" than the original. Agreed...which is pretty hard to do if one has no experience with either tweeter in the 4x. Meaningless debates based on speculation and conjecture are distracting. The Mods and Tweaks section is probably the only place for this to go. Quote Link to comment Share on other sites More sharing options...
ReliaBill Engineer Posted March 21 Report Share Posted March 21 3 hours ago, genek said: The question is whether you are trying to improve the PRT by making it sound like the original AR tweeter or to make it sound "better" than the original. This is the key to determining whether to post here or in Mods and Tweaks. Too much pushback in here, for either approach or reason. Quote Link to comment Share on other sites More sharing options...
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