Carlspeak Posted January 23, 2009 Report Share Posted January 23, 2009 Attached is a document summarizing some testing I did on a pair of these tweeters. This particular brand and model has garnered some serious ink here as of late with regard to it's being a replacement for the 3/4 inch AR tweeter. Thus my interest was elevated sufficiently to justify the effort since my work involves a number of AR restorations and upgrades.Measurements do not tell the whole story regarding the performance of a speaker driver. However, they do allow a more objective assessment which should be part of one's decision process when considering the purchase of replacement tweeters. Anecdotal comments following subjective assessments are limited by the fact that everyone hears things somewhat differently and have varied opinions on what sounds good.Perhaps some additional measurements taken by others who post here would be useful in getting a clearer picture of this tweeter's true potential.Hi_Vi_test_results.pdf Link to comment Share on other sites More sharing options...
genek Posted January 23, 2009 Report Share Posted January 23, 2009 Measurements do not tell the whole story regarding the performance of a speaker driver. However, they do allow a more objective assessment which should be part of one's decision process when considering the purchase of replacement tweeters. Anecdotal comments following subjective assessments are limited by the fact that everyone hears things somewhat differently and have varied opinions on what sounds good.Carl, any thoughts (measured data or otherwise) on how these compare to the 3/4" AR tweeters you got through PE last year? Link to comment Share on other sites More sharing options...
Carlspeak Posted January 23, 2009 Author Report Share Posted January 23, 2009 No thoughts yet on how they sound. Off-axis response was similar to the PE's.The PE's impedance was more like the 3/4 inch AR tweeter than the Hi-Vi.The PE's efficiency was higher than the Hi-Vi's and thus there's more 'room' for rheostate adjustment.The Hi-Vi's advantage is it doesn't require an adapter plate. Link to comment Share on other sites More sharing options...
onplane Posted January 23, 2009 Report Share Posted January 23, 2009 No thoughts yet on how they sound. Off-axis response was similar to the PE's.The PE's impedance was more like the 3/4 inch AR tweeter than the Hi-Vi.The PE's efficiency was higher than the Hi-Vi's and thus there's more 'room' for rheostate adjustment.The Hi-Vi's advantage is it doesn't require an adapter plate.Carl, as always, thank you for sharing your results!! I mean this is just great that people like you are willing to share your hard work.To me that advantage of the NOT requiring an adapter plate is pretty important. Now, couple that with the fact that I can't hear anything above 11.5KHz, seems like I'll be in business once my "over driven" 3a tweeters finally "give up".Regards,Jerry Link to comment Share on other sites More sharing options...
RoyC Posted January 23, 2009 Report Share Posted January 23, 2009 Perhaps some additional measurements taken by others who post here would be useful in getting a clearer picture of this tweeter's true potential.Hi Carl,Thanks for the Q1R data!I agree with your conclusions that the faceplate is probably the Q1R's strongest advantage, and that it should NOT be considered a direct "match" to the original tweeter. IMO, when installed in pairs, however, it is a nice sounding driver for our old beasts. It is easy to implement, and sounds better than the very costly AB Tech "replacement tweeter". Measurements of the Q1R with a .05 to .1mh parallel inductor would be more applicable to my experience with it.I first tried the Q1R, after reading some good things about this driver and the manufacturer, as well as having had some positive experiences with the less expensive X1R. The large faceplate was what drew me to both drivers in the first place. (For some time now I have had a strong interest in finding a fairly priced, readily available replacement tweeter for the 3a, 2ax and 5 that does not greatly disturb the original "AR" character, AND is easy to install.) As I have posted previously, I was pleasantly surprised to find the Q1R sounding very acceptable to me in the 2ax and 3a with a small parallel inductor, as Carl found with the AR303 tweeter. The fact remains, however, that there are still NO electrical "drop-in replacements" currently available for the the original tweeters. This includes the AB Tech tweeter, which, after much experience, is a $10 tweeter behind a $50 "AR" plastic faceplate, IMO:-)....and, as with our other "replacement" candidates to date, should be installed in pairs as well.After a dozen or so dissections, I am convinced that many, if not most, of the original AR 3/4" tweeters out there do not sound the same as they once did, and today are inconsistent at best. Replacing them with used originals can be an expensive crapshoot...so here we are. Consequently, the problem remains that, out of necessity, we may be talking "mod" as much as we are "restoration".It has been established that the original tweeter is quite unique, and among other things, has superior dispersion. Soundminded and others have discussed off axis response at length, and it is something to be considered. It seems to me (Carl, I know you have mentioned this as well) that dispersion may not be near the top of the list of requirements for these old cabinets. The baffle is recessed about one inch, and the tweeter is behind a grille of masonite covered with rather heavy grille cloth. (See photos below of a 3a with a clothless frame in place). Other variables attributed to an individual's listening environment also need to be taken into consideration. I have heard response differences between various tweeters, and we have seen measured differences, and I question whether dispersion should be an overriding consideration. Of course it would be nice to have it all:-)!Further, when we are required to use shunt inductors along with the level controls, I doubt the replacement candidate's impedance is much of a factor, as long as it has high enough sensitivity, and can achieve the desired response.Thanks again , Carl...Roy Link to comment Share on other sites More sharing options...
Carlspeak Posted January 24, 2009 Author Report Share Posted January 24, 2009 Roy, your points regarding the limiting geometry of the vintage AR cabinetry potentially being detrimental to the tweeter's acknowledged dispersion properties are well taken. I only wish I had the ambition, carpentry skills and (oh yeah) time to build a pair of modern styled cabinets of comparable internal volume for these vintage drivers. Cabinets with generous rounded corners and all drivers flush mounted and back wired. Maybe someone who stumbles on this discussion with those attributes could do us all a great favor to build them and report on how they sound. Link to comment Share on other sites More sharing options...
genek Posted January 24, 2009 Report Share Posted January 24, 2009 Roy, your points regarding the limiting geometry of the vintage AR cabinetry potentially being detrimental to the tweeter's acknowledged dispersion properties are well taken.I've only done tweeter comparisons using an original 3a tweeter vs a 10pi/11 tweeter vs the PE supplied AR tweeter, I haven't tried building a super-smooth flush front cabinet, and I'm sure that the stuff mounted on the front of the 3a box cuts into the dispersion of the original dome tweeters compared to a bare, unobstructed driver. Nevertheless, I can attest to the fact that even with all the stuff in the front to block the sides the old AR domes still have audibly wider dispersion in situ than the newer units do. I certainly do agree that dispersion shouldn't be the overriding consideration, and if my only options were a choice between replacement tweeters with the right on-axis tonal balance and a narrower field vs playing the speakers with dead tweeters in them I'd definitely opt for the replacements. Link to comment Share on other sites More sharing options...
RoyC Posted January 24, 2009 Report Share Posted January 24, 2009 Roy, your points regarding the limiting geometry of the vintage AR cabinetry potentially being detrimental to the tweeter's acknowledged dispersion properties are well taken. I only wish I had the ambition, carpentry skills and (oh yeah) time to build a pair of modern styled cabinets of comparable internal volume for these vintage drivers. Cabinets with generous rounded corners and all drivers flush mounted and back wired. Maybe someone who stumbles on this discussion with those attributes could do us all a great favor to build them and report on how they sound.Carl,Actually I do have a pair of more modern style cabinets, which were built for me 15 years ago as a project to build "brand new" AR-3as. They served to initially house AB Tech drivers, then original 3a components, and, later still, "AR-3a Limited" guts. Ultimately they became project/test cabinets when I decided that the sound was not all that much "better" than that of the much more attractive original cabinets. (It was also when I first realized that the AB Tech drivers, which I initially used, were not the same as the original 3a drivers!). One of the pair is partially pictured below, housing a later AR midrange and a planar tweeter I was testing a couple of years ago.Roy Link to comment Share on other sites More sharing options...
RoyC Posted January 24, 2009 Report Share Posted January 24, 2009 The only tweeter that I found troublesome in regard to dispersion were some planars (pictured in my post above) that sounded very nice on axis, and not so great off axis. Though I have never heard them, I am willing to bet Carl's "super mod" 3a will sound better to most folks in direct comparison to an original 3a, (even though his tweeters' dispersion measurements probably show them to have less dispersion than that of the 3a:-)). Debating theory, response curves, and 1" vs 3/4" domes, is always interesting, but in the end the tonal balance is most important in the typical listening environment for most folks. I have officially retired my original 3/4" AR tweeters for daily listening. I have tested and dissected many of the old domes, especially over the past few years, and I still own 8 of them (counting a pair of the 8 ohm version). They still make sound, but not the way they used to. Their greatest deficiencies today are the inability to extend into the midrange frequencies, and inconsistent overall output. The suspensions are stiff, and the foam material under the domes has deteriorated. IMO, a dying tweeter is as inferior as a dead one. To date there are 3 modern tweeters I have preferred over the old ones, with the Q1R being my current favorite. I also prefer the AR-11/10pi era AR tweeter over the original 3/4" hard dome tweeter, as it has held up better.I know this probably all sounds like heresy coming from a hardcore AR fan, but I think it will be beneficial for us in the long run to continue to explore alternative solutions to the tweeter issue, as we make every effort to mantain the sonic character of our old beasts. (and based on recent offerings, I suspect AB Tech will continue to become less helpful). Those of you still enjoying your old ARs should ignore this post for the time being:-)! Roy Link to comment Share on other sites More sharing options...
genek Posted January 24, 2009 Report Share Posted January 24, 2009 Those of you still enjoying your old ARs should ignore this post for the time being:-)!Oh, no way. I'm socking away spare parts against the day my working original tweeters give up the ghost. So far I've laid in a pair of 10pi/11 domes with Ken Kantor's recommended 0.07mH coils and a pair of the 218V domes with Carl's adapter plates and 0.15mH coils. I might have ordered up a pair of the Hi Vi's if not for the fact that Carl says their only advantage over the ones I already got from him is that they don't need adapters. Link to comment Share on other sites More sharing options...
dick Posted January 24, 2009 Report Share Posted January 24, 2009 As a few will recall, I'm a recent AR fan thanks to a find at the town dump: AR-3a's. Thanks to Carl, the woofers are now great, and thanks too to all on the AR Forum because you all guided me in my restoration project. And, now luking on this Forum and reading and thinking, I've just installed the Hi-Vi tweeters with inductor coils. They've been going about 3 - 4 hours a day for almost a week (mostly classical but jazz too). We're in love with them and our 'refurbished in toto' AR-3a's. YUM. I know, I know, the tweeter isn't the same as the original, but the sound is right on. You'll have to try it to believe it.Carl: "It's all about the music!"Duke Ellington: "If it sounds good, it IS good."Me: "If it sounds better, it IS better."The quantitative data that Carl submitted, unfortunately, is beyond my limited technical capacity to evaluate. But the difference between the old original tweeters and the new Hi-Vi's has been qualitatively evaluated by me and by my wife who has very critical ears (she says the same of me). At first we thought the Hi-Vi's were too bright but we eventually brought them into the fold of the other speakers by careful adjustiment of the pots. While I have no way of knowing what the original 3a sounded like, I do like the Hi-Vi addition to the speakers. The sound is balanced, well articulated, broadly heard, and...well...simply wonderous.I do believe that the ear is the ulitimate measuring device for speaker evaluation and while some ears are better or more educated than others, I'm willing to say, that to date we're mightily impressed with the Hi-Vi tweeters as integrated members of the 3a assembly.So I'm happy. Although, to be honest, I was at the dump again today and...darn!...I was a bit depressed that no one had brought an LST or a 3a to drop off. Link to comment Share on other sites More sharing options...
soundminded Posted January 25, 2009 Report Share Posted January 25, 2009 The AR3a is by design intent a wide dispersion loudspeaker system across the entire audible frequency spectrum. This is evidinced not only but the fact that both the midrange and tweeters are domes but that the domes project well in front of the baffle with no groove around them to focus their sound. This makes them less efficient. Efficiency is sacrificed for improved off axis dispersion. The philosophy of loudspeaker design today is rather different and so comparable tweeters are extremely rare and in this regard are not equal in dispersion, at least not in a single driver.The precise difference that is audible depends on a number of factors. The difference in dispersion between the replacement and the original, the angle you sit at, the speaker placement, and the room acoustics. Program content counts too. In theory, if you sat on axis of the speaker in an anechoic chamber and the FR was the same on axis as the original, the sound would be the same. But none of us live in anechoic chambers, we couldn't have one in our homes if we wanted it (unless we were very rich and at least a little crazy), and it is a horrible place to listen to music in anyway. As your room differs from an anechoic chamber, to that degree there will be audible differences assuming your hearing is normal. If you can't hear above 8khz, this won't apply to you. The AR tweeter had an output falloff of 5 db at 15 khz 60 degrees off axis. 5db is a loss of about 70%. The Hi Vi falls of 30 db. Thats a loss of 99.9%. It essentially beams its high frequencies in a narrow cone. It means that early reflections from the general direction of the speaker will have no high frequency content at all. The more and louder the reflections, the greater the difference. This is why I suggested the Vifa tweeter. It also is not as good as the AR tweeter in dispersion but it's a lot closer.Audiophiles today try to get around this limitation by pulling their speakers away from walls into the room and building live end-dead end rooms. Pulling the speakers away from the walls reduces these reflections at middle and lower frequencies at the spot they listen at. The dead end behind and to the sides of the speaker does the same while the live end behind the listener reflects high frequencies that are propagated back at the listener. It mitigates the problem to a degree but it does not solve it. Audiophiles and engineers who cater to them today work on the philosophy that they try to reduce or eliminate the effects of room acoustics. They fight the acoustics of the listening room in a battle that is hopeless, it's one they cannot win.Here is an interesting technique/trick you can try with an inexpensive tweeter such as the Vifa I learned from Peter Snell's mother of all people when I spoke to her at a trade show where she was introducing the AIIIi shortly after he son's tragic death at an early age. I asked her what the purpose of a small piece of polyfoam glued to the front center surface of the tweeter was. She said it was to improve dispersion. And thinking about it she was right. This decreases the efficiency of sound launched on axis of the tweeter relative to what is launched off axis. As with AR's tweeter, it sacrifices efficiency for dispersion. Of course, whatever tweeter you use, you have to match the FR, sound level, and high pass crossover characteristics of the replacement tweeter to the rest of the system in the same way the original did. This can most effectively and easily be accomplished with an active crossover network a 1/3 or 1/6 octave equalizer, and a separate amplifier. This effort is more expensive and complex than most people are able or willing to try but it would be the most efffective. Once this is done, passive schemes to obtain equivalent results can be experimented with and persistance will probably yield a much lower cost method.Recently, I have added more indirect tweeters to my AR9s and my Bose 901s to improve off axis dispersion in the lateral plane for AR9 and in the vertical plane for Bose 901. For AR9, it is the first design change I have made in 19 years. This of course required other relatively minor changes to keep the speaker from being too bright. I'm not going to say there was a radical improvement but I think there is a noticable improvement to both. Being an inveterate tinkerer and not having an obsession to "restore" speakers to their original sound, I feel no remorse, I want what the original designer wanted, the best most accurate sound I can get. For others this may not be their goal and that's OK too. Link to comment Share on other sites More sharing options...
Carlspeak Posted January 25, 2009 Author Report Share Posted January 25, 2009 Carl,Actually I do have a pair of more modern style cabinets, which were built for me 15 years ago as a project to build "brand new" AR-3as. They served to initially house AB Tech drivers, then original 3a components, and, later still, "AR-3a Limited" guts. Ultimately they became project/test cabinets when I decided that the sound was not all that much "better" than that of the much more attractive original cabinets. (It was also when I first realized that the AB Tech drivers, which I initially used, were not the same as the original 3a drivers!). One of the pair is partially pictured below, housing a later AR midrange and a planar tweeter I was testing a couple of years ago.RoyRoy, Here's Zigfried L. take on diffraction. A nice presentation. Bottom line: he's not overly concerned about it.http://www.linkwitzlab.com/diffraction.htm Link to comment Share on other sites More sharing options...
Mexicomike Posted January 25, 2009 Report Share Posted January 25, 2009 Interesting thread and it makes me think that one use of these new tweeters where the dispersion might be less important is in a pair of LSTs!Frankly, just for the heck of it I would be interested in taking one of my all original-driver LSTs and, for scientific purposes, trying 4 of the tweeters in one of them and directly comparing that LST to the other... Not sure how I would actually do this since I live in Mexico and getting the tweeters down here is definitely NOT cost effective. But it's worth thinking about...Of course if the tweeter dispersion is as bad as it sounds per the description, what you might get with LSTs is a series of "holes" in the response as you move across in front of the speakers which might be much worse sounding than it would be in a 3A. Link to comment Share on other sites More sharing options...
genek Posted January 25, 2009 Report Share Posted January 25, 2009 Interesting thread and it makes me think that one use of these new tweeters where the dispersion might be less important is in a pair of LSTs!I would think so as well. So why is getting tweeters to Mexico not cost efficient? Shipping, customs or both? Is there some way we could work around it from here? Link to comment Share on other sites More sharing options...
soundminded Posted January 25, 2009 Report Share Posted January 25, 2009 I would think so as well. So why is getting tweeters to Mexico not cost efficient? Shipping, customs or both? Is there some way we could work around it from here?Smuggle them into Mexico by disguising them as drugs. The government always looks the other way at that. Link to comment Share on other sites More sharing options...
dick Posted January 25, 2009 Report Share Posted January 25, 2009 Not sure how I would actually do this since I live in Mexico and getting the tweeters down here is definitely NOT cost effective. But it's worth thinking about...MexicoMike! !Buenos Dias! Hey, I wondered about your name, and now I know: that's where you live. Where in Mexico? I too had problems getting packages to me. I've lived in Mexico (1960, 1986) where things were sometimes problematic. In Papua New Guinea, the most problematic for mail, eventually things did get to me--too long in getting to me but they did get to me without fail. Resorting to DHL (then with an out-office in the small city where I was working--Lae--at a state university), it was easy to move things in and out. So I mention this to suggest to you that UPS, FedEx or DHL would be -- as you mention -- not terrible cost effective, but highly dependable and -=- at least here in the US -=- with an automatic US$100 insurance deal wrapped up in the delivery. Based on my experience with the 3a, I'd say the extra cost will be forgotten in minutes after installation and tuning of pots. I'd be especially pleased to hear about your experience with the Hi-Vi Q1 R tweeters and...if you go for it...don't forget the inductor coils. Check with RoyC too; he is immensely helpful.Oh, and if it doesn't work out? Just send those LST dawgs to me Link to comment Share on other sites More sharing options...
Carlspeak Posted January 25, 2009 Author Report Share Posted January 25, 2009 Roy, I see from your post #8 that you have experimented with ribbon tweeter replacements for the 3/4 inch dome. It looks like a Hi-Vi model.I did a Super-Mod last year for a customer using a Fountek Neo CD3 ribbon tweeter which worked out quite well. The impetus behind the choice of a ribbon was the customer's desire to extend the high frequency response into the 'super-tweeter' range well above 20 kHz and, have improved off-axis response over dome types. The link below is to Fountek's information on this tweeter.http://www.fountek.net/products/neocd3.pdfTheir data shows very good horizontal off-axis response but poor vertical off-axis response which, I believe, is typical of ribbon tweeters. The diameter of this one is 4 3/8 inches. I don't remember if I fabricated an adapter plate or not. I searched my test database but couldn't find any of my own off-axis testing. These tweeters are a bit power shy. Fountek recommends a 3rd order xover at 2500 hz. I used a 2nd order at 5 kHz.Prior to getting the Fountek tweeter I initially got a pair of Arum Cantus G2 tweeters. These tested terrible and were subsequently sent back. Link to comment Share on other sites More sharing options...
soundminded Posted January 25, 2009 Report Share Posted January 25, 2009 This may sound like sacrelege but I'd try a 3/8 or 1/2 inch polydome similar to Audax. These are my favorites used in arrays but even if you just try one....They are available in 4 and 8 ohm versions, some have round plates that should easily adapt to the AR cutout. They are fairly efficient. The small diameter and the baffle at the center similar to a Mercedes emblem improves dispersion. They are very cheap and widely available although Parts Express doesn't carry them anymore. Many have 20 to 30 watt capacities and can be crossed over at 5khz. I'd avoid the titanium versions and the low power capacity cloth versions. They usually sell for well under $10 so they aren't much of a gamble. Lots of speaker systems use them. Link to comment Share on other sites More sharing options...
Mexicomike Posted January 25, 2009 Report Share Posted January 25, 2009 We live in Mexico City. The problem is with customs and shipping. Shipping itself isn't horrible, though high but customs imposes a minimum of 30% duty on anything being shipped in. I ordered a computer board from the states when I was new here and dumb. The board cost 39 bucks and was a few inches square, shipping was 25 bucks and DUTY was 40 dollars... I never did that again.Oddly, if you bring something with you on the plane or in the car that is NOT in its original factory box, there is no duty. I brought a new just removed from the box Macintosh 20" IMac in my suitcase on the plane about a year ago and customs didn't even look twice.Re drugs and guns. If you are caught crossing the border/airport into Mexico with any drugs or even a single cartridge for a pistol/rifle, you go directly to jail; you do not pass "Go." You do not collect two hundred dollars!As noted here before, I restored my 3As and my LSTs, per the guidelines posted on the site and with personal assistance of some folks here, primarily John O. I personally believe my LSTs sound marvelous and do not need improvements. However I do accept the fact that, as Roy says, the tweeters (and the mids as well, I assume) may not be performing as they once did. As as often been discussed, this is difficult to determine unless they are clearly damaged or not working because there is no brand new set of LSTs to compare them to. But they throw an absolutely marvelous soundstage and tweeters that do not disperse as well might not be an improvement at all, even if they are capable of better high freq response that the current tweeters. As I said, it would be interesting. Link to comment Share on other sites More sharing options...
dick Posted January 25, 2009 Report Share Posted January 25, 2009 We live in Mexico City. The problem is with customs and shipping. Shipping itself isn't horrible, though high but customs imposes a minimum of 30% duty on anything being shipped in. I ordered a computer board from the states when I was new here and dumb. The board cost 39 bucks and was a few inches square, shipping was 25 bucks and DUTY was 40 dollars... I never did that again.Maybe the deal is to have someone in the US repackage the tweeters for you so that they pass for used, and along with cookies and such, send them on. Has that been tried? --Lived for a year in El D.F., down near UNAM, then another 6 months up on Baja California near Insurgentes. Hear the air has improved somewhat! Link to comment Share on other sites More sharing options...
Mexicomike Posted January 25, 2009 Report Share Posted January 25, 2009 Actually yes, it's been done...last year John O sent me the new caps I needed for the LSTs in that fashion, packaged with a bunch of old, used caps and the customs value stated as 10 bucks and no duty was charged. And now that I'm thinking about it, I'm upset that he didn't send some cookies along! So it might be workable that way. Or...I'm going to be in the US for 6 weeks in late Apr/May. So I could also get the drivers then and bring them back down I guess. But of course I'd have to consider whether to buy 4 or 8! If they actually DID improve the performance of the LSTs, I wouldn't want to have only one of the two speakers modified. UGH, can't believe I used the term "modified" re AR speakers. I am totally against modding them, I've always believed if you want different (not AR) speakers, than BUY different speakers. But I digress...So I'd probably want to get 8 tweeters and if they DON"T sound any better on the first LST, then I have 8 matching paperweights! Link to comment Share on other sites More sharing options...
JKent Posted January 25, 2009 Report Share Posted January 25, 2009 We live in Mexico City. The problem is with customs and shipping. Shipping itself isn't horrible, though high but customs imposes a minimum of 30% duty on anything being shipped in.Somebody remind me--how was NAFTA supposed to benefit us? Link to comment Share on other sites More sharing options...
Guest John Faulkner Posted January 25, 2009 Report Share Posted January 25, 2009 MexicoMikeI will be visiting Mexico City next month. staying at the Red Tree House from Feb.11-15, and again Feb. 19 and 20. If you want, I could "smuggle" 4 or 8 or however many tweeters you want.Are you the same MexicoMike that posts on Tripadvisor?you can email me at dogdrjohn@peoplepc.comJohn Link to comment Share on other sites More sharing options...
Guest John Faulkner Posted January 25, 2009 Report Share Posted January 25, 2009 What inductor coils did you use - wire gauge and value?Did you add any series resistance?thanksjohn Link to comment Share on other sites More sharing options...
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