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RoyC

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  1. AR 5's: The bargain AR

    The difference in dcr between the 3a and 5 tweeter and mid drivers is approximately 2.5 ohms. AR-3a mids and tweeters are easily adapted to the AR-5 with inexpensive resistors placed in line with each. Increasing the AR-5's tweeter capacitor from 4uf to 6uf allows the AR-3a tweeter to be used in the 5 as is, without the need for the series resistor. In fact, Chris' rebuild of an AR-5/later 2ax tweeter with the 3a tweeter's voice coil would also work well in this way. The body and the magnet of the tweeters (and mids) are the same. Roy
  2. I'm afraid it has happened?

    Fortunately we know the coil and cap values AR used with their later tweeters in various models, which can serve as starting points. For example, the AR-3a Limited crossover used the AR-11/9 type of tweeter with a 4uf cap and .16mh coil, along with 8 ohm L-pads. That is a valid starting point, beyond which (motivation and resource dependent) tweaking and response measurements could be conducted. Keep in mind, knowledge of how crossover components affect response is extremely helpful and saves lots of time. Roy
  3. HiVi q1r install

    These tweaks are pretty subtle and basically fall into the category of preference. If using original pots, the original 6uf cap is a good starting point. If using the L-pads (without parallel resistor) lower values between 3uf and 5uf may be preferable, as L-pads result in more output. The variable condition of the original tweeter makes it difficult to know which values actually produce a "technically correct" response...and the addition of the parallel coil brings optimal polarity into the mix as well. I prefer the .05mh coil, 5uf cap, L-pads/no resistor, and like-polarity. If more tweeter output is desired, increase the cap value a bit and/or reverse the polarity. If less tweeter output is desired, decrease the cap value a bit. Personal preferences and listening space variables easily supersede these tweaks, and the level controls can compensate for minor differences. I've always felt the HiVi tweeter/coil arrangement puts it in the ballpark of the original sound, but there is room for small adjustments as desired. Those who prefer the very reticent nature of the original tweeter may be more likely to prefer a 3uf cap value, achieved by placing a 6uf cap in series with the original crossover's 6uf cap as described above by Kent. This method makes it easier to go back to the original value if desired. Although it is prudent to place a spacer between the coil and the back of the HiVi tweeter, it's not critical. The Q1R magnet is shielded and any effect is tiny. (Larry/"Vintage AR" does not use a spacer.) Roy
  4. Need help for AR-12 refurbish

    Agreed, Jeff. Subsequent to my 2012 post I found SpeakerWorks.com to have a good AR-12 replacement, as well as other hard to find items...excellent retailer. http://www.speakerworks.com/speaker_repair_kits_s/65.htm Roy
  5. I'm afraid it has happened?

    rl1856, This new tweeter is for all practical purposes an AR-11 tweeter, which is not, and never was, an electrical "drop-in" replacement for an AR-3a style tweeter. AR modified the crossover by the addition of a small series capacitor when the AR-11 tweeter was used as a replacement for the earlier tweeter, and changed the crossover when it was used as the AR-3a Limited tweeter. My point above is that I presently find it too expensive to experiment with when there are already satisfactory solutions for the AR-3a type of tweeter. If anyone here has the $150 for a pair to experiment with for this purpose, I'm sure we would all be interested in the results. My educated guess is it will probably need a parallel coil of around .1mh to work in a similar fashion to the earlier tweeters in models like the 3a, etc. On the other hand, I played around with it enough to believe it is an excellent candidate as a drop-in replacement for any model originally equipped with the AR-11 or AR-9 type of tweeter. Jeff, I meant "roll off" in the other direction, as this tweeter and the AR-11 tweeter have much more midrange response than the 3a type tweeter. The solution for the AR-11 tweeter, as implemented in the AR-11 speaker, is a .1 parallel coil in the crossover. It is also the purpose of the .05 coil for the HiVi tweeter when used in the AR-3a. Roy
  6. WTB: KLH model fives

    I have a nice pair available, but I'm in NY. I sent you a message. Roy
  7. I'm afraid it has happened?

    Agreed, Kent...That was largely Larry's perspective. My perspective is that it is too expensive to experiment with for use in early speakers when Chris' rebuilds and much less costly HiVi tweeters are available. On the other hand, I'm convinced there has never been a better post-AR general replacement tweeter for models from the AR-11 onward. For these models the MW tweeter may be as close to a "drop-in" replacement as we are ever likely to see. Roy
  8. I'm afraid it has happened?

    No...the tweeter is back in Larry's shop. The off-axis numbers are primarily a function of dome construction and position. I'm willing to bet the off-axis response is at least as good as the AR-11 tweeter, as these tweeters are virtually identical. In fact, the AR-9 tweeter dome is identical as well, with the exception of its (deliberately) recessed position to minimize off-axis response. (One reason the HiVi tweeter does fairly well as an early AR tweeter replacement is its semi-exposed dome.) I'm sure there are differences, but of all concerns regarding the integration of the MW tweeter, off-axis response will easily be the least critical. After discussing the tweeter with Larry today he said he will continue to sell only the HiVi tweeter as a replacement for early AR models, and he seems to have a large inventory of original AR-11 and AR-9 tweeters for later models. We agreed the greatest drawback to the MW tweeter at this point is cost. Roy
  9. I'm afraid it has happened?

    The photo is of one cabinet (serial number C19973) of a pair of 3's I acquired from an estate. The speakers were in their original AR shipping boxes which are labeled as "teak". The solid wood front trim pieces do look like oak. Roy
  10. I'm afraid it has happened?

    ra.ra and ar_pro, I completely agree with your comments, guys...though I'm personally curious as to what the leads look like under the covering. My motto seems to have evolved into "if it ain't broke, break it". Aadams, As mentioned above, I have no measurements. It is best to think of it as an AR-11 tweeter, which is more than adequate for the AR-3a...but like the AR-11, AR-9 series, HiVi, and any other tweeter of modern construction, the MW tweeter's response will require a crossover modification to properly integrate with early models (3, 3a, 5, 2a/2ax, LST, and LST-2). No tweeter of modern construction has the natural roll off characteristics of the early AR dome tweeters. Compared to the others, the MW tweeter's primary positive attributes are likely to be its appearance, ease of installation, and as a good general replacement for later models. Roy
  11. I'm afraid it has happened?

    I finally had a chance to examine the new AR replacement tweeter sold by Midwest Speaker Repair. Larry/Vintage AR provided the Midwest tweeter and an original (black dome) AR-11 tweeter, and I had an AR-9 tweeter on hand for comparison. The construction of the new tweeter is very impressive, and at least as good as the original AR tweeters. The integrated faceplate/magnet cup is the same as the AR tweeters, but it is made of aluminum vs the plastic of the originals. A convenient feature vs either original tweeter are the recessed, gold plated terminals, making it a simple drop-in fit for any AR dome tweeter cabinet hole from the AR-3 (see photo below) through the AR-9x series into the 80's. The new tweeter is otherwise physically identical to the black dome AR-11/10pi/12 tweeter. Other observations: -DCR of the two AR tweeters measured 3.3 ohms vs 3.7 ohms for the Midwest tweeter. (The MW tweeter is also available in an 8 ohm version.) -The cloth domes of all three tweeters appear to be identical, including the dome shaped piece of hard material just underneath each dome (based on past dissections, this material is wood in the AR tweeters). The AR 9 series tweeter dome is recessed in the faceplate, but is otherwise identical. -All tweeters weigh 1.5 lbs+/-. Magnet size is identical. -No measurement equipment was used, but the new tweeter subjectively has very similar tonal qualities to that of both original tweeters. It is, however, slightly more sensitive. -I quickly dropped the tweeter into an AR-3a and believe a larger parallel coil than the .05mh coil used with the HiVi tweeter will be needed to properly integrate it...but it sounds very promising. One downside is the front covering of the new tweeter would have to be cut to access the leads for front-wiring. -It may serve as a very easy tweeter replacement for the AR-11, 10pi, 12 (8 ohm version), and AR-9x series models with no crossover adjustments (for most people) when satisfactory originals are not available. -The Midwest tweeter is head and shoulders above any AR 3/4" general replacement tweeter I have seen since the very early 90's when AB Tech ran out of Tonegen-made replacements, and in my opinion, it is worthy of experimentation in many models. Between the HiVi Q1R, Chris' (chris1this1) early tweeter restorations, and the Midwest tweeters, we have never had better options for as many AR models. Attached are photos of the new tweeter next to an AR-11 tweeter, as well as one showing its perfect fit in an AR-3 cabinet hole. Roy
  12. I found two of 'em, Kent. I'll put one in the mail tomorrow. Roy
  13. Polarity determination

    Your 2ax's do jive with other accounts I've heard about, so I'm sure they are OK, Dean. The two mids I measured were in a box of parts, and very well could be the exception. In retrospect, given the similarities, they could have been from earlier AR models equipped with the fiberglass covered cone driver. It is also entirely possible folks drawing 2ax schematics just assumed the yellow dot represented the positive side of the driver. Though it would be interesting to know for sure, I honestly don't see it as a problem. In my opinion routinely prying the grills off the mids as part of a 2ax restoration is unnecessary and potentially damaging. AR conveniently placed a yellow dot where the yellow wire should go. Roy
  14. Polarity determination

    I would be much more concerned if the mids were wired differently or opposite of each other. Despite variations in voice coil installation and labeling of drivers (usually early woofers), it is very rare to find an improperly wired AR speaker. I believe the best rule of thumb is to stay with the original wiring (yellow wire to yellow dot, as found in your specimens), and not to overthink it. Another thought...Given the variable state of the original tweeters, it could be interesting to experiment with the mids' polarity, and simply going with what sounds best. Roy
  15. Crossover Potentiometers revisited

    To clarify a bit: - 15 watt 8 ohm L-pads purchased from Vintage AR, Parts Express, or Madisound are the same. Shaft lengths vary, but they are otherwise identical. The "8 ohm" designation of the L-pad does not mean the same thing as the "15 or 16 ohm" designation of the potentiometer, so disregard this spec. Vintage AR removes the "8 ohm" stamp from the back of his controls to avoid confusion. -Adding the 25 ohm parallel resistor makes the L-pad electrically the same as the original pot for most of the rotation (off maximum). It lowers parallel resistance to that of the pot at the most often used settings. -The additional 25 ohm parallel resistor is often of limited benefit when used with original 3a/2ax type tweeters, and more output can be achieved from degraded tweeters without it (though the crossover point is lowered and power handling is reduced). I strongly recommend its use, however, with the midrange L-pad. The level control circuit's power handling and the mid's crossover point are adversely affected without it. The mid's response will not be as smooth as it should be. Roy
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