Glitch

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  1. It looks like the seller is having a hard time putting a price on the speaker (i.e. starting bid, BIN). Am I reading the ad right? Is this for a single speaker?
  2. Now that is something special. It is a shame that the seller isn't offering to ship them. I'm sure there are many people that would want to bid on them that aren't able to make the trip to pick them up locally.
  3. Regarding the that AR9LS auction, I would not consider the final auction price being an indication of the speaker's value. IMHO, it is more a function of supply & demand. "Local pickup" auctions usually kill the opportunity for there to be a reasonable "demand". You need to have at least two serious bidders for an action to be successful from a sellers perspective. I've noticed a big difference in final pricing for shipped versus local pickup auctions. It seems like to only successful local pickup auctions (from a sellers perspective) are reasonably priced but-it-now auctions. Some of the unrealistically high prices can be attributed to "auction fever". This is what every seller hopes to achieve. The good things about this situation is usually both the buyer and seller are happy with the outcome. The seller gets a great price for his item, and the buyer has the satisfaction of winning. Sure, there are cases of "buyers remorse", but these are more the exception than the rule.
  4. GlennW: How can you tell that they are a Motorola piezo versus one of the many low cost piezos that were (and still are) made?
  5. audiofreak: L1590's set the bar pretty high when it comes to listening pleasure. One setup that could arguably "better" the L1590's is a pair of L1290's combined with a nice pair of subwoofers. This would give you the ADS voicing (that I assume you like) and addresses the disadvantage the L1290's have compared to the L1590's for the low frequencies. I paired my L1290's with a pair of Hsu Research ULS-15 MK2 subs. From a budget standpoint, a nice set of L1290's (shipped) would be about $1000-1200 and the ULS-15's would be $1500. I have listened to both combinations in the same room. The L1290/ULS15 combo has the edge on the lowest of the low notes. The upper bass is also a bit punchier. The L1590's have the edge with slightly clearer mids/highs that have a sharper attack. I'd be hard pressed to pick a clear winner between these two combinations. When I did my comparisons, the "better sound" was mostly a function of how the particular piece of music matched to the relative strengths and weaknesses of the speaker combos. Another candidate the comes to mind is the AR-9. There are also the AR-90 and other similar variations thereof. Maybe other can opine here. From the ADS line, I would expect the L980 to be a worth mentioning. I don't have first hand experience with this speaker, but from a driver specification standpoint, it should be pretty competitive. I don't think that anything "lower" in the ADS line would keep up. The L880's bass, while very nice, is a tad boomy and doesn't have the lower reach of the others. A L1090 & musical sub pairing might work, but nice pairs of L1090's are harder to find than L1290's. Speaking of hard to find, it seems like it may take some time to find clean, unabused examples of anything I mentioned above. I can think of other possible combinations, but exactly how they would sound would be too speculative on my part. DavidDru: I like your suggestion of the Aerial Acoustics. Which particular models were you thinking of? It seems like the 6T or 7T might be a similar enough to considered. However, I can't recall ever seeing these for sale used. They would have to be "used" to meet the budget constraints. Do you know the used market price for these? I've seen 10T's that are in the right price range, but they seem to be a different animal.
  6. Juan, For a resto-mod, I would try to selectively restore the crossover as an original AR3a improved. Based on the schematic in JKent’s post, L1, R1, & C1 make the low pass filter for the woofer. Using the stock values would be a safe start. This will give you the crossover frequency that the AR engineers felt was acceptable for the woofer. The rest of the circuit gets more complicated. I would leave the switch out of the circuit and hard wire the circuit equivalent to the switch position shown. C2+C3 & L3 set the high pass frequency for the midrange. The stock values for these will give you a reasonable match to the woofer low pass circuit. L2 and C4 set the low pass for the midrange. These may be OK for whatever midrange you end up using or might not work at all. You will need to check the driver spec sheet to know for sure. C5 & L4 set the high pass for the tweeter. As with the midrange, these values may or may not work with whatever tweeter you pick. I believe that this is what Roy has been trying to warn you about. The other resistors in the circuit may not be needed. What is more likely is different resistor values would be required to level match the various drivers. If you pick the right set of midrange and tweeters, the crossover design could be fairly straightforward. This is why I was suggesting that you use an existing DIY design as a start. These designs typically use very forgiving drivers that work with simple crossovers. You may not get the results of a more expensive setup, but it should be very listenable. The hard part (maybe very hard) is finding a design with drivers that fit the existing holes. Have you decided which direction that you want to take the project (i.e. restoration, resto-mod, or something in between)? Glitch
  7. Roy: Of course there "is much more to speaker design". Perhaps, my statement would have been better stated as the woofer/cabinet matching as the hardest part of "speaker building" instead of "speaker design". For many people, soldering together crossover components is much easier than building a suitable cabinet from scratch. Starting with a well-designed and matched woofer combination goes a long way. Combining this with a properly sealed cabinet and the right amount of fiberglass stuffing, and one would be pretty much guaranteed good bass response. The mid/highs are trickier. There are many ways to tackle this problem. There are many modern, solid 3-way DIY designs that could be used as a starting point. One could use the high/mid crossover design from DIY setup. The low/mid crossover design from the AR could be used as a starting point. This crossover frequency is designed for the woofers in question and has the added benefit to be at a low enough frequency where the crossover design is relatively forgiving. It would be fairly easy to pick mids/tweeters that are more efficient that the original/missing AR parts. The final speaker voicing for the mid/high could be dialed back using L-pads or adding resistors. JKent: You make a excellent point about verifying that the woofers are good. It would be prudent to take this step regardless of whether the goal is a full restoration or a resto-mod. Juan: If you decide to go the resto-mod route, be sure to buy a sealed back midrange. It might also be worth sending an email to the fine folks at Parts Express to see if they could make specific driver recommendations. It sounds like you have reasonable expectations about what you will end up if you pursue the project. I'm quite confident that whatever you do, you will end up with a set of speakers that sound much better than what you currently have. Anyone: Can you comment on the chances for success of sourcing used, 50 year old AR drivers? My experience with vintage parts is that it can be difficult to find two drivers that match. It is ever harder to find two drivers that match AND are close to the original performance specifications. From what I've read, some AR mids/tweeters are experiencing the ravages of time. How much consideration should be given to this when planning a restoration? As a side comment: I think that it is a great accomplishment to restore a pair of vintage speakers to their original aesthetics and performance. This is not an easy thing to do.
  8. Juan, A full restoration might very well be expensive, but unless you have your heart set on originality, you have other options. You already have the most expensive parts of a speaker with the woofers and cabinets. You also already have the most expensive part of the crossovers, the inductors. I don't know your budget, but there are many "modern" components that you could substitute for the missing pieces and have a nice set of speakers. It might be worth asking the same questions in a DIY speaker building forum before you take a saw to the cabinets. I've built several pairs of speakers based on old woofers and cabinets with Chinese made tweeters. You can get very good value for your money with careful shopping. For instance, digging around a "popular auction site" can yield you a set of dirt cheap foam surrounds from China. The only drawbacks are that the shipping time is long and the woofers aren't original (but more original than the woofers being in a trash can). Your could order the other parts you need from a discount speaker parts website. Stick with non-polar electrolytic capacitors and low cost, highly rated (based on customer feedback) drivers. You may be pleasantly surprised about how good a $15 tweeter can sound. For the cabinets, some wood filler and black paint can make most anything look presentable. Pick a grill cloth that is in line with your taste, install this neatly, and nobody will ever know about the other choices you made or how expertly you did the other work. The hardest part of the speaker design, properly matching the cabinet size to the woofer characteristics, is already done for you. Set the mid/woofer crossover value to something close to the original. Set the mid/tweeter crossover value to something close to whatever the driver manufacturers recommends. This project could be a lot of fun (if you like doing this kind of stuff). Glitch
  9. I forgot to add a few more things... It would make sense that you would have no bass if the PA-1's were installed with the speaker switch in the full range position, The low frequencies from the amp would be routed to the woofer terminals that are disconnected in that switch position. The higher frequencies from the amp would be routed to the all of the drivers from the full-range terminals. Between the active crossovers in the amps and the passive crossovers in the speakers, no low frequency sound would make it to the woofers. I would get your setup working and let it run for a while before trying the resistor modifications. This way, in the unlikely event that something dies early on, you won't be wondering if it was something that you did while making the mods. Glitch
  10. Mark, You can "test" your amps by hooking the outputs to a known working set of speakers. Hook up one speaker to the mid/tweeter output of the amp and the the other speaker to the low output (i.e. one amp, two speakers). You should get full range, mono sound out of this unconventional setup. You could also test your speakers with a known good amp. Set the switch to the bi-amp mode and hook the left channel to the lows and right channel to the mid/high input. In the bi-amp mode, the low inputs are connected directly to the woofers. The mid/tweeters are still protected by the crossovers from low frequencies. Regardless of this, I would keep the amplifier volumes low to reduce the risk of burning out a driver. The attached picture shows the location of the "second" piggyback resistor (upper right of photo). I would recommend that you configure the resistors to match the speakers if you are comfortable with soldering. This is a fairly easy modification to make since resistors are relatively tolerant of too much heat being applied. I've run all four combinations of matched and mismatched setups. None of them sound awful (but why have a suboptimal setup?). Glitch
  11. For reference, here is a picture of the "piggybacked" resistor on the input board with one lead disconnected...
  12. I have a couple of pairs of PA-1's as well as L1290's and L1590's. Hopefully I can help you get your system working. 1) Did you change the "biamp" switch in the back of the L1590s to the "biamp" position? This is the lower switch in the back of the speaker behind the cover (and below the fuses if you have fuses). The switch needs to be set to the left with the PA-1's. You should get a full range of sound regardless of how the L1290/L1590 resistors are set internally to the amp. FYI, the upper switch sets the tweeter level to -0dB (right) or -1.5dB (left). 2) There are at least two versions of the PA-1's. One version needs to needs to change one resistor to configure for L1290/L1590 and the other need to change two resistors. There should be a diagram on the back of the PA-1 cover that indicates which one you have. The common resistor location is on the input board. This in in the bottom of the amp. The resistor is on the lower right-hand side of the board. There will be two resistors soldered in a piggyback fashion (one lead may or may not be connected). The second resistor (if you have that model) is on the main amp board. This is also easy to find since it also has the piggybacked resistor. 3) I believe that the resistors just change the amps crossover frequency to match passive crossover in the speaker. Depending on the mismatch, it either won't make any difference (the crossovers overlap) or you will have a small "hole" near the mid-woofer crossover frequency. A schematic for the PA-1 can be downloaded for free here. http://www.vintageshifi.com/repertoire-pdf/Braun.php The caveat is the manual is in German. There is also a on-line website that the sells an English version of the manual. I don't recall the name of the place but can look it up later if you would like. Glitch
  13. stupidhead, Personally, I wouldn't get too hung up on trying to save the existing veneer, especially if the primary reason is to save the interesting grain. There are many sources for buying beautiful and highly unusual walnut veneer. The sky (and your checkbook) is the limit. A complete re-veneer also opens up the possibility of changing wood species. If you like unusual and breathtaking, there are many, many options. I would be concerned that the marks from where panels were glued on will show through the finial finish. There will likely be marks/flaws from where you patched the veneer and to a lesser extent the nail holes. I don't know what your goals are. If your primary goal is originality, then you are heading down the right track. Of course, you could always complete the speakers the per your current plan and see if you are happy with the results. Re-veneering is always an option. Glitch
  14. Tom, Yes, I did spend some time comparing the L1590s and L1290s. I found the speakers to be very similar in the overlapping frequency bands. For this comparison, I used a Crown pro amp and used the built-in DSP to filter off the lower frequencies (where the L1590s have a clear advantage). This allowed me to more easily evaluate the mid, tweeter and crossover performance. I found overall tonality/voicing of the speakers to be remarkably consistent. I think the biggest difference between the two models is in the "attack" of sharp sounds like a hard snare hit. For these kinds of sounds, the L1590s seem not only faster, but also better damped. Both models exhibit the celebrated ADS sparkle. Both speakers reached highs that are beyond my hearing range. I didn’t notice any difference in the lower mid-range at the mid-woofer crossover frequency. I replaced the L1290s in my main system with the L1590s. I put them in the same location. The overall imaging was slightly better with the L1590s. I found the need to use an acoustic panel with the L1290s to tame some upper mid-range harshness. The L1590s also benefited similarly from the panel at the same location. I believe this confirms my theory that the problem lies in the room geometry and speaker placement. Unfortunately, my speaker placement is more governed by WAF than acoustic optimization. The most dramatic difference between the speakers is in the lower frequencies. The L1290s simply don’t go as low. I used a pair of subwoofers with the L1290s to extend the ultra-low frequencies. I was very happy with how well this worked. I am using the same subs with the L1590s. I had a much harder time integrating the subs with the L1590s. The subs ended up in a very different configuration than with the L1290s. I could live without the subs with the L1590s. I moved the L1290s into my basement workshop and added them to what we affectionately call “The Pile”. The Pile contains many of the speakers that I’m working on. They are all connected to a speaker switch where I can run A-B comparisons as I’m tweaking things. I decided to rework the mids and tweeters in the L1290s. I recently did the same to a pair of L880s and a set of spare mids and tweeters that I had on hand. I replaced the ferrofluid and realigned the voice coils. I performed measurements on all of these drivers and used the data to create matched pairs. Matching the drivers greatly improved the imaging of both the L1290s and L880s. Both of these speakers are Series 2 and use the same mids and tweeters. I’m still doing experiments on these where I’m varying the ferrofluid viscosity. The jury is still out on which combination I prefer the most. The experiments are a slow process. I hope to have this nailed down by summertime. I think that I have been able to improve the “attack” of the L1290s to be more like the L1590s with the tweaks. I suspect that the L1290s may now outperform the L1590s in imaging performance. I won’t really know how successful the changes were until I move the L1290s back upstairs and do direct A-B comparisons. I recently picked up a pair of PA1 amps. One of the amps was dead when I bought it. I was able to repair the broken one and went through both amps to ensure that everything is working well. I have the PA1s installed in the L1290s now. Glitch
  15. It is hard to say if rebuilding is necessary. I can say that the drivers (mids/tweets) that I rebuilt are measurably different. However, almost all of the differences are in the lower frequency of the driver, well below the crossover cutoff frequency. Aside from the quantitative measurements, I also did some qualitative A-B testing using a speaker switch. In general, the tonality of the speakers didn't change. The measurements appear to correlate to the listening tests. I used the Ferrotech ferrofluid from PE. This fluid is noticeably thinner that the ferrofluid that I removed. What I don't know is if the ADS ferrofluid is supposed to be more viscous than the Ferrotech ferrofluid. One could make the argument that the original fluid was thicker because it "evaporated" over the years. An equally plausible argument is that the fluid start off thicker and hasn't changed. I'd love to be able to pick the brain of some of the engineers that designed the drivers. Does anyone know what ferrofluid Richard So uses when he rebuilds the drivers? Does he use Ferrotech or does he have a supply of the original fluid? I'm still on the fence on whether it could "hurt" or not. If the drivers "need" the original ferrofluid (and the original ferrofluid is not available), yes, it could hurt. The place that it is most likely to "hurt" is marking up the cabinets trying to remove the drivers. There is also the possibility of not getting the voice coils properly centered. The ADS drivers do not have a positive indexing system between the cone/coil and the magnet. I found the alignment to be extremely sensitive (i.e. time consuming to get right). If this part of the job is done carelessly, the driver performance will be diminished.