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Glitch

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  1. I'm afraid it has happened?

    It has been some time since I did the phenolic tweeter comparisons. My recollection of the RT-6 is that it didn't do anything particularly bad. However, it didn't do anything remarkably good. I recall that it didn't seem to reach the higher frequencies as well as the PRT-8. Nor did it provide the classic CTS phenolic tweeter sound signature as well. My basic assumption is that the reason that people are buying the reproduction phenolics is that they are trying to reproduce the sound signature of a particular classic speaker. The PRT-8 also seemed to be built better with heavier metal for the basket and a bigger magnet. I liked the integrated grill of the RT-6 since this mimics the style of the drivers I was trying to replace. Unfortunately, the sound quality wasn't what I was looking for. I ended up buying a used pair of vintage/original CTS phenolics to complete the project.
  2. I'm afraid it has happened?

    I bought a pair of the GRS PRT-8 mentioned above as part of a restoration project of a 70's era pair of speakers. One of the speakers had the factory original CTS tweeter. The other had a slightly different CTS tweeter that was replaced under warranty. There was enough of a mismatch between the two tweeters to motivate me to replace them with a new "matched pair". Unfortunately, I was not happy with the sound quality of the PRT-8. The original CTS phenolics tended to be a bit squawky. The PRT-8 is much more so. I found the PRT-8 to be harsher than every other of the vintage/original phenolic tweeters that I own. I can see why the PRT-8 gets good reviews. It is certainly a good match visually. It also exhibits the sonic character that most people associate with the original CTS phenolic (perhaps to a fault). I might have been happy with the PRT-8 if I had not done A/B testing against the originals. I also tried the RT-6 phenolic that PE sells. The PRT-8 is a better driver than the RT-6.
  3. A/D/S/ L1590

    Setting up a listening comparison between those two speakers would be a real treat. I have neither, so it could be a long while until I have the opportunity. Based on my experience with the L1590, L1290 and L880, I would think that you would be able to A/B your 3a's and L1290's and get a very good feel for how they stack up. The tricky part of the experiment might be getting the room setup right since each of those speakers would have a fairly different "ideal" spot in the room. I'm guessing that you already thought of this and is one of the reasons why you suggested the 3a to L980 comparison. (i.e. both would benefit from a similar setup position, etc.). The Stereophile Magazine article was a trip down memory lane. To me, it seems "right" that there weren't any ADS offerings on the list. I've never thought of ADS as one of those companies that was targeting the stereotypical audiophile personality. Sure, there were other companies on the list that are arguably similar in this regard. IMHO, there products were more revolutionary than anything ADS did. As big of an ADS fan as I am, I don't feel slighted at all by the list. Here are some relevant part numbers (from the ADS parts list) L880: tweeter 206-0117, mid 206-0211, woofer 206-0346 L880/2: tweeter 206-0117, mid 206-0215, woofer 206-0357 L1290: tweeter 206-0117, mid 206-0211, woofer 206-0349 L1290/2: tweeter 206-0117, mid 206-0215, woofer 206-0359 or 206-0360 L980: tweeter 206-0118, mid 206-0212, woofer 206-0347 L980/2: tweeter 206-0118, mid 206-0214, woofer 206-0353 L1590: tweeter 206-0119, mid 206-0213, woofer 206-0350 L1590/2: tweeter 206-0118, mid 206-0214, woofer 206-0361 I'm a bit surprised that drivers pattern on the L980/L1590 doesn't follow the same pattern as the L880/L1290. I wonder if the L980 was introduced "late" relative to the L1590? (i.e I expected that it, L980/1, would have a 206-0119 tweeter & 206-0213 mid)
  4. A/D/S/ L1590

    The L1590 has different tweeters, mids and woofers than the L1290. I assume that each one of the components in the L1590 is rated for more power, but can't find any data right now to back up my theory. I'm sure that I have data from the L1290 and L880 drivers somewhere on my computer. Unfortunately, I'm pretty thorough at testing and analyzing data, but usually not very good at documenting the results. If I found the data, it might not be clear what I actually tested. It all may be a moot point since I tested individual drivers from the L1290 and L880, but didn't disassemble the L1590 for individual driver testing. My comparisons between the L1290 and L1590 were done with the speakers side by side connected to a speaker selector switch. In the past, I've tried to run quantitative comparisons of overall speaker performance, but never obtained results that I thought I could trust. I typically end up doing qualitative evaluations (which may be too subjective to be useful to anyone else). I recall reading somewhere that the L1590 mids and tweeters had stronger magnets than the L1290. However, I can't recall where I read that. I've only experienced one ADS driver with a ferrofluid issue. The best way I can describe it is that the fluid "crusted over". The fluid under the crust seemed fine. I originally repaired the driver by cleaning out all of the dried fluid "chunks" and running the driver with the remaining fluid. I've since completely replaced the fluid (several times) in the course of my various experiments. I believe that improvements in imaging in my L1290 (and L880) were more from using matched driver pairs than anything else. I'd love to be able to repeat the driver matching experiment on the L1590s, but I don't have a suitable pool of spare parts to make it happen. Unfortunately, no. There are only a couple of ADS speakers that are on my watch list and the L980 is one of them.
  5. “ AR-LST, after Forty Six Years of Use”

    I'm a bit confused by the discussion of blown tweeters in Frank's LST's. I don't recall him saying that his current tweeters weren't working. Did I miss something? There was a comment about needing to make cabinet modifications to try back wired tweeters. Wouldn't the connections to the back wired tweeters be made inside the cabinet? Frank: I forgot that you have three pairs of LST's. If this was my project, I would pick the "worst" pair and experiment on them. This way you could try your modifications, do the A/B testing, and track your progress without taking down your main system. I concur with the others that suggested that you try to make the modifications in such a way that everything is reversible. There are many really good suggestions about how you should proceed. You have lots of options. In the end, you'll have to decide for yourself if the modifications are an improvement. Unfortunately, the very nature of sound perception makes it impossible for somebody else to predict what you'll interpret as an improvement in sound quality.
  6. “ AR-LST, after Forty Six Years of Use”

    xmas111: I believe that you are correct about the schematic. With one blown tweeter, the others will still function, but with an unequal sound output. The total impedance of the remaining three drivers would be 1.5 times that of a single driver.
  7. “ AR-LST, after Forty Six Years of Use”

    This sounds like a fun project. You seem to have some specific goals in mind. This is great since it is hard to plan a route or get directions if you don't know your final destination. Having two pairs of speakers puts you in a unique position to fully evaluate the effects of the modifications. Do you have the ability to do A/B testing? If not, you may want to establish a methodology before you start. I suggest that you A/B the speakers before you make any modifications to establish a baseline. You are in great shape if the speakers start out sounding the same. You could then make one modification at a time and then evaluate the change (or no change) in the sound. You have lots of options on how to proceed. You could modify the speakers in pairs or one at a time. You could evaluate each change cumulatively against the baseline or evaluate the changes in a leapfrog fashion. Having a plan in place on how to proceed should increase your odds of meeting your goals. I'm mentioning this since you seem to be pretty happy with your starting point. I'd hate to hear that you strayed too far away from it and couldn't get back. Do you have capacitance/ESR meter? If not, you might want to purchase one so you can better understand the changes that you are making. For example, if you like the way a particular crossover sounds with aged or "well broken-in caps" you may want to try replacements with the actual aged values versus the original values. You might want to do something like this if you wanted to retain the overall voicing, but improve the imaging by having the left/right pairs better matched (assuming that the caps left/right aged to different values). I wish you the best of luck with this project and am looking forward to reading about the progress.
  8. Woofer repair

    Nice job on the repair. Be sure to re-glue the repaired wires to the cone or else the vibration from normal use will cause them to break again.
  9. Could one use a MiniDSP programmed to match the frequency curve of the AR speaker? It seems the dynamic response would be different (i.e. impossible to match), but the general voicing character might be close enough to be believable.
  10. ADS 1290 - have drivers updated? Driving me insane!

    edit: removed double post
  11. ADS 1290 - have drivers updated? Driving me insane!

    I have also perceived occasional "harshness" from my ADS speakers. I attribute this more to the recording than the speaker. I have a pair of L1290/2 and L880/2 (which use the same tweeter) as well as a pair of L1590/2. All of these exhibit similar behavior. I've removed the drivers from the L1290 & L880 and tested them for consistency. I've also ran the same tests on my matching "spare" tweeters. All of them were fairly consistent. I've also experimented with various ferrofluid replacement with the same tweeters. I was able to make subtle changes to the driver's performance. I doubt that "I" would have been able to tell the difference if I wasn't able to A/B the changes as I was making them. Where I usually notice the harshness is with relatively modern alternative rock where distortion is (intentionally) incorporated as part of the music. One band that come to mind is Bleachers. This music sounds horrible on the ADS's. It is much easier to listen to on other speakers that I own. I can't really comment on the sonic performance for the Richard So rebuilds. I'm really curious if anyone has ever tested their drivers before and after sending them to Richard. I've asked this in the past but never got any replies. One thing that I have noticed about the rebuilds is that they sometimes come back looking like they have cataracts. I don't know if this is how they really look in person or is an anomaly from flash photography. That said, I don't recall ever reading about anyone being unhappy with a Richard So rebuild. I would expect that the failure mode for these tweeters would be from the ferrofluid degrading. My experience with ferrofluid (from non ADS speakers) is that it becomes more viscous and the driver starts to sound dull. I suppose that if it dried up completely, the driver would be underdamped and this could cause harshness. You could check the ferrofluid by removing the top plate from the tweeter. The downside to this is you would need to realign the voice coil when you put it back together. Also, you would likely leave witness marks in the paint by the mounting screws. I guess how you proceed depends on how much the "distortion" bugs you.
  12. AR 3a's in the house...outstanding pair.

    What is wrong with me? I'm looking at the pictures and contemplating how nice those shipping cartons are.
  13. ADS L520

    Swapping woofers would tell you what you need to know. The woofers may (or may not) be difficult to remove from the cabinets. As a first step, you could disconnect one wire from the woofer (between the woofer and crossover) and repeat the "receiver test" again connecting directly to the woofer. This will eliminate the crossover from the test and saves the work of removing the woofer. Another possibility for debugging is to swap crossovers. All of the "all uppercase" era ADS speakers (i.e. ADS versus aDs or a/d/s) that I own use spade connectors to connect to the drivers. I'm a bit surprised by your comment about the connections being soldered. However, you never really know what you will find inside of a vintage speaker. Soldering is pretty easy and a worthwhile skill to have. Please post some pictures of what you have. It will make it easier for people to provide advice. As I said in my first reply, I haven't worked on that particular model. I'm making some guesses about what you have based on experience with other ADS speakers.
  14. ADS L520

    An ADS document lists the woofer part number as 206-0326 for speaker serial numbers 0 to 10199. For serial numbers 10200 and up, the part number is 206-0323. This seems odd since one would expect the "higher" number to be used in the newer speakers. Have you done any debugging to verify that the woofer is the actual problem? For example, check with a multimeter or swap woofers between speakers.
  15. ADS L520

    Congratulations on your purchase! I learned something new about the wood patterned vinyl finish on the early L520s. ADS also used a simulated wood finish on the L470s, even into the metal grill era. It sounds like you scored on the records. Some kinds of vinyl are better than others. I'd be interested in hearing your impressions (and seeing more pictures) once you get settled in with the speakers.
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