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Dchristie

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  1. Libertus, in the model 5, the woofer has a natural acoustic rolloff at 2000 hz( no additional crossover components are needed) . The woofer rolls off by itself at the crossover point and is wired directly to the amp. The tweeter crossover is very similar to the model 6. A 1.0 mh mh coil is shunted across the positive (+) and ground (-) inputs and a 4.0 uf cap is in series with the positive input which provides a 2nd order cutoff for the tweeter at all times. There is also a 10 ohm, 5 watt resistor shunted across the tweeter terminals. These components are always active in the crossover circuit. A 3 ohm, 5 watt resistor in series with the positive input and A 10 ohm, 5 watt resistor shunted across the + and - inputs of the tweeter, are switch operated to provide an increase and decrease in the tweeter output, respectively.
  2. Could possibly have different versions of the Marantz Imperial 6 speaker. But the version I am familiar with here in the USA is as described in the above forum discussion. The schematic from the Marantz 6 service manual is attached for your information. Imperial6_crossover_schematic.pdf
  3. In the Imperial 6, 6B, and 6G speakers, the 0.6 mh coil is shunted across the positive (+) and ground (-) inputs and the 7.0 uf cap is in series with the positive input which provides a 2nd order cutoff for the tweeter at all times. These components are always active in the crossover circuit along with a 3 ohm, 5 watt resistor in series with the positive input. An 8 ohm resistor is also shunted across the + and - inputs of the tweeter. The 1 ohm and 6 ohm resistors are switch operated to provide an increase and decrease in the tweeter output, respectively. The normal position on the switch takes the 1 and 6 ohm resistors out of the circuit. All of the rest of the components remain active in the crossover at all times.
  4. I am looking for bass drivers (25 F-EW) for the Dynaco A25 XL or A40 XL series speakers. I have a pair of original 25 TV-EW drivers for the A25/35 speakers that I would trade if so desired or I am willing to purchase F-EW drivers as well. Please send a PM if anyone can help me out. Thanks, Dean
  5. Found a pair of M1 speakers so disregard my WTB request. Thanks Dean
  6. I recently bought a pair of AR M1 holographic speakers and unfortunately, one of the bass drivers is bad so I am looking to purchase a replacement driver. If anyone has one that they are willing to part with , please send me a personal message. I would buy one, or a pair or possibly even 2 complete M1 speakers if necessary. Thanks Dean
  7. Just reread my response above and realized that I referred to the AR 3 with "the phenolic tweeter " a couple of times which is obvious since I think that all of the AR 3 versions may have had the phenolic tweeter in common. What I meant to say was phenolic midrange since this was the topic of concern. Probably most folks understood the intent but I wanted to clarify just in case.
  8. Hi Cropper, as Roy has pointed out in other discussions , a late model AR 3 with the factory approved later cloth midrange and the appropriate crossover mod is still an AR 3 speaker but it may not sound identical the the AR 3 speaker with the phenolic tweeter. However, this is always subjective but it stands to reason that the changes could be audible to some listeners. Personally, my AR 3 speakers with the cloth mid sound very good to me but I have not directly compared them to the earlier model with the phenolic tweeter. But, they are still an AR 3 sold as an AR 3 by AR so I am not as worried about the cloth mid so much. Probably the bigger issue with reselling AR vintage speakers is whether for not they are original as replacing crossovers, refinishing cabinets , and so forth often are issues with buyers who want everything to be original. Once again, I restore my speakers with new crossover components, cabinet restorations and other changes to meet my approval and not necessarily to keep them original. I do not believe that the later cloth mid necessarily made the late production AR 3 inferior to the original as this would once again be subjective to the listener but certainly AR was not concerned as the evolution of the AR 3 to the AR3a was never considered a step back . My AR 3s do sound different compared to my AR 3a speakers but I enjoy both. I am sure you will also like the sound of your restored AR3s. Sometimes we get concerned about issues which seem to be really important to the final sound but in reality, contribute less to the final sound than a lot of things that we have no control over since the adhesives, compliance, and other physical characteristics of these decade old drivers have changed since they were new. However, it is amazing that they still work and also still provide a lot of satisfaction to those of us that like to fool around with them. I am sure others have their own opinions and may chime in as well, but I try to not take this hobby too seriously and just enjoy the whole vintage audio experience. Just my 2 cents worth!
  9. Thanks Chris. Any chance you would be willing to just remove one of the mids from your AR 3a speaker and replace it for one of the phenolic mids in one of the new AR3 speakers ( with the correct xover mod of course) and then you could compare a single AR3 with the modified cloth dome to your other AR 3 speaker with the original phenolic dome mid. Although you would only be comparing essentially mono AR 3 speakers with different mids, it would most likely give you some idea what the AR3 speaker with the cloth dome sounds like in comparison to the AR 3 speaker with the phenolic dome mid . Just an idea. Dean
  10. Hi Chris, now that you actually have a working original phenolic 3 dome midrange, it would be great if you could compare it with the 3a midrange dome for sonic comparisons. I have been very impressed with the cloth 1.5 dome and actually have it in my pair of 3s ( with the crossover mod) since I have not had the luck of finding an original, properly working phenolic mid. Would be great to get your impressions of the 2 different midranges and how they do or do not affect the final sound of a 3 speaker. If no negative difference is detected , then using a more durable, modified, 3a cloth mid in a 3 speaker might be a good thing in the long run IMO . Thanks Dean
  11. Hi Fran, as Roy stated above, even the front wired 1.5 dome mids may have the leads reversed with respect to the left or right side of the faceplate. Since the mids handle lower frequencies compared to the tweeters, the movement of the dome is much more noticeable ( especially with the metal grill removed). I have found this to be occasionally true with the very early midranges , and in my case, only one of the mids in the pair was reversed. Since Roy has dealt with many more mids ( and tweeters) he may have a better feel for how commonly this lead reversal occurs . Although It is not easy, it is possible to see the dome move with the battery test . I position the midrange driver so that a bright light source reflects off the dome surface where it can be observed between the damping material attached to the metal screen ( usually the best place to see the dome is near it's base ) . The dome surface is somewhat shiny and any imperfections on the surface of the dome can provide a point of reference for the light reflection. I usually also use reading magnifying glasses to help see the movement . Although not dramatic, applying the 1.5 volts to each of the leads does show the reflected area of the dome move up or down as per the + or - characteristic of the respective leads. Dean
  12. And not to confuse (hopefully) the issue further, but all of the Chris 1 REBUILT AR 3a tweeters that I have received from Chris ( 4 pairs to date) have had the positive lead of the tweeter on the RIGHT side of the tweeter faceplate (when viewed straight on) which would then NOT require the leads to be crossed under the tape when resoldered back to the middle tabs on the cabinet front. Chris has the ability to place the leads wherever he sees fit when he does his rebuilds and usually places the + lead on the right side. As Roy has stated above, the key is to make sure the + leads from both the mids and the tweeters are always soldered to the tabs where the yellow wires are attached from the xover. (I have also had one each of both pairs of the mids on my AR 3a and AR 5's crossed under the tape as well). And as Chris has also stated above , the most prudent thing to do to verify which lead is + or - is to do a battery test and confirm the dome moves up (when the positive lead is attached to + battery terminal and negative lead is attached to the - battery terminal) or down if the leads to the battery terminals are reversed. Although not always easy to see on old, original tweeters due to their stiffened suspensions, it is easy to see movement on Chris's rebuilds and can often even be seen on original tweeters with the help of some magnification. Dean
  13. Also wondering about the square cutouts for the Altec drivers. I am not very familiar with the AR-1 speaker, but I have never seen square cutouts behind the Altecs before. Almost looks like the cabinets are open as there appears to be damping material showing behind the drivers in the cutout corners. Does not look quite right to me, but again, I am not that familiar with all of the model changes for the AR-1speaker.
  14. Hi Tom, just touching base with you to see if you might know of a potential source for some AR 3a midrange domes. I need a couple for my AR 3a speakers . Also , along the same lines, I have a pair of AR 5 domes that were trashed ( they were shipped minus the protective screens). I have managed to get them working again but am now in need of the protective screens. So, if you would happen to know where I might get a couple of these screens (from dead AR 3a or AR 5 midranges or ?) I would be very grateful.

    Thanks for whatever assistance you can provide.

    Dean

  15. Thanks Pete. Yes, I have revision 2 (later Original Large Advent crossovers) as per your baselaudiolab info. Dean
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