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Beltway

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  1. Great info on the potential replacements for the original tweeter. While I may be headed in that direction eventually, it seems that my original drivers are all still running strong. I installed 15.7 ohm Mills resistors in parallel for the tweet and mid, with a 1/2 ohm in series for the mid in one speaker so far. A/B comparisons with the un-modded speaker suggest that the mids have opened up considerably with the elimination of the pot. Even at full-on position the pot seems to be choking the sound. Not really attenuating it, but just keeping it from sounding its best. I suspect the wiper/coil energy transfer in the pot isn't the best under ideal conditions, and 40 years hasn't done much to improve it. Then again, I am new to all this and could be totally wrong. Regardless, the modded speaker sounds fantastic to my ears and I can't wait to do the other. Anyway, thanks to all for the great information!
  2. Thank you VERY much, Roy, for that clear explanation. It sounds like my best bet is to insert 15 ohms of resistance in parallel for the tweeter, as I really do not want to stress it by lowering the crossover. With that done, do you think I'm ok going back to the .5 ohm resistor in series and 15 ohm in parallel for the mid? With the tweet crossover point set back to normal, I'd think lowering the attenuation in the mid from 2.5 to .5 would be best. FWIW, the .5 ohm reading was found by measuring the existing pot just shy of full-on. Thanks again!
  3. Ooops. I said the exact wrong thing re: the resistors. 15 ohm across from pos. to neg. .5 ohm parallel with pos. to attenuate mid frequencies a tad. Again, thanks in advance for your input.
  4. Thanks very much for your replies, Carl and Roy. I understand your point re: the "mods and tweaks" forum, but there has been so much discussion about caps and pots on this forum I feel it isn't totally out of place to continue. If the moderators feel otherwise I won't object, but there is so much more traffic here I'd prefer it stay here. Most importantly, I am only trying to get these speakers to sound as close to original as possible. I love their sound, but don't need to adjust the levels via pots or lpads so would like to eliminate them. I use a computer playing lossless music files with an outboard DAC as my source and can digitally tweak the levels all I want. Anywho, I'm a bit confused by Roy's post. Why do I need a resistor or l-pad for the tweet? Won't running it straight from the capacitor give me maximum high frequency boost? Am I putting the tweets in danger by not having a resistor? They sound great to my ears at this point, but I don't want to damage anything. As for the mid, I wanted to set the level permanently at a point just shy of full-on. my thought was to shunt only about .5 ohm. That is, I'd use: (20ohm)(68ohm) or (120ohm)(18ohm) to positive terminal, both values soldered together in parallel to equal 15.5 ohms. AND (.5ohm) (to negative) That should bring me to a point very close to the "sweet spot" on the mid pots. I think. Right? Thanks again for the help!! Cheers.
  5. Ok. Further research has yielded the following impressions: The phenolic tweet does not have the dispersion or efficiency of the later 3/4" unit and is thus not so deeply loved. It does, however, have excellent transient response and seems to be more resistant to deterioration. While both tweets are suspended with urethane foam, the butyl coating on the older may help slow down decay. The two ways it most commonly fails is in the separation of the aluminum voice coil and by "popping" the dome due to the pressure of the compacted fiberglass dampening material. Barring that, it is pretty hard to hurt these units. Please correct me if I am wrong. I can honestly say that they sound fantastic to my ears. Perhaps a bit rolled off, but that seems to be the price one pays for fatigue-free listening. I haven't been able to find solid answers to my other questions re: pot elimination. Any input would be most appreciated, even if it is simply pointing me in the direction of a post that already covered my question. I'm still searching the archives. Thanks again for any help y'all can offer. Cheers.
  6. Greetings all. I recently picked up a pair of first gen. 2ax's (alnico magnet/linen surround woofer and dark red phenolic tweet) in beautiful condition. Many thanks to all the contributors on this site for (inadvertently) helping me select which model to get, as I am very pleased with the sound. After reading MANY posts on this and other sites, I felt confident enough to perform a minor recondition by recapping with Daytons and working on the pots. I am using somewhat modern but mellow gear (AES AE3 tube pre/Bedini 150/150 mkII amp) and love the laid back, lush sound. As I move forward with the never-ending quest for improvement, I have a few questions: When I recapped, I also eliminated the tweet pots. No resistor was installed to attenuate the high frequencies; the tweets are running wide open. It sounds great, but I'd like to hear what the experts think about it. I don't need to adjust the mid level and have been thinking about eliminating those pots as well. My plan would be to install Miller resistors in place of the pots, shunting about 1/2 an ohm to approximate the "sweet spot". Any thoughts on this? I'm a noob when it comes to this stuff, so any input is welcome. I love the sound, but definitely see why people don't think these are great rock speakers. They simply refuse to be rude! We mostly listen to acoustic/vocals, so no big worry, but listening to rock for the first time made me wonder if the tweeters had degraded over time. Are the old phenolic tweets subject to degradation? If so, can anything be done to help them out? Thanks very much for your input! Cheers.
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