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kryten79

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  1. Your approach with parallel resistors makes sense in terms of power handling. For these little 2ax, I won't chase down the power handling specs for the drivers. Ultimately it is the current going to the driver that matters, too much for too long and the VC overheats, too large or too rapid transients and excursions can damage the driver. My going from a single 10 to a 12 watt resistor won't greatly affect how hard I can push these. Upon further review, using two 50 Ohm resistors in parallel to get my 25 Ohm target could provide some tweeter protection by splitting the current so either resistor could blow, hopefully before the VC, if I don't change the resistor wattage much, assuming the two resistors are effectively equal. I accept that smaller caps can be made with lower, more controlled (tighter?) ESR values so using two small to replace one large cap can result in a faster, smoother response. As we all know, ESR is temperature and frequency dependent because their inductive aspect gives them s charge-discharge time constant (which varies with frequency). We're trying to get good sound (however that is defined) from 20Hz to 20kHz in imperfect environments. Some days we play our music quietly and other days we turn the big knob. My thought from reading a bunch of threads and experience is the designers took ESR into account to create a particular sound under a set of chosen conditions and I may not be able to improve on what they did and the L-pads and room acoustics will have more of an effect than a small change in ESR. I don't know the original ESR values the designers chose but having a faster circuit should lead to a smoother output for the tweeter and maybe the mid, so thanks for the comment, @DavidR You have given me yet another thing to consider ? Oil, Film, Poly, non-polarized electrolytic; wound versus sandcast versus ........ Life is good
  2. I appreciate the responses and the level of thought. I did not find the cap fantasists quote thread anywhere but located a few others which address capacitor selection. I really wasn't trying to start yet another thread on caps. I was more curious whether boutique poly/film caps were worth it or more appropriate in the 2ax. As we all know, the engineers 40 years ago made their component choices based on what was available at the time. Obviously ESR values and recovery or transient time were important then as they still are now. Quoting from RoyC in http://www.classicspeakerpages.net/IP.Board/index.php?/topic/9863-ar-2ax-project/page/3/ "if you prefer purchasing from one source the capacitors can also be purchased from Parts Express: https://www.parts-express.com/dayton-audio-dmpc-40-40uf-250v-polypropylene-capacitor--027-421 https://www.parts-express.com/dayton-audio-dmpc-62-62uf-250v-polypropylene-capacitor--027-427 Before the geek squad weighs in, the 2ax level controls more than compensate for any differences in ESR of the caps, and the difference between a 5% tolerance 6uf cap and 6.2 cap for this application is insignificant. Electrolytic capacitors of the appropriate values can also be used." It is clear from the thread that he did not eliminate other brands from consideration: In fact, in http://www.classicspeakerpages.net/IP.Board/index.php?/topic/10570-ar-3a-capacitor-advice/, RoyC says "I've used Dayton film (as well as Parts Express NPE) capacitors in hundreds of repairs and restorations. They, as well as the Clarity caps, all work very well as replacements for old worn out capacitors." "... If your original AR-3a capacitors are "Sprague" brand, you probably do not need to replace them at all. Let the silly capacitor games begin..." Later he states "The OP wanted to know if the expense of film capacitors was worth the expense versus non-polar electrolytic capacitors in a pair of AR-3a's. With regard to sound, the simple answer is no. " Yeah, I agree with that response, pretty much what I suspected when I asked my question here. Other threads I viewed include .http://www.classicspeakerpages.net/IP.Board/index.php?/topic/953-speaker-voicing-and-capacitor-types-used/ http://www.classicspeakerpages.net/IP.Board/index.php?/topic/9788-capacitors-redux/ http://www.classicspeakerpages.net/IP.Board/index.php?/topic/9223-all-things-speaker-resistor-questions-and-answers/ RoyC addresses the resistor question (it depends) in the last link as well "I'm increasingly becoming an advocate of using npe's to replace npe's when the goal is to retain "original" performance. (Ken Kantor posted this view rather emphatically some time ago in another forum.)" I have a couple other projects ahead of the 2ax speakers but I will pull the grills and drivers and take a look at the crossovers to see what is there before placing the order. I'm leaning towards the shopping list I posted originally, Dayton NPEs, and maybe resistors after measuring what is installed. I can't justify spending the money on Sonicaps for these. (That hurt me to admit it, seeing as how I haven't heard a pair of ARs in ages). I can always go back in later as suggested if I hear something I don't expect or "like". I'm not sure other comments suggesting that using two or three caps in parallel to make up one big value is better or more accurate. Tolerances now are amazing. I had not considered putting resistors in series to increase power handling. Seems like a risk for a pair of 2ax. This wouldn't seem to protect the drivers at all. I have big speakers when I want to shake, rattle and roll.
  3. I was excited to buy my first pair of ARs from Salvation Army quite awhile back. I have Klipsch and Pioneer HPMs and can't remember the last pair of ARs I heard so these went into the queue to be resurrected. I have not even played them nor removed the grills but it is obvious they have not been molested and the cabinets are in good shape. I restore with originality in mind. When I (rarely) sell, I do not try to get the last dollar out of a buyer. It's more important to me to save items from being parted out or sent to the dump. I took advantage of a snowy day to do my research at AudioKarma and here, initially searching the L-pad problem, I found much more to bookmark. Y'all are incredible, by the way. In the recent thread "Options in restoring AR-2ax" , the Parts Express shopping list came out as: 2 x Dayton Audio DNR-25 25 Ohm 10W Precision Audio Grade Resistor 2 x Dayton Audio PMPC-6.2 6.2uF 250V Precision Audio Capacitor 2 x Dayton Audio PMPC-4.0 4.0uF 250V Precision Audio Capacitor 2 x Parts Express Speaker L-Pad Attenuator 15W Mono 3/8" Shaft 8 Ohm In the PE shopping cart, the capacitors and resistors total $21. If I price out the same at Sonic Craft, choosing 12W Vishay Mills and 200V Gen1 Sonicaps, my cart is at $83 !!! I typically will choose Mills and Sonicaps (and have Sonic Craft L1 or L2 match them) for floor standers with a 3 or 4 way crossover. I figure if the value of the speakers restored is over $400 or so, I may as well use the best I know about. They're not too huge and the reviews say the caps are neutral and consistent and the values and ESR are accurate. So ..... I'm leaning towards the lower cost option. My initial reasoning is I don't know if the crossover requires more "accurate", for lack of a better term, components; whether I will love the sound and keep them, or their value if I do choose to sell. I will leave the items in the two shopping carts for a bit while I think about it and wait for you to add your $0.02. Opinions on these manufacturers or others anyone? What is your reasoning? I'll refill my cup while the discussion warms up. ?
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