ar_pro Posted February 27, 2018 Report Share Posted February 27, 2018 David - I've heard AR-9 systems that included combinations of original, factory-replacement, and the Japanese Tonegen woofers, and never noticed a problem - the bass extension was always there, and clean as could be. Were the 8" lower-mids factory replacements as well? I've never, ever encountered a bad lower-midrange, and this makes me wonder how - short of vandalism - all of these drivers were damaged! Quote Link to comment Share on other sites More sharing options...
harry398 Posted February 28, 2018 Report Share Posted February 28, 2018 4 hours ago, DavidR said: I finally recovered from the flu and took some time to pull all the drivers from the 9's and record the part numbers and voice coil DCR (below). (FYI: I always label/choose a left and right speaker when restoring). All the drivers except one tweeter had replacement stickers on the magnet (WTF?). Since three of the woofers are late production models will I loose bass? Or can I expect them to perform as if all drivers were the originals? I guess the original owner got some stuff replaced under warranty? What is your plan on surrounds....ie type and which seller? what will you do for dust caps? what differences are there in the 8 inch 20027 and the AR18 woofer? I see NO reason for any difference in BASS output with those drivers......pictures always are nice of course. Quote Link to comment Share on other sites More sharing options...
DavidR Posted February 28, 2018 Author Report Share Posted February 28, 2018 Good to know about the woofers. I was ready to give up. The square magnet LMR is like an original but has the replacement sticker. The round magnet is way more modern and has the modern AR symbol. Most likely a Tonegen driver. Both have the AR replacement sticker. The round magnet/more modern still has the original surround with the bead of rubber around the edge. I think the original owner may be the reason for blown drivers. All of the screws holding the drivers were loose and he was playing both the 10pi and 9's with one amp and hitting them hard. I also think he used them outdoors a lot. Quote Link to comment Share on other sites More sharing options...
DavidR Posted February 28, 2018 Author Report Share Posted February 28, 2018 2 hours ago, harry398 said: What is your plan on surrounds....ie type and which seller? All surrounds are good. The LMR with the round magnet is original and won't last long. Will use the BA filleted foam from Rick Cobb 2 hours ago, harry398 said: what differences are there in the 8 inch 20027 and the AR18 woofer? Square magnet vs round magnet. Both have the AR 20027 (and 20027-0) label. Quote Link to comment Share on other sites More sharing options...
DavidR Posted March 3, 2018 Author Report Share Posted March 3, 2018 I'm starting to make an order list of caps and resistors for the 10Pi speakers. I'm going to use all NPE caps and the only one that is an issue finding is the 20uF. I can get 18uF and 22uF but NOT 20uF. This cap appears to be a woofer shunt cap that can be added, via an attenuation switch, to the 100uF cap. I'm not sure at what switch position the 20uF comes into play. I want to run the woofers in the 4TT position. > Does anyone know if the 20uF is in the circuit when 4TT is selected AND will the 22uF be OK to use? > Also, what is the 10 ohm resistor doing to the xover circuit where they put it across (parallel) the cap leads of the 2500uF cap? Quote Link to comment Share on other sites More sharing options...
DavidR Posted March 8, 2018 Author Report Share Posted March 8, 2018 I spoke with a buddy that has an electrical back ground so I guess I'll answer my own questions. On 3/3/2018 at 1:39 PM, DavidR said: > Does anyone know if the 20uF is in the circuit when 4TT is selected ? The 20uF capacitor is open circuit (not in use) when the woofer switch is in the 4TT position. But is in parallel with the 100uF in the other 2 positions. On 3/3/2018 at 1:39 PM, DavidR said: > Also, what is the 10 ohm resistor doing to the xover circuit where they put it across (parallel) the cap leads of the 2500uF cap? It is lowering the cap resistance. Just like when you put (2) 10 ohm resistors in parallel you get 5 ohms and when you put (2) 10 ohm resistors in series you get 20 ohms. On 3/3/2018 at 1:39 PM, DavidR said: > Will a 22uF be OK to use in place of the 20uF cap? It's at the top end of the 10% tolerance and probably would be OK but I'll see if they have any that measure low. Quote Link to comment Share on other sites More sharing options...
fedeleluigi Posted March 8, 2018 Report Share Posted March 8, 2018 15 hours ago, DavidR said: On 3/3/2018 at 7:39 PM, DavidR said: > Also, what is the 10 ohm resistor doing to the xover circuit where they put it across (parallel) the cap leads of the 2500uF cap? It is lowering the cap resistance. Just like when you put (2) 10 ohm resistors in parallel you get 5 ohms and when you put (2) 10 ohm resistors in series you get 20 ohms. The 2500 uF cap and the 10 Ohm resistor carry out a protective role against the inductive load caused by the presence of an autotransformer in the 10 Pi crossover network. Moreover, the 10 Ohm resistor, the 2500 uF cap and the autotransformer inductance constitute a special type of RCL network with a specific Resonance Frequency and Q factor. The resistor is important to determing both the Q factor and the Resonance Frequency of this particular type of RLC circuit. The Q factor can greatly affect the speaker bass response. You can examine the mathematics at the attached links (exersice 8 with solution). Pay attention that Q Factor, Resonance Frequency and Voltage drop through the capacitor also depend on R (R2 in the example) value. Unfortunately it is in Italian. Excercise n.8: https://it.m.wikibooks.org/wiki/Esercizi_di_fisica_con_soluzioni/Correnti_alternate solutionhttps://it.m.wikibooks.org/wiki/Esercizi_di_fisica_con_soluzioni/Correnti_alternate#8._Circuito_risonante_con_2_R_2 Also In English you can observe how the R affects the Resonance Frequency of this type of RLC circuit at fig.5 of this link: https://en.wikipedia.org/wiki/RLC_circuit Luigi Quote Link to comment Share on other sites More sharing options...
fedeleluigi Posted March 8, 2018 Report Share Posted March 8, 2018 A parallel R and C circuit in series with a loudspeaker load can also be used with pro amps in order to protect them from very inductive loads. As an example, you can look at this link:https://adn.harmanpro.com/site_elements/resources/1010_1425481978/Macro-Tech-Series-600-1200-2400-Reference-Manual-130252_original.pdfthat's the Crown Macro-Tech amplifier manual. Please look at fig 3.14 at page 17. Even though the Macro-Tech amplifier were very stable amps into reactive loads, they can have problems with very inductive loads such as those caused by the presence of an autotransformer. Anyway, although the RC circuit shown in the fig. 3.14 will probably not give a flat frequency responce in the lowest frequencies (especially with a low impedance loudspeakers ) it will effectively protect the amp from most of dangerous inductive loads. Quote Link to comment Share on other sites More sharing options...
DavidR Posted March 8, 2018 Author Report Share Posted March 8, 2018 Lost power. Had a bad storm - heavy wet snow. Lots of trees, limbs and power lines down. Stealing a bit of power from the generator that is running essentials. Will be back once power is restored. Could be days they say. Quote Link to comment Share on other sites More sharing options...
Stimpy Posted March 8, 2018 Report Share Posted March 8, 2018 Wow. Crazy March weather. Be safe my friend. Quote Link to comment Share on other sites More sharing options...
DavidR Posted March 9, 2018 Author Report Share Posted March 9, 2018 Quote Link to comment Share on other sites More sharing options...
ar_pro Posted March 9, 2018 Report Share Posted March 9, 2018 Stinks. We lost power for 24 hours in last week's nor'easter, but kept it through this one. It did make for about 6 hours' worth of shoveling, though. Good luck! Quote Link to comment Share on other sites More sharing options...
ra.ra Posted March 9, 2018 Report Share Posted March 9, 2018 David, sorry to hear about your power outage. I'm located a bit closer to city center and was just saying earlier today how thankful I was that we've retained power in these parts. Those were two hellish storms in the space of one week. 8 hours ago, DavidR said: ....a bit of power from the generator.... Sounds like the time to rely on low wattage amps. Quote Link to comment Share on other sites More sharing options...
fedeleluigi Posted March 9, 2018 Report Share Posted March 9, 2018 12 hours ago, DavidR said: Will be back once power is restored. Could be days they say David, I'm sorry for the the snow storm and power outage. Hope they are "pessimistic" and you can have power again in a short while. Luigi Quote Link to comment Share on other sites More sharing options...
DavidR Posted March 10, 2018 Author Report Share Posted March 10, 2018 On 3/8/2018 at 11:24 PM, ra.ra said: David, sorry to hear about your power outage. I'm located a bit closer to city center and was just saying earlier today how thankful I was that we've retained power in these parts. Those were two hellish storms in the space of one week. Sounds like the time to rely on low wattage amps. My wife and I want to relocate and are now only looking at houses in areas that have all underground utilities and no big trees near the house. We will also have a Generac whole house generator. I'd never run an amp off of a generator. Dirty power and tend to run at high voltage - 130v to 150v. Quote Link to comment Share on other sites More sharing options...
DavidR Posted March 10, 2018 Author Report Share Posted March 10, 2018 On 3/9/2018 at 3:09 AM, fedeleluigi said: David, I'm sorry for the the snow storm and power outage. Hope they are "pessimistic" and you can have power again in a short while. Luigi 5:15 am today ! Quote Link to comment Share on other sites More sharing options...
DavidR Posted June 25, 2018 Author Report Share Posted June 25, 2018 I finally began to work on the xovers in my 10Pi speakers and it didn't take long before I ran into an issue. Attached is a picture of the xovers and the 100uF has a black and red wire on the same terminal. WTF? This red wire comes from the terminal board and goes over to the cap and then the transformer. I've looked at some diagrams people have posted and it does show a blue wire. Do you think they just used the wrong color? Quote Link to comment Share on other sites More sharing options...
DavidR Posted June 25, 2018 Author Report Share Posted June 25, 2018 I got the 2500uF unsoldered and measured it with my Agilent U1733C at 100 and 120Hz. It will not measure that size at a higher (i.e. 1kHz and above) frequency. OLD 2500: 2465 @ 100Hz; 2462 @ 120Hz NEW 2500 bundle: the 3 caps measured at 1kHz added up equal 2417uF and measure 2429 @ 100Hz; 2426 @120Hz. Based on this data the old 2500uF is still good. Should I use the new ones or go with the old one? Quote Link to comment Share on other sites More sharing options...
DavidR Posted June 26, 2018 Author Report Share Posted June 26, 2018 Never mind. I pulled the 2500uF cap from the other speaker and it measured over 2840uF. Moot point now. Both are being replaced by a bundle of large Bennic caps. Quote Link to comment Share on other sites More sharing options...
Stimpy Posted June 26, 2018 Report Share Posted June 26, 2018 I didn't realize that Callins made the large can capacitors too. I only noticed the red/black Callins caps for whatever reason? Not surprised then that they test out. I'm glad you're replacing them. Quote Link to comment Share on other sites More sharing options...
DavidR Posted June 26, 2018 Author Report Share Posted June 26, 2018 Stimpy, There's a pic above of the xover. I'll hold onto the one that tested OK and when I get to the 9's I'll see how those measure. Maybe I will find one good and one bad there too. I have no idea how good or bad the Bennics are compared to a Callins. Very hard to work on the 10Pi. Lots of wires and little room between points on the terminal strip. My eye sight is poor and that doesn't help. One step at a time right now. Got the 15 ohm resistor replaced and waiting for the goop to harden. Will solder it tomorrow and then on to the 40uF cap. Quote Link to comment Share on other sites More sharing options...
DavidR Posted June 29, 2018 Author Report Share Posted June 29, 2018 Got one done - FINALLY! I finally got around to the 10Pi speakers. I had to get some other things done that have been on the bench. One was a box I made for my phono cartridges. The AR10Pi xovers were difficult because of limited space and a LOT of wires. I had to do it in steps as I use goop to hold down the caps and resistors. So it was glue one or two pieces and come back tomorrow to wire and solder. I guess I got the wiring correct as it WORKS!!! The reason for the piece of blue tape at the end of that red wire in the center is because its supposed to be blue according to the schematic. I noticed that the 100 and 2500uF can caps had a PLUS (+) mark at one of the two terminals. As they are NPE caps I was wondering if this indicates either the inner or outer foil? Some of the screws were rusty so I picked up some stainless steel screws AND they were a bit cheaper than (a few pennies less) than the black oxide. Now it's off to do the second speaker. Oh, and they got new 5-way binding posts. Quote Link to comment Share on other sites More sharing options...
stupidhead Posted June 29, 2018 Report Share Posted June 29, 2018 good looking box David. I have my eyes out for a set of these. look forward to hearing your listening impressions. Quote Link to comment Share on other sites More sharing options...
DavidR Posted June 29, 2018 Author Report Share Posted June 29, 2018 Thanks. So far the bass is GREAT! When I'm done I'll post old and new cap and resistor readings. Quote Link to comment Share on other sites More sharing options...
ar_pro Posted June 29, 2018 Report Share Posted June 29, 2018 Very neat job of bundling the caps & resistors - interested in your comparison against the AR-91. Nice cartridge cubby, too! Quote Link to comment Share on other sites More sharing options...
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