Deang Posted July 28, 2002 Share Posted July 28, 2002 I should have posted this here to begin with -- but the 2 Channel forum is where I live. What a completely frustrating experience it is trying to find exact matches for the resitor values that are on my DQ-10 schematic. I went to all the sources posted in the "sources" thread and then some. There is plenty to choose from in the low wattage arena, but as you climb up in wattage -- the selection shrinks down considerably. I also have the problem of finding the same type of resistor. The resistors found in the crossovers are the bar type resistors (sand or cement I can not tell for sure). The most trouble has been the 5.5 ohm 7.5 watter. I found a 5.6 ohm 7 watter. 30 ohm 5 watts, and 33 ohm 5 watts -- I found 27 and 30.9. These are Mills non-inductive wire-wound resistors, instead of the bar types actually used in the crossover. What troubles me is the thought that "close" may not be close enough. How about just a 4 ohm type. Jeepers, one would think these would be everywhere. I needed this in a 15 watter. After 45 minutes, I managed to find a 3.9 ohm. Much of this same type of thing seems to apply to the capacitors as well. I initially was going to buy the cap upgrade kit from Regnar for the DQ's, but thought I might save some money and get slightly better parts as well -- if I found them on my own. This isn't working out exactly as I planned. Good parts cost good money. The Solens and Wondercaps look like good values -- everything else is pretty much ridiculous. How about $56 for one 80uF Hovland? I've been mindful of Mdeneens statement regarding many "audiophile" parts just being repackaged generic goods. However, if there is a Solen generic cap -- I sure can't find it. I have to admit that this is quite a bit of fun. Sort of like working on a jig-saw puzzle with some of the pieces missing. Quote Link to comment Share on other sites More sharing options...
STL Posted July 30, 2002 Share Posted July 30, 2002 Just use multiple resistors/caps to get the value you need. Remember resistor values add when they are put in series, and cap values add when placed in parallel. BTW, neither subtract when doing the opposite. Quote Link to comment Share on other sites More sharing options...
kfalls Posted September 13, 2002 Share Posted September 13, 2002 I'm not surprised about your frustration precision caps and resistors can be a pain to find. As long as you're going the precision route, let me confuse you even more. There are different tolerences as well, 1%, 5% and 10%. This may, or may not be a bad thing. Lets say you are looking for a 1K ohm resistor. If the engineer specified a resistor with a 10% tolerence, your replacement can be between 900 ohms and 1.1K ohm. However, the bad news is precision resistors and caps have a much lower tolerence (1%) which narrows your range quite a bit. I believe the "sand or cement" material you're talking about is actually ceramic used because of it's ability to withstand and dissipate heat. As long as you keep to the specified wattage, it doesn't matter which type you use (wire-wound, carbon, or ceramic, the problem you may run into is they are not usually the same size for the same wattage which may be a problem if your circuit board has limited space. I'm surprised you have problems with the 33 ohm resistor since this is a standard resistor value. As the above poster stated, you can parallel and series resistors and capacitors to get the value you need. For resistors the formulas to calculate resistance are r1 + r2 + r3 (series) and (r1 X r2 X r3) / (r1 + r2 + r3) (parallel). For capacitance it's just the opposite c1 + c2 + c3 (parallel). The important thing to consider with capacitance is to ensure you equal or exceed the "working voltage" of the capacitor usually listed as "35V WDC" or 35 working volts DC. Hope this helps. Quote Link to comment Share on other sites More sharing options...
edwardre Posted September 16, 2002 Share Posted September 16, 2002 Fiddlesticks!!! I thought caps were the SAME as resistors. Additive in series, 'averaged' in parallel. Oooops! So....I needed a 7500pF. I paralleled a 10000 and a 5000. So now I have double what I need? This is on my pre-amp. Part of the left channel tone control circuitry on my PAS2. Funny thing is that it sounds the same as the right channel, for which I have the correct 7.5uF cap! I should probably get right on 'de-parallel-ing' them and then 'series-ing'. So, with this in mind, would it be better to use 1 7500pf in one channel and the combo in the other, or since they're out of 7500's, should I 'combo' both channels to more or less 'mirror'? They are all the same type caps. Thanks. ------------------ Ed Quote Link to comment Share on other sites More sharing options...
edwardre Posted September 16, 2002 Share Posted September 16, 2002 Ooops again. Guess my basic electronics is waaaay rusty. Can't series them, doesn't come out to 7500pf. Guess it's back to the parts bin...... ------------------ Ed Quote Link to comment Share on other sites More sharing options...
STL Posted September 16, 2002 Share Posted September 16, 2002 I would go ahead and 'combo' both channels since these parts are so cheap. ------------------ ----------------------- Mitsubishi 55807 HDTV RCA DTC-100 DirecTV & OTA HDTV Receiver Panasonic RP-56 Progressive Scan DVD Panasonic PV-V4620 VHS Sony CDP-545 CD Sony STR-DA333ES A/V Receiver KG5.5s (mains) built-in TV speaker (center - TEMPORARY) Infinity SM-165 (rears - TEMPORARY) COMING SOON... KG4.2 (center) -- needs new enclosure KG3.5s (rears) -- needs new enclosure Quote Link to comment Share on other sites More sharing options...
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