mark kirchner Posted November 29, 2015 Report Share Posted November 29, 2015 (edited) -35 dB ATTENUATION CABLE This project came directly from Jay Rose’s book Producing Great Sound for Film and Video, 3rd edition. On pages 179 to 181 Jay explains what resistors to use and diagrams three different circuits. I chose to make the “balanced output to balanced input” as a cable instead of building it into a XLRm to XLRf barrel. This attenuating circuit uses (4) – 301 Ohms 1/4 watt 1% film resistor and (1) – 15 Ohm 1/4 watt 1% film resistor. The challenge for me was figuring out how to get all 5 resistors soldered in the correct circuit design and still fit into a xlr connector. I have included 5 photographs that I made as I progressed, they uploaded out of order, tried to put them in order, no luck, I hope they are understandable. Thank you Jay for all your books. 1. Resistor "web" 2. Finished (side view) 3. Finished (end view) 4. Connecting to pin 2 and pin 3 5. 15 Ohm Resistor has the green band Edited November 30, 2015 by mark kirchner the photographs uploaded out of order, made new file names. Hope this will help. Quote Link to comment Share on other sites More sharing options...
Mirror Posted November 30, 2015 Report Share Posted November 30, 2015 Great! Thanks for the write-up and pics. Having tried to cram just one resister into an XLR was a challenge for me so my hats off to you for shoehorning 5 into an impossibly small space. Oh, and how did you get the shrink wrap on after you made the resistor web? Some of my great soldering challenges is to not shrink the wrap from the soldering iron heat while soldering before the wrap is in place. You might have to read that last sentence a few times to unwrap it's meaning. Quote Link to comment Share on other sites More sharing options...
mark kirchner Posted November 30, 2015 Author Report Share Posted November 30, 2015 Mirror, The heat shrink tubing was a larger diameter than I normally use. I did have to plan carefully and I reheated the tubing and pushed while it was soft. I understand your last sentence. I have had the same challenge. Quote Link to comment Share on other sites More sharing options...
Jack Norflus Posted November 30, 2015 Report Share Posted November 30, 2015 Some of my great soldering challenges is to not shrink the wrap from the soldering iron heat while soldering before the wrap is in place. I have the same issue. Quote Link to comment Share on other sites More sharing options...
Rick Reineke Posted November 30, 2015 Report Share Posted November 30, 2015 On some attenuation (and other type of ) cables I've made, I'll split the components between female and male connectors. "Some of my great soldering challenges is to not shrink the wrap from the soldering iron heat" - Same here, I often use a heat sink if there's enough room BTW, real nice CU photos Mark. Quote Link to comment Share on other sites More sharing options...
Jim Gilchrist Posted November 30, 2015 Report Share Posted November 30, 2015 (edited) I've had success by building out in the open and then after testing to be sure the pad is working as intended potting the whole mess thing with silicone. Hard to repair, but so's any pad. Best regards, Jim Edited November 30, 2015 by Jim Gilchrist Quote Link to comment Share on other sites More sharing options...
soundtrane Posted November 30, 2015 Report Share Posted November 30, 2015 I have the same issue. That's the time for teflon... Quote Link to comment Share on other sites More sharing options...
Mirror Posted November 30, 2015 Report Share Posted November 30, 2015 I've had success by building out in the open and then after testing to be sure the pad is working as intended potting the whole mess thing with silicone. Hard to repair, but so's any pad. Best regards, Jim I was just thinking about that the other day and was wondering what the down side would be (besides repairs). Quote Link to comment Share on other sites More sharing options...
Jim Gilchrist Posted November 30, 2015 Report Share Posted November 30, 2015 I was just thinking about that the other day and was wondering what the down side would be (besides repairs). Biggest downside is the silicone itself. Gloves are required and it can be hard to clean up. Other than that, it's nonconductive, goes where you put it and stays there. Stays on my clothes and in my beard no matter how careful I am. Quote Link to comment Share on other sites More sharing options...
CraigF Posted December 1, 2015 Report Share Posted December 1, 2015 hot glue work as well, heat gun to melt it off Quote Link to comment Share on other sites More sharing options...
mark kirchner Posted December 1, 2015 Author Report Share Posted December 1, 2015 Thanks for the idea of using silicone or hot glue. This is the second pad I made and more compact than the first. I also like Rick's idea about splitting up the resistors on both male and female XLRs. Thanks Rick, Jim, Vin and Craig for your ideas. Quote Link to comment Share on other sites More sharing options...
Jack Norflus Posted December 1, 2015 Report Share Posted December 1, 2015 That's the time for teflon... can you elaborate? Quote Link to comment Share on other sites More sharing options...
soundtrane Posted December 1, 2015 Report Share Posted December 1, 2015 can you elaborate? teflon tube, it does not shrink, but also does not get affected by heat. Quote Link to comment Share on other sites More sharing options...
Jay Rose Posted December 1, 2015 Report Share Posted December 1, 2015 Wow! Thanks, all, for the ideas and feedback. I'll try to work some of it into the next edition. (When I've built H pads, I've usually put all the resistors on a tiny piece of perf board... then wrapped the whole assembly in tape -- sometimes in the middle of the short cable; sometimes including the XLR pin insert in the taped blob). Yours looks a lot nicer and more professional from the outside. Quote Link to comment Share on other sites More sharing options...
Jim Gilchrist Posted December 1, 2015 Report Share Posted December 1, 2015 Jay, I've built them on perf board as well but then build them into the Switchcraft S3FM XLR male to female barrel. Neutrik also makes 'em, the NA3FM or the NA housing used with Neutrik D connectors for bigger circuits. Best regards, Jim Quote Link to comment Share on other sites More sharing options...
Glen Trew Posted December 1, 2015 Report Share Posted December 1, 2015 Fun topic, pads. Mark, you may want to consider using 1/8W resistors instead of 1/4W because they will perform the same and take up almost half the space. Also, save some unnecessary expense and consider 5% or even 10% carbon resistors, especially for the shunt resistor (the 15-Ohm, in this case). The argument could be made that 1% resistors could improve common mode rejection, but I doubt anyone would ever experience an issue with this, especially considering the line level source and the fact that the pad should be installed at the load end. GT Quote Link to comment Share on other sites More sharing options...
mark kirchner Posted December 2, 2015 Author Report Share Posted December 2, 2015 Glen, Thanks you for your thoughts on the resistors. I did try to purchase 1/8-watt resistors, but my local supplier did not have them in stock. This was my first attempt in making a pad and so I did not mind spending a little more money for the 1% resistors. I also want to thank you for the great information you have posted on JW Sound over the years; I have gleaned a lot from them. Quote Link to comment Share on other sites More sharing options...
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