Pars Posted October 2, 2008 Report Share Posted October 2, 2008 I know navships has some single conductor shielded such as these. This is the type of stuff used in alot of '80s and '90s gear, such as my Counterpoint preamp. Might be worth a shot for the input wiring. The shield is usually silver plated copper, so its good, though fine strands. The teflon tape outer wrap can be fun to deal with as well. Quote Link to comment Share on other sites More sharing options...
n_maher Posted October 2, 2008 Report Share Posted October 2, 2008 Belden also has shielded wire that is suitable for input/internal use. Hand Made Audio used to carry it although I don't know if they still do. Quote Link to comment Share on other sites More sharing options...
luvdunhill Posted October 2, 2008 Author Report Share Posted October 2, 2008 Belden also has shielded wire that is suitable for input/internal use. Hand Made Audio used to carry it although I don't know if they still do. yup, I have some of that on hand I think this is what AMB uses for his internal wiring, but I could be wrong. Quote Link to comment Share on other sites More sharing options...
luvdunhill Posted October 6, 2008 Author Report Share Posted October 6, 2008 I have a lot of things to post, but first things first.. I have mailed out all the JFETs. The numbers on the tape indicate the Idss that I measured for that device. Perhaps somewhat counter-intuitive, you may want to match the higher Idss value with the higher resistance values.. for example, measure the 4 22 ohm resistors and pair the highest value with the highest value written on the piece of tape for a given group of four. Reason being that forward transfer admittance (Yfs) varies directly with Idss. The inverse of Yfs is the apparent resistance of the JFET and we want to match the drain currents across the four JFETs. To to this, we want to ensure that 1/Yf_i + R_i is close the the same value, for all pairs i. Quote Link to comment Share on other sites More sharing options...
swt61 Posted October 6, 2008 Report Share Posted October 6, 2008 Yeah what he said. Quote Link to comment Share on other sites More sharing options...
luvdunhill Posted October 8, 2008 Author Report Share Posted October 8, 2008 quiet as a church mouse... notice the creative location of the 2 MOSFETs... Quote Link to comment Share on other sites More sharing options...
luvdunhill Posted October 8, 2008 Author Report Share Posted October 8, 2008 cannot post pics I get: "Your submission could not be processed because a security token was missing. If this occurred unexpectedly, please inform the administrator and describe the action you performed before you received this error." So, they are here: Picasa Web Albums - M - Pearl edit: notice the stray shielding... haven't figured out what to do with it yet Probably tie it to the earth post and connect that to chassis with a thermistor, Papa-style.. Quote Link to comment Share on other sites More sharing options...
swt61 Posted October 8, 2008 Report Share Posted October 8, 2008 Wow Marc, that's very cool! Was it as big a PITA working in that small space as it looks like it would be? It's definitely a full case. Houston is going to be a fun meet for yours truly indeed! Oh, and I'll post 'em for ya... Quote Link to comment Share on other sites More sharing options...
luvdunhill Posted October 8, 2008 Author Report Share Posted October 8, 2008 yeah, so this definitely doesn't have enough gain for a 0.24mV cartridge. Whatever Postjack's Bugle is set to would be as low as I would go. I was listening to this with my PPAv2 turned all the way up and the volume was moderate. Unfortunately, I feel like the verdict is still out on whether or not the toroids will cause trouble. I couldn't hear anything last night, but just didn't have enough gain the chain to know 100%. Also, it's really not that bad of a build. Since the boards are mounted to the top and bottom panel and they just slide out, and you can simply remove either one of the side panels and get access to either side... Quote Link to comment Share on other sites More sharing options...
n_maher Posted October 8, 2008 Report Share Posted October 8, 2008 If the toroids prove to be a problem let me know. I have some Mu metal from LessEMF and could send you some to see if it would help. Quote Link to comment Share on other sites More sharing options...
luvdunhill Posted October 8, 2008 Author Report Share Posted October 8, 2008 If the toroids prove to be a problem let me know. I have some Mu metal from LessEMF and could send you some to see if it would help. do you think I could take a square of it and just stick it to the toroid mounting dish? Quote Link to comment Share on other sites More sharing options...
n_maher Posted October 8, 2008 Report Share Posted October 8, 2008 Don't see why not. You could also call Avel and ask if they would be willing to send you some core banding (they've done this for me in the past) - just be sure to tell them which trafos you're using so they can send the right width band. I've found both radial and longitudinal fields to be problematic, depending on the application. Quote Link to comment Share on other sites More sharing options...
luvdunhill Posted October 8, 2008 Author Report Share Posted October 8, 2008 Don't see why not. You could also call Avel and ask if they would be willing to send you some core banding (they've done this for me in the past) - just be sure to tell them which trafos you're using so they can send the right width band. I've found both radial and longitudinal fields to be problematic, depending on the application. cool, just talked with Avel and they are sending a small roll out. Also, they recommended orienting where the primaries and secondaries exit away from the sensitive circuity, as there is a gap there that can leak. Thanks for the suggestion! Quote Link to comment Share on other sites More sharing options...
richard4g Posted October 21, 2008 Report Share Posted October 21, 2008 Late to the party - are 2 boards plus parts kit still available?? Quote Link to comment Share on other sites More sharing options...
swt61 Posted October 27, 2008 Report Share Posted October 27, 2008 Just listened to mine Saturday at the Houston meet. Dead quiet, no issues w/the toroids whatsoever. Beautiful build Marc! Quote Link to comment Share on other sites More sharing options...
luvdunhill Posted October 27, 2008 Author Report Share Posted October 27, 2008 Steve: One thing to realize is that you will have to alter the loading once you put the step-up in line. The Consonance seems to have 20dB and 17dB taps, which refer to the amount of gain you can get. Assuming you want to stick to around 100 ohms loading and want to use the 20dB (i.e. the higher gain) taps, then by my calculations you will need a pair of 12.7k resistors. I'll order them this week for you. If you want 150 ohm loading, then you'll need a pair of 22k resistors, ironically the exact same value I purchased for your other cartridge, so I'll have these on hand as well for you. Quote Link to comment Share on other sites More sharing options...
swt61 Posted October 28, 2008 Report Share Posted October 28, 2008 Steve: One thing to realize is that you will have to alter the loading once you put the step-up in line. The Consonance seems to have 20dB and 17dB taps, which refer to the amount of gain you can get. Assuming you want to stick to around 100 ohms loading and want to use the 20dB (i.e. the higher gain) taps, then by my calculations you will need a pair of 12.7k resistors. I'll order them this week for you. If you want 150 ohm loading, then you'll need a pair of 22k resistors, ironically the exact same value I purchased for your other cartridge, so I'll have these on hand as well for you. Cool, 100 Ohms loading will be great. This is something I can most likely do, once you map out the right location for me? Quote Link to comment Share on other sites More sharing options...
luvdunhill Posted October 28, 2008 Author Report Share Posted October 28, 2008 Cool, 100 Ohms loading will be great. This is something I can most likely do, once you map out the right location for me? yes, of course... it shouldn't be too hard at all. Also, the banding for the toroids came in today as well. Once I get the mu metal and the new resistors from Canada, I'll send you a package. Quote Link to comment Share on other sites More sharing options...
swt61 Posted October 28, 2008 Report Share Posted October 28, 2008 That sounds great. I'll need better instructions on tweaking the speed controller with the piece you gave me as well. My strobe and strobe disc came in yesterday, and both 33 & 45 RPM are a little past the the settings we have now. They're not far off though. I've inquired about a custom dust cover too. We'll see what they have to say. I actually missed the fidgetyness (is that a word?) of a vinyl rig. It suits my personality. Quote Link to comment Share on other sites More sharing options...
luvdunhill Posted October 28, 2008 Author Report Share Posted October 28, 2008 That sounds great. I'll need better instructions on tweaking the speed controller with the piece you gave me as well. My strobe and strobe disc came in yesterday, and both 33 & 45 RPM are a little past the the settings we have now. They're not far off though. I've inquired about a custom dust cover too. We'll see what they have to say. I actually missed the fidgetyness (is that a word?) of a vinyl rig. It suits my personality. sure. I need you to do 2 measurements for me. First, put your meter in DC volts mode. If you get one of those cheap Centex red ones from Harbor Freight, like this: Harbor Freight Tools - Quality Tools at the Lowest Prices then place the knob in the position that points to "20 DCV" and the black probe in the "Common" location and the red probe in the VOmA location in the lower right hand corner. Then place the probes across the motor terminals inside the case. Just follow the wires going from the socket to the PC board and measure at the terminal block. I believe it's marked X3. It doesn't really matter which probe goes where, as we just need an absolute reading. Be careful not to slip and short things out, in other words, don't let the probes touch each other when you're measuring. This measurement needs to be done with the table running for a minute or two so the speed is able to stabilize. Repeat the same measurement for the 45rpm setting. Just to give you an idea, mine measured around 7.5V for 45rpm and 6.0V for 33rpm. Quote Link to comment Share on other sites More sharing options...
DigiPete Posted October 28, 2008 Report Share Posted October 28, 2008 Anyone have a suggestion for a power supply case for the Pearl, steel would be preferred Quote Link to comment Share on other sites More sharing options...
n_maher Posted October 28, 2008 Report Share Posted October 28, 2008 Anyone have a suggestion for a power supply case for the Pearl, steel would be preferred Careful working with steel, it doesn't drill nearly as nicely as that aluminium stuff. Quote Link to comment Share on other sites More sharing options...
DigiPete Posted October 28, 2008 Report Share Posted October 28, 2008 Careful working with steel, it doesn't drill nearly as nicely as that aluminium stuff. But it does offer better EMI shielding... Quote Link to comment Share on other sites More sharing options...
n_maher Posted October 28, 2008 Report Share Posted October 28, 2008 But it does offer better EMI shielding... True, just be prepared for the additional hassle. Quote Link to comment Share on other sites More sharing options...
DigiPete Posted October 28, 2008 Report Share Posted October 28, 2008 True, just be prepared for the additional hassle. Any suggestions for a case? Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.