while JFet gate is dictating voltage at own source
200R is "just" taking voltage from CCS, JFets source is tracking own gate
sorry...off topic again. D1 is now 10V, R6 is what value? and below Q2 is now a 200R resistor over a jumper?
Yes. You also need the correct size of regular drill bits for each tap you will use.
A center punch will also be useful.
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Its worth double checking the tap size/ drill bit chart if you're not certain. For imperial measurements, drill sizes for taps are often given in a 2 digit sizing index used by machinist.
Automatic center punches are super handy. One handed use opens up a bunch of possibilities
Automatic center punches are super handy. One handed use opens up a bunch of possibilities
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And if you know size of hole, you can buy a two piece set of tap and matching drill bit.
I don’t really know I thought I read that ums is 3mm but Ive seen other places that says 2mm
I don't have any metric bits, so I use a 3/32" imperial bit with no problems for M3 tapped holes.
Irwin is the brand you see most often in retail stores. Ace Hardware has them and Home Depot has them. I've bought them at both places. When you buy the tap, look at the package and it will tell you specifically what size bit to get that works with that tap.
6-32 screws are a fine alternative if you don't require 3mm screws/standoffs. That's a number 6 screw (~3.5mm) with 32 threads per inch
Just hit Amazon for "M3 tsp and bit set" or whatever size you need. I usually use 3mm for heatsinks. I did go up to M4 I think it was, for the big puck mosfets.
With the benefit of the great advice I’ve received here, I’ve been able to solve the noise issue I had. I have added capacitance to the final C in the CRC filter, and I’ve rotated the PS PCB to an orientation that allows the AC and DC wiring to be more cleanly separated.
I added 2x6800µF to the existing 2x4700µF for V+, and the same for V-, soldering them to the underside of the PS PCB. I used Vishay 6800µF/50V 256 PMG-SI caps that I purchased back in 2016, and have sat unused since. These Vishay are a good match to the ripple rating and ESR of the EPCOS caps from the kit. The PS PCB now stands taller, and I lashed a couple of wine corks to the nylon posts on the opposite side of the PCB so it would sit level. I returned the F5m to the system at this point, but was disappointed to find no discernible change in the buzz. I was thinking I would just remove the extra caps, but I tempered this with the thought that they might need some time to reform, and decided to listen to music while waiting. Well, I played some of my favorite tracks, and despite my disappointed mood, I was more than surprised to find they sounded better than ever; e.g, details like the shimmer in symbols was even more distinct, there was a greater 3D spatial effect. So I cut short the waiting for buzz reduction and went back to the bench to cut wires and reorient the PS PCB.
I rotated the PCB 90° CW, and repositioned the secondaries from the transformer to keep them out of the way of DC wiring, plus a few other minor tweaks. Once fully warmed up, I measured AC on the speaker terminals: 0.12mVAC R, 0.14mVAC L (the latter is closest to the transformer). This is a considerable reduction from the 0.30-0.55mVAC I was getting before. I returned the F5m to the system, and all warmed up, I can’t hear anything from the speakers with my ear against them.
I want to thank again all here who offered suggestions and took on the burden of my ignorance as a first-time chassis builder, especially since I chose a less-than-ideal chassis to work with. I’ve learned a great deal. I want to send a special thanks to Ben Mah and william2001 for suggesting the specific steps which proved so effective.
I added 2x6800µF to the existing 2x4700µF for V+, and the same for V-, soldering them to the underside of the PS PCB. I used Vishay 6800µF/50V 256 PMG-SI caps that I purchased back in 2016, and have sat unused since. These Vishay are a good match to the ripple rating and ESR of the EPCOS caps from the kit. The PS PCB now stands taller, and I lashed a couple of wine corks to the nylon posts on the opposite side of the PCB so it would sit level. I returned the F5m to the system at this point, but was disappointed to find no discernible change in the buzz. I was thinking I would just remove the extra caps, but I tempered this with the thought that they might need some time to reform, and decided to listen to music while waiting. Well, I played some of my favorite tracks, and despite my disappointed mood, I was more than surprised to find they sounded better than ever; e.g, details like the shimmer in symbols was even more distinct, there was a greater 3D spatial effect. So I cut short the waiting for buzz reduction and went back to the bench to cut wires and reorient the PS PCB.
I rotated the PCB 90° CW, and repositioned the secondaries from the transformer to keep them out of the way of DC wiring, plus a few other minor tweaks. Once fully warmed up, I measured AC on the speaker terminals: 0.12mVAC R, 0.14mVAC L (the latter is closest to the transformer). This is a considerable reduction from the 0.30-0.55mVAC I was getting before. I returned the F5m to the system, and all warmed up, I can’t hear anything from the speakers with my ear against them.
I want to thank again all here who offered suggestions and took on the burden of my ignorance as a first-time chassis builder, especially since I chose a less-than-ideal chassis to work with. I’ve learned a great deal. I want to send a special thanks to Ben Mah and william2001 for suggesting the specific steps which proved so effective.
Your approach, persistence and patience does you credit. I’m sure many followed it with interest and lessons were learned. Thanks for the well-documented reports and enjoy the amp.
Thank you for the kind words. Whatever was accomplished was only possible by the kindness of others here.