I was thinking of doing that but found the 681R resistors. I used a short piece of magnet wire heated the ends of the resistors and they popped out. Cleaned the holes with some solder wick and pop the new resistors in. It was a lot easier than I thought. The entire process took me about 15 to 20 minutes.
The are no trade offs or disadvantages in increasing (or decreasing if needed…) R27’s value. A “typical” J112 should work with the specified 220ohm, however, the J112 have a very wide rage of Idss from the factory and adjusting R27 to suit the individual Jfet you got in the kit is always beneficial, as it sinks the current in the circuit that Wayne designed.
Can you ignore this if you want? Yep. The Pearl will still work beautifully. However, trimming the resistor to meet the design spec strikes me as a neat thing to do.
Of course the next question is, could the J112 be sorted/chosen to be “ideal”? Well, yes, they could, but they kits will not be supplied that way, as it’s easier and simpler to adjust the resistor as needed, because the outcome is going to be the same in the end.
Can you ignore this if you want? Yep. The Pearl will still work beautifully. However, trimming the resistor to meet the design spec strikes me as a neat thing to do.
Of course the next question is, could the J112 be sorted/chosen to be “ideal”? Well, yes, they could, but they kits will not be supplied that way, as it’s easier and simpler to adjust the resistor as needed, because the outcome is going to be the same in the end.
Another Dual PSU build done, and...
Thought I would share some info for prospective builders. Attached is a jpeg.
The total cost of this project was $400 -- see the attached pdf for specifics (covers only the outboard PSU of course). This does not include the simple wiring, umbilical sheath, and assorted other common parts. While it is some money, it is eclipsed by the improved quality.
Any prospective builders are welcome to contact me for BoM lists from DigiKey and Mouser. Unlike the current kit, these parts are all available as of this post.
Thought I would share some info for prospective builders. Attached is a jpeg.
The total cost of this project was $400 -- see the attached pdf for specifics (covers only the outboard PSU of course). This does not include the simple wiring, umbilical sheath, and assorted other common parts. While it is some money, it is eclipsed by the improved quality.
Any prospective builders are welcome to contact me for BoM lists from DigiKey and Mouser. Unlike the current kit, these parts are all available as of this post.
Attachments
I thought there would be no problem finishing the Pearl 3 while on vacation visiting family, but alas, I ran into parts issues. I had already populated the boards, so it was just chassis and wiring to get it working. I used a Neutrik D XLR on the PSU side with a 4-pin patch cable. This required drilling out the hole sized for the gland.
Next, I forgot the RCA panel mounts in WA, so ordered nice looking ones off Amazon, which meant 3 days for those. Then I realized I also left the XLR cord sitting on my workbench, so back to Amazon. At this point I set aside the Pearl 3 and built an Aleph Jzm edition, which took a few days. I picked up the Pearl 3 again yesterday only to find the RCAs are too big for the predrilled Modushop chassis holes. They fit, but touch the hole sides and the spacer washer won't fit into the hole. I decided to pause there and order the right connectors that fit without having to drill chassis back panel.
I was able to get the PSU side completed shy of finalizing the front panel LED connection. Unloaded I get +/- 24VDC, so it looks to be working. I'll have to set this one aside and pick back up next time when I'm back in Minnesota. Aleph Jzm and half of a Pearl 3, that's progress right? Family thinks I'm crazy now after turning their basement into an audio workshop. Parts and tools strewn about, no place to even sit. Good times.
Lesson learned....buy part numbers that match BOM and ship directly to location where fabrication will take place.
Next, I forgot the RCA panel mounts in WA, so ordered nice looking ones off Amazon, which meant 3 days for those. Then I realized I also left the XLR cord sitting on my workbench, so back to Amazon. At this point I set aside the Pearl 3 and built an Aleph Jzm edition, which took a few days. I picked up the Pearl 3 again yesterday only to find the RCAs are too big for the predrilled Modushop chassis holes. They fit, but touch the hole sides and the spacer washer won't fit into the hole. I decided to pause there and order the right connectors that fit without having to drill chassis back panel.
I was able to get the PSU side completed shy of finalizing the front panel LED connection. Unloaded I get +/- 24VDC, so it looks to be working. I'll have to set this one aside and pick back up next time when I'm back in Minnesota. Aleph Jzm and half of a Pearl 3, that's progress right? Family thinks I'm crazy now after turning their basement into an audio workshop. Parts and tools strewn about, no place to even sit. Good times.
Lesson learned....buy part numbers that match BOM and ship directly to location where fabrication will take place.
Attachments
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How were the opamps damaged? Bent pins? They straighten out...
Yes, OPA2134 will work very well indeed.
Jumper - https://mou.sr/3Kwv1sd
Did you damage or lose your jumpers? Or missing in the kit?
Yes, OPA2134 will work very well indeed.
Jumper - https://mou.sr/3Kwv1sd
Did you damage or lose your jumpers? Or missing in the kit?
I bought the Pearl3 kit in DIYaudio-shop and the cabinets from Modus. I was surprised no LEDs for the on-indication on the front of the cabinets are supplied. But I have bought some 5mm blue ones. Also that the holes are so small in the front plate. I thought the LED should stick through the hold, but is it intended the LED is pushed close to the hole from behind, and glued in place and it will lite through the hole to the front side?
I have ordered the last components for the power board, that was easy, nice work 6L6 Now I can wait to hear music through the Pearl3
I have ordered the last components for the power board, that was easy, nice work 6L6
Now I can wait to hear music through the Pearl3 If I recall, mine came with LEDs. Seems like one or the other, power supply or phono part had a BOM the showed what was included.
I've bought a bunch of different LEDs here recently so may be getting confused. IIRC, it came with the red LED for the board, which is a critical value I believe, and two other ones in a sack, Maybe those were ones on board that were blue in my case. Ive had 3 projects going on at once....I may have added those myself. For just on/off indicator, no special one needed.
I've bought a bunch of different LEDs here recently so may be getting confused. IIRC, it came with the red LED for the board, which is a critical value I believe, and two other ones in a sack, Maybe those were ones on board that were blue in my case. Ive had 3 projects going on at once....I may have added those myself. For just on/off indicator, no special one needed.
If you got the PSU kit from @rhthatcher , he even sent extra LEDs! Thanks Randy!
I also received a bag of different LEDs, and maybe one is blue, it has a clear/greenish look. But the modus box is prepared for to LEDs to indicate on state. And the holes in the front plate are smaller than the LEDs. That is why I am a bit confused how to mount these LEDs in the front-plate. I guess on should find LEDs by yourself for this.
This is my typical method for drilling LED indicator holes ^. Drill a 3mm hole, then countersink a 5mm hold from the back. This way, either a 5mm or 3mm LED can be used. Hot glue, silicone, or other glue can be used to affix the LED.
I do the same thing when using fiber optic light pipes: drill a 3mm hole that corresponds to the diameter of the fibers, and countersink a 4.75mm hole for the sleeving. Glue in place.
Those clear LEDs in the kit should be blue when lit.
I do the same thing when using fiber optic light pipes: drill a 3mm hole that corresponds to the diameter of the fibers, and countersink a 4.75mm hole for the sleeving. Glue in place.
Those clear LEDs in the kit should be blue when lit.