Post #527 for switch PN. Nelson's paper has his instructions that I followed for testing the circuit... others may do other tests.
M3 for nuts and bolts, washers and lock washers, for mosfets and sinks. And thermal pads: https://www.mouser.com/ProductDetail/Bergquist-Company/SPK4-0006-00-58?qs=jQRjkUoUCJe9KEbxrbMehQ%3D%3D
M3 for nuts and bolts, washers and lock washers, for mosfets and sinks. And thermal pads: https://www.mouser.com/ProductDetail/Bergquist-Company/SPK4-0006-00-58?qs=jQRjkUoUCJe9KEbxrbMehQ%3D%3D
Thanks PFarrell much appreciated i should have searched for the switch! I did search for testing but didn't find anything relating to this. I know these are pretty basic questions but this is my first real build and nelsons guide is a bit over my head as I have little experience. here are the testing outline from his guide and my questions relating in green
At this point, you should be able to confirm +24 volts with your muli-meter
Do I test this at the power input jack terminals?
measure the DC voltage drop across R18. The preamp draws about 0.3 amps, and
so you expect to see about 0.3V across this 1 ohm resistor.
I'm honestly not sure about this, do i measure voltage to ground before and after r18?
After that, you check the point on each channel labeled DC1 (near R12 and R13) and confirm
about 11 volts DC. Exact value is not critical, plus or minus a volt....
This is measured from the channel dc1 near r12,13 but does it matter which ground point i test to?
At this point, you should be able to confirm +24 volts with your muli-meter
Do I test this at the power input jack terminals?
measure the DC voltage drop across R18. The preamp draws about 0.3 amps, and
so you expect to see about 0.3V across this 1 ohm resistor.
I'm honestly not sure about this, do i measure voltage to ground before and after r18?
After that, you check the point on each channel labeled DC1 (near R12 and R13) and confirm
about 11 volts DC. Exact value is not critical, plus or minus a volt....
This is measured from the channel dc1 near r12,13 but does it matter which ground point i test to?
Those are "Vias", to get connection from one side of the PCB to the other.
LED is a power indicator. use whatever color you like.
switch - 2M1-SP1-T1-B1-M2QE Carling Technologies | Mouser
You’ll put one lead on one leg of R18 and the other lead on the remaining leg of R18. 0.3V/1R = 0.3 amps
Any ground point should work - I clipped onto the screws that I used to fasten circuit to ground plane.
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You could measure on the jack itself, but the easiest spot is the pads labelled "V+" and "GND" next to the power jack.
Thanks everyone for the amazing support, I was able to finish this and all tests passed perfectly!
I’m using the ground plane at the moment and when I turn the volume knob, up around 1 o’clock to 2 o’clock I get some hum. It goes away when I let go of the knob, or turn past this location up of down! Is There any thing I should check?
I’m using the ground plane at the moment and when I turn the volume knob, up around 1 o’clock to 2 o’clock I get some hum. It goes away when I let go of the knob, or turn past this location up of down! Is There any thing I should check?
Can you share a pic? That might help identify any issues. My immediate thought was to ask what kind of hardware you used to to connect the circuit board to the ground plane.
dgcoffee, if the hum only happens when you’re touching the pot/knob, it sounds like you just need to ground your pot. Assuming you used the Alps pot as spec’d in Nelson’s article, it’s as easy as this:
1) solder one end of a short, thin gauge piece of wire to the nearest ground pad (Probably the front left pad on the HP jack)
2) loosen one of the screws on the back of the pot
3) Strip maybe 1/4” of the loose end of the wire, wrap it around the loosened screw head on the pot, and tighten it down
1) solder one end of a short, thin gauge piece of wire to the nearest ground pad (Probably the front left pad on the HP jack)
2) loosen one of the screws on the back of the pot
3) Strip maybe 1/4” of the loose end of the wire, wrap it around the loosened screw head on the pot, and tighten it down
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I’m pretty sure the four mounting holes are connected to ground. I can’t tell if you have the ground plane underneath or not. If you do, I’d fasten them with nuts to make a solid connection. If you don’t and are just testing, try removing the screws.
Hey all thanks for the suggestions.
The only workaround i had on the build was to solder the suggested power brick to the input jack as the input jack in the parts list has a larger ID than the suggested wall wart did (or i ordered one of them wrong). I did check the polarity on this and believe I got it correct as all board checks passed.
I'm using some standoffs I had with another kit, they appear to be brass. I did a little more troubleshooting and at normal volumes its imperceptible over headphones, but when you for up past noon with nothing playing (because that would be really loud) I get a buzz when touching the alps pot or the knob.
Not a huge deal if its normal but this being one of my first builds I want to understand if i stuffed something up or if it might be normal.
IMG_4147.jpg - Google Drive
IMG_4148.jpg - Google Drive
The only workaround i had on the build was to solder the suggested power brick to the input jack as the input jack in the parts list has a larger ID than the suggested wall wart did (or i ordered one of them wrong). I did check the polarity on this and believe I got it correct as all board checks passed.
I'm using some standoffs I had with another kit, they appear to be brass. I did a little more troubleshooting and at normal volumes its imperceptible over headphones, but when you for up past noon with nothing playing (because that would be really loud) I get a buzz when touching the alps pot or the knob.
Not a huge deal if its normal but this being one of my first builds I want to understand if i stuffed something up or if it might be normal.
IMG_4147.jpg - Google Drive
IMG_4148.jpg - Google Drive
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Ours does this too. VERY minimal with the inputs shorted—what's it do with a source? There's a PN discrepancy on the parts list. You want 2.1mm for both parts. We also had the wrong brick in the right labeling and package from Mouser! True story—ended up with a center neg brick—I swear. Made me/us crazy trying to figure it out. In other preamp builds I almost always have to specifically ground the pot since I'm using wood related faceplates—I'd imagine that if you put it in a chassis the knob buzz would be gone.
It's a great sounding preamp that makes us smile every time we look at it (and listen to it)—worth not having it in a chassis.
It's a great sounding preamp that makes us smile every time we look at it (and listen to it)—worth not having it in a chassis.
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Thats comforting to hear that yours does it as well, and that you made the same mistake with the bricks!
Mine was only tested with a source plugged in, with music playing its hard to perceive. I've only used it with headphones to date, i'll give it a go with a power amp later today.
Agree 1000% on the music it makes, I'm using a pair of Ultrasones that I've always felt were a little flat, even with a el34 tube integrated with tube headphone stage. This little guy really makes them sing!
Mine was only tested with a source plugged in, with music playing its hard to perceive. I've only used it with headphones to date, i'll give it a go with a power amp later today.
Agree 1000% on the music it makes, I'm using a pair of Ultrasones that I've always felt were a little flat, even with a el34 tube integrated with tube headphone stage. This little guy really makes them sing!
