Internal isolation
So I ordered a slimline 2u case from the diyaudio store and passed on the aluminum top and bottom upgrade thinking steel would probably offer better emi rejection. I plan to mount the volume attenuators and selector switch in the back with extended shafts. I would think steel would be better than aluminum as well and maybe put in a wall isolating the power supply’s as well . Is plane steel sheet metal effective or is there a better material ? Also is there any one way better to pass wires through the barriers, and last of all is this stuff so quiet it is not worth the trouble ?
Bill
So I ordered a slimline 2u case from the diyaudio store and passed on the aluminum top and bottom upgrade thinking steel would probably offer better emi rejection. I plan to mount the volume attenuators and selector switch in the back with extended shafts. I would think steel would be better than aluminum as well and maybe put in a wall isolating the power supply’s as well . Is plane steel sheet metal effective or is there a better material ? Also is there any one way better to pass wires through the barriers, and last of all is this stuff so quiet it is not worth the trouble ?
Bill
build without barriers then add them if you feel need for
point is - if problem with magnetic field is substantial, you really need substantial thickness of Fe to stop it, not just some flimsy plates here and there
even in my Iron Pumpkins, being ubercriticall due to AVCs inside, I don't need anything special besides positioning care , and little Donuts having both static and magnetic shields
accent on "little" (meaning - big enough,not unnecessary overkill) and "shields"
point is - if problem with magnetic field is substantial, you really need substantial thickness of Fe to stop it, not just some flimsy plates here and there
even in my Iron Pumpkins, being ubercriticall due to AVCs inside, I don't need anything special besides positioning care , and little Donuts having both static and magnetic shields
accent on "little" (meaning - big enough,not unnecessary overkill) and "shields"
I still have to do all my signal wiring, but I did my layout so I could possibly add some partitions if needed:
This is a 2U Slimline chassis. Since I had extra headroom inside I added the optional bottom plate (installed upside down). The wires from the IEC to the front switch go underneath. After the switch it goes to a terminal block with a noise suppression cap. Then the power splits to the two 15VA transformers, each with its own fuse. I am hoping that putting the transformers into the corners helps with any noise.
If there is a noise issue I can see 2 options. Buy some angle iron and install between the PSUs and the preamp. I also have a large piece of mu-metal (I think) that came with my F5 transformer. Assuming I don't need it in the F5 I may cut it and wrap it around the smaller transformers. I won't be bending it, just making a smaller circle, so hopefully that doesn't ruin the mu-metal.
Fun stuff! Haven't tested anything with speakers yet though, just multimeters, so it will definitely be interesting using the BA2018 and F5 for the first time!
This is a 2U Slimline chassis. Since I had extra headroom inside I added the optional bottom plate (installed upside down). The wires from the IEC to the front switch go underneath. After the switch it goes to a terminal block with a noise suppression cap. Then the power splits to the two 15VA transformers, each with its own fuse. I am hoping that putting the transformers into the corners helps with any noise.
If there is a noise issue I can see 2 options. Buy some angle iron and install between the PSUs and the preamp. I also have a large piece of mu-metal (I think) that came with my F5 transformer. Assuming I don't need it in the F5 I may cut it and wrap it around the smaller transformers. I won't be bending it, just making a smaller circle, so hopefully that doesn't ruin the mu-metal.
Fun stuff! Haven't tested anything with speakers yet though, just multimeters, so it will definitely be interesting using the BA2018 and F5 for the first time!
Thanks. They are like miniature donuts.
Feel free to also laugh at the effort I went through to carefully measure and chop the VRDN heatsinks to fit 1U. And then I end up buying a 2U chassis.
I think the signal wiring is going to be a rats nest, especially if I max out at 6 inputs (the most the rotary switch can handle). But if I do only 4 inputs it will make the wiring and the back panel layout a bit easier. 6 might be more attractive if/when I sell this on in the future, but really I'll only probably have my RPi/DAC, TV, and maybe a TT phono stage someday?. I really don't need more than 4.
Yeah, there is still a lot of flexibility with the placement of that board. I had it that way around since the run from the board to the outputs would be very short. I'm considering having the outputs be laid out symmetrically, one per side, similar to the inputs on the back of the Deluxe chassis. But if that is noisy I will explore turning the board around.
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Generally, input signals are more "delicate".
I think the signal board can also be cut in half to separate the channels and, perhaps, allow more flexibility in layout particularly since you've gone all "dual power supply".
That might not be as helpful at this point since you've committed to locations of your selector and pot.
I think the signal board can also be cut in half to separate the channels and, perhaps, allow more flexibility in layout particularly since you've gone all "dual power supply".
That might not be as helpful at this point since you've committed to locations of your selector and pot.
Your build is looking great.
In terms of noise—Wayne's pre is the quietest amp I've built—absolutely nothing to be heard in headphones or speaks (92db):
Wayne's BA 2018 linestage
Post #932—nothing nuts in terms of layout.
Also used In-Select—Tea's GB—I think for all the Salas boards—closes on Oct. 4th for the next round.
In terms of noise—Wayne's pre is the quietest amp I've built—absolutely nothing to be heard in headphones or speaks (92db):
Wayne's BA 2018 linestage
Post #932—nothing nuts in terms of layout.
Also used In-Select—Tea's GB—I think for all the Salas boards—closes on Oct. 4th for the next round.