John Curl's Blowtorch preamplifier

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#19,401
syn08 said:



I'll let you take care of the RFI issues using those 40 year ago russian NOS bypass caps, in particular in tube amps. I have no ducks in my speakers and light doesn't dim when I'm powering the microwave oven.
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I don't need them for such a purpose, especially in tube amps. 😎 But designing grounding I always assume that the equipment connected to mine will have different ground issues. It helps.
 
#19,402
syn08 said:


Flashnews: this is Anno Domini 2009 and North America; ham radio is almost extinct. Meantime, we got cell phones and the Internet to communicate. And Internet on the cell phones.

I'll let you take care of the RFI issues using those 40 year ago russian NOS bypass caps, in particular in tube amps. I have no ducks in my speakers and light doesn't dim when I'm powering the microwave oven.
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😀
 
#19,403
Allen Wright said:
I was serioiusly curious, as living about 2 mils from this tower, I could get 50 hz frame buzz into phonostages. After some prodding, he told me the trick: All the shielded cables entering the mixer had their shields earthed directly to the case, at the EXACT point of entry.

No conductor that was externally accessable by RFI was allowed any path inside the casing. Signal or powersupply.

Worked for him, and apparently ALWAYS worked.

Regards, Allen
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Sounds so simple when some one smart says it...
 
#19,406
MikeBettinger said:



Grounding is not an art if you understand it.
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Sure. It is always an optimum between many possibilities. Like any art. 😉

Just assume currents that flow, and what they cause and where. It is simple, but first of all the most complete picture has to be drawn, either in imagination, or on paper. SIM helps also, when you replace each wire by an inductor and a resistor.
 
#19,414
syn08 said:


I have to check if this would really work/fit. Cable XLR's are affordable, the panel models are not.
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It wouldn't fit as-is. I have one of those in front of me, I was trying to replace the stock jack in the cup with another one for direct PCB mounting.
Neutrik will sell you the empty cups, though. For Dimitri's idea to work the mounting hole in the cup needs to be enlarged, not that difficult.
Starts to sound like a group buy 😉

Jan Didden
 
#19,417
dimitri said:


This is only sketch. Depending on the app, inductor can be replaced with bead(s) or common mode choke. There are also spark gaps on PCB (by default) and ESD diodes.
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It would be much easier to build those rings on a custom PCB with appropriate size and populated with chip caps in house. Unfortunately, I'm not aware of any PCB manufacturer that would route round small double sided PCBs with vias, in relatively small quantities, for a reasonable price. If anybody is aware of such, I can do a design for the PCB to fit in a Neutrik cup and provide the Gerbers.

Spak gaps and ESD diodes on the PCB are really an overkill for audio.
 
#19,418
syn08 said:


It would be much easier to build those rings on a custom PCB with appropriate size and populated with chip caps in house. Unfortunately, I'm not aware of any PCB manufacturer that would route round small double sided PCBs with vias, in relatively small quantities, for a reasonable price. If anybody is aware of such, I can do a design for the PCB to fit in a Neutrik cup and provide the Gerbers.

Spak gaps and ESD diodes on the PCB are really an overkill for audio.
Click to expand...


Why not have the board made with all etching and holes drilled and routed, then use a punch to punch out the round boards?
 
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