• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

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#11,222
kodabmx said:
Testing out the monoblocs after a few months of idle... Guinea pig found the "hole"... That's where the waves cancel and it's the quietest place in the house!
Smart rodent!
Heater has a tilt switch... BF must have "turned off the heat"...

View attachment 1138926
Click to expand...
Either that or construction across the street has ended- lmao

"Smart Rodent" indeed... he's lounging warmest room in the house ;<))
 
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#11,223
Sven79 said:
Initially the heaters were all AC. That would still work fine with 6N2P or similar (12AX7). However, with the 6N1P it required DC heating as there was too much hum which I couldn't neutralize enough with hampot. Therefore I switched to DC and it remain there. Had to revert back to 6N2P anyway, 6N1P needs double heater current. On the long run that would overload the transformer. But beside of that, I always would try to keep the heater traces on PCB as short as possible, since they have to be much wider and waste space.

Here's a pic showing the power supply with AC heater (humpot is at the back of the chassis). PCB were first revision, not usable in that chassis because of long leads.
View attachment 1138104
Click to expand...
A lesson in design- exemplary procedures
Especially liked your router w/ liquid fill for labeling. My CAD software just recently added alphabet to sketches.
I see KiCad can export gerbers. Was this the format used to export to your engraver? Or a CAD style .dxf or .dwg?
Jim
 
#11,224
Facebook says this was 9 years ago.

All of these amps have been recycled!
1675568228945.png
 
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#11,225
oemcar said:
A lesson in design- exemplary procedures
Especially liked your router w/ liquid fill for labeling. My CAD software just recently added alphabet to sketches.
I see KiCad can export gerbers. Was this the format used to export to your engraver? Or a CAD style .dxf or .dwg?
Jim
Click to expand...
For the engraving (and all the other CNC milling/drilling tasks) I use FreeCAD. It has a CAM plugin (called "Path") which can export GRBL directly. The router uses GRBL.
 
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#11,227
Thank you for your detailed response Sven- I value the discussion of fabrication- It is an important part of presentation, imo
Jim
Click to expand...
Hi Jim, since this is a photo thread I couldn't be as detailed as I would have liked to be. Maybe the next project I'll document somehow more detailed, as also the workflows might be interesting. So agree with you that the "how" may also be importaqnt, espacially for DIY community since there atre many different ways to accomplish something - and all of those also depend on indvidual capabilities 🙂
 
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#11,228
Sven79 said:
Hi together, yet another phono preamp. Nothing special, EF86 and double triode, passive equalization. I use JJ EF806S goldpin and 6N2П-ЕВ. However, I designed the PCB in a way that also a ordinary 12AX7 etc. would work. PCB's designed with KiCad. All the milling-engraving done with cheap chinese desktop-CNC. Verneer is american cherry tree, finish is just oil. Maybe I'll create another enclosure with reduced height but for now I'm fine with the result (given the limited DIY possibilities). BR Sven
Click to expand...
Your "cheap chinese desktop-CNC" work looks good. Any links to this device?
 
#11,230
Just a single pic of some projects I recently finished.

Left is a choke-loaded 6SL7 to EL34 transformer coupled cathode follower power stage headphone amp, right is a NOS parallel PCM63 (two per channel) to E182CC tube output stage DAC. Sowter SUT I/V conversion, battery bias, Sowter line output transformers. Headphone is the ZMF Caldera (I didn't make that, Zach at ZMF did).

PXL_20230209_193535053.NIGHT-2.jpg
 
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#11,232
Karpov's Crystal Start 7 mm phono pre.

Phono pcb layout changed to suit THT elements & those I had.

6N23P with paralleld triodes 1st stage, split RIAA, E180F + IRF830 SRPP output stage.

HV changed from original to multiple C-RC's + TL783 regulator.

Heaters were done from PM schematic, with small changes to suit transformer voltages - LM1085 regulator with Triad CMMR inductor at output.
 

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