To be fair, I originally asked about a cutdown version of Lufo, along the lines of MoFo, and coined the name LuFo-Lite with the use-case of driving high-efficiency full-range speakers, in particular my 15ohm Lowthers. I will still aim in that direction when the turn of this project arrives. Oh to be as productive as X with progressing projects...
The 422H have extreme sensitivity and that’s surprising the bass was less. I would have thought they would have been fine bass wise.
NB, yes - I think we can try to aim for a fleawatt amp for 16ohm speakers still. I have been productive, but not as much on my LuFo due to other urgent demands of managing like 8 projects in the pipeline. 3 headphone amps, 2 speaker amps, 4 speakers, a DAC, a streamer, …. oMg more like 11 now that I count them up… no wonder I don’t have any time for DIY.
NB, yes - I think we can try to aim for a fleawatt amp for 16ohm speakers still. I have been productive, but not as much on my LuFo due to other urgent demands of managing like 8 projects in the pipeline. 3 headphone amps, 2 speaker amps, 4 speakers, a DAC, a streamer, …. oMg more like 11 now that I count them up… no wonder I don’t have any time for DIY.
This is a source follower, isn't it? Then damping will be mostly about the FET and the current, not the choke.
12Ω DCR feeding 4Ω-16Ω loads promises terrible efficiency; but that may not matter for headphones.
It is a 0,2mm2 silver plated wire from ship, I acquired 1km roll, and IIRC, it was about 180m on each spool.
I also made germanium follower with similar chokes, works well over year, 0,8A bias, 19V supply, heat is okay with little active cooling.
Edit: wire resistance calc suggests more like 150m. The germanium one had 15ohmish, those were 180m, I think.
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Looks like 24 gauge which is 0.020" (0.51mm).
"0,2mm^2" is the area, not the diameter.
No, unless you need really high SPL levels. As impedance goes up, the amp needs to provide more voltage swing. With a 15v supply, you should easily get up to 20vpp and that should be more than enough for 600ohm Beyers. Assuming we use the 16vpp simulation results, that is 5.6Vrms or 52mW into 600ohms.
Assuming the Beyer’s have 96dB sensitivity at 1mW, 52mW is about 5.5x3dB or 16.5dB. Or 112.5dB SPL - more than loud enough for most music.
I think it’s going to work fine. You need a good preamp capable of 16vpp though.
Assuming the Beyer’s have 96dB sensitivity at 1mW, 52mW is about 5.5x3dB or 16.5dB. Or 112.5dB SPL - more than loud enough for most music.
I think it’s going to work fine. You need a good preamp capable of 16vpp though.
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LuFoLite
I replaced the power resistor R3 with a 12v 20w halogen light bulb. I increased the rail voltage to 20.0v (used 24v SMPS brick upstream of cap Mx). This ends up with 1.63A bias current and 12.9v at the LU1014D source and 12.0v at the light bulb. About perfect for an amp! Fortuitous situation.
No resistor heatsink needed! Lots more headroom on the amp now.
Doubles as a desk lamp!
I replaced the power resistor R3 with a 12v 20w halogen light bulb. I increased the rail voltage to 20.0v (used 24v SMPS brick upstream of cap Mx). This ends up with 1.63A bias current and 12.9v at the LU1014D source and 12.0v at the light bulb. About perfect for an amp! Fortuitous situation.
No resistor heatsink needed! Lots more headroom on the amp now.
Doubles as a desk lamp!
LuFo Lite Manufacturing Data
As I have determined that LuFo Lite works fine with a proper resistive load or a halogen light bulb (12v 20w), I think the current Gerbers will work as-is.
Here is the manufacturing data including Gerber files for anyone wishing to order their own PCB's. I might have some in my shop at some point in the future as well.
A big thank you to JPS64 for another superb layout.
As I have determined that LuFo Lite works fine with a proper resistive load or a halogen light bulb (12v 20w), I think the current Gerbers will work as-is.
Here is the manufacturing data including Gerber files for anyone wishing to order their own PCB's. I might have some in my shop at some point in the future as well.
A big thank you to JPS64 for another superb layout.