L'Amp: A simple SIT Amp

just finished hand wound inductor (1of 4) for CLC supply using hellenic copper wire 14awg around 50m length. ebay plastic bobbin 8cmx3cm really help to wound it. since i dont have any L meter, using web calculator should give around 4mH, and measured DCR is 0.51 ohm

with 3hrs of working and $8 wire, i think that no any commercial inductor will close to this diy inductor for price/value :D

i've completed making UMS on 2 heatsink, hand drilling and tapping for 50holes is really good exercise for my muscle. still got another 2 heatsink to be completed

i have question, why most of sample that i find, B+ supply is connected to drain using a screw? i'm planning to use power connector spade
 

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Hello,
I have my 2sj82 L' Amp with the ZV2 CCS up and running with a strange sine wave at clip (see pic) Ive never seen that before. In square wave it rings. Why is it doing that ?
Ive have updated my scheme with actual voltages and notes. I was so excited to get the CCS working!.
Does it look like my operating point pretty high up the load line or is it an oval load with a CCS?
Thank you guys best regards David
 

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Official Court Jester
Joined 2003
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then nothing wrong

you can't expect symmetrical clipping from circuit which isn't symmetrical
read enclosed for example and more insight

(you have sine flipped upside down due to flipped voltage/phase)

regarding square ringing .... either leave it or compensate ......... probably irrelevant to sound in this case
 

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Interestingly, if we try to bias the stage to saturate more symmetrically, distortion and maximum power are altered, usually for the worse.
This soft saturation is something that makes clipping noticeable only when the THD is very high; It works like a compressor. So, in this conditions, SIT amps makes the sound appear more powerful than really is!
 
I recall I hooked my headphones up to one of the LuminAria prototypes just for fun. You could certainly work up a circuit for headphones without much trouble. :)

Hi Michael,

What value of output capacitor you used when you tried that? I thought about using LuminAria to drive my headphones (mostly 32 ohm) also, but was held back by the need of using big electrolytic output caps.
 
Thanks Michael and ZM, makes me want to try again :)

Some more questions if you don't mind:
- Since Vds of the output device in LuminAria is quite high, do I need high voltage rated ones (say, 100V).
- Some people said that the turn on thumb from big electrolytic could damage the headphones, is that something I should worry about.
 
Thanks Michael and ZM, makes me want to try again :)

Some more questions if you don't mind:
- Since Vds of the output device in LuminAria is quite high, do I need high voltage rated ones (say, 100V).
- Some people said that the turn on thumb from big electrolytic could damage the headphones, is that something I should worry about.
For turn-on thump you can use an small capacity cap for headphones output or use an timer relay with proper wiring.
 
For turn-on thump you can use an small capacity cap for headphones output or use an timer relay with proper wiring.

Thanks, but I believe C can't be too small or I'll be starting to lose my low frequency. Michael mentioned he used a couple thousand uF, and I think I won't go lower than 2700uF (-3dB freq around 1.9Hz).

Timer relay is an option, though I would like to avoid the extra complexity if possible.