L'Amp: A simple SIT Amp

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Here's a mono-block of the L'amp v193. It's in the "lay-out" phase.

I'm still on the fence regarding using the heat sink pictured. :scratch:
 

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Back from the gulf. No turtles, but I got to swim among a large school of "devil" manta rays.

Here's an opened 2SK82. 2 x 4mm dies. $25 for science.


Does open up unusual possibilites to cool the device .
  • Fashion dry ice into 1 inch circular pillars to fit in the open well and contact the base.
  • Drip de-ionized and distilled water in the well at a certain rate to a stable level without its overflow.
 
I just found out that participating Home Depot stores rent FLIR cameras, so I'll give that a try later. Thanks for the info.
Just in the case you are not familiar with these things, imaging shiny metal objects like 2sk82s, 28s or whatever gives improper temp readings due to low emisivity. Looking at TO3P (plastic) packages is 97% correct but shinny metal will need to be coated with something to get correct temp readings. I used to use white out correction fluid but, I've been using Cerameque thermal compund lately. It's basically that you get reflectivity from the shinny surface instead of emisivity. Generally you will see black or low temp indications on something you know is hot if you've got this problem. You can even get reflected emisive energy from a shinny object. Different surfaces have a different emisivity. You can probably google and find a chart, I couldn't find mine. Shinny metal is the worst offender :D
Don't forget to post pics here.
 
Thoughts about amplifier gain:

If I've understood correctly in theory the gain of the amp is ( current source in parallel with speaker ) / ( 1/0.4 )

And it is because of this that gain increases with the inductor since the inductor has much higher resistance? Though not massively since the 8 ohm speaker still limits the gain.

So if we simplify and assume that the inductor has a resistance of 100 since we won't use the amp for bass the gain with an 8 ohm speaker would be close to 3 or 9.6 dB if I remember my math correctly.

But that is not what I wonder... what I wonder is that does this mean that if I use an 18 ohm speaker instead the gain jumps up to 6.1, or 15.6 dB?
 
The input cap is there in Figure 11 in case your SIT has enough gate leakage current to drop some voltage across the input. If you measure the input, and it is at 0V, then perhaps you can go without.
Hi Michael,
I was wondering how to test for gate leakage of your final circuit for the inductor version. If the input cap needs to be there what is the lowest value it could be without affecting circuit if possible.
Thanks,
Eric