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Michael Rothacher Michael Rothacher is offline

diyAudio Member

About Me

  • About Michael Rothacher
    United States
    Author Bio
    Michael Rothacher is a regular guy with a regular job, but his alter ego is a mad scientist. He caught the audio bug over twenty years ago and has been building audio gear ever since. Like many others here, he both thanks and blames Nelson Pass for this.

    Mike likes his feedback low, his bias high, and is a big fan of super-simple Zen type designs. He is a firm believer that many of lifeís problems can be solved with Ohmís Law, and encourages you to not worry so much about what other people think, try your crazy ideas, trust your ears, and never stop learning.
    Author Name
    Michael Rothacher
  • Signature
    My Youtube Channel / My Website / Email: mike (at)


Total Posts
General Information
  • Join Date: 25th May 2001


Showing Friends 1 to 5 of 5


Latest Blog Entry

Posted 7th May 2014 at 10:16 PM by Michael Rothacher Comments 0
Posted in Uncategorized

Posted 1st November 2013 at 12:56 AM by Michael Rothacher Comments 0
Posted in Uncategorized
Ironamp project video posted here:

I hope you enjoy it.

I updated the captions if you want to try Youtube's translation option - should be funny

Posted 26th November 2011 at 11:24 PM by Michael Rothacher Comments 0
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The topic of JFET and MOSFET matching comes up often in the forums, so I thought I'd show you the jigs I use.

First up, is my trusty old JFET IDSS matcher.

There's a 9V battery inside, and the meter probes are conneted across a 10 Ohm resistor which is connected to the JFET drain. I included a polarity switch for convenience when testing P channel parts.

It's pretty easy to connect the microclips, count to five, and take a reading.

And here's what I use for the big stuff. This is my MOSFET Vgs matcher.

First, I install a sample part and let it warm up for about an hour. There's a thermistor hot-glued to the heat sink,...

Posted 24th January 2011 at 11:59 PM by Michael Rothacher Comments 3
Posted in Uncategorized
This is the artwork for the PCB in the pictures. It fits into the ExpressPCB miniboard profile so it's a little cheaper to have made.

It will be necessary to check the orientation of the bias pots (I can't remember). I wouldn't want you to blow-up your $30 JFETs.

Posted 22nd January 2011 at 10:29 PM by Michael Rothacher Comments 0
Posted in Uncategorized
I've been mostly out of the audio hobby for a while, but I've had a few inquiries about the SemiSouth version of the Amazing FET Circlotron as of late. So, I wanted to post the performance graphs here before I lose them.
Recent Comments
I still adjust for around...
Posted 27th November 2011 at 12:22 PM by Michael Rothacher Michael Rothacher is offline
The entire article can...
Posted 8th February 2011 at 06:18 PM by Michael Rothacher Michael Rothacher is offline
I've been searching...
Posted 5th February 2011 at 07:08 PM by ichiban ichiban is offline
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