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MPF102 Answered


I'm trying to build Ruby guitar amp for my brother, but my problem is that I can't find this MPF102 transistor or any of its equivalents where I live. and if I order it online it will cost me as much as a Marshall amp costs.

I will appreciate any help or suggestions whether to replace the transistor or modifying the circuit.



10 months ago

I've bought them from Tayda, online. If the shipping is mucho, buy as much at one time as you'll need for years.

Most discrete transistors used for guitar projects are designated "obsolete" now, and won't be available in ten years anyway (or will be at crazy prices), so it's a good time to stock up.


11 months ago

That is high frequency JFET

That article mention some alternatives.

"An MPF102 FET is specified for the buffer,
though a 2N5457 will offer similar results. A J201 will work, but
produces a slightly lower output. Also, Ruby was developed using a
JRC386D (available from Small Bear Electronics), but any 386 can be used, including the type sold at Radio Shack."

Did you try these or are the to expensive too ?

Thanks for your comment.

I'm sorry if I forgot to mention that I already looked for all of its equivalents but non of my local stores have them, and that I live in Iraq and the international shipping will cost me a lot if I buy it on any online store.

I was thinking if you would know in which type of circuitry or device that I can find any of these transistor?

What the Jfet does for the amplifier is present a high input signal impedance and deliver a nice low impedance to drive the 10k pot from a 1.5meg input..

You should be able to use most any N-Mosfet but use two resistors to put the gate at a voltage to the middle of the linear fet gain..