F-5 Transistor Kit

Please note: the numbers on the MOSFETs are ID numbers only, and are not related to their measurements nor their matching

F-5 Transistor Kit

29⁰⁰

Included in this kit are the semiconductors needed to complete an F-5 amplifier, with the exception of the input JFETs, which can be sourced separately through the store. MOSFETs were matched in accordance with standard operating conditions. This is enough MOSFETs for 2 channels (one stereo amplifier).

2 x IRFP240
2 x IRFP9141 (replacing IRFP9240)
2 x ZTX450
2 x ZTX550

Change history

2022-04-20 - At Nelson's suggestion, this kit contains Harris P channel MOSFETs instead of International Rectifier MOSFETs. These are considered better parts, with less distortion, and match nicely (.1V Vgs at 0.1A). They have a lower maximum voltage at 100V however 100V is suitable for this application.

F5 Transistors and build.

I live in the UK, the transistors and boards arrived within two weeks. The build was straight forward and housed in a 4U Galaxy case. The two 500 VA transformers are bolted the the front panel. It’s not pretty but it’s functional. Unfortunately the build guide called for the bias and offset pots to be rotated fully anti clockwise before power on. At power on the two boards fried themselves with added dramatic smoke. The penny dropped, maybe next time I’ll ensure the pots are fully clockwise before turn on. I replaced two blackened resistors on each board and ordered a new set of transistors, just to be on the safe side although the previous traumatised ones tested OK. Second power on no smoke or blackening slowly increased the pots counter clockwise following the build guide to 0.59 volts. Heatsinks about 50 degrees C when stable. It sounds fantastic. I was so impressed I have since ordered the boards and transistor kit and built an F5 Turbo in a 5U Galaxy case. which sounds about the same but slightly more dynamic. The bias issue was not a problem with the Turbo as you set the bias pots to full resistance via test points. Prior to switch on. Two superb products that sound amazing. I’m presently building a Pearl 2 Phono stage from Pass DIY. Thank you Nelson, Wayne and all the team at DIY Audio.

F-5 Transistors

Another well packaged kit, the work the staff do at diyAudio is amazing thank you, cant wait to get this build up and running.

Excellent service

Fast service. The match was excellent. I used the Mosfets in my M2X and set the offset pot to center the bias resistance between the P and N sides. . Upon power-up I only needed to touch up the offset.

F-5 Transistors

Yes, then F-5 transistors have been received and PCB came a little earlier, so now is the time to collect the rest of the necessary components. But the summertime that comes now makes the Diy activity go down a bit.