My millennium POP when using 2n548xxx. I solved it by using 2n5458.

[rogeryu_ph]

DIYer,
What is the difference between this two FET? (2n5484 to 2n5458) co'z I replaced the 2n5484 and solved the POPPING using 2n5458. Maybe this is good news to those have problem encountered so I'm just sharing this... Anyone.... very much appreciated.

[Ethan]

Hi, I compared the data sheet for 2n5484 and the 2n5458.  It seems they are not that different.  The main thing I could see was the Vgs(off) for the 2n5484was from -.5 to -3 volts.  While the Vgs(off) for the 2n5458 was from 1 volt to 7 volts. Jfets can vary from one another. Did you try another 2n5484?  You can check the Vgs (off) by reading the resistance between drain and source and hooking a power supply to gate.  Lower gate voltage and see when device is open (infinite resitance) This is your Vgs(off).
-ethan

[rogeryu_ph]

Thanks Ethan, Yap I have two 2n5484 and one 2n5486 but no 2n5485 hard to find.  I tried both but to no avail. I browsed to some web site selling on-line and found out one of them put their descriptions was 2n548X series RF AMPLIFIER N-CHANNEL FET and the 2n5458 was JFET N-CHANNEL only. I don't know whats the difference but I opted to used the 2n5458 and wella it's gone!!! Actually I used 2n5458 already in my first and second project which is the BigMuff and TS clone but no more stock of 2n5458 so I replaced it with 2n5484 which I had co'z I also built the MXR noisegate using it but not satisfied. For I while I thought there was a problem on my Rebote2.5 that I was building it  so I cried to the forum seeking help "Rebote Builder Pop when switching on" Now I realised that the culprit was the 2n5484. I once read a column saying maybe the CAPACITANCE that's why I even replaced it with higher value of resistor on the mil circuit but still to no avail I don't know if I'm right co'z i'm already desperated    By the way, this is a new tip I learn from you "how to measure the Vgs(off)" Many thanks again to you Ethan. To ALL DIYer this is just my small experience I could share with you. If you could get away with POP by just using tin wire why not just share it to me  Thanks