Solid State Guitar Amp Forum | DIY Guitar Amplifiers

Please login or register.

Login with username, password and session length
Advanced search  

News:

collapse
Pages: 1 [2]   Go Down

Author Topic: Sunn Concert Lead PA  (Read 4910 times)

gbono

  • Elite SSGuitarist
  • *****
  • Chip Points: 5
  • Posts: 142
    • View Profile
Re: Sunn Concert Lead PA
« Reply #15 on: August 23, 2010, 01:37:29 PM »

I spent some time testing the preamp sections on this amplifier - Sunn used JFETS in the input stages of their design (Concert series). The original part is a "glob top" (preceded TO-92) package - 2N4304. I tried using Fairchild J201's and though they had the same PIN OUT and similar IDSS specifications they produced more 2nd order spurs (without change the circuit) - the PN4303 is still available and seems to give about the same results as the orginal part - FYI

I had to rebuild much of the signal path of the second channel including sourcing a new reverb pan.

Now to dial in the bias for the best distortion/power dissipation at idle.

Thanks for the help.
Logged
Pages: 1 [2]   Go Up
 

* User Info
 
 
Welcome, Guest. Please login or register.
Did you miss your activation email?
* Recent Posts
ampeg vt-22 PI by Roly
[July 24, 2014, 02:35:31 PM]


Roland JC120 HELP!! by Enzo
[July 23, 2014, 03:26:57 PM]


Common Source Amplifier Questions by Roly
[July 23, 2014, 01:28:14 PM]


Pignose 7-100 (2013) schematic and PCB layout by J M Fahey
[July 22, 2014, 06:32:59 PM]


Common Emitter Amplifier Questions by Roly
[July 22, 2014, 05:04:29 PM]

* Sponsors