Solid State Guitar Amp Forum | DIY Guitar Amplifiers

Please login or register.

Login with username, password and session length
Advanced search  


Pages: 1 [2]   Go Down

Author Topic: Sunn Concert Lead PA  (Read 7039 times)


  • Elite SSGuitarist
  • *****
  • Chip Points: 6
  • Posts: 209
    • 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.
Pages: 1 [2]   Go Up

* User Info
Welcome, Guest. Please login or register.
Did you miss your activation email?
* Recent Posts
Need some beginners help. by
[June 27, 2016, 09:58:05 PM]

Can someone help me with this test question? by Den.
[June 27, 2016, 08:27:33 PM]

Ampeg SVT 350 by tubes
[June 27, 2016, 08:11:15 PM]

Transformer wired into 6x15 Speaker cabinet...trying to figure out Impedance.. by Vitrolin
[June 27, 2016, 05:16:55 PM]

LEM baby tape echo by ilyaa
[June 27, 2016, 03:52:44 PM]

* Sponsors