1. Win a Broadcaster or one of 3 Teles! The annual Supporting Member Giveaway is on. To enter Click Here. To see all the prizes and full details Click Here. To view the thread about the giveaway Click Here.

6G3 Circuit Question

Discussion in 'Amp Tech Center' started by Viejo, Feb 25, 2021.

  1. Viejo

    Viejo Tele-Afflicted Silver Supporter

    Posts:
    1,442
    Joined:
    Feb 12, 2011
    Location:
    Central IL
    People with electronics education, what is the purpose of the.002 bypass cap on the 220K plate load resistor of the Normal channel V1 of a 6G3?
     
  2. Jowes_84

    Jowes_84 Tele-Meister

    Posts:
    181
    Joined:
    Mar 18, 2018
    Location:
    Kraut-Island, Chiemsee
    My electronics basics are very old and rusty but it seems it would attenuate high frequencies on the normal channel (vs the bright channel w/o the cap)
     
  3. Uncle Daddy

    Uncle Daddy Tele-Afflicted

    Posts:
    1,631
    Joined:
    Sep 26, 2015
    Location:
    Maldon, England
    It's a basic RC circuit to block specific frequencies. I think! A bit like a capacitor on a tone pot, in this case a variable resistor.
     
  4. cobaltu

    cobaltu Tele-Meister

    Posts:
    164
    Joined:
    Feb 19, 2010
    Location:
    New York, NY
    Everyone's right. It's a 'low-pass filter' or 'high-cut', and a pretty significant on at that. It's -3dB point is ~2KHz. The normal channel should be a heck of a lot darker sounding than the bright channel.

    This amp doesn't have an actual 'bright channel' in the traditional sense but an 'anti-bright channel'. Where the highs are cut on the normal channel rather than boosted on the bight channel.
     
    jsnwhite619 likes this.
  5. dougstrum

    dougstrum Friend of Leo's

    Posts:
    2,234
    Joined:
    Oct 6, 2015
    Location:
    blu ridge mtn cabin
    A cap on the plate resistor of preamp tube is used to control squealing. It works but really kills the highs.
     
  6. Viejo

    Viejo Tele-Afflicted Silver Supporter

    Posts:
    1,442
    Joined:
    Feb 12, 2011
    Location:
    Central IL
    Thank You. I was looking at the 6G3 schematic last night and I had never seen that used before. I knew someone here could enlighten me.
     
  7. Jowes_84

    Jowes_84 Tele-Meister

    Posts:
    181
    Joined:
    Mar 18, 2018
    Location:
    Kraut-Island, Chiemsee
    another special thing about the 6G3 is that compared to the later Fenders (Blackface/Silverface) there is no separate grid leak to ground at the second gain stage
    Also see the voltage divider used after that second stage in order to reduce the signal to a level that does not turn the thing into a distortion machine
    It does do things differently but it works great :) - wish I had one
     
  8. Uncle Daddy

    Uncle Daddy Tele-Afflicted

    Posts:
    1,631
    Joined:
    Sep 26, 2015
    Location:
    Maldon, England

    Like this? I only just got it back from the tec. I built it but left the final startup to him. The "Normal" channel is warmer, less toppy than the Bright channel, which is where the juice is. Volume halfway up equals creamy overdrive, and after that it gets more saturated rather than louder.

    P1130198.JPG
     
    NTC and Jowes_84 like this.
  9. mexicanyella

    mexicanyella Friend of Leo's

    Posts:
    2,737
    Joined:
    Jan 26, 2012
    Location:
    Troy, MO
    I think my idea of prettiest amps ever are from the Fender brownface era. That Strat/brownface Deluxe photo ^^ belongs on a calendar or something.

    Really wishing I’d not passed up a pretty good deal on a brownface Princeton many years ago...I could have some socially distant fun with one of those right about now.
     
  10. NTC

    NTC Tele-Holic

    Posts:
    542
    Joined:
    Mar 17, 2003
    I bet jumpering the channels is very interesting. I really want to try a 6G3 - the circuit is very out of character for Fender.

    Uncle Daddy, what speaker is in your amp?
     
  11. jsnwhite619

    jsnwhite619 Friend of Leo's

    Age:
    36
    Posts:
    3,537
    Joined:
    Sep 10, 2013
    Location:
    Georgia
    I always thought that was an interesting way of doing things. I'll finally be able to hear it for myself one of these days when I finish mine. I'm embarrassed to say how long ago I started it...

    IMG_20210225_221243178_HDR.jpg
     
IMPORTANT: Treat everyone here with respect, no matter how difficult!
No sex, drug, political, religion or hate discussion permitted here.