Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: clyde on October 01, 2016, 04:19:03 pm

Title: 6G6-A Grid Blocking?
Post by: clyde on October 01, 2016, 04:19:03 pm

This one has me stumped.  All new tubes, everything seems to spec inside the amp.  When you strum hard with the volume and bass up on the Bass channel, the signal seems to disappear and then is distorted.  I lowered the value of the grid resistor on stage 3 to 470k from 1M and it helped but didn't completely stop it.  The normal channel is unaffected.  It has to be an extremely loud transient to make it happen.  Under rather more normal playing the amp sounds killer.  The bass control doesn't seem to be very effective as well, not sure if this is part and parcel of it.  Thanks.


http://el34world.com/charts/Schematics/files/fender/Fender_BASSMAN_6G6A.pdf (http://el34world.com/charts/Schematics/files/fender/Fender_BASSMAN_6G6A.pdf)

Title: Re: 6G6-A Grid Blocking?
Post by: PRR on October 01, 2016, 11:06:00 pm

Voltages on that Bass channel first tube?

Title: Re: 6G6-A Grid Blocking?
Post by: clyde on October 02, 2016, 08:16:07 am

P1 (G2)- 153v, C1- 1.5v, P2- 276v, C2- 155v.  Thanks again. 

Title: Re: 6G6-A Grid Blocking?
Post by: clyde on October 12, 2016, 08:08:12 am

Bump before page 2 obscurity.