acorkos 6/15/2017 6:43 PM
94 Twin Amp problem...
Clean channel 1 sounds thin...if I switch to the gain boost setting on channel 1, all is fine. Channel 2 is fine as well. If I stay in the clean setting of channel 1, and engage the bright boost switch, the overall gain is boosted and the thin-ness is gone. What gives? Thanks for your help!
 
Randall 6/15/2017 7:15 PM
http://allpartsuk.files.wordpress.co...03/94-twin.pdf
 
acorkos 6/16/2017 10:12 AM
[QUOTE=Randall;457344][URL="http://allpartsuk.files.wordpress.com/2012/03/94

do you mean that the manual will describe this as normal?
 
g1 6/16/2017 11:48 AM
No, that is the service manual. I think he just wanted to get the schematic in here to aid discussion.
So, when you are on the clean channel, turning the bright boost off makes it sound more thin?
 
acorkos 6/19/2017 2:02 PM
Quote Originally Posted by g1 View Post
No, that is the service manual. I think he just wanted to get the schematic in here to aid discussion.
So, when you are on the clean channel, turning the bright boost off makes it sound more thin?
yes

turning on the bright boost seems to boost all frequencies and overall gain
 
lowell 6/19/2017 3:35 PM
Sounds like maybe the bright cap is shorted.

This would cause the bright setting to be perceived as louder, and potentially thicker.

Is it possible the thin sound is normal and the bright setting is overly loud and thick? Just a thought.
 
acorkos 6/20/2017 4:38 PM
Quote Originally Posted by lowell View Post
Sounds like maybe the bright cap is shorted.
Bingo

not sure if it is shorted, but it's leaking, metering erratically when I set my DMM to 200MOhm...other caps meter at about 1.0 on that setting. I swapped in a new 100pF cap and all is well (original was 68pF)

Thanks for your help!
 
lowell 6/20/2017 4:59 PM
Awesome!