Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: dude on October 16, 2018, 01:05:11 pm
-
Where would one look if distortion is raspy?
Marshall amp turned up, 6V6s, distortion has that raspy sound with a power cord and les Paul, coming after the chord is hit hard I hear an unwanted raspy distortion "a fraction of a second after"? Bias is right on, amp sounds great at lower volumes, tubes are good. doesn't do it as much with a strat but it's there if vols are up.
Just where do I start looking?
al
-
Since you are using the term "raspy" I am assuming you are hearing it audibly vs. seeing it on a scope. Does it sound raspy with other speakers? A raspy sound and loud volume when you first strike a power chord could be indicative of a speaker distorting, bumping or partially blown.
-
Speakers are good, don't have a scope, raspy with other speakers even a Blue dog. Maybe this is normal when gain is up..? Where can I read about blocking distortion?
-
Where can I read about blocking distortion?
Google is the first place I always check.
-
Read about Blocking Distortion and Crossover Distortion at Aiken's site. All my speakers have that raspy distortion with the same amp, good quality G12H30's, Blue dog and a Red Fang, hopefully their all not blown, :sad2: . All my other amps have that raspy distortion with a Les Paul too. I think I have the gain up too high and I'm a strat player, my ears aren't use to humbuckers. I need to listen to Hendrix on my CD's and listen if I hear that crunchy, raspy tone, might be normal, ha. I don't usually play with high distortion, just at the edge or a hair beyond. Listen long enough I might hear the cows coming home :laugh: .
This a good site , plain and simple: https://robrobinette.com/Tube_Guitar_Amp_Overdrive.htm
Don't fix it if it ain't broke!
-
I can't hear raspy for all the string buzzes and other finger farts. :icon_biggrin:
But raspy is not a sound I would associate with blocking distortion.
-
Marshall copied the 5F6A Bassman for their JTM45, the bassman used 270K mixing resistors to vols ,the JTM45 uses 470K, what does this difference do to tone?
Also, if I wanted to reduce the brightness on the bright vol (JTM45): what if I take the 500p cap off the 470K mixing R and put a say 100p bright cap on the vol pot, wiper to input, would this give me the 5F6A tones on the vol pots? like the bassman
Also, I have the Neg feedback R 47K (JTM45) to 8 ohm tap, the 16 ohm tap would give more feedback? Thus less or later distortion?
-
As I understand mixing resistors, their goal is to reduce channel interaction, providing a worse path backwards for the signal to the other channel, but otherwise they shouldn't impact the tone at all.
~Phil