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tweed bassman mod for classic 30


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5/30/2000 6:36 PM
dale
tweed bassman mod for classic 30
i posted this yesterday but it seems to have disappeared. anyway, has anyone done david becker's tweed bassman mod for the pv classic 30 on steve aloha's site. this is not the mods steve did, but the david becker mod tweed mod. any thoughts on the results? was it worth it, and what were the sonic differences?  
 
thanks,-dale
 
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6/9/2000 1:51 AM
Steve Ahola

Dale:  
 
    David Becker basically just translated my Classic 50 mods over to his Classic 30, with a few changes. I've heard from a few people who did the mod to their Classic 50 but I'm not sure about the Classic 30... David (like me!) was utterly blown away at how different his amp sounded after doing this mod. (I had figured that I would be in for some long nights fine-tuning the design, but it sounded pretty damned good right out of the box, so to speak.)  
 
... what were the sonic differences?  
 
    Like night and day... instead of having a wannabe-Boogie preamp, the modded amp has a real dc-coupled pair with cathode follower (just like a tweed bassman or an early Marshall) for lots of vintage crunch. The cathode-follower does not drive the tone stack directly, but there is an additional gain stage that drives the tone stack from the anode (this was part of the basic Peavey design that I did not change). Having that extra stage between the CF and tone stack seems to give the circuit some added "zing" compared to other 5F6A-based designs. So much so that I may try adding that "extra" stage to some of my other amps...  
 
    While my Classic 50 doesn't have the fuller bass response of my Hot Rod Tweed modded SF bassman head, what is nice about it is that you can get interesting sounds at all of the settings of the pre-gain control... on some of my amps there are just a few "sweet" spots on the pre-gain control, with the other settings sounding a bit "dull and uninteresting" to my ears.  
 
Steve Ahola
 

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