Grateful Dead Music Forum

A place to talk about the music of the Grateful Dead 

 #107049  by JonnyBoy
 Mon Dec 26, 2011 1:44 pm
Is it possible to remove tubes in the power section, basically only run it off two tubes to get it to sound more like a Deluxe kinda thing? If yes, which ones? (I Thought I heard you could do this, but never have.)
 #107051  by waldo041
 Mon Dec 26, 2011 1:51 pm
the outside 2 or the inside 2, but the amps output impedance changes from 4ohm to 8ohm so you may want to rewire the speakers as well.

 #107054  by playingdead
 Mon Dec 26, 2011 4:33 pm
True ... it only drops to f-cking LOUD from REALLY f-cking LOUD. Gotta love tube amps!

I had a new Twin Reverb in high school ... we played a party in someone's living room when there was some orange sunshine going around ... among the things I noticed (other than the neck of my Les Paul curving like a banana if I looked at it) was the louder I turned the amp up, the CLEARER it sounded ... not louder, just clearer. I had that sucker dimed. I can only imagine how damn loud that must have been in that little room. The drummer snapped the steel shaft on his kick drum pedal beater, that's how hard he was playing. LOL
 #107057  by JonnyBoy
 Mon Dec 26, 2011 5:44 pm
HA! that is what I was afraid of. I would think others would be doing this more often if not. I have been wanting a Hot Rod deluxe III for various reasons, also for the super Jerry clean on it. The presence knob is something different for me and I liked it too. I got some new filter caps and tubes coming so I wanna see if I still love my twin. Using it as a preamp fried my 400 volt filter caps, and the tubes are shot. I am replacing them with 500volts. If I don't see the need it will be traded in to the guitar store for the deluxe! Unless someone here wants to buy it for $450.
 #107067  by JonnyBoy
 Tue Dec 27, 2011 4:35 am
cuz I pulled the tubes and didn't have the power section shunted properly so I removed it. Moral of the story? As Waldo mentioned a few times, If you are tapped and don't have a shunt to the power section AND remove the power tubes, you run the risk of fried filter caps. They were 16 yrs old when I got it/tapped it, prolly ready for new ones then anyway. I played it an awful lot that year before I got my SMS.
 #107072  by waldo041
 Tue Dec 27, 2011 7:20 am
not too mention that pulling the power tubes increases the voltages across the board! the recommended voltage for the bigger filter caps is 500volts or higher if you play with the tubes removed.

 #107124  by mijknahs
 Wed Dec 28, 2011 7:53 pm
How do you know if your filter caps are fried?

Mine were new around 1995 and I've used it as a preamp pretty much the whole time since then.

My preamp tap does shunt the power section to ground but I don't know if that helps. I usually don't have power tubes in it unless I'm using it as a combo amp (which is rare).