Biasing a Silvertone 1484

sixstring531

Silver Supporting Member
Messages
3,232
Ok - friend needs some help. He has a Silvertone 1484 and I am looking to rebias it for him but can't find any bias pots -- is there something I don't know on these older amps? I have the equipment to bias (I do my own) but I can't find anywhere to adjust it on this old beast.

Help anyone?
 

SatelliteAmps

Member
Messages
6,168
It doesn't have a bias pot. It is a cathode biased amp, so you have to change out the resistor. It's the one attached to the cathode of the power tube(s).

Is the bias way off?
 

sixstring531

Silver Supporting Member
Messages
3,232
Haven't even checked it yet - didn't want to do anything before I got all my ducks in a row. Now I know, thanks man. :) I love this place :)
 

soldersucker

Member
Messages
2,768
Congrats! cool amp eh.Found mine last weekend and i'm liking it.Did you get the cab to?
2009_0812tray412norce14840148.jpg
2009_0812tray412norce14840151.jpg

2009_0812tray412norce14840154.jpg
 

Trout

Member
Messages
7,549
It doesn't have a bias pot. It is a cathode biased amp, so you have to change out the resistor. It's the one attached to the cathode of the power tube(s).

Is the bias way off?


Hey Adam,

Do you have a better copy of that particular amp schematic?

The one over at schematic heaven is weird.
Looking at the thing it looks like fixed bias (almost) or possibly some drawing someone drew on lol
http://www.schematicheaven.com/bargainbin/silvertone1484.pdf
 

SatelliteAmps

Member
Messages
6,168
It is fixed bias. I mistakenly said it was cathode biased (I had been working on a 1471 all day, and just got them backwards in my head). Same deal as JerryP pointed out.

Trout-Sorry, I don't have anything better than that one. It's pretty crappy, and with the rats nest that is inside those amps, it just takes a bit of extra care to get it all sorted out.
 




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