Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => PC Express and JSchem - Schematics and Layout diagrams => Topic started by: tubenit on November 13, 2006, 04:44:57 pm

Title: 1482 Silvertone amp & Dano Centurian
Post by: tubenit on November 13, 2006, 04:44:57 pm

This is an original schematic copy for the Silvertone 1482. Check for errors.

This shows a modern 3 prong plug and 100 ohm resistors to ground for an artificial centertap for the 6.3v.


also

I owned a Dano Centurian model #275 that was a wonderful amp with an original C12Q Jensen. Very cool tweed sounding amp.  Essentially the same amp as a 1482 but with reverb and a different tone stack.

I converted my Dano from the incredibly goofy piezo reverb (ugh) to a very nice sounding reverb. I also paralleled V1 and eliminated one channel.  This schematic represents what I did.

Tubenit

EDIT:  added a draft design for 1482 Silvertone with one tube reverb. Compare schematic with layout, if there is a difference ........ go with the schematic.

Title: Re: 1482 Silvertone amp & Dano Centurian
Post by: jjasilli on May 14, 2009, 09:25:30 pm

My Version 4 - continuing mods to brighten the tone of this amp.  Previously an Emi Screaming Eagle improved tone and helped somewhat with needed brightness.  To compensate for the speaker, the power tube bypass cap was increased from 25 to 47uF to recapture bass response.  New Mods:

1.  Ch 1 retains a simple "guitar-style" one knob, treble-cut tone control.  The tone cap was reduced by trial and error sound testing from .003uF way down to 470pF!!! This really brought Ch 1 to life. 

I considered trying a Big Muff tone circuit; I'm intrigued by the one knob, mid-cut circuit.   But the simple treble-cut now sounds good; and gets bright enough (I think).  Also it meets my goal of keeping Ch1 close to the stock 1482 circuit and topology.

2.  Ch 2 was further "Fenderized" by lowering the stock plate resistor from 330K down to 100K.  This increased the plate voltage from +108 to +210VDC.  The tone stack had already been converted to 5F2A specs, but remained too dark.  The caps were reduced from Fender spec to 300pF / .003uF.  Now Ch 2 seems to be bright enough and has more headroom.

3.  Finally got around to installing shorting jacks for the inputs.  And, all other plate resistors were replaced with stock values.  The amp is pretty quiet now. 

All in all I'm happy with the results; and it's still great for slide guitar.

EDIT:  schematic revised with minor corrections.  Note correct power tube bypass cap value.

* Note there is a modified schematic also posted by Platefire.