From mzait–(at)–ol.com Fri Feb 7 10:31:05 CST 1997
Article: 37595 of alt.guitar.amps
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From: mzait–(at)–ol.com (MZaite)
Newsgroups: alt.guitar.amps
Subject: Re: Harp amp mods
Date: 7 Feb 1997 01:34:01 GMT
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If you are using a Fender Blackface or Silver as your test bed, try one
with a 2
output tube set-up.
1) replace the 1M on the 1st input jack with a 5M resistor.
2) replace that channels 100K plate resistor with a 470K
3) replace the 1.5K cathode res. with a 2.7K, and leave the 25/25 bipass
cap in place.
4) decouple the stage with a .047 uF.
5) decrease slope res. from 100K to 56K
6) replace the Phase Inverter 12AT7 with a 12AX7.
7) If it has a tube rectifier, try a big bottle 5U4
8) here comes the BIG one install 6V6’s to replace the 6L6’s, and install
a dropping res. of high wattage to lower the screen voltage, say 500 ohm
10 watt.
9) set the bias to 27mA / tube .
10) plug in and give it a blow.
Later DR.Z