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sIII Tweakers Notes. Other builders feel free to post yours!

This file contains information on tweaking the sIII TMB Channel. Note: the tweaks are not listed in any order. There are several places to adjust gain and tone in this circuit and each of them do it in a different way and to different effect. You may find you only need one of them, a few of them, all of them, or none of them.

**To Increase Gain on TMB Channel**

1. Remove R8
2. Change VR1 to 1M-A
3. Change R9 to any value between 470R and 2.7K--lower values = more gain
4. Bypass R9 with a cap between 0.68uF and 47uF. Higher values = more bass
5. Increase R4 to 220K
6. Increase R7 to 220K
7. You may need to change VR7 to 250K-A or 100K-A to keep the PI from overloading from the increased gain



**To Fatten Tone on TMB Channel**

1. Change C1 to 0.022uF
2. Change C2 to 2.2uF -OR- change R5 to 2.7K -OR- both
3. Change R11 to 33K
4. Change VR5 to 500K-A or 250K-A to give the bass control more useful range.

Enjoy!

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

s2 & I put together some thoughts on how to tone tweak the sIII Normal channel.

The normal channel tone stack configuration is the original 18 Watt Tremolo Channel without the tremolo.

For less distortion:

The normal channel uses two capacitors in series (.0047 uF) off V1b 12AX7 plate with the junction of them going to a 470K bleeder (R29) then to ground . The bleeder resistor from the coupling cap to ground is R29. Replace it with a 100K or 56K.

Changing the cathode resistor by itself won't lower gain if it is bypassed by a capacitor (C16). If you lower the bypass capacitor you will filter out certain low frequencies, which will lower gain a tiny bit. Another option is to just remove the cathode bypass cap C16. Then maybe also increase the Cathode resistor R27 to 1k, 1.5K.

Bass Response:
To tighten up the bass (e.g. for humbuckers) , drop the cathode cap C16 from 47uF to something like 2uF, 1uF, or .68uF

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps