Trinity TRIWATT User manual

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TRIWATT
Builders Guide
For the sole personal use of Trinity Amps Customers.
January 2020, Version 3.7
Parts © Trinity Amps 2005 - 2020
www.trinityamps.com

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Table of Contents
Table of Contents ............................................................................................................................................................... 2
Introduction......................................................................................................................................................................... 5
Acknowledgements............................................................................................................................................................. 5
WARNING ......................................................................................................................................................................... 6
Please Read this Information Carefully................................................................................................................. 6
Version Control................................................................................................................................................................... 8
Guitar Amplifier Basics.................................................................................................................................................... 12
Distortion...................................................................................................................................................................... 13
General Amplifier Operation..................................................................................................................................... 15
Some DO NOTS......................................................................................................................................................... 15
Some DOs..................................................................................................................................................................... 16
Introduction to Vacuum Tubes and Common Terms ............................................................................................... 17
Introduction.................................................................................................................................................................. 20
Switches and wire......................................................................................................................................................... 20
Physical layout .............................................................................................................................................................. 20
Grounding..................................................................................................................................................................... 20
Insulated jacks .............................................................................................................................................................. 21
Minimizing transformer interference........................................................................................................................ 21
Wiring ............................................................................................................................................................................ 21
Assembling the amp ......................................................................................................................................................... 21
Before You Begin ........................................................................................................................................................ 21
Tools .............................................................................................................................................................................. 21
Soldering........................................................................................................................................................................ 22
Tube Pin Numbering .................................................................................................................................................. 22
Assembly Steps Summary................................................................................................................................................ 24
1. Install the Hardware................................................................................................................................................ 24
2 Wiring ......................................................................................................................................................................... 28
Grounding Scheme................................................................................................................................................. 28
3 Install Transformers................................................................................................................................................. 32
4 Power Supply Wiring ............................................................................................................................................... 33
Test the Power Transformer................................................................................................................................. 37
5 Turret Board Construction ..................................................................................................................................... 38
6 Connecting the Turret Board ................................................................................................................................. 40
7 Connecting the Turret Board to Controls............................................................................................................ 42
8 Output Transformer - Output Jacks ..................................................................................................................... 42
9 Input Jacks ................................................................................................................................................................. 45
Input to V1 .............................................................................................................................................................. 47
9 Final checkout........................................................................................................................................................... 48
10 Power Up................................................................................................................................................................. 49
WARNING ....................................................................................................................................................................... 54
Please Read this Information Carefully............................................................................................................... 54
Troubleshooting................................................................................................................................................................ 55
Hum ............................................................................................................................................................................... 55
Volume Test ................................................................................................................................................................. 55
Faulty tube..................................................................................................................................................................... 55
Severely unmatched output tubes in a push pull amplifier ................................................................................... 56
Faulty power supply filter caps .................................................................................................................................. 56
Faulty bias supply in fixed bias amplifiers................................................................................................................ 57

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Unbalanced or not-ground-referenced filament winding...................................................................................... 57
Defective input jack..................................................................................................................................................... 57
Poor AC grounding ..................................................................................................................................................... 57
Induced hum................................................................................................................................................................. 57
Poor internal wire routing .......................................................................................................................................... 58
Poor AC Chassis Ground at Power Transformer .................................................................................................. 58
Defective internal grounding ..................................................................................................................................... 58
Hiss................................................................................................................................................................................. 58
Metal Film Resistor Substitutions ............................................................................................................................. 58
Squealing/Feedback .................................................................................................................................................... 59
Radio Interference ....................................................................................................................................................... 59
Scratchy Sounds on Potentiometer(s)....................................................................................................................... 60
Amp Buzz or Rattle When Installed in Cabinet ..................................................................................................... 60
More Tips for fine tuning your amp......................................................................................................................... 62
Running EL34 Tubes in the TRIWATT.................................................................................................................. 63
Installing a Passive Effects Loop .............................................................................................................................. 64
First the code........................................................................................................................................................... 66
How to read the Color Code ................................................................................................................................ 66
Appendix 6- TRIWATT Bill of Materials..................................................................................................................... 73
Appendix 7- TRIWATT Overdrive Footswitch.......................................................................................................... 77
Trinity Amps 9642-EX-1 Transformer Schematics .................................................................................................... 78
Trinity Amps Schematics and Layouts.......................................................................................................................... 84

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Thank You
Thank you for purchasing your TRIWATT kit from Trinity Amps. We truly hope that you
enjoy building it and that it will be enjoyed for many years. If you have any questions please
do not hesitate to contact us and. Please be sure to check the package contents in case there
are any missing items.
we are always looking for feedback form our Customers on our products. We have checked
the build instructions over thoroughly and are confident in our product. However, mistakes
do happen so our advice is that as you connect each wire and part according to the layout,
cross-check against the schematic. If you find any inconsistencies, or have any concerns,
please let us know. Do not hesitate to contact us! We want this build to be successful for
you and for Trinity Amps!
We’re confident that you will like our product and our support and when you’re completed,
we’d appreciate your comments posted on any of the internet forums such as
thegearpage.net, 18watt.com, AX84.com or trinityamps.com. You will find some extra
business cards in the package. Please keep one and pass the rest around.
We know you have a choice in suppliers and do appreciate your business. If there is any
other product we can provide to you or your associates, please get in touch and we will be
happy to discuss requirements.
Sincerely,
Stephen Cohrs,
Trinity Amps
Web site: www.trinityamps.com
email: [e-mail]

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Introduction
This guide has been prepared for builders of Trinity Amps Kits. It is always being improved
and we would appreciate your feedback and comments to: [e-mail]
Accordingly, content and specifications are subject to change without notice.
We do try to make it as accurate as possible, but it is sometimes hard to keep up with the
changes. Therefore, if you do find an error, please let us know about it and we will correct it.
Suggestions are welcome so if you have one, please get in touch with us.
Sources of help.
Forums: Please use the various forums to get help. They are an excellent resource and can
be found at trinityamps.com, AX84.com, the Gear Page etc..
Color assembly pictures and the latest drawings, tips, techniques are all in the Trinity Amps
Forum, in the Resources Forum. To view the Resources, you need to sign up so go to
www.trinityamps.com and click on the Forum button.
Email: We can’t help with every problem but if you can not get your problem resolved, email
us and we’ll do our best to help.
Phone Call: If your problem can’t be solved, email for a phone appointment.
Acknowledgements
Much of the content in this document is original. Rather than reinvent content, some parts
are based on content from other excellent sources and are hereby acknowledged.
R.G. Keen’s site www.geofex.com - Tube Amp FAQ, Tube Amp Debugging
AX84.com site www.AX84.com - Gary Anwyl's P1 construction guide version 1.0
GM Arts website http://users.chariot.net.au/~gmarts/index.html - Guitar Amp
Basics
www.18watt.com - website for various content and diagrams –Richie TMB
Aron from diystompboxes.com
Parts © Trinity Amps 2005. No part of this document may be copied or reprinted without
written permission of Trinity Amps or contributing authors listed above.

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WARNING
Please Read this Information Carefully
The projects described in these pages utilize POTENTIALLY FATAL HIGH
VOLTAGES. If you are in any way unfamiliar with high voltage circuits or are
uncomfortable working around high voltages, PLEASE DO NOT RISK YOUR LIFE
BY BUILDING THEM.Seek help from a competent technician before building any
unfamiliar electronics circuit. While efforts are made to ensure accuracy of these circuits, no
guarantee is provided, of any kind!
USE AT YOUR OWN RISK: TRINITY AMPS EXPRESSLY DISCLAIM
ALL LIABILITY FOR INJURY OR PROPERTY DAMAGE RESULTING
FROM THIS INFORMATION! ALL INFORMATION IS PROVIDED 'AS-
IS' AND WITHOUT WARRANTY OF ANY KIND.
REMEMBER: NEVER OPERATE YOUR AMP WITHOUT A LOAD. YOU
WILL RUIN YOUR OUTPUT TRANSFORMER!

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Version Control
Version
Date
Change
1.3
12May11
1.4
22Jun, 13
Updated BOM
1.5
29Jun14
Alternative methods to connect leads to turret
1.6
28Jul14
Update impedance switch diagram; note on ROHS added
1.7
23Aug14
Added EL34 Tweak
1.8
20Oct14
Updated bias wiring diagrams
1.9
25Oct15
Updated OD Footswitch ; added PSU layout
2.0
15Nov15
Updated heater wiring description and fuse wiring description
per Occleshaw
2.1
2Dec15
Added mod for Effects loop
2.3
3Feb17
Updated Output Jack layout
2.31
8Mar18
Clarified heater wiring colours to match layout.
3.1
21Mar19
Updated to new Relay Board OD Footswitch
3.2
21Apr19
Clarified new Relay Board OD Footswitch& Installation
3.3
26May19
Corrected R value for bias and OT conns. V5, V6 (G. Vosters)
3.4
15Oct19
Added new OT with additional 3.5K primary schematic
3.6
26Oct19
Updated OD Relay installation Transformer Board
3.7
12Jan20
Updated input jack wiring, clarified fasteners, hardware and
wire. (E. Knapp)

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Custom TRIWATT Lead Description
The TRIWATT was designed by Trinity Amps to capture the classic HIWATT sound
without the usual classic ear-bleeding volume levels. It is closely based on an early '70s style
Hiwatt DR, but utilising either 6V6 or KT66 power tubes for more usable power output.
Furthermore, it has the 3-input configuration used by David Gilmour of Pink Floyd, plus an
Overdrive stage, as found in early '80's “Biacrown era” Hiwatt Lead amps.
Bright channel - perfect right out of the gate. The entire travel of gain knob yields usable
tones. Bright is AMAZING from zero to dimed, with lots of subtle colours in between. This
channel really cuts through the mix.
Normal channel - has usable gain from the bottom all the way to the top, and lots of
subtle shades of clean and semi-clean from around 10 o'clock to 3 o'clock. This channel is
important because it's where most people will probably spend most of their time. The tone,
is big and more detailed.
Link - is like jumping the two channels on a 4-holer. There are infinite shades of tone
possible by blending the two channels' volume controls. The actual "sound" of the link
inputs is subtly more scooped-mid and sparkly, giving one set of knob settings two slightly
different tones.
Tone Controls - Treble, Middle, Bass, Presence - these are less like "boost/cut" knobs and
more like “real” tone controls. They do a lot to the tone in a very subtle way. With
Fenders/Marshalls extreme settings can get painful. TRIWATT never gets painful. Presence
in particular is very authentic - rather than boosting a high treble, it opens up or extends the
top end of the tone to add “air” to the sound. TRIWATT EQ knobs are in very similar
places when compared to original Hiwatt amps, dialed in to similar tones.
Master Volume - turning the master down isn't a tone killer like in some amps. The tone is
not compromised when the master is under around 11 o'clock. IF you set the OD up
appropriately (see below), even with the MV way down - 7 or 8 o' clock, it still sounds huge.
This control sounds big, quiet, and it it sounds big loud!
Overdrive - This control may be the reason someone who owns arguably a Hylight-era
Hiwatt 4-holer, would want the TRIWATT. This is where the TRIWATT "art" lives –a .
Pull out the Overdrive control and you get the extra gain stage of a Biacrown era Hiwatt
Lead amp (push the knob in and it's out of the circuit). This gain stage naturally gives you
more gain and more distortion, as well as more compression. So, for rhythms as well as
leads, it's incredible! The way it works, is that when the Overdrive stage is engaged by pulling
the Overdrive knob, the stage's drive/gain level is set by the Normal and Bright volume
controls, and the stage's outout level is set by means of the Overdrive knob. So it's possible
to set the stage to provide a lot of extra gain but at the same volume level as when its not
engaged. But there are more possibilities. If you have to play lead, bring up the
bright/normal gain stage and starve the overdrive gain and the tone comes forward is more
dynamic and bigger. Turning up the Overdrive, with an LP and humbuckers reveals big
metal tones, yet rolling back the guitar volume and playing more gently yields delicate,
transparent, sparkling cleans with the Overdrive still on. And you can imagine all the shades
in between!!!

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Guitars - The TRIWATT can handle many guitars with aplomb. Tele, Strat, Danos, Ric, Les
Paul with P90's for the single coils, and Les Paul, SG, Seymour Duncan hot-rodded Fender
Cyclone for 'buckers, PRS Mira in both 'bucker and single mode - have all been tested with
this amp, and every guitar sounds GREAT. Also, Hiwatts are known for taking a lot of
pedals really well. The TRIWATT does not disappoint in this area either.
Key Points about the TRIWATT Design
•Big Hiwatt DR clean tones and breakup at more ear-friendly levels
•Vintage style early '70s 103 preamp (with cathode-follower)
•Three-inputs - Normal, Bright and Link, like Dave Gilmour's 3-input amps
•Switchable 80s' "Biacrown era" high-gain OL/Lead mode, with Overdrive control
and optional footswitch
•Early Hiwatt style 12AT7 phase invertor, with 12AX7 option for increased breakup
•Solid State rectified, fixed-bias, 22 Watt 6V6 power stage, based closely on Hiwatt
original
•Optional 6V6 or KT66 operation with External Bias Control and Bias Test Points
•Transformers closely based on original Hiwatt Partridge transformers for definitive
tone
•Preamp easily modded for Pete Townshend or Jimmy Page/SAP variants
•Compact physical format and cabinet - chassis also fits other standard cabs

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Guitar Amplifier Basics
Electric guitarists can be fairly criticized for their reluctance to change to new ideas
and technologies; however, there is no doubt that a classic 1950’s guitar and tube
amplifier in good condition still sounds great in modern recordings. This is a
testament to good design from the start. What has improved today is consistency,
and the cost benefits of production line manufacturing. This is offset by the rarity of
good guitar wood (it makes a huge difference, even on an electric guitar), increased
labour costs for both guitars and amplification equipment, and the availability of good
and consistent quality tubes.
There is also an element of nostalgia, with memories of many of the great players of
years gone by, and the desire to use the same types of instruments and equipment to
recapture the magic. Vintage instruments and equipment have also become valuable
collectors items (some with very inflated prices) which adds further to the desirability
of older tools of the trade. There has been a recent trend by many companies to re-
market their original instruments and equipment; new guitars can even be bought now
‘pre-aged’!
This desire for vintage equipment is also related to guitarists’ reluctance to part with
tube amplification, and there are many reasons why tube and solid state amplifiers
behave differently. Quite simply, if players prefer the sound of tubes, they will
continue to buy and use them. Below are some fundamentals.
Input Impedance Typically 1M, 500K minimum (humbucking pickup guitars
have volume pots up to 500K, single coil pickup guitars typically of 250K) .
Tone Controls Magnetic guitar pickups are inductive, and require
compensation, although this opportunity is also used for tone enhancement, not just
correction. Without compensation, they have a strong low middle emphasis and
little high frequency response - overall a very muddy and muffled sound. This is
why typical hi-fi Baxandall treble & bass controls are unsuitable.
To hear the natural sound of a pickup, use a typical guitar amp with the middle set to
full, and bass and treble on 0. This is actually sets a flat response in the amp (see
below). Expect to hear a muffled and muddy sound. And that's the whole point of
these tone controls providing compensation for the natural sound of a pickup - the
middle control simply boosts the pickup's normal ‘middley’ sound. The treble and
bass controls do the opposite - they boost higher and lower frequency levels, leaving
a notch in-between for middle cut (see the Fender/Marshall comparison below). So
with typical settings of a bit of bass, middle and treble, the overall tone equalization
complements the natural pickup sound for a balanced response of lows, mids and
highs.

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Distortion
The overdriven sound of a tube power amplifier is highly desirable, with many different
output stage designs to produce the variety of trademark sounds heard on modern
recordings. The only problem is that a tube power amplifier is only capable of producing
this sound at one volume (usually, fairly loud!).
There are probably 3 distinctly identifiable types of tube power amplifiers used:
Leo Fender's classic early designs used 6V6 tubes, and later, the higher powered 6L6's. This
gave a characteristic full and punchy sound, suitable for many styles of the day, and later.
Steel and country players like the chime-like clean sounds, and blues players were quick to
discover the classic way it breaks up when pushed hard. At really high overdrive, though,
the sound becomes quite dirty, with bass in particular sounding flabby.
Marshall designs started as Fender copies, but soon switched to EL34 output tubes, possibly
for local supply reasons. Anyway, the rest is history. These tubes exhibit a softer overdrive
transition, and maintain clarity even at high overdrive levels. They also have a limited
middle response, giving rise to the famous Marshall crunch sound. The lower powered
EL84 tubes have similar characteristics.
Vox AC30 (and the more popular top boost model) uses a Class AB power amplifier design,
with the tubes biased ‘hot’, so while this operates in class A at lower levels, it is a class AB
design. There's no negative feedback in the power amp either, so this gives a different
sound, often described as a sweeter overdrive. Listen to Brian May's sounds for plenty of
good examples.
The Fender and Marshall designs use class AB for their output designs, biased with the
tubes almost off with no signal. This is more efficient (more watts per tube), and better for
tube life. When you play, tubes take turns handling each half of the signal. This leads to
some (unwanted) distortion as the tubes cross over. Class A designs are rare in medium to
high power guitar amps, but true class A has the tubes operating at half power, with no
signal applied. When you play, the tube fluctuates between full and no power, so there is no
switching to add unwanted distortion. This is a very superficial explanation; please read
elsewhere on the Internet for more detailed descriptions.
Wide Dynamic Range A plucked guitar string requires a wide dynamic range
to handle the initial peak, and then cleanly amplify the decaying string
vibrations. Some poor designs do not have this capability in their preamp stages, let
alone the power amp to handle this. Pre-amplifier stages need generous power rails,
and should not have gain stages which cause the initial plucked part of the string
sustain envelope to be clipped.
Instrument Speakers Unlike hi-fi speakers, which are designed to keep the
coil entirely within the magnetic field to maximize linearity, instrument speakers are
designed to have the coil partially leave the magnetic field at the extremes of cone
travel. This is partly to protect the speaker, but also produces a ‘soft-clipping’ effect

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which is desirable with guitar amplifiers. It is also therefore important to match
speaker power ratings reasonably closely with the power of the amplifier. Popular
instrument speakers are available from Tone Tubby, Celestion, Jensen and others.
Note: If you were to use two cabinets hooked directly into the amp, be sure to set
the amp at half the impedance of the cabinets. For example, if your cabinets are 8
ohms each, set the impedance selector to 4 ohms.
Durability Most musical styles will require the amplifier to be overdriven for
extended periods of time, and the amplifier must be designed to provide this without
duress on any components. Common non-guitar design principles assume that
circuitry will be designed to avoid overdrive, and technicians working in this field
have to ‘un-learn’ many basic assumptions. Popular circuits have evolved through
trial and error, due to a general lack of documented knowledge in the field of non-
linear amplification.
Road Worthiness Musical equipment of this type needs both physical and
electrical protection. A band often has its equipment transported and set up by a
road crew with little guarantee of physical care. Likewise, an assumption should be
made that the output stage will at times be inadvertently shorted, so most
professional equipment is designed to handle this contingency, preferably
electronically, and at the very least without fuses inside the chassis.

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General Amplifier Operation
Some DO NOTS
•Never, Never, Never run the amp without a speaker plugged in. This can cause
major damage.
•Do not flip the power switch off, and then back on rapidly. This can cause
power supply damage.
•Never replace a burned out fuse with a bigger-amperage one. Remember -
there was a reason the first one burned out, usually protecting something
more expensive. Putting a bigger fuse in will just ratchet up the power level
until something really vital burns out. If the second equal-rating fuse pops,
turn it off and get a tech to look at it.
•Never ignore signs of high heat inside - a wisp of smoke or a burning smell is
NOT normal.

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•Your amp produces lots of heat, and will continue to do so even if you block
the fresh air vents. Blocking the vents will overheat the amp and you may
have to get some very expensive repairs done.
•Never ignore a red glow other than the small orange ends of the filaments. A
red glow over a large part of the internal plates of the output tubes means
they're about to melt. If you notice this, shut it down and get a tech to help
you find out what it wrong.
Some DOs
Add another speaker into the "external speaker" jack; a mismatched speaker load
won't kill it, while an open circuit (disconnected speakers) may do so.
Overdrive the stuffing out of it. Tubes are very forgiving of massive overdrives,
unlike solid state gear. As long as they tubes don't overheat for long periods, it's not
fatal.

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Introduction to Vacuum Tubes and Common Terms
Reprinted with permission from Aron from diystompboxes.com
Here are a few terms that you may see online when referencing tube schematics. Like distortion
pedals, tube circuits seemingly have their own language! I present this knowledge in the hopes that
it may help you decipher the interesting life of tubes! :-) Below, is a picture and a very simplistic
view of a tube stage.
As you can see above, in this tiny snippet
of a tube schematic, the terms you commonly see are there in this triode stage example.
Plate - the plate is usually connected to a plate resistor which is usually connected to the B+ or
power supply voltage. Typical Plate Resistor values are 100K, 150K, 220K. Larger values equal
more gain.
The Grid is where the signal enters the tube.
The Cathode is usually connected to a cathode resistor which usually goes to ground. The cathode
resistor, along with the Plate resistor, control the gain of the tube stage. Typical values are
anywhere from 100 ohms to 10K. Smaller values = more gain.
It is common to see a cathode bypass cap connected in parallel with the cathode resistor. By
altering the values of the cathode resistor and cathode bypass cap, it is possible to roll off various
degrees of bass with this triode stage. The cathode resistor and plate resistor control the biasing of
the tube. The cathode bypass cap also gives the stage more gain.
Sometimes you see a capacitor in parallel with the plate resistor, much like the cathode resistor
bypass cap. It is usually a small value (i.e. .001uF) and it rolls off highs in the stage. Sometimes you
see a high frequency roll off cap going from the plate pin to the cathode pin - 350pf->500pf in
value.

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You will also see a coupling cap in
between triode stages. The coupling cap controls the bass and rolls off bass between stages and
blocks DC from entering the next stage - which could throw off the bias on the next tube stage.
As usual, smaller values roll off more bass, larger values retain more bass between stages.
Another modification you may see is a Grid Stopper Resistor, this can also control gain between
stages and also interacts with the tube to roll off highs. Values can be 1.5K->100K. Larger values
roll off more highs and reduce gain between stages. The Grid Stopper Resistor works best when
mounted directly or as close as possible to the grid pin.
"Complete" typical tube preamp stage:

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The grid ("leak") resistor, typically sets the impedance of the stage and biasing. It is interesting
because it and the previous stage's plate resistor form a voltage divider on the signal. What this
means to you is that the grid leak resistor can be used to control the level into the stage. Low grid
leak values will attenuate the signal into the tube stage. If you look at different tube amp
schematics, you can see where they control the level into the stage by using different values for the
grid leak resistor. There is a maximum value that you need to adhere to. Check the datasheet for
the tube you are using to see the typical value of the grid leak resistor. This particular circuit is
called cathode bias which you can read about here.
In summary, the cathode resistor, plate resistor and grid resistor, determine the biasing of the tube
stage. The cathode bypass cap controls the degree of bass reduction - generally 25uF passes all
frequencies - commonly used in Fender amps, 1uF an 0.68uF are used in Marshall amps. A
capacitor can be placed in parallel with the plate resistor to roll off highs and you see this in bass
channels of amps sometimes. The plate receives the voltage from the power supply through a plate
resistor, the grid receives the AC signal as input and the cathode is grounded through a cathode
resistor.

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Building an Amp
Warning: Do not attempt to build a guitar amp unless you know how to work safely with the
dangerous voltages present in a tube amp. These can exceed 700 volts.
Introduction
If you have purchased your Trinity Amp as a kit, this guide will help you build a tube guitar
amplifier. It is oriented towards someone who knows a little about electronics but is new to do-it-
yourself amps. It outlines a simple path to getting a quality amp build.
Switches and wire
Use standard UL approved switches with a 125V/3A rating for the Power and Standby switches.
Use 20 or 20 Gauge insulated solid wire with a 600V rating. It is good to get a variety of colors so
you can color code your wiring.
Use 18 Gauge stranded for mains wiring.
Physical layout
Make sure the jacks, sockets and pots mounted along the edge won't interfere with parts mounted
on the underside of the chassis. Imagine how chassis will be mounted in the cabinet and make sure
there is enough clearance for the speaker and mounting brackets. Trinity amp chassis are laid out
with serviceability and neatness in mind.
Grounding
It is recommended that you follow the layout provided with your Trinity Amp. It has been tested
and has proven reliable. If you choose to deviate, consider the following information.
Amps traditionally use the chassis for signal ground. This is not the best choice since it can create
ground loops and bad ground connections may develop over time. It is better to use star
grounding in which all of the local grounds are collected at a single ‘star ground’ point. With star
grounding there is only one connection between the chassis and signal ground.
Here are some rules for laying out a star ground. More information on grounding can be found in
the Tube Amp FAQ and the Tech Info page of Aiken Amplification.
(1) Connect the power transformer center tap directly to the negative terminal of the first power
supply filter capacitor (cap) then run a separate wire from the negative terminal to the star ground
point.
(2) Collect the ground points of each tube and its associated resistors and capacitors to a local
ground point that is not connected to the chassis. Run one wire to the star ground point from each
collection.