Not All 45s are Colts
                         by Ross Hershberger

OK,  I'm on to your tactics now.  I want the Anti-45 Cabal to reveal
yourselves and make a clean breast of it for your own good and the good of our
hobby.  Excuse me, I'm speaking to the fiendish plotters who have conspired to
keep from us the TRUTH that the 45 triode is an ASTONISHING REPRODUCER OF
Permit me to explain.
I have been planning for some time to build a small SE triode amp to drive
headphones.  I originally intended to use the little 10Y DHT because nobody
else had and that's a good reason for me to do it.  Finding no affordable OPTs
for it, I relegated my 10Ys to display status.  Recent articles on SE 45 amps
piqued my interest in that tube, particularly Gordon Rankin's piece in Sound
Practices on the Wavelength Bugle amp.  I collected the necessary parts from
diverse sources (thanks, Karin Preeda for OPTs, and Tony Cirella for oil caps,
Black Gates, A-B resistors and patience),  and set to work cutting, drilling,
punching, reaming, nibbling, sawing, grinding, filing, sanding and painting a
9 X 15 aluminum chassis and bottom plate.  I had all of the parts mounted and
everything wired except the filament supplies and passive audio components
when the project was interrupted by a 2 week vacation in Europe.  I completed
it upon returning and proceeded to break the amp in by playing a random
variety of discs through it and a pair of Spica TC60s.  After a day or two I
opened the amp up to build a DC heater supply for the input tube and rearrange
some grounding to get rid of hum and powerline buzz that was audible through
the headphones.  I didn't expect much from it.  I had planned the amp
primarily to run 'phones and had added 'speaker binding posts as an
afterthought, thinking that someday I might use it as a near-field desk
system, or buy Lowthers or something really efficient and need (and only have
ROOM FOR) a teeny amp.  I expected no dynamics, flat soundstage and restricted
bandwidth from 87dB efficient speakers. 
  I was DEAD WRONG! This cheap, dinky old tube is nothing short of a stop-
dead-in-your-tracks-staring WONDER!  After only 10 hours of playing it in the
background and expecting nothing, its unique sound repeatedly dragged me out
of the kitchen, away from the computer, up from a nap and out of the shower to
shuffle into the living room pushing carpet fuzz with my dragging chin,
knocked mindless with awe that a handfull of parts, a 60-year-old tube and a
quickie design was showing me all of the tangible musical loveliness that a
half-dozen high dollar commercial amps had all managed to hide.
  Why didn't I know this before?  Who sat on this secret, this 300 MPG carb of
the audio world?  Howcum Gordon R and a few others had this clue that so many
of us ignored?  Well, Conspiracy, that's how.  We are being BRAINWASHED by an
EVIL CABAL!  HOODWINKED by the WICKED PLOT to deprive us of midrange
loveliness and acoustic beauty of the Marvelous 45 in our living rooms!
  How did I manage to slide in under the radar and make this discovery without
bringing down upon me the cabal's Ninja Strike Force and its full-strength
mind control efforts (quote: "The 300B is best", whispered over and over in
your ear all day long, just below the noise threshold, but persistently
worming into your subconscious to BLOT OUT any thought of alternative DHTs)?
How did I avoid this?  By accident.  I didn't tell anyone that I was going to
build it.  Nobody who believed me, anyway.  I didn't watch TV (and haven't
since the late '70s).  I didn't read mainstream audio magazines.  The Cabal
were unaware of me and their most powerful mind control conduits were blocked,
allowing me to stumble by accident into the secret that they have been hiding:
the 45 triode reproduces vocal and instrumental music with startling realism
and breathtaking beauty.  I don't know what part of all of my many previous
amps has been choking off the presence, harmonic balance and natural timbre of
my favorite recordings, but the 45 DHT is letting it through in all of its
  Sorry. I'm raving, but I can't help it.  I would prefer to write restrained,
equivocal, self deprecating descriptions of this project like "sounds pretty
good, considering how little it cost to build" and "as good as some commercial
amps for certain undemanding kinds of music".  I'm sure my credibility will
suffer for characterizing a simple, cost-compromised SE amp like it was a
revolution, but the difference in sound between this dinky little thing and
the host of PP amps that it shares a room with is at least as great as the
difference that I heard between my first tube amp (PP EL34s, Dyna OPTs, custom
built from VTL designs by a local tech) and the previous two decades of
transistor amps (SAE, Sony, Adcom, Parasound, etc).  Seriously.  I'm not the
only one who thinks so.  Yesterday, Gina T, known to many REC.AUDIO.TUBES
readers as TRILLN451 and "Gina The Warrior Princess" to RAT's guiding light
Uncle Ned Carlson,  confirmed my subjective impressions.  She has heard at
least 10 amps and as many sets of speakers in my home in the last 3 years,
including high-buck Jadis and VAC designs.  She was amazed by the naturalness
of vocal presentations and stringed instruments from the SE 45. We played one
disk after another and every time heard more presence, less electronic sound,
more depth and greater realism.  This was not a subtle, incremental
improvement.  It was just the most musical reproduction that I have ever had
in my home.  Second place (custom A-N SE 300B Kit 1/Unity Audio Sig Pyramids)
isn't even on the same lap.  Recordings that I have played over and over for
years grabbed my attention with an immediacy that I had no idea was there.  I
remain stunned, amazed and chagrined that so much could come from so little.
  It's not perfect.  Surprisingly, with only 2 WPC available, power output is
not a problem.  With the 87dB efficient Spica TC60s, I get 75dB levels at my
listening position with about 1V RMS to each 8 Ohm speaker, about 125mW each.
That's more than sufficient volume for most music and leaves adequate headroom
for dynamics.  The lowest bass is not up to the best current standard.  Below
100Hz, it goes kinda warm and unresolved, but not boomy or flabby.  The pitch
definition is still good down there, but the balance on bass-heavy material
(say, Chemical Brothers' "Block Rockin' Beats" as an extreme example) is
notably light and could be tighter, even on these 'easy' 2-ways that roll off
steeply below 50Hz.  The bass into 32 Ohm 'phones driven from the 16 Ohm tap
is as deep and tight as you could want, however.  I have to give some of the
blame for bass problems to my substandard room (8' X 15' X 24"), which has
never given a credible bottom octave from any of the many amp/speaker
combinations that I have tried.  I finally gave up a few months ago on the
bottom octave, selling my Sumo subwoofer and trading off a Crown power amp.
The bass has improved as the SE 45 amp has broken in, with considerable
changes over its approximately 50 hours of use.  Better bass may be coming as
all of the bits inside become comfortable with each other.
  Large scale, complex music like Wagner is better served by something
(speaker and amp) with bigger power reserves, wider bandwidth and tighter
woofer control.  This SE 45 plays it, but can sound closed-in during passages
where a lot is going on, loudly, all at once.  I wouldn't expect a big
orchestra to be this amp's strong suit, and indeed it's a rare product that
sounds credible with that material, in my experience.
  I'm not blowing my horn over a great, worldbeating design that I came up
with.  I built a decent amp that's dead conventional, as you can see from the
description below. You can build a better SE 45 amp than mine with
ridiculously little effort.  It you decide to, see Mike LaFevre at Magnequest
for OPTs and you'll get better trannies than mine at a very fair price.  Use a
higher voltage PT than my castoff vintage unit and design around a choke input
filter for the HT, maybe using all Black Gate or Cerafine caps, for better
regulation.  I intended to use the parts at hand to make something unique,
cool looking and functional for headphones, not an ultimate sonic masterpiece.
I'm not responsible for this awesome sound, it's the 45 DHT gracefully guiding
the music through my clumsy design.
  Music lovers need this tube.  Audiophiles should have it to combat the mind
control of the Evil Cabal's 300B agenda.  Home amp builders will bless it for
ease of implementation.  Get yours now and start hearing what the Cabal has

Long live the 45.
Down with the Wicked Cabal.
Ross Hershberger


Type: 2-stage single ended tube power amp with input attenuator. 1 6CA4, 1
6SL7GT, 2 #45.

B+ power supply:
approx 550 VRMS CT from PT of scrapped Olson 6BM8 PP integrated amp.
6CA4 rectifier.
input cap:  22uF 630V Angela MP paralleled with NOS 8uF 400V Astron oil/paper
Filter choke: 5H 100ma (Thanks, Kevin Carter).
Main reservoir cap: (325v available here) Black Gate 150uF 350V paralleled
with NOS 8uF 400V Astron oil/paper (100k 2w 'bleeder' resistor across).
B2 supply to input tube:
choke: 20H 20ma Hammond 1700 Ohm choke from 'main' reservoir cap.
driver reservoir cap: 22uF 630V Angela MP paralleled with NOS 8uF 400V Astron
oil/paper (308V available here)

OPTs: One Electron UBT2 air gapped SE 15W units.  Pri Z 4800 Ohms.  Max DC:
110mA.  Note: Pri DCR of 455 Ohms knocks 15V off of the B+ at 35mA! Note #2:
These are a screaming bargain at $230/pair.

input/driver tube: 6SL7GT or 5691, one 'half' per channel. 100K resistive
anode load (I used some NOS 50 year old molded carbon resistors from a
Hamfest).  1K cathode resistor (carbon film) bypassed by 100uf 10V Black Gate

Output tube cathode resistor: 2 2K7 Allen-Bradley 2W CC in parallel (1K35)
with 220uF(?) 100V Black Gate bypass cap.

driver-power Coupling Cap:  .25uF Handmade Electronics oil cap (Thanks, Tony)

Input attenuator: Alps conductive plastic 100K log stereo with big square
black metal body, placed within 1" of both input RCA jacks and 6SL7.

All filament and heater supplies (3) use 15A, 45V Schottky barrier rectifiers
with heat sinks, C-R-C filtering using conventional electrolytic caps
(bypassed with film caps cuz I'm anal, but if you've read this far, you are
The 45 fil supplies run from 2  2A 6.3VCT Hammond transformers.
The 6SL7 heater supply relies on 2  6.3V windings on the B+ PT. 

The following are star-grounded to a point on the chassis at a forward corner
of the PT:
PT internal shield
IEC power socket earth pin
B+ winding center tap
all B+ filter cap negative leads
negative lead of input tube filament supply
probably other stuff that I can't think of at the moment.

Each channel has a ground 'bus' running from its OPT sec. common (back of
chassis) to its input jack common (front of chassis), which is chassis
attached to this bus are the channel's tubes' cathode returns.

k d lang: Drag
Emily Bezar: The Moon in Grenadine
Madeline Peyroux: Dreamland
"  : Automatic For The People
Red House Painters: Ocean Beach
"                  : Songs For a Blue Guitar
Richard Thompson: Mirror Blue
The Sundays: Static and Silence
Andres Segovia: Decca Centennial Box Set
Meat Puppets: Too High to Die*
suddenly, tammy: We Get There When We Do
Miles Davis: Kind of Blue
Portishead: PNYC Live
Belle and Sebastian: The Boy With The Arab Strap
Massive Attack: Mezzanine
Morcheeba: Big Calm
Moloko: Do You Like My Tight Sweater?
Clannad: Banba
X: Unclogged
10,000 Maniacs: Unplugged
June Tabor and The Oyster Band: Freedom and Rain
Holly Cole: Blame it on My Youth
Joni Mitchell: Hejira
Elvis Costello and Bert Bacharach: Painted From Memory
Mazzy Star: Among My Swan
The Handsome Family: Through The Trees
Liz Phair: Whitechocolatespaceegg
P J Harvey: Is This Desire?
Over The Rhine: Home Recordings
Cowboy Junkies: Trinity Sessions
Mu-Ziq: Lunatic Harness
Air: Moon Safari
Bill Laswell and others: Ekstasis
High Priests of Electronic Dub
Esthero: Desire
One White Dove: Mourning Dove White
Bela Fleck: Tales From The Acoustic Planet

*Go ahead and laugh.  For some reason The Meat Puppets' "Severed Goddess Hand"
and "Violet Eyes" just make me have to sing along with them.  I'll never tire
of this recording.

Ancillary gear:
Musical Design CD1 player used as a transport
Brightstar Airmass transport support base
1996 West Detroit Yellow Pages (damping Transport)
XLO 'Purple' power cord
Audio Alchemy DTI Plus with tweaked power supply
Counterpoint DA-11 DAC with JAC Card, Master Clock, HDCD, Ultra Analog DAC
another XLO 'Purple' power cord
XLO grey 1.5M interconnect
XLO 'Green' power cord.
VTL Ultimate preamp (modded) w/Telefunken tubes
Maplenoll Ariadne Signature 'table
Benz MC3 cart
Brightstar sand turntable base thingy
Michael Green Justarack
Clodhopper component spikes
PAC IDOS powerline filter
Custom Kimber silver interconnects
XLO cheap ($15/foot) black/green speaker cable. 4' pair.
Spica TC 60 speakers on Spica Gravity stands (sand/shot filled)
Microscan speaker vibration absorbers.
10lb dumbbells on top of speakers
Solidsteel large amp stand.
Arcici Superstructure 2 stand
Handstitched silk kimono.
Custom sterling-mounted pipe from Peterson's of Dublin.
Peterson's 'Old Dublin' smoking blend.
Tiger Brand Sher Bidis.
Dexter and Spike, The World's Loudest Birds.
The Famous Grouse Scotch Whiskey (in great moderation).




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