I found an old email from Pat from when I was thinking about buying this kit. Some info about his preferences in power supplies, why the input cap, output transformers, sales pitch, etc. Thought it might be of interest to someone. I left it unedited for entertainment value. -jl
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i will answer all the above here..
first, YES i show THREE differant power supplies, including one very simple
one that is constructed on a terminal strip, or tag strip..
BUT, i have to say this..
you can save a bit of money, using simple three pin regulators..building
your own supply.
( they are dead easy, in is too high, ground, and output ..extra voltage
burned off as heat/.//they are quite forgiving of input voltages....so a
good choice, where you dont know the REAL, in circuit voltage of a power
transformer..especially, as i like to use OVERSIZE for everything, if i
can, why not..)
HOWEVER, i personally now use premade POWER ONE and other equivelent linear
regulated supplies. $55 will give you one big enough to run 8
channels...they are TOTAL OVERKILL..way more advanced than anything a
normal home brewer can make, in terms of a low impedance modern circuit
design.
they can make vintage gear like quad8, which is essentially similar to the
jensen 990, though an earlier version, sound every bit as good as the later
versions.
( your power supply regulation can happen at the supply, or in the circuit,
or both, but both is redundant..)
this type of premade supply is very common now, in the vintage and new
gear, even..brent averill,etc, all use the power one.
you asked about voltage..the millenia amp is rated up to +/-28volts, but i
run it at +/-24
this gives SO MUCH MORE HEADROOM than most vintage gear ever had..
there was ONLY quad8, in the high headroom game..its over twice the swing a
neve can give you, and even api was only +/-20 volts..probably due to the
potting of the gain blocks.
the millennia is extensively tested and graded, then potted with NEW
technology in potting material, its actually a heat sink.
needless to say, i recomend the premade power supplies, at that price.
there is a fellow in the USA who makes a kit phantom supply for $35, or you
can get yet another power one unit, probably very close in price.( another
$10 gets you a state of the art supply, why not?
me, i dont use phantom at aLL. all tube mics, ribbons, dynamics.
HOWEVER, if you want to save money, its very easy to make your own supply.
i will enclose the pictorial view of the terminal strip , if you ask for it.
also included in the kit, is the API power supply design for phantom.
its very cool, in that it USES THE SAME plus and minus power supply
transfomer you use for your main supply, but just adds a few components, to
make a voltage doubler and regulator for phantom.
still, i prefer the premade.
thekit is dead simple.
no one hasnt been able to make it work..and EVERYONE, without exception,
reports that it quickly becomse thier referance preamp, EVEN when they have
unlimited budgets, and AVALON, DW FEARN, MILLENNIA, NEVE, API, TELEFUNKEN,
GRACE, GREAT RIVER, etc to choose from.
Also, is the output transformer for balancing? Is it an unbalanced
output without the transformer? How much is the output transformer? Are
they all Lundahl transformers?
here is a big issue./
i spent a long time with lundahl, working out the input transfomrer.
it has EXCEPTIONAL PERFORMANCE, and sonics, and is a high ratio transformer.
it has better specs than utc linear standard does at 1:1..which is AMAZING,
as its 1:10.
this is unheard of.
the only DOWN side, is you cant run DC through it, and the coils are a bit
high impedance for an output transformer, where the norm is to make
something that is capable of line driving 1000 feet of cable.
NO ONE in the modern home studio ever needs this, and i have been working
with lundahl on an output transformer..but SO FAR, i havent found ANY NEW
transfomrer from any manufacturer to compare with the UTC LS30 on the
output, but these are getting rare, and hard to find with the same date
codes, one at a time, on the used market.
so, i depend on finding the bests vintage models i can.
normally, there ARENT ANY, that i like the sonics of, as much as the
unbalanced out.
( remember, i am dealing in ABSOLUTES HERE..trying to outperform EVERYTHING.
you can of course use a NEVE output transfomer, api, or others..but they
arent as good as the circuit can produce without them)
that said, and i have compared hundreds of transformers in my hunt, both
new and vintage, i only came up with 3 types of vintage that i like enough
to sell...or recoomend.
RIGHT NOW, you are lucky..if the gods are with me, i will recieve a small
bulk order of about 40 transfomers,in the two types i liked best.
ONE, is a vintage JENSEN, made for quad8..which sounds AMAZING...but no
modern jensen is as good. ( this one AVALON sells for $150, as an optional
balanced output for thier units..i sell at $75)
OR, ANOTHER vintage jensen made for quad8..these are HUGE, oversize
ones..which were mounted on pc cards for late model line amps. they DONT
HAVE conventional leads, they have the ACTUAL WIRES for the transformer
windings brought out and soldered to the pc board..so they are a bit
fragile, but WOW, these were almost $300 each new..and they are my top model.
( dont worry about the fragile, i deal with that..i mount a little
connector and wire the leads onto it.)
the price is $125 for those, though. EACH.
needless to say, the higher the level gets ( my preamp can give +30 at
clipping, which is HUGE headroom, much more than ANY digital i/o can match
at this time) the harder it is to find a REALLY amazing transformer for the
job.
UTC LS30 are the only OTHER one i reccomend, i dont have these to sell you
can find em on ebay, sometimes.
they arent as CLEAR and present as the jensen, they have more relaxed
sound..but still amazing.
you ONLY NEED TRANSFORMERS if you need balanced output.
there is a psudo balanced method, ( also designed by dean jensen) shown in
the documentation.
this works for noise cancelling in the cable, but wont do anything for UNIT
TO UNIT noise.
( unit to unit noise comes mostly from the interconnection of VASTLY
differant power supplies, ie tubes and chips..much less so where the
voltages are similar...and differancial.. as is the case in this power
supply and most digital converters)
with a really nice transformer, though, you start ACTUALLY GETTING those
=-124db noise floor in your electronics.
most home studios, though, have about a 50db signal to noise, in terms of
ambient noise, anyway ( that DAMN computer fan) and, truth be told, peoples
perceptions of things often prefer much less dynamic range, anyway..most
pop songs dont have 20db of dynamics, start to finish.
so, you ready for the best preamp in the world?
let me know.
any questions, let me know, nowor later.
all sorts of other info is included with the kit..parts sources, design
tips in general for studio upgrades, everything down to the wire types, even.
