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High-Voltage Entertainment in the Home This
Old Turntable
I
have
a Rek-O-Kut K-33 broadcast turntable that somebody removed from some
local
radio station. It is a very simple belt-driven unit, meant for
decades of uninterrupted service.
At purchase, it was covered in very trendy faux-mahogany Formica,
giving it that classic pulled-from-the-dumpster appearance. I painted
it with many coats of black lacquer, which is reasonably tough, but I
did not acquire the piano-lacquer finish I had hoped for. I filled
the base with concrete for mass, and the whole thing sits on eight
Sorbothane pucks. A 70's vintage Sony PUA-237 12" tonearm (below)
is mounted on the turntable. After maintaining for nearly ten
years that moving-coil
cartridges were a trendy excuse to spend money, and that cartridge
comparisons were an excuse to
spend money that was not even trendy, I was convinced otherwise by two
audiophiles who descended on my house with a Thorens TD-124 and an
Ortofon SPU. I am now the proud owner of
a Denon
DL-103 moving coil cartridge. This is a relatively
inexpensive cart with a spherical stylus that was
allegedly
designed thirty years ago for broadcast use, although, having worked at
my college radio station, I cannot imagine such a fragile, nude-diamond
stylus
lasting more than fifteen seconds with a typical radio disk
jockey
(if there
are such things any more), let alone the contemporary club-variety DJ.
This
little unit is much-beloved by vinyl cheapskates all over the world,
and now I'll vouch for it, too.
However, the Denon
makes it
clear that the speed consistency of this turntable is not what it ought
to be, but the turntable's just about as old as I am and my speed
consistency isn't so good anymore, either.
The New Turntable  Nothing
I tried fixed the speed
variation problem in the Rek-O-Kut. I cleaned the pulley
(it's
really more like a spindle). That made it worse. I
replaced
the belt. That made it worse. Changing the angle of
the
motor at least didn't make it worse, but didn't help. The
basic
problem is that the spindle is an integral part of the motor and is
quite worn after 40+ years of wear. And all the boys who came
over to my house made
fun of me.
What could I do? I chose The
American Way; I threw money
at the
problem, I bought a new
turntable, in fact a new new turntable, since the turntables I saw on
eBay were
not inspiring. I purchased a Basis 2000 with a Graham Robin
tonearm from Vladimir at North
Country Audio.
I like
the Basis
turntable line because, although not inexpensive, they have no fru-fru
features, like little weights dangling from the platter, or weird bases
that appear to allow the turntable to take off and hover over the
listening area when playing records. As promised, it was easy
to
set up.
I was so happy with the
Graham Robin arm that I procured a Graham 2.2 with a ceramic armwand--a
drop-in upgrade for the Robin, requring no custom-drilled armboards--on
Audiogon.
Unlike the Robin, which is similar to midprice arms from Rega, the 2.2
is a unipivot arm, meaning that the arm actually balances on a single
pivot, attached to the cap, that sits in a well of about 0.75 cc of
damping fluid that inhibits the arm from bobbing about in all
directions, which something balanced on a single point and not
spinning tends to do. The arm is balanced by weights
on
the rear
and to the sides of the pivot (adjusting, respectively, the tracking
force and the azimuth), and has further adjustments for height (and,
thereby, the tracking angle) and anti-skating. After
reading
the supplied manual several times over, I
found the 2.2 straightforward to install and easier to adjust than the
old Sony arm, since the
indivdual settings stay where you put them, and do not interact (for
instance, on the Sony, adjusting the height, which tends to drift over
time, also tends to change the
cueing position). The arm comes with a spiffy gauge that
allows
the positioning of the stylus to the sub-mm range, although one must
adjust the VTA and azimuth by eye. I bought an Axe
±0.1 gm scale to set the tracking force, which, while not
quite
as well-adapted to the task at hand as some of the $400 scales from
Needle Doctor, costs $50 including shipping and seems to work
fine. The damping fluid had become something of an issue; it
costs $25 for a 3cc syringe and must be removed from the arm prior to
shipping, so the arm arrived without any, and none of the
various
oils I had around the house were anywhere near sufficiently gooey.
The retail outlets all promised to get it for me real soon now,
but Graham wouldn't ship it, so, after a little research, I determined
that the special purpose audiophile-approved Graham Cobalt Blue High
Viscosity Damping Fluid is pretty damn close to 30,000 cSt
Diff-Lock Silicone Oil (cSt stands for
centiStokes, a measure of viscosity,
described in this interesting
table), which can be purchased for
about $10/2 ounces--enough for about 80 arms--from
your local RC hobby store. Go
crazy.
 I obtained from Vladimir a Michell Engineering reflex record clamp (much less expensive than the exotic Basis record clamp) to couple the record to the platter and eliminate slippage, thereby enhancing rotational consistency. I also purchased directly from Boston Audio Design in a moment of weakness a graphite Mat 1, which may have some benefits connected to the resonance of the system I will be able to hear in the next life, but is more than likely audiofoolishness. If ye are without sin, ye may cast the first stone, but I'd be willing to bet if ye've read this far, ye're not. Hey, I think it all sounds Absolutely Fabulous, I spent all that money, what the hell do you expect me to say, sweetie? It's a vast improvement over my old way of life. Of course. The Phono Pre-Amp
The
black box with the glowing interior behind the Basis is a
modified Diego Nardi phi 42 from Sound
Practices #14(the
design is copyrighted and I can't post it here, so you should go to
eBay, search for "Sound Practices magazine archive CD" and send Joe
Roberts $29, he deserves it). I
built the special model, which features
copper-in-oil caps and tantalum resistors. This design uses
no feedback, and splits
the equalization between amplification stages: first VA stage;
high-frequency cut; cascode stage; low-frequency boost;
cathode-follower driver. The load resistors in the first and last
stages specified in the original design have been replaced by
constant current sources and sinks, respectively. The constant
current units, which are sprinkled throughout the rig, are knockoffs
of Doc
Bottlehead's
C4S
units (I bought
several of these from Doc, so I
believe I have done my duty by John Camille's estate). The constant
current sources, which appear to the tubes they load as very high-value
resistors dropping very large voltages, reduce power-supply noise and
linearize the response of
the cathode follower output stage. I also parallelled two sections of a
12AY7 for each channel to reduce the noise another 3dB. The phono
stage is point-to-point
wired on an aluminum frame that is suspended in the box, which is a
vented steel model made by Hammond. I know some of you don't like
steel, but it shields the preamp
from induced hum. The
whole thing is driven by the regulated preamp power supply. The phi 42 does not have the gain for a moving-coil
cartridge, so I use a
pair of
Brian Sowter's
lovely little
9580f step-up transformers (recommended among the Sowter line for the
relatively hi-impedance Denon). As a whole, this unit now has
an
impressively low noise floor, barely distinguishable from the SACD
player (below). I also built several head amps with
Burr-Brown OPA-627,
Analog
Devices OP-275 and Linear
Technologies LT-1028 op amps;
the LT-1028 was lower in noise, but I
thought
the OP-275, and at a much higher price, the OPA-627 had crisper
presentations, almost
indistinguishable from the transformer. However, this is
where
older technology is built to win; moving coil cartridges, which have
lower voltage output than moving magnet cartridges, also have higher
current output. Neither tubed nor solid-state amplification
stages take advantage of this higher current, but a
transformer
does. The next step is to see if the noise floor on the first VA
stage can be improved by either a JFET cascode, by a pentode stage with feedback, or by complete
replacement with a OP-275.
Life is a research project.
Cleaning the Vinyl Of course, with the whiz-bang
turntable, arm and cartridge, spotless vinyl is a must. Although
I, like any right-thinking American, lust after a spiffy record
cleaning machine, when it actually came time to cut the check, I not
only couldn't justify it, but I worried about how to drain the thing
without causing a waterfall over any irreplaceable electronics below
(the natural home for such a device is next door to the
turntable). I had uncharacteristic second thoughts.
So, I bought a quart of Disc Doctor no-rinse record cleaning
fluid, a record cleaning pad, a carbon bristle brush, a Zerostat gun
and audiophile-approved flannel-backed vinyl tablecloth and Rubbermaid
dish drainer. Now I have a protocol:
1. Remove any obvious dust from the record.
2. Wet and clean the record with the solution using the pad. 3. Gently sponge excess fluid from the surface using audiophile-approved deep-napped washcloth. 4. Dry the record in the rack for 15 minutes. 5. Shoot the record with the Zerostat gun. 6. Remove dust with carbon bristle brush. 7. Gently return to sleeve. It seems to work OK. The records look shiny, and I don't seem to be doing any damage. But I am sure you have some criticism of my technique. Let me know. I can take it. |
