-edible zone-
No.6435
Overview Starting
Line Arrival Deconstruction
Beneath Decks
First Night's Spin
Listening to Plinths
Motor
System:The Tonearm Tweaks Articles
Bookshelf
Transit
*
Fastening The 301 To The Plinth
At this
point in my investigations, I'm against putting fasteners into the
mix... Certainly Metal Fasteners of any mass or bulk. It's not strength
that is the overall objective here; in point of fact you could do a few
'dots' of glue per layer and the plinth would be strong enough, and so
would the armboard mount.
What I'm after is to keep motor rumble
travelling --- conduct it, punch it's ticket, make sure it doesn't leave
any baggage behind at the station--- and send it on it's way.
If
it manages the whole trip and exits at the spikes, cones, or the Aurios
I'm now using, great. Sayonara, keep moving. If it falls asleep on the
trip and kind of just zones out and deteriorates to nothing on it's way
thru the plinth..... Fine, as long as it doesn't wake up again.
What I'm not after is having the motor rumble bouncing back off a weird
boundary layer or pinging off steel fasteners and coming back in a time
& phase shifted way to the armboard. In my previous plinth I ended up
using hardwood pegs to attach the armboard for a similar reason. Steel
(I tried it) conducted some aspect of audio-band motor rumble directly
to the armboard it was fastening.
What I'm also not after is any
detour or translation taking place with the motor signature, hence no
'contrast' layers for me in the plinth -- whether similar to the birch
ply or dissimilar, like lead. The glue I'm using, which luthiers use for
difficult bonding chores like violin bodies, does more to integrate
adjacent layers, and fuse them physically and sonically ...than it does
to form any intermediary layer.
The 'purist' (take w/ grain of
salt, everybody's a purist, and nobody agrees) approach I'm taking on my
current project is : Baltic Birch only, hardrock maple armboard, hide
glue only, roller bearings for footers. Wide and deep (20x24"), but not
too (3.75") thick, keeping that heavy motor very low to the ground, and
very seriously rigid.
Every plinth maker seems to want the 'Only
Way To Do It' crown for his way, which is ridiculous. I will, however,
mention the following :
Nine out of ten articles about 301/401
practices properly mention that the Japanese are roundly regarded as the
sponsors of the Garrard 301 Rennaisance that took place somewhere around
the mid-eighties, just as we here in the enlightened West were
discovering Compact Disc to our extended delight.
If you take a
long trip thru the Japanese sites that show a 301/401 being used in
Japan, most are in plinths of stacked ply & glue. Coincidence ?
Possibly. Can it be done other ways ? Very definitely could be, but
isn't. Conclusion ? Your call.
One last thing to wonder about is
why Shindo-San doesn't do birchply plinths, when in fact he knows quite
a lot about the issue. I think the answer there has to do with the fact
that he's in the business of selling $20K super-luxe iterations of the
301, and can afford, in those budget confines, to be more luxurious with
every phase of design and materials.
( A parallel question would be
--- can you order a top-of-the-line Lexus or Benz without leather seats
? I don't think you can. A certain level of clientele don't do fabric
seats, don't ever take the subway, and don't do birch ply. )
That's
my guess, anyway.
*****
Spin It Up Long Before You Play Records
The Garrard 301 doesn't just sound better, it needs warmup to settle
into equilibrium. Lots of heavy metal there, more than a couple moving
bearings, and a tall column of grease that need warmup. It's not a big
ordeal to warm it up for about thirty minutes before playing Lps, and it
improves performance.
*****
Removing A Vibration Loop
Something
I've come across that I thought I'd post is a little vibration-exchange
point that I think goes overlooked in some 301 setups.
It should
be mentioned that the 301 game is largely one of tracking and re-routing
vibration pathways, and the motor-leads are one of the primary venues
for motor vibration. Which wants to be either A) handled by the six
motor suspension-springmounts or B) safely routed down and away, into
plinth, rack or beyond.
So here goes ................. The little
bakelite 'junction box' for the AC feeds and voltage-strapping is
attached to a section of fiberboard by a threaded machine bolt which has
several nuts (to attach to the fiberboard, to attach the 'strap'
section, and then to attach the bakelite cover.)
Adjacent to that
machine bolt-- kind of 'behind' the box-- is the lower-motor-cover
fixing bolt (that on some models has the ground tag).
These two were
inadvertently touching on my 301.
It stands to reason that Garrard
wouldn't go to the multiple standoffs approach (board, then box, then
connections, then ac cable) as well as multiple materials (phenolic
panel, then bakelite housing, then brass fittings, then cable) -- if
they didn't also intend a bit of isolation between motor, leads & AC
cabling.....
So if the bolts in question TOUCH they are creating
(by de-isolating) a vibration-loop that would be unintended and
deleterious to the noise levels. If these two bolts are transferring
energy, it's raw unsuspended motor pulse, and they're nulling a kind of
iso-mount.
It's pretty logical to me that since one of the common
things that get changed on a 301 during it's lifespan is the mains
cable, and that the junction-box fixing bolt may get backed up into the
motor unnoticeably. It needs only to be backed away incrementally so it
no longer touches, then tightened again.
*****
Keeping motor and linkage clean during the
plinthing procedure.
Cover the motor, suspension and adjacent
linkage levers in a taut wrap of 'saran' or other kitchen clear-plastic
wrap. This keeps the lubricated parts shielded from stray dust or debris
while still allowing the multiple fittings and try-outs necessary for a
contour-cut plinth. Simple but worthwhile precaution.
*****
Two Specific Modifications
There
are a couple of interesting modifications of the 301 which have surfaced
in various places on the internet, which I'll be looking into.
First is the Thrust Plate Cover modification to the spindle assembly,
which replaces Garrard part no. 9, a thin sheet-metal plate that
captures the spindle bearing's Thrust Pad, with an 8mm thick bronze
plate. Noticeable improvements are reported.
The Second is the
H-Bracket modification, which takes a stiff steel bracket and imposes it
as a bridge across the interior of the platter well, traversing the
spindle-bearing mount, and adding some 'spine' to the
structurally-challenged motor-plate area.
Both of these have
gotten good marks from reliable users, and I'll be looking into
installing both at some time in the near future. Additionally I'll try
to nail down and offer credit as to their origin ........
*****
