[sdiy] nagra revisited - mod monologue

[Anthony Bisset]

hey guys,

i've been meaning to do more mod's to this nagra 4.2 after i added a dummy
load and pot for pushing/pulling the erase head signal between the
dummy and head.

now i came across this today - check out the physical time stretching
machine by gabor at the bottom:

http://granularsynthesis.music.net.au/hthesis/gabor2.html

this got me thinking.  the nagra could be easily wired to do a similar
thing.  anyway on that note, i realized i should really finish my mods up
but need a service manual.  i've asked before but got a response of "it's
sacred" or something like that.  Anyone out there want to induct me into
the church of nagra and let me borrow a service manual or have a spare
around?  this is for a 4.2.  Mods i'm trying to sort:

now that i have an effective tape loop i need to figure out a mod for the
internal clock so i can sync it to an external clock and possibly still
have the IPS clock/divide settings work.  second the magnetics of a tape
head and a mmc pickup appear to be close, and i've used a nagra tape head
input as a record player needle pre-amp before.  so i'm going to figure
out how to mount a turntable arm on this nagra for ultra hi-fi
pre-amplification with really crappy everything else...

next, the pilot track is begging to take audio.. why not.. we could even
play buffer games with it as a nested tape loop since the heads can't all
be in the same place (or is it a dual read head)... hmm, writing from a
different position is nice though, so i guess we've got some time
differential to play with.

that's about it.  i'm going mobile and would really love a battery
operated tape loop record player and general purpose hi-fi pre amp for
contact microphones... okay it already does this.. i've got record player
cartridge input sorted already...

anyone want to talk nagra mod's off list..   I'll take this thing to dan
dugan the authorized rep here in san francisco and see if he can help out
if i can't locate a service manual, but i'd much rather learn something
by doing.

i'll sign any reasonable NDA

-anthony




On Sat, 25 Nov 2006, Grant Richter wrote:

> The know the Buchla 218 uses guitar fret wire between keys for a
> local ground connection.
>
> The 221 appears to use a similar design. The fret wires have a very
> pleasant tactile feel and the close location of a ground contact is
> really needed for the touch sensing technology in the 217 and 218.
>
> I have been testing the Freescale Design E-field technology
>
> http://www.freescale.com/webapp/sps/site/prod_summary.jsp?
> code=MC34940&nodeId=0112698268
>
> using their inexpensive eval board and a home made printed copper
> keyboard (sprayed with 3 coats of polyurethane varnish).
>
> As long as the electronics has an earth ground reference somewhere,
> the single key electrodes work well with no ground needed for the
> human operator. The only problem is the 2.5 millisecond settling time
> between each key detection for the diode / LP envelope detector.
>
> But I believe I have worked out how to scan all 32 keys in 1
> millisecond while keeping the "pressure" sensing capability. At this
> point, performance appears as good or better than the Buchla and
> Serge key feel, but I do not yet have a microprocessor connected for
> outputing CV or MIDI data that can be played in real time.
>
> Q-prox is another source of modern capacitive key sensing technology.
>
> http://www.qprox.com/products/qmatrix.php
>
> The problem with these modern technologies is that they are not
> optimized for fast enough key scanning to be acceptable for
> traditional musical keyboards.
>
> > Both Buchla 221 & Serge 115 has capacitive one conductor laquercoated
> > keys!
> > I know that for a fact since I had two 221:s and one 115 on my
> > workbench
> > last week!
> >
> > /Daniel
>
>