[sdiy] tape loops, nagra tape machine erase head hack / AKA dummy load

[Anthony Bisset]

With a question being almost as useful as an answer, I write:

I'm having trouble disabling my nagra erase head.  After disconnecting the
erase head I've tried dummy resister loads between 10meg and 1k, but the
recorded sound volume rolls off far quicker than it should.  By the
second repeat, the sound is gone.  If I put tape over the erase head
and re-enable the erase head then we're in good shape.

Do I need an inductive dummy load and if so, how do you calculate such a
thing?

I can't resort to scotch taping the head because during live performances
I need to be able to erase the loop and start fresh.  Playing with scotch
tape would be amusing, but only once.

I would like to encourage others to do this mod as the capstans on the
nagra provide enough tension for looping and the forward/reverse toggle
doesn't have any application during recording which means you can replace
it with a dual throw toggle switch and wire your dummyload/erase head to
it.

Also, any suggestions for a small dummy load package i can fit in a very
limited space.   If I had room up top a light bulb seemed cool, but
I don't know what I'm doing, this deck is older than I am.

-anthony





playback of recordings on a looped tape


 tried disconnecting my nagra erase head and no l no real luck.
I've
tried dummy resister loads between 10meg and 1k in order for the nagra


resistance on the

On Wed, 5 Oct 2005, harrybissell wrote:

> You could use multichannel FM as well... but that would get kind of
> tricky.
> Switched capacitor filters would be a good choice here. But watch out,
> as higher
> order filters carry their own problems like group delay etc.
>
> Might be easier to do CV-midi conversion and record the data in
> something
> like Cakewalk (or whatever you kids are using these days :^).  I used to
> stripe
> one channel with SMPTE time code and lock synths to that. Po' man's
> multitrack.
>
> H^) harry
>
> Jeff Farr wrote:
>
> > I was thinking about 8 bands per audio channel, starting around 16k on
> > downward in octaves.  However, I realize this will take a steep BP
> > curve to decode so that there is enough headroom between bands for
> > good resolution, I'm not sure what kinds of slope can be easily
> > achieved but I imagine having 12 or 24db of  space for each octave may
> > not be high enough for a good resolution 'decode'.
> > On 10/5/05, Harry Bissell Jr <harrybissell at prodigy.net> wrote:
> >
> >      > On 10/4/05, Eric Honour <autophage at gmail.com > wrote:
> >      > >
> >      > > What about using a channel as one half of a
> >      > vocoder?
> >      > >
> >      > > IE, one audio channel carries twenty different
> >      > CV's by having twenty
> >      > > different (harmonically unrelated) tones of
> >      > varying amplitude... much like
> >      > > the 'ghosting' technique previously mentioned, but
> >      > not actually containing
> >      > > usable audio (it'd just sound like a crappy
> >      > dissonant chord) - then using a
> >      > > series of very narrow bandpass filters into a
> >      > bunch of envelope followers?
> >
> >      You don't need 'harmonically unrelated' tones if you
> >      are using sine waves (which have no harmonics). The
> >      limiting factor would be how steep you can make the
> >      bandpass filters... and how stable the recording
> >      method is (wow, flutter, speed changes ?)
> >
> >      The lower audio tones will STILL be much slower to
> >      recover.  I'd think that twenty tones would be really
> >      pushing the limits of what you could do with practical
> >      bandpass filters...
> >
> >      H^) harry
> >
>
>