On Mon, 17 Dec 2012 09:23:21 +0000 (GMT), Jim Lesurf
wrote:

In article , Johny B Good
wrote:
On Sun, 16 Dec 2012 09:57:51 +0000 (GMT), Jim Lesurf
wrote:

The very idea of sending the cartridge output directly to phono sockets
on a seperate amplifier via a yard or so of screened cable didn't appeal
one iota to me. After all, you don't do this to the replay head of a
tape deck.

Actually, back in the 1950s/60s people did often buy the tape 'deck' with
no electronics and seperately buy or DIY the electronics, using a
reasonably length of coax between the head and the preamp! People like
Armstrong used to sell PABO units (playback amp and bias oscillator) units
for this to punters.


Indeed. I remember buying such a unit (a Garrard, IIRC) sometime in
the early to mid sixties. AFAICR, it was designed to take 4 inch reels
but came with a forerunner of the Philips cassette designed to be
loaded with 3 and 3 1/2 inch reels. I never used it in anger.

Just prior to that, I'd bought a small (and very cheap) battery
operated portable reel to reel recorder (3 inch reels) that was so
primitive that it didn't have a capstain, tape transport during
recording and playback was courtesy of the take up reel driven by a
speed stabilised dc motor. Also, it used DC bias and the erase
function was impleneted by a small permanent magnet mounted on a swing
away arm.

That one I did use. I've got a few of those late night 'Horror'
stories that Radio Caroline (South? Not sure because the one in the
Irish Sea (North) was our local Pirate Radio station of choice[1])
used to broadcast just around midnight.

I no longer have that crude portable recorder but the tapes are quite
playable on a normal deck set to 3 3/4 ips (IIRC - it may even have
approximated the cassette tape speed of 1 7/8 ips - I might dig my
portable philips reel to reel (3 inch reel tables) out of the basement
(proper capstain drive, AC erase and bias, you know, the full works
;-) ) and try some of those old recordings[2].

If there's any interstation heterodyne in those recordings (4 or
5KHz) I might even be able to stabilise and regulate the playback
speed in CoolEdit Pro (even if there isn't any usable heterodyne, I
can still manually adjust the playback speed along the length of the
recording and resample). Considering all the other defficiencies of
that crude tape recorder, tape speed will be the least of my problems.

[1] Unlike the locals, I was able to recieve Caroline South any time
of the day on my home brewed transistorised 'Superhet' MW portable
radio using only the internal 7 or 8 inch ferrite rod as the aerial.
Admittedly, the LO sideband noise became rather intrusive at these
very low signal levels.

I'd added an extra tuned IF stage to beef up the sensitivity and
selectivity somewhat which also allowed the AGC to operate over a
wider range. I didn't have to turn the volume up on a weak station,
you knew it was weak without looking at the S meter simply from the
amount of LO sideband noise that polluted such reception. A weak
station didn't go quieter than a strong one, just noisier.

[2] If this doesn't work with the Philips tape recorder, I can always
fall back on my antique Akai M8 tape recorder to play them since it
has a 1 7/8 ips speed option as well as the more standard 3 3/4 and 7
1/2 ips speeds.

--
Regards, J B Good

In article , Johny B Good
wrote:
On Mon, 17 Dec 2012 09:23:21 +0000 (GMT), Jim Lesurf
wrote:

I

Indeed. I remember buying such a unit (a Garrard, IIRC) sometime in the
early to mid sixties. AFAICR, it was designed to take 4 inch reels but
came with a forerunner of the Philips cassette designed to be loaded
with 3 and 3 1/2 inch reels. I never used it in anger.

Somebody gave me one of those in the 1990s and I passed it on to a local
technology museum! :-)


[2] If this doesn't work with the Philips tape recorder, I can always
fall back on my antique Akai M8 tape recorder to play them since it has
a 1 7/8 ips speed option as well as the more standard 3 3/4 and 7 1/2
ips speeds.

Given the problems I'm having getting my old Tanberg working I think I now
envy your M8. :-)

Alas, although many second-hand dealers seem to have cassette decks. Reel
recorders like the Tandbergs in decent working order seem scarce now... Or
maybe I simply haven't found the right rugs to seach under!

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Johny B Good wrote:

However, a mere Dolby B decoding DSP plugin doesn't really cut it.
What I'm after is a self calibrating intelligent DSP that will adapt
to the actual distortions introduced by the magnetic
recording/playback process itself as well as provide a dolby B decode
function that precisely matches the inverse of the encoding actually
used.


Just an aside from a lurker. It strikes me as ironic that one can obtain
software VSTi plugins designed to *introduce* tape machine artifacts into
digitally produced audio data.
Examples he
http://freemusicsoftware.org/categor...ape-simulation

On Mon, 17 Dec 2012 17:03:22 -0000, "TonyL"
wrote:

Johny B Good wrote:

However, a mere Dolby B decoding DSP plugin doesn't really cut it.
What I'm after is a self calibrating intelligent DSP that will adapt
to the actual distortions introduced by the magnetic
recording/playback process itself as well as provide a dolby B decode
function that precisely matches the inverse of the encoding actually
used.


Just an aside from a lurker. It strikes me as ironic that one can obtain
software VSTi plugins designed to *introduce* tape machine artifacts into
digitally produced audio data.
Examples he
http://freemusicsoftware.org/categor...ape-simulation


Wow! That's an awful lot damage. Most of them are to digitally
recreate the sound of old analog tape delay machines. BTW, I was taken
aback by the Wow and Flutter plugin. I reckon if it had a select by
model option, the GX630DB one would simply be a euphemism for the off
switch.

--
Regards, J B Good

On Mon, 17 Dec 2012 16:45:35 +0000 (GMT), Jim Lesurf
wrote:

In article , Johny B Good
wrote:
On Mon, 17 Dec 2012 09:23:21 +0000 (GMT), Jim Lesurf
wrote:

I

Indeed. I remember buying such a unit (a Garrard, IIRC) sometime in the
early to mid sixties. AFAICR, it was designed to take 4 inch reels but
came with a forerunner of the Philips cassette designed to be loaded
with 3 and 3 1/2 inch reels. I never used it in anger.

Somebody gave me one of those in the 1990s and I passed it on to a local
technology museum! :-)


[2] If this doesn't work with the Philips tape recorder, I can always
fall back on my antique Akai M8 tape recorder to play them since it has
a 1 7/8 ips speed option as well as the more standard 3 3/4 and 7 1/2
ips speeds.


Given the problems I'm having getting my old Tanberg working I think I now
envy your M8. :-)

Alas, although many second-hand dealers seem to have cassette decks. Reel
recorders like the Tandbergs in decent working order seem scarce now... Or
maybe I simply haven't found the right rugs to seach under!

I retrieved the portable Philips tape recorder from out of the
basement. Considering the generally high humidity of that environment
in the Autumn and Winter months, it was in no worse shape than when I
last used it several years back.

Unfortunately the record/playback select switch contacts could do
with a bit of TLC. I had to press it against the interlock to get a
decent playback quality (as well as press my fingertip over the supply
reel spindle to provide back tension since it seems the rewind drive
belt must have slipped off or snapped).

Despite its single 1 7/8 ips speed, the playback quality is
surprisingly good compared to its portable cassette recorder cousins.
Obviously half track mono on quarter inch tape is a major factor here.

Having retrieved that tape recorder (and borrowed 6 D cells from a
couple of torches to power it up) , I had need of some tapes to try it
out on and and found a biscuit tin with 19 3 inch reels of tape in the
attic. Eleven of them were Ampex 661 (fortunately not the later Ampex
formulation that suffered the sticky tape syndrome).

The rest of the tapes were brand named "International Electronics"
which were really poor quality, on a par with the crappy Philips Tape
brand quality (both having a propensity to readily shed oxide - unlike
those superior quality Ampex tapes).

From the numbering on the tape boxes, I rather think there must be
some more of those tapes hidden away somehwere in the attic. I'll see
how I get on with this first box before going off on a treasure hunt
for the rest.

Anyway, since the Philips was in such poor condition, I set up the
M-8 and had a listen to a few of those tapes. Interestingly, the
biscuit tin contained a tape marked "Radio Caroline Ghost Stories
1967" on its plain white box. This is the one I'd recorded on the
cheap battery powered tape recorder which relied on the take up reel
alone to transport the tape.

I figure the original speed to be around the 2 1/2 ips mark since
playback at 1 7/8 ips was more intelligable than when it was played
back at 3 3/4 ips. You'd expect such a recording to progressively
slow down when played back on a conventional tape recorder but I
didn't notice that much, if any, further flattening of pitch (but it
was more than flat enough to begin with which probably masked the
effect).

I have to say, the audio quality on that recording sounded atrocious,
even allowing for the speed error, and I couldn't detect any inter
station heterodyne suggesting the response was way down at 4.5Khz.
That's one I'm going to replay on the GX630DB deck when I digitise it.

Since I'll have to resample to correct the replay speed either way,
it won't matter that it'll be played back so much faster, there isn't
anything above the 4KHz mark to be lost to a less than doubling of
pitch. Aside from the minor matter of playback speed, the GX630DB will
give me the best possible information retrieval quality (low noise amp
and 1 micron glass crystal replay head are the key factors here).

The rest of the tapes appear to have been recorded at 1 7/8 or 3 3/4
ips (in at least one case, both speeds had been used on the same
tape). The slower speed recordings seemed to be half track which makes
me think they must have been made using the Philips recorder (the only
other possibilty I can think of would be a crappy TrueVox I'd had for
a very short while, prior to buying the Akai 4000DS).

Most of the recordings are dubs of reel to reel copies of vynil made
so I could listen to them in the workshop on the Philips portable tape
recorder. The built in speaker was much bigger than those used by the
ubiquitous portable mono cassette machines of the day which provided
better bass performance. I'd have had to tote a seperate speaker
around if I'd wanted a similar quality from a cassette recorder setup.

I won't be digitising those tape dubs. However, I did come across a
couple of recordings of personal historic interest that I will be
digitising, along with any other such recordings I might find.

--
Regards, J B Good