Wire Recorder Restoration Project

[atkelar]

[disclaimer] if this isn't the right place for this content, feel free to move/delete

I just recently finished restoring a wire recorder - Webster Model 80 - and thought it migt be an interesting subject in here on "old school electronics" - i.e. tube based stuffs. I ran into some issues along the way, but most of them were actually more mechanical than electrical. I ended up replacing most of the components, as the age was getting to them. To the best of my knowledge, the device was made around 1947 so some dead capacitors are to be expected.

I learned quite a bit about tube amplifier circuits in this; still not quite sure how that record bias oscillator works; I can identify the relevant components, but I'm not quite sure what makes it tick... maybe somebody on here has a few pointers? I'm pretty well versed in DC and digital circuitry, but when it comes to higher frequency stuff or even RF... it's... magic. 

I found it interesting that the service manual already talks about "wow and flutter" - when the speed of the wire is 100% dictated by the mains frequency and a simple shaded pole motor with some rubber wheels pulling it along... not even anything resembling the "capstan/pinch roller" of a typical tape deck.

The project video (including my usual "special" presentation style) is available here - along with the mechanical parts.


EDIT: moved video link down because of preview image.

[bob91343]

I used to have one of those.  Not that exact model, but close.  Wow and flutter are concerns primarily when recording music, evinced by an unsteadiness in pitch.  The wire is wound up on a drum which also acts as a flywheel, keeping W&F fairly low.

Due to the wire only offering one channel, the machine couldn't do stereo.  Its best purpose was for communication, where one would dictate a letter and then mail the wire spool to the recipient.  It also worked as an audio notepad.

Broken wire was easily repaired by tying a knot.  The bias oscillator provided both a demagnetizing force and a linearization of recording (to reduce distortion).

[atkelar]

I used to have one of those.  Not that exact model, but close.  Wow and flutter are concerns primarily when recording music, evinced by an unsteadiness in pitch.  The wire is wound up on a drum which also acts as a flywheel, keeping W&F fairly low.

It has a resonable good performance on that, yes, but I always had the impression that these measurements were added to - for lack of a better word - "show off" the quality of tape machines. I did not expect them to be established measurements before the reel to reel times. That caught me by surprise.

Due to the wire only offering one channel, the machine couldn't do stereo.  Its best purpose was for communication, where one would dictate a letter and then mail the wire spool to the recipient.  It also worked as an audio notepad.

I made the comparison with a dictaphone in the first part of the series. This model comes in a "mobile" box after all so it seemed logical. At 13kg it's about as "mobile" as the SX-64, but the idea is there 

Broken wire was easily repaired by tying a knot.  The bias oscillator provided both a demagnetizing force and a linearization of recording (to reduce distortion).

In the few tape devices I had on my desk so far, combining the two signals for the record head was done "electrically" though. It took me a bit to realize that the head construction, which has one erase and one record coil on the same core, is doing that same thing in the magnetic realm. But then, with tapes we usually see two heads for the purpose where this device has one.

Overall, I was really surprised to see just how similar wire recording was to tape already. I'm born in the mid-70s so I never saw any of these myself and even movies and TV series didn't seem to mention them. The only one instance I can name is one episode of "Mission Impossible" where the wire is a plot element. And in that context, I dismissed it as "spy gadget" until I found out that it actually was a thing. I'm still proud I made this work and look nice again 

[Conrad Hoffman]

I restored one of those some years back. Access to some of the electronics and some of the lube points was quite difficult. Really cool device. Anybody who describes tying those fine wires together as "easy" is a better man than I.

[atkelar]

I restored one of those some years back. Access to some of the electronics and some of the lube points was quite difficult. Really cool device. Anybody who describes tying those fine wires together as "easy" is a better man than I.

I have seen an official "knot type" for that purpose somewhere. Can't find it right now, but one of the manuals I saw during research had a specific knot shown. Having handled an actual wire by now... these things are stiff. It's like handling a very fine spring, so I would assume the attempt to tie one knot results in several others down the wire.

[Bill158]

What a blast from my past!
My father bought one of these probably in 1948 or so to amaze his friends.  This was just after WW II ( as Archie would say "The Big One" ) and things like this started to be made again for the consumer market.  I was just fascinated by it and that it could record and playback from a wire, let alone anything at all.  I was around 8 or so.  It was "lug-able" at best.  We probably had 3 or 4 rolls of wire which were constantly being reused.
The record/playback head would go up and down so as to evenly distribute the wire on the take up reel ( on the right side ) and then when rewinding back onto the supply reel.  One issue I remember was the sound level would be inconsistent because sometimes the wire would face the record/playback head and then it could twist so that the "backside" of the wire would present itself to the head.  Of course during recording you couldn't guarantee which "side" of the wire would be recorded upon.  It certainly was not Hi Fi.  Yes I remember "splicing" the wire when it broke.  A square knot worked the best and scissors to trim the excess wire from the knot.  I think AMPEX was just getting started and Bing Crosby had just ordered a couple of tape recorders.  I do remember it broke one time and it cost a fortune to get it repaired.  I think it sat around for years unused and was finally tossed away in a move from home to home.
Thanks,
Bill

[atkelar]

One issue I remember was the sound level would be inconsistent because sometimes the wire would face the record/playback head and then it could twist so that the "backside" of the wire would present itself to the head.  Of course during recording you couldn't guarantee which "side" of the wire would be recorded upon.  It certainly was not Hi Fi.

I have not experienced that with the two spools I have; The head itself has a groove that guides the wire, so it might compensate a bit for that?
The recording levels seem to be all over the place though, different with every segment I hear. The unit I have has a neon bulb that acts as a peak-indicator to let you know how far you have to turn up the volume during recording for a good level; the service manual mentions that this was a late addition.

[artag]

Really interesting videos. Thank you !

[Bill158]

I have not experienced that with the two spools I have; The head itself has a groove that guides the wire, so it might compensate a bit for that?
The recording levels seem to be all over the place though, different with every segment I hear. The unit I have has a neon bulb that acts as a peak-indicator to let you know how far you have to turn up the volume during recording for a good level; the service manual mentions that this was a late addition.

I do remember the grove in the R/P head.  Now what I remember about the twisting of the wire it seems to me that there could be a variation of the recording level.  Let's face it that little neon glow bulb "peak indicator" was only for the crudest of indications that you were not saturating the magnetic wire.  Nothing like a VU meter, which I believe existed before WW II in the broadcast industry.  Also, I believe that wire recording existed before WW II, but not for home use.  But don't quote me on that one.  I also remember when the wire broke it could turn into a huge mess that took a while to unravel. 
Bill

[atkelar]

Also, I believe that wire recording existed before WW II, but not for home use.  But don't quote me on that one.

Wikipedia mentions patents going back to 1890-ish. So I assume experimental or "professional/military" use was pre WW-II. But the lack of pop culture references makes me believe that it was never a "huge" consumer thing. But it was "a thing" over 30 years before I was born, so I can only quote others on that 

[jcrubin]

Would you happen to know the no load HV AC output of your power transformer.  Ive got one with an internal short. And the documentation I can get my hands on ranges from 350 to 400V.



many thanks, jordan

[atkelar]

Would you happen to know the HV AC output of your power transformer.  Ive got one with an internal short. And the documentation I can get my hands on ranges from 350 to 400V.

Not from the top of my head; I can hook it up and measure it later this week if that helps? It is in storage right now.

[jcrubin]

Yes that would be great , thanks. Ive not found any concise 180-1 documentation.

[Messtechniker]

A frequency response measurement and some fft distortion measurements would be nice.

[atkelar]

A frequency response measurement and some fft distortion measurements would be nice.

I'm pretty sure the quality level would be below any such instrument  - I might be able to feed some test signal from a PC back into the PC and check that... But not sure if that works out this week, since I don't have a matching transformer: tube stuff is high impedance. There's a quick microphone sound sample in the video, near the end (around 16:20)...

[Wallace Gasiewicz]

I have a recording of Benny Goodman at Carnegie Hall in 1938, originally on wire. The recording I have is remastered on vinyl
It is a very, very good recording.
However the equipment used included special condenser microphones (and everything else) that was specific to Carnegie Hall.
The recording was not released until 1950, when Bennie first heard it and was impressed. At least that is what I read.
The delay in releasing it is attributed to the "Big One"

Anyway, wire recordings can be quite good.
Many military wire recorders used on stuff like bombers, were not great since they had to only record voice communication.

[jcrubin]

I have documentation of two different models, neither are exact or complete.

One is a model 80.  This apparently has a motor switch as contacts on the main knob instead of the wire held mechanism. The other says 180 but is a reprint with no voltage values.

With the motor running, No bulb and no rectifier, the power pulled was 200W.  I don't believe the transformer prognosis looks good.

[jcrubin]

The heater is a 28 turn center tapped coil. at 6.3v its .225v/turn.   The rest is not yet apart

[jcrubin]

Secondary shows about 484 give or take a turn or two.  Hard to compute given the operational range of the unit is between 110/120v

484 turns against 28 turns to produce 6.3vac is around 109mains voltage, 117V would be 520turns, 123v would be 547 turns.

I still have one more layer to remove.

[jcrubin]

HT is 1559 turns to center tap. given 547 turns for 123v to produce 6.3v at 28 turns, the HT would be almost exactly 350vac off Each lead to ground.  I believe this is my answer.

[atkelar]

It sounds plausible... sorry, my day job got very hectic - self employment means no regular working hours - should I validate it for you?

[jcrubin]

I moved all of my stuff into a new thread

https://www.eevblog.com/forum/projects/webster-chicago-180-1-wire-recorder-restoration/