Thermionic Soundmirror

[Volatile]

So, while i was on ebay browsing a few days ago i came across this, A late 40's Thermionic (Brush) SoundMirror tape recorder. It came with the (i htink) original reels and paper tape, Microphone and a power lead that had been rather nicely made for it. In the description the seller stated they had powered the machine on a variable AC supply,

When it arrived, i thought, Why not just plug it in and see what it does and i did. Too my supprise after plugging it in, i was greeted with fantastic audio quality, a nice strong amplifier, Period recordings and recording capability.

Im going to get a few of the critical capacitors replaced, but as it sits, its working fine with all original components, not even filter hum !!

On a side note, Does anyone know the factory belt configuration? Mine came with a long belt wrapped and twisted round the reel tables and motor, I used a rubber band to test playback,

ALSO I am looking for a top deck cover? I believe this to be missing on my machine


Here are some pictures of the unit ********************gallery/z4XaVOg

[kalee20]

There are 2 belts. One drives the capstan. The other is quite long and drives the pulleys under the two turntables, there is a crossover so they run in opposite directions, and the motor pulley has twin grooves so there's no rubbing at the crossover.

It has an unusual circuit, the output to drive the loudspeaker is a 6SN7 twin triode, the two halves in push-pull. On record, there is an EF91 configured as bias oscillator (this valve has no function on Play).

The reels have a non-standard drive, although the hole in the centre is standard size. But rather than 3 lobes to drive the reel, there are a couple of tabs which engage in 'D' shaped cut-outs.

Definitely replace the critical capacitors, but at least it is an easy chassis to work on!

Yes, there is a top cover missing, I may be able to oblige, I grabbed spares for my Soundmirror when they appear (very occasionally) on eBay.

[Volatile]

I would love to get a replacement top cover, I am currently working on the mechanical side of the machine now, I got the belt sorted thank very much, Just re lubricating bearings in the reel tables, i must put it down now its getting late and i have work tomorrow Haha

[ricard]

Great find!

In acquaintance of mine has one or two of these, the reel holder belt had first loosened and then just gone hard so could be lifted out in its figure-8 shape. I've never seen that happen before.

I have the impression that especially the figure-8 type belt and also the joystick control inspired Tandberg in their design of the model 2 in the mid-1950s.

[Volatile]

Just an update,
I have now got the mechanical side of things working, Getting the reel tables to move up off the drive platter in FF and RW was a real pain, but i got there in the end, Just need to replace the belt now

Here are some photos of the Amp and PSU, Both still currently unrestored and still working perfectly on original components, They will be tackled soon

[Volatile]

Also, i am still on the look out for, and willing to buy a top deck cover for my SoundMirror

[brenellic2000]

Originally Posted by ricard

I have the impression that especially the figure-8 type belt and also the joystick control inspired Tandberg in their design of the model 2 in the mid-1950s.

Col Colley of Thermionic Products secured the British and European license to the Brush BK411 / TP411 Soundmirror and Recordon but although records are scant, TP rather than Brush almost certainly licensed it to Tandberg and others (Revox's origins are found in the earlier Brush BK401 Soundmirror design).

There were several variants of the TP411. The TP Soundmirror was built under contract to TP by Walter Instruments - you can see the TP heritage in their own cheapo budget models after Soundmirror production ended - hence Walter's truthful claim to being Britain's oldest tape-deck maker!

[Ted Kendall]

Originally Posted by brenellic2000

...hence Walter's truthful claim to being Britain's oldest tape-deck maker!

And probably the worst...

[Volatile]

I hear you there Ted when you say the worst, Im having nothing but issues with this, was working fine last night, now i have no FF, RW and its shredded any tape ive wound onto it, oh dear me

[Techman]

I expect you'll be able to work out what's going wrong as you're good with the mechanical side of these machines. It's probably best not to use the rare paper tape that you've got and rather use some old sacrificial ordinary tape while you're experimenting with it - or better still, no tape at all until you sort the mechanism out. Also, as I said yesterday, don't run it for too long until a couple of capacitors are checked/replaced. With the amplifier having connections via plugs and sockets, perhaps it could be disconnected from mains power while you're working on the deck mechanics, if it'll run as a stand alone.

[Volatile]

To be honest, Im about to give up and immediatley retire this to the loft, or your house permanently, Here is its latest issue, The tape isnt running straight though the pinch roller, yet the tape path itself is level, the roller is smooth, as is the capstan, i have cleaned it several times but this tape just makes it brown instantly , no idea whats causing this
https://www.youtube.com/watch?v=0ftZjUkh1-4
But if clutch mechanism adjusted so theres enough tension to make the tape go through the head correctly the thing barely moves, i dont know, will make a nice piece for bonfire night i think

[Ted Kendall]

Originally Posted by Volatile

I hear you there Ted when you say the worst, Im having nothing but issues with this, was working fine last night, now i have no FF, RW and its shredded any tape ive wound onto it, oh dear me

To be fair, the Soundmirror has antiquity in its defence, although it was unreliable enough in its day for Thermionic to keep a man on the road fixing them. He later (much later) was my first boss at the BBC, and told me the story of suffering at the hands of the Goons whilst fixing Peter Sellers' machine.

If you haven't dealt with a Walter, it's hard to convey just how shoddy it is. When decent budget decks from Collaro and particularly BSR became available, Walter's end was not long in coming.

[Volatile]

I havent dealt with any walter machines before, Its mostly been BSR and philips machines, Know a BSR like the back of my hand, I was loosing interest in tape recorders and moved on to wire recorders.

I bought this machine to restore as it was something different, but it seems like i have a worn out mechanism and no spares at all

[Techman]

I've just had a phone call from the OP regarding this recorder and he's about fed up with it. I may not be able to get on the internet over the next couple of days, so it's down to other members to offer advice/encouragement, or even, as seems to be the case, to just admit that these Soundmirrors weren't all that good, being at the dawn of the technology, so perhaps best cosigned to the loft for another time, another day.

[ricard]

I recall having a machine where the tape ran all wobbly like this not too long ago, trying desperately to remember what the actual culprit was. Like the OP's, it ran fine when the tape tension was increased to an insane level. I think it was a Tandberg, and it came down to the pinch roller although smooth being too hard. The fact that it goes brown quickly also indicates something amiss with the surface. In my case I could relieve my anxiety quickly by swapping in a good pinch roller which I had on hand, which cured the problem. But upon initial inspection the initial roller seemed servicable enough. One guess is that as it ages the rubber does not uniformly harden, resulting in a surface which although looking smooth has varying elastic properties. In the video, it does look as if the roller is not running true but wobbles a bit along with the tape.

By best advice would be don't dispair, I've had macihines initially work fine but a couple of things then fail rather rapidly as it is put into service, with half-century-old-parts not being up to the task for more than a short time. I don't know if the Soundmirror has any Akilles heels, otherwise I would expect most parts to perish in a machine of this vintage would be rubber, and often some form of replacement can be had in some form. Pinch rollers and idlers can be refurbished, even though it might cost more than a few £, and belts can be replaced.

[Diabolical Artificer]

" i have cleaned it several times but this tape just makes it brown instantly "Has it got sticky shed? This can cause issue's with PB.

Andy.

[Hartley118]

ISTR many years ago struggling with a deck where the pinch roller had deformed so that, instead of its original cylindrical form, it had deformed into a conical shape and persisted in sending the tape upwards or downwards instead of straight to the take up spool.

Martin

[Ted Kendall]

Good point - sticky shed can trip up any transport, Studers not excluded.

Tape in a pinch runs to the point of greatest pressure, so deformity of the pinch roller may also be something to check - it will, after all, be six decades old.

Crudity notwithstanding, the Soundmirror could make quite decent recordings, even on that paper tape.

In any event, don't junk it - set it aside or pass it on...

[Volatile]

I'm going to try a BSR pinch roller in it again tonight after work,and replace the tape on the reels once again I'm not too sure what to do if that fails.

[brenellic2000]

One problem with paper tape is that it absorbs moisture and 'cups' across its width making for difficult tracking on the capstan... and don't forget that it records 'full track' but only in the centre 3/4 of the tape, quite unlike a 2-track (there was a final 2-track version).