Unusual Thorens 1940s 78rpm Turntable

[Macquid]

Just picked up a Thorens 78rpm turntable ca 1945 with an unusual "Design" tonearm that has an original round Thorens cartridge in it (images below).

Via Google I only managed to find one single reference to this turntable and that hit only contained very limited information about this model... Could you tell me anything about this particular Thorens turntable?

Also all the other vintage Thorens “phonographs” I own or have owned are/were non-electronic acoustic units. So I'd greatly appreciate a few “how to use” tips...

Can anyone give me an idea of what the impedance of the cartridge might be?

I'd also appreciate any suggestions regarding 1) an appropriate modern preamp to use with this cartridge feeding into my PC to create digital audio files 2) an appropriate vintage preamp and amp for direct listening.

Thanks for any info you could share with me.

Friendly regards

[Blue Angel]

Beautiful old 'musicke box' you have there. My guess it played with ceramic or perhaps crystal cartridges - mono of course. These are high output type of needles for which you need a pre-amp with ceramic capability. I play 78rpm records and have a Dynaco valve integrated amplifier which has a ceramic input.

I also have a Leak valve mono pre-amp which offers a control for all the equalization curves used in 'the day'.

There are forum members here who know far more than I do which will give you better advice.

Step up, JoeZ

ba

[Macquid]

Thanks Joe. So I'll begin my list of "candidates" with the Dynaco and the Leak. Greatly appreciate your input!

Friendly regards,
Alan

P.S. I see you're located in one of the MOST BEAUTIFUL places there are on this Earth

[Blue Angel]

Hello Alan

The Dynaco mentioned is designated model SCA35. The ancient Leak pre is packed away. I'll find and post pics of the mentioned suspects to show you what they look like.

"Step up JoeZ" means I'm inviting fellow VE member Joe Zannieri - a US gentleman - to present you with more and better advice than I can.

Since I acquired the Dynaco a few years ago, I set up a vintage 12" arm which I re-wired mono "X2" so as to give me mono sound from 2 speakers when playing 78rpm records. Although I have ceramic cartridges, I prefer to use a Shure SC35C magnetic cartridge for which I have made a new harder suspension and a spherical diamond stylus.

I don't know what your objectives are with the Thorens but such adaptations (for better sound from 78's) could possibly be done to your Thorens and still be invisible. Since I'm not familiar with your turntable, my ideas offered may of course also be just speculation until the type of cartridge fitted is confirmed.

Yes, Cape Town is beautiful - sunny for a few days, but cold at night.

Regards

blue angel

[Macquid]

Thank you again.

Regarding "my objectives" yes in this particular case I set out specifically looking for a 78rpm turntable that would enable me to "reproduce the music" under optimal conditions.

I think I started to forget that in the excitement of finding this particular unit. But reading your remark reminded me of it again and made me realize that in fact this was the first time I had been searching for a piece where it was only about “playing the music" and not about "collecting the machine"

[Macquid]

Just finished examining the Thorens turntable in detail…

First I noted that the right hand side of the tonearm is pivoted and snaps into play position held in place by a spring loaded steel ball that pushes into a hole on the opposite fork of the tonearm. This is to allow the cartridge to be turned upright in order to make replacing the needles easy.

Removing the case’s bottom wood panel revealed just how heavy-duty and ROBUST the turntable motor’s construction is (photo below)! The motor’s housing is heavy gauge cast steel, like nothing I’ve personally ever seen before in vintage “consumer electronics”.

The motor has an ID plate which specifies:

Thorens Switzerland; Fab.(rication) Suisse; Type: RAI
N° 24623; W(atts) 15 W.
V(olts): 100-220; 50 ~ 60
photo below)

After that with the cartridge pivoted up into the “needle replacement” position the following inscription on the cartridge’s underside can be read:

Made in Switzerland
Thorens
Brown Boveri Crystal
(see photo below)

There doesn’t appear to be any model or serial number; but perhaps there’ll be one inside the cartridge when it’s dismounted or taken apart.

BTW the inscription “Brown Boveri Crystal” was intriguing to me. Swiss multinational heavy industry Brown Boveri is Switzerland’s biggest company; but I never associated them with crystal cartridges before… rather with railroad locomotives/wagons, heavy armament, mega power generators, turbines, etc.

Finally measuring the electrical resistance/continuity across the cartridge showed that the circuit is broken. But with the help of a flashlight I discovered the word “CRYSTAL” imprinted into the side of the tonearm (photo below).

Moving forward I’d be grateful for 1) Any historical, technical, etc. information you could give me about this particular Thorens turntable 2) Does anybody (HOPEFULLY!) rebuild crystal cartridges like this one… and if not (in the worst case) what would be an appropriate available cartridge for playing shellac 78rpm mono records that I could adapt into the tonearm’s 55 mm diameter by 17 mm deep opening for the cartridge?

Thank you.

Friendly regards.

[zwarte-romantiek]

Hi,

Congratulations with your beautiful Thorens. For more info and even a nice short movie check this website from a Dutch guy, who has over 200 turntables.
http://www.electricgramophone.nl/thorens/65.html
I would suggest that you contact this guy (see "contact" in right upper corner) for any of your questions. He repares old turntables and restores them to their former glory so he is probably will be able to give you a correct answer.

Your THORENS tonearm is called FUGUE according to Gerard Weichler's book on THORENS. And is Electro-dynamic. It was produced between 1945 - 1952. THORENS used this tonearm for their CB 33 turntable. It should be used with a tracking force of 40-60 grams!

You wrote that you owned different types of THORENS turntables. As a THORENS fan myself, could you describe which you owned and which you liked best?

Enjoy your turntable,

Niels

[Coffee Phil]

Hi Mcquid,

I have been following this machine on the cartridge forum. This has later info.
Since we now know that the pickup is crystal the fact that you don't measure continuty is correct. There is some chance that the crystal is still OK as the machine appears to have had an easy life. To check, connect the output to an auxillary input and play a record. If it appears that the suspension is dried out just GENTLY rub the tip of the needle with your finger to see if it has an output.

I seem to remember seeing something on the internet where someone "restored" an old Astitic crystal cartridge by installing the ceramic bar from a modern ceramic cartridge.

With nice artifacts like what you have I tend to want to do as little as necessary.
If the crystal is still good I'd let it be and just replace any rubber parts if necessary.

You mentioned that you want to play 78s as well as possible. To do that something like a GE RPX will I believe blow away any crystal cartridge. Again it pains me to alter something like what you have however if your pickup is teriminally dead it may be possible to gut it and make its case into a head-shell into which you can mount a GE RPX. You will have to get the tracking force down to about 5 grams for that approach. They did make a single stylus RPX so you won't have to deal with the little knob coming through the top.

There are two more concerns with going to a magnetic cartridge in a machine with a crystal or ceramic. 1. If the platter is steel it can be attracted my the cartridge effecting tracking force. 2. AC fields from the motor which were not an issue with a crystal can give rise to hum with some magnetics.

Phil

Phil

[Blue Angel]

I'm not sure if you can measure anything between the pins of a (Rochelle?) crystal cartridge. Information I have seen points to the fact that crystal cartridges absorb moisture over time, rendering them useless.

I have some of these old things here, as well as old audio books which I can read up on.

In recent months, I have dusted off some ceramic cartridges and the sound which I hear from them is much inferior to that of a purpose built for 78rpm magnetic cartridge.

blue angel

[Macquid]

Thank you zwarte-romantiek for all the information you replied with. Your identification of the turntable as CB33 allowed me to find further links via Google, including the reference to an auction last year that showed the same turntable (different wooden case), and also an eBay listing (current) of a several print ads one of which I immediately purchased that included many details about the motor…. http://www.ebay.co.uk/itm/Thorens-Turnt ... 2ec0428c89

Thank you Coffee Phil for sharing your expertise. Your most recent comments gave me the courage to hook the turntable up to a little amp I had on-hand. Quite honestly I’d been worried I’d be very disappointed if the cartridge was indeed dead. But it’s working fine and putting out a strong signal. I also hooked the turntable to a computer and recorded then removed the noise on some tracks using free audio software called Audacity that my son pointed me at. So I’m really happy

Thank you Blue Angel for all the information you provided. This is a GREAT forum and I intend to return regularly to follow and keep learning about vintage audio.

Friendly regards,
Macquid (Alan)

[Coffee Phil]

Hi Alan,

I think this is the best outcome. Your machine works and it is configured as Thorens made it in the first place.

Since you are digitizing some of your 78s please do attach a file for us to hear.
Also when the literature which you bought arrives if you would scan it for the library I would be grateful. It will be interesting to see Thorens description of their gear-drive motor.

Enjoy your beautiful machine.

Phil

Thank you zwarte-romantiek for all the information you replied with. Your identification of the turntable as CB33 allowed me to find further links via Google, including the reference to an auction last year that showed the same turntable (different wooden case), and also an eBay listing (current) of a several print ads one of which I immediately purchased that included many details about the motor…. http://www.ebay.co.uk/itm/Thorens-Turnt ... 2ec0428c89

Thank you Coffee Phil for sharing your expertise. Your most recent comments gave me the courage to hook the turntable up to a little amp I had on-hand. Quite honestly I’d been worried I’d be very disappointed if the cartridge was indeed dead. But it’s working fine and putting out a strong signal. I also hooked the turntable to a computer and recorded then removed the noise on some tracks using free audio software called Audacity that my son pointed me at. So I’m really happy

Thank you Blue Angel for all the information you provided. This is a GREAT forum and I intend to return regularly to follow and keep learning about vintage audio.

Friendly regards,
Macquid (Alan)

[Macquid]

Right Coffee Phil. I was very "Lucky"

I'll post the ad to the forum's library as soon as I receive it... and a couple of sound tracks generated with the turntable to the thread here.

Thank you again everybody!

Friendly regards,
Alan