JS Transformers ( Jørgen Schou) 1:40, 20ohm-30kohm, recomended applications?

Hi, does anyone knows about this type, what type of applications (all possible) would you suggest for this type of transformer?

JS 0,32M nr 6213, Input transformer. 20ohm , 30kohm. 1:40
also marked BO (bang olufsen? ..Its taken from some 1950-60´s tubeamps I heard )

And, would in addition be very happy to hear from anyone whos had the opportunity to try this very model, or same type of specs JS transformer.
Quite hard to find any info, and I would love some suggestions before I start on any wrong tracks...

Interrested in building Mic pre, DI box ( Hansén ), Micpre/Di combo. Or any other combinations/twists, for wider use of applications..?

I guess its not usable in any stages of analog eq circuits or mastering chains?

Greetings

It's probably a moving-coil pickup input transformer...

Jakob E.

Hi Jakob

Yes, I saw a japaneese site with this model as mc trafos. Still, Im not 100% sure in overall, because I was told they are mic inputs buy the person I bought it from,
and he was quite experienced in Tube amp Diy for example.
And some discussions around JS mc-trafos, have other ratios.. Still, Im yet no expert in ohm and ratio calculations, this is also why Im asking.

Positive is, that if they are mc, then I could get some good payed for them, and buy something else for a project, more suiting for me.

Some pictures:

http://2.bp.blogspot.com/_It_nwX6Bc0k/S7HdZV4dtOI/AAAAAAAAATo/CX1M8-cInCQ/s1600/JS+trafos.jpg

Hi!
I have some JS transformers too...
Type 3,15M Line Transformers
And
3,15P Output transformers.

Came from SS lineamps,
So just wondering what to with them?
The Line Transformers have
1K ohms
4K CT ohms
15K ohms

And the output transformer has
40 ohms
200 ohms

Not too sure how to use them, was thinking
of making some DIY stuff...

Any info or ideas?

Thanks!

Tom

Almost the only JS Transformer info floating around (in Danish, use e.g. GoogleTranslate):

http://www.hifi4all.dk/forum/forum_posts.asp?TID=80982

Jakob E.

hi,

has anyone come up with any JS datasheets or catalogue scans?

found the attached scan of a catalogue page listing some MC transformers.( maybe the same stuff the jakob's link had, but the picture links are unfortunately now dead.)

did anyone download the pictures from the link? would be interesting to check them out.

thanks!

MeteorMan said:

hi,

has anyone come up with any JS datasheets or catalogue scans?

found the attached scan of a catalogue page listing some MC transformers.( maybe the same stuff the jakob's link had, but the picture links are unfortunately now dead.)

did anyone download the pictures from the link? would be interesting to check them out.

thanks!

Click to expand...

As far as I know, there's no datasheets around. I have some scans from retailers of JS (Gösta Bäckström among others), but they only show ratios and intended purposes.

Best,
Olle

From the Bäckström catalogue #2

I picked up this page on line transformers somewhere, maybe here at GDIY?

Conviction said:

As far as I know, there's no datasheets around. I have some scans from retailers of JS (Gösta Bäckström among others), but they only show ratios and intended purposes.
Best,
Olle

Click to expand...

Olle, thank you so much for scanning the Williamson output transformer JS model 350/808 - I had only seen photos of that transformer, but no details.  That page shows the power transformers, and chokes that would have been used by diy or manufacturers make in the 1950's to clone the Williamson amp.

Could I ask if there were any other pages/details relating to the Williamson parts?  I know the 808 was used in Williamson amps.  The  768 may just have had different output impedances.  The main photo of a 618/2 appears to be an output transformer (and the 350 type appears to be for output transformer), but there are no technical details on that model number on the page.

Ciao, Tim

here is a hard to read print of the OPT for the Heathkit Williamson,

huge core, hard to wind, got a rep on evilbay for big $$$

winding data, many different types of insulation, hard to fit it all on there without stretching wire as tight as a snare drum,

quad filar sec,  #26 used for pri and sec with 5 lams of Ni in the middle of the core to make the engineers gloat,

10 Hz to 100 K Hz with good sq wave response,  either two 6550's or four 6L6GC types,

Top stuff CJ.  That is for the later W-6M, which has a number of circuit changes from the original Williamson, and certainly had power boosted to 80W - not a lightweight OT by any means.  That's a rare find, as not many manufacturing specs would ever get past a dumpster after a few decades of gathering dust in a large organisation.

The W-5M output transformer is the topic of a current thread at audiokarma - it was thought that the Ni lams were only used in one of those transformers - from circa 1955.  Photo of core in link:
http://audiokarma.org/forums/index.php?threads/output-transformer-for-a-heathkit-w5m.759575/

Tim

thanks for the scans!

found one more MC cartridge related document, attached.

Conviction said:

From the Bäckström catalogue #2

Click to expand...

does anyone know more about this JSO 32M mic transformer( no specific model number in the catalogue page) with 50-250-600ohm primaries and 100k secondary?

i have one quite similar 0.32M newer model that has 50-200-600 primaries and 100k secondary. 1:45 ratio.

the scan i attached earlier has "pick-up stikpropper med inbrygged transformer" (cartridge with built-in transformer?) with similar 50ohm- 100k ohm specs.

uncommon ratios for mic transformer. just wondering for which actual application they are designed for.

"pick-up stikpropper med inbygged transformer" is "phono cartridge connectors with built-in transformer" - probably pointing to phono cartridge use..

Jakob E.

PS: the real naming is like JS 0,32 xx - NOT JSO 32 as some of these papers say...

ah yeah thanks, makes more sense. 

trobbins said:

Olle, thank you so much for scanning the Williamson output transformer JS model 350/808 - I had only seen photos of that transformer, but no details.  That page shows the power transformers, and chokes that would have been used by diy or manufacturers make in the 1950's to clone the Williamson amp.

Could I ask if there were any other pages/details relating to the Williamson parts?  I know the 808 was used in Williamson amps.  The  768 may just have had different output impedances.  The main photo of a 618/2 appears to be an output transformer (and the 350 type appears to be for output transformer), but there are no technical details on that model number on the page.

Ciao, Tim

Click to expand...

You're welcome! I think that was it, but I'll check the catalogue again to be sure.
Do you need higher quality scans?

350 is indeed the type no for output transformers. I have a few on the shelves.... extremely heavy. They all come from Bäckström EL34 push-pull amps.

I actually got quite a JS collection. I'm a huge fan of the 3313/2 and 5372/5 mike inputs. Speaking of Williamson, several microphone amps I have are fully differential (Williamson-ish). That was the common practice at the Swedish Radio and Televerket in the 1950's.

MeteorMan said:

does anyone know more about this JSO 32M mic transformer( no specific model number in the catalogue page) with 50-250-600ohm primaries and 100k secondary?

i have one quite similar 0.32M newer model that has 50-200-600 primaries and 100k secondary. 1:45 ratio.

the scan i attached earlier has "pick-up stikpropper med inbrygged transformer" (cartridge with built-in transformer?) with similar 50ohm- 100k ohm specs.

uncommon ratios for mic transformer. just wondering for which actual application they are designed for.

Click to expand...

As Jakob says, a 50 ohms primary might point to phono cartridge use. However, a 50 ohms primary was actually not that uncommon for microphone use in the mid 1950's. At least not at SR/Televerket. I've got scans of several preamp designs utilising JS transformers with a 50 ohms primary (only). The input valve would have been EF12 or EF14 and later on ECC40 and EF86.
Likewise, loads of (ribbon) microphones were wired for 50 ohms.

Conviction said:

You're welcome! I think that was it, but I'll check the catalogue again to be sure.
Do you need higher quality scans?

Click to expand...

That scan was fine 
Does the Bäckström catalog have a date?  If you don't mind, I will add it to a collation of Williamson details on http://dalmura.com.au/projects/Williamson.php

If you come across any late 1940 / 1950 articles in local tech mags, etc on the Williamson amp I would really appreciate knowing about them.

Tim