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[electricsky]

I bought this M49 recently but i'm not sure of the version it is !
I was sold this mic as an M49C then when i opened it, i thought it was an early M49 as there is no tag board with 50/200 ohm settings
but the seller now says it's  an M49 converted to C  and that the small red dot after M49 means it been converted to  C !
But when i search on the net, i found out that the little red dot means it left the factory wired  for 50 ohm, so i don't really know what to think !
It's the version without selector on the mic but from the power supply , with M7 capsule and what seems to be an AC701 tube.
Could you tell me what version it is and if i can switch it to 200 ohm as seeing teh output level , i would tend to think it's wired for 50 ohm !

[electricsky]

I would tend to think it's an early version , not a B  or C as there is no tag board to select 50 or 200 ohm and i see only one setting  possible although i might be wrong (These verification things before posting make me crazy ...) !

[electricsky]

Here's what seems to be an AC701.

[klaus]

Judging by the components, wiring material and parts layout, this is a pre- "b" or "c" M49 model, with a retrofitted "c" cathode biasing, and a replaced or refurbished head basket and bottom bell (notice the shiny metal next to the pitted bottom connector sleeve).
When the body work was done, was probably when the i.d. plate might also have been replaced or modified:

As this M49 shows a late version of the C49/1 transformer, thus lacking the BV11 transformer with the 50/200Ω switchable secondary, it was made before June 1956, and therefore the red dot is a fake, unless the transformer was custom-wound to 50Ω by Neumann, sometime after ca. 1958, when, to my knowledge, the red dot that identifies factory-delivered 50Ω mics was first used.

[usattler]

I concur with Klaus: this microphone was most likely manufactured before 1956 (probably after 1954) as evident by the red pilot light cover/crystal where later versions after around 1962 sported the Neumann diamond. Also, the serial number is below 1600 - after which the b-version started. Actually there was never an a-version! Microphones below serial number 1600 simply were M49, without any suffix. This specimen apparently was subsequently modified to the biasing scheme of the c-version. Even early output transformers of this microphone with the Telefunken AC701k (instead of the Hiller MSC2 used in the very first M49) tube featured a dual secondary, and it is likely that the selector board was removed along the way and the output directly hard wired. Follow the leads to pins 1 and 2 (AF out) to the transformer and you may discover whether the secondaries are wired in series (200 Ω or parallel (50 Ω).

[electricsky]

Thanks very much for your answers !
It sounds even more weird and complicated than i would have thought, i'm not even sure i understood all you wrote; i will read it again but from what i understand , this might be an early version , converted to C (cathode bias)  but you seem to say it still has an early CT 49/1 transformer !
Was the early transformer possible to wire for 50 and / or 200 ohm , as for the BV11  or was it only having one secondary wired at the factory for ?? ohm ?

Also, Mr Heyne seem to say the  mic has only one secondary if i understood it all and seeing the output level, i would tend to think it's wired for 50 ohm ( the red dot , if done by Neumann as the seller seems to say , would  confirm that i suppose) but the other person seems to say it has a dual secondary and that it could be wired for 50 or 200 ohm , so i'm not sure what to  think !
I thought part of the C specifications is to have 50 and 200 ohm on top of the biasing method that gives a better  noise floor or so !

From what i read , some people tend to think the early transformer was sounding quite good, so maybe it's not a bad thing i still have the early transformer ?

So, what is the difference now , with a real C (apart from those who have a selector on the mic body) apart from teh different transformer , is it just  the fact i might only have one secondary ?

[usattler]

The transformer question can not be reliably answered without closer insopection by a knowledgeable and qualified technician. The photographs are simply inconclusive on this topic, and since it is clear that this specimen experienced some 'intervention' and modifications during its nearly 60 years, who knows?... The photos reveal at least that these services appear to have been carried out expertly.

[klaus]

I concur with Uwe, and add:
The transformer model that is shown in the picture was not switchable, as it only had one secondary.

It's quite easy to determine whether you have a 50Ω secondary on your transformer: do a resistance test, where you measure the resistance between output connector pins 1 and 2. Then report back.

The 'C' spec of later M49 had a lot of changes built into the model: low end cut, improved noise floor, improved headroom, etc.
But I also agree that the early M49 have a very attractive tone which, with the right owner, can make up for some of these later changes.

[electricsky]

Thanks for youer answers.
Which output connector ?
I don't really understand, do you mean on pin 2 and 3 of the xlr connector that goes out of the power supply  (i got the original power supply + another power supply stamped Teldec , with an xlr connector instead of the standard connector found on the original ones ) ?

Do you mean  it might have been  a good idea to upgrade this early M49 to "C" version if it has been done correctly , to get the tone of the early ones with some specs from the C version ?

[klaus]

You could measure at the 3-pin XLR connector of the power supply between pins 2 and 3, but I prefer you measure the resistance at the actual male mic connector, mounted at the bottom of the mic.

Modification of any tube operation to 'C' -type cathode biasing has some sonic changes associated with it: any tube biasing contains a frequency equalizing component. I'd suggest, to leave the current set-up alone, fat least for the time being. It is a good starting point and compromise between good sound and low noise in an M49.

[electricsky]

I'd suggest, to leave the current set-up alone, fat least for the time being. It is a good starting point and compromise between good sound and low noise in an M49.

Thanks for your answer.
i have no will to modify anything for the moment, except maybe have the capsule reskinned by Mr Thiersch, especialy as when i opened the mic box when i received it, the mic was making a noise " gling, gling , gling ...' coming from under the grill , next to the capsule !
There was a little metal ring moving inside  under the grill next to the capsule and  i wondered what it was as  saw no reason to see this part here !
The seller said it was coming from the top  , inside the grill and that it got unsoldered during shipment but Mr Schneider at Sennheiser/ Neumann, told me that this little metal ring  should not be used for a M49, only for  M50, so i don't  know why the seller put it here , as obviously, it made 2 or 3 little dings in the capsule ( it could gave ruined it totaly knowing the thickness  !) !

Also, the output level doesn't seem  very high, i have to compare with some other mics but i thought it was wired for 50 ohm at first but the  seller says it's wired for 200 ohm and Mr Schneider  answered me after i sent  hilm several pictures of the mic :
" It's the old transformer, no rewiring to 50 ohms " .

The seller sold it to me as a M49C , without other explanations but that's not exactlyt what it is !

[klaus]

Your mic was obviously manipulated more than initially revealed.

About that mystery ring: All M50 mics used a 40mm Plexiglass sphere surrounding the omni capsule. To prevent the Plexiglass ball from hitting the inside of the mic's conical head basket, a cylindrical rubber nipple was installed on the top of the ball that fit into a cylindrical guide ring (shown in the picture). The ring was hard-soldered to the inside top of the basket (you should still find remnants of the attachment/solder inside the basket, at the top). With the Plexiglass ball stabilized that way, body shock could no longer whiplash the capsule and its Plexiglass ball against the head basket's walls.

As this guide ring was only attached to M50, someone sold you an M50 head basket for your M49, instead of an M49 basket, and replaced the white M50 jewel with a red one.

This confirms earlier suspicion that your mic was put together from different parts, in addition to sporting a non-conforming i.d. plate.

P.S.: I'd be careful with premature capsule diagnosis: hearing "gling, gling, gling" is an insufficient method to pinpoint capsule or diaphragm failure. As no aftermarket reskinner can accurately reproduce the glorious sound of an original M7, please consult with a qualified technician before assuming the capsule is at fault, and that it is unrestorable in its current, stock, configuration.

[electricsky]

Thanks very much for your answer Klaus (sorry for the delay) !
I didn ´t say the capsule is not working but it has 2 or 3 physical dents on the thin " skin" what bothers me as it was in correct condition apart from that !
I didn ´t have much time to try it for the moment as i have several things to deal with (including finding a good place to instal the recording studio...)
I don ´t know what to do with it if the capsule still seems to work correctly despite the damages !
Maybe keep it this way if it works but i'm extremely angry at the seller , cause he didn ´t want to hear about the problems he created (and also as it´s some money !) and i could not find a solution with him to resolve the problem (dishonnest seller !); on top of the fact i dońt like to have a mic  with a damaged capsule !

What about the earlier ones that have the capsule holder made of transparent plastic and not made of metal  , no problem of any sort with those transparent plastic capsule  "foot" / holder ?

[klaus]

Small nicks in diaphragms usually do not cause serious trouble. But a close-up picture of the affected area might confirm that better than just speculating.

What about the earlier ones that have the capsule holder made of transparent plastic and not made of metal

Original M49 capsule mounts are always made of metal. Maybe you meant something else?

[electricsky]

I meant made  ( the base , just under the capsule , that holds the capsule ) of transparent plastic like that (see picture ,sorry i couldn't load it better than that yet)
Unfortunately ,the time i asked about it and tried to deal with a problem with my credit card and the mic got sold ; i' m quiet disapointed as i was looking for another like mine to make a pair for a correct price ...