Neumann M49 Clone : Build Thread Puck Style (TLM49 Conversion To M49 b-c)

[TillM]

This is the Schematic
https://cdn.groupbuilder.com/groupdiy/u/39511/58d1402a05456.pdf

 

[TillM]

So i find finally the mistake.
Today I check my mic with the working mic I sold to my friend.
I just check the resistance with my DMM.
In Pin 3 and 7 i realized that the working mic shows 0,8 ohm and the faulty mic goes up and up.
I connected pin 3 with the mic body, cause with my old mic it works great.
I don’t know why it don’t work with the Aputis body, but the fix was, to connect pin 3 with the pin 7 from the connector (as mentioned in the guide from Dan).
Now everything works like it should !
Thanks to everybody for your help.

 

[Moby]

Finally  we told you to check the wires; )

 

[rmburrow]

The ground return was missing....

 

[Banzai]

I don’t know why it don’t work with the Aputis body

Might be a non-conductive coating on the body. Check with a DMM to see if there's continuity between two different points of the body surface.

 

[TillM]

Hi guys,
after months without any issue, my M49 starts to make crazy noises.
I've to say the preamp is pushed really hard, but has anybody an idea, what could be the issue ?
I reflow every solder pads.
Clean the PCB again and changed the styroflex, this was the first, what comes into my mind.
I hope anybody can help.
Do you know, where the noise can come from ?

https://www.dropbox.com/s/88zubsc66wm1lwy/M49%20probleme.wav?dl=0

 

[Ericbazaar]

Its the Tube. The 6s6b is a good Tube but many of them make noise after a while.
I think they are different in quality.

Best

 

[TillM]

thanks for chiming in Andreas !
I will change the tube. I hope it will work as it should.

 

[TillM]

great, from the first test with a new tube the buzzing is away. When I push the preamp now hard, the noise seams to be more from my computer and so on.
Well I never push the pre so hard, but a friend of mine need it for a record.
thank you very much !
Will test it with my other M49, than I can compare it better.

 

[Nele]

I'm organizing a group-buy for Cinemag transformers but will the CM-6511 be suitable for the 6V6S tube version or should I get a different one?

 

[Moby]

I'm organizing a group-buy for Cinemag transformers but will the CM-6511 be suitable for the 6V6S tube version or should I get a different one?

Why don't you proceed with the classic Bv.11?

 

[Nele]

Why don't you proceed with the classic Bv.11?

Isn't the CM-6511 a reproduction/replacement for the BV11?

 

[Moby]

Isn't the CM-6511 a reproduction/replacement for the BV11?

Replacement, yes, reproduction, no. I really don't want to judge about the quality of this transformer, but it doesn't match the original Bv.11 in many aspects.

 

[e.oelberg]

soooo.. I have this wonderful sounding, quiet (almost) m49c with 6s6b, BUT  there is a low volume gsm audible, only on headphones and only with good quipment ……… it's annoying me ... any community tip ?

cheers, Nicholas

 

[JMPGuitars]

I’ll do a pic of the round connector as well!!

Have you considered making an adapter to house a standard 7 pin jack instead of the binder jack for the M49 puck bodies?

 

[JMPGuitars]

soooo.. I have this wonderful sounding, quiet (almost) m49c with 6s6b, BUT  there is a low volume gsm audible, only on headphones and only with good quipment ……… it's annoying me ... any community tip ?

cheers, Nicholas

What values are you using for C4 and R3?

 

[JMPGuitars]

Can a couple people please post their M49c voltages for each pattern?

My voltages change with each pattern, and performance is much different. Omni is much louder and sounds best. Cardiod sounds like it has a bass roll-off or something. F8 sounds lethargic.

In Omni my cathode is 1.65V and anode is 54V. If I switch to Cardioid or F8, K is 2V and A drops to around 33V.

Thanks,
Josh

 

[Delta Sigma]

Can a couple people please post their M49c voltages for each pattern?

My voltages change with each pattern, and performance is much different. Omni is much louder and sounds best. Cardiod sounds like it has a bass roll-off or something. F8 sounds lethargic.

In Omni my cathode is 1.65V and anode is 54V. If I switch to Cardioid or F8, K is 2V and A drops to around 33V.

Thanks,
Josh

Mine is the B version so bias voltages will be different but you've got an issue there. Is your B+ changing as you change patterns?A change in bias may cause that much change in your anode voltage but I'm curious if you have current flowing somewhere in your pattern selection and capsule bias circuit.

It's possible you have an incorrect value component somewhere or a "short" in your hi-z section. Did you wear gloves and clean thoroughly when working on the hi-z components?

 

[JMPGuitars]

Mine is the B version so bias voltages will be different but you've got an issue there. Is your B+ changing as you change patterns?A change in bias may cause that much change in your anode voltage but I'm curious if you have current flowing somewhere in your pattern selection and capsule bias circuit.

It's possible you have an incorrect value component somewhere or a "short" in your hi-z section. Did you wear gloves and clean thoroughly when working on the hi-z components?

Thanks for the response. Yes, I wear gloves, and the circuit is very clean. Not wearing gloves can contribute to noise, but I don't see how that would cause these issues? I also test and verify every value of every component before installing.

My inclination is that there's more likely something wrong in the PSU, but without seeing other M49c reference voltages, I'd be guessing and going in blind.

Thanks,
Josh

 

[TillM]

Shouldn't it be stable no matter which pattern you choose? (Really honest question, I've to learn a lot about tube circuits)
Cathode on circa 1,3-1,6v and Anode at 44-46v (I think yours also fine).