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

[Nele]

Thanks, that's what I figured.
It turns out there is something wrong with the secondaries, I measure nothing, it's an open connection.

 

[Nele]

There was a broken wirelink inside of the transformer...

 

[Moby]

There was a broken wirelink inside of the transformer...

Well, it happen when you wind it in hurry

 

[Nele]

Well, to their credit: I contacted Advancedaudio and they will send me a new transformer free of charge even though I bought this one more than two years ago. And it is going to be their BV18 which is more like the original BV11.

 

[MagnetoSound]

Hi, sorry for such a silly question after all this time, but is it M3 screw threads inside the Banzai bodies? The 3 little holes in the top of the connector housing for mounting the boards.

TIA

 

[Vac11]

Yes, those are M3´s…

 

[MagnetoSound]

Yes, those are M3´s…

Thanks Vac

 

[Purplenoise]

Hey guys. I just finished my 49 C version build and it came out great. I made it cardioid only using a k49fet capsule (cardioid k49). I have a couple of questions.
- if I want to get more output level I could swap the 8pf cap to a 2pf cap correct?
- I didn’t use a rotary switch since it’s cardioid only so I just jumped COM and CARD pads on psu pcb. Is this correct? Should I have jumped COM and OMNI instead?
Thanks in advance. Cheers.

 

[Delta Sigma]

- if I want to get more output level I could swap the 8pf cap to a 2pf cap correct?

Yes, less feedback, more output. I tried a lot of values here then settled on less than 2pF (maybe 1.4ish). I played with R3 and C6 values as well and found what I thought was best. Listening back to my tests later, I realized I liked some of the removed component tests better. I restarted my tests and ended up removing C4, R3 and C6. I think this is the most common state of a modded M49. I'm pretty sure a lot of clones are like this too. I probably should've trusted Oliver's schematic, he had them removed.

I also increased the grid resistor. Mine is an M49b.

- I didn’t use a rotary switch since it’s cardioid only so I just jumped COM and CARD pads on psu pcb. Is this correct? Should I have jumped COM and OMNI instead?

The 47FET capsule doesn't have its rear diapragm terminated, right? In that case, voltage to your pattern wire doesn't matter. There's a few components in the mic that you don't have to use as well but you might as well leave them in. THat way, if you ever terminate the rear diaphragm, you're ready to go.

Is there a jumper for S2 on the board? maybe you could leave that open.

 

[Purplenoise]

Yes, less feedback, more output. I tried a lot of values here then settled on less than 2pF (maybe 1.4ish). I played with R3 and C6 values as well and found what I thought was best. Listening back to my tests later, I realized I liked some of the removed component tests better. I restarted my tests and ended up removing C4, R3 and C6. I think this is the most common state of a modded M49. I'm pretty sure a lot of clones are like this too. I probably should've trusted Oliver's schematic, he had them removed.

I also increased the grid resistor. Mine is an M49b.

The 47FET capsule doesn't have its rear diapragm terminated, right? In that case, voltage to your pattern wire doesn't matter. There's a few components in the mic that you don't have to use as well but you might as well leave them in. THat way, if you ever terminate the rear diaphragm, you're ready to go.

Is there a jumper for S2 on the board? maybe you could leave that open.

Thank you so much. I’ll definitely change the 8pf then. How did the omissions of c4,c6 and r3 affect the response of the mic? R3 more low end? C4 full output and C6 more high end?
Yes the capsule is cardioid only ( back diaphragm is not gold sputtered). I believe it was taken out of a tlm49. I have jumped the s2 yes.

 

[Delta Sigma]

Thank you so much. I’ll definitely change the 8pf then. How did the omissions of c4,c6 and r3 affect the response of the mic? R3 more low end? C4 full output and C6 more high end?
Yes the capsule is cardioid only ( back diaphragm is not gold sputtered). I believe it was taken out of a tlm49. I have jumped the s2 yes.

Might as well take the S2 jumper out; leave it open.

Changing C4 changes the sound of the mic as well as increasing the output. It's been a while but I believe it sounded more "tubey" without it and more "hi-fi" or clean with it. R3, yes more low end. Someone posted an explanation of this in previous posts. Increasing the grid resistor will also up the low end.

C6 is just high end attenuation. I may revisit this one depending on capsule. Right now I have a Beesneez M7 in my M49 and a Beesneez K7 in my EF-U47. I plan on swapping the capsules to see which one I prefer in which mic. The K7 seems to have more high end and could benefit from having C6 in the M49. We'll see though.

The M49 saturates in a real special (but subtle) way. That's the part I like most about it and I think it was softened by C4/R3.

 

[Purplenoise]

Might as well take the S2 jumper out; leave it open.

Changing C4 changes the sound of the mic as well as increasing the output. It's been a while but I believe it sounded more "tubey" without it and more "hi-fi" or clean with it. R3, yes more low end. Someone posted an explanation of this in previous posts. Increasing the grid resistor will also up the low end.

C6 is just high end attenuation. I may revisit this one depending on capsule. Right now I have a Beesneez M7 in my M49 and a Beesneez K7 in my EF-U47. I plan on swapping the capsules to see which one I prefer in which mic. The K7 seems to have more high end and could benefit from having C6 in the M49. We'll see though.

The M49 saturates in a real special (but subtle) way. That's the part I like most about it and I think it was softened by C4/R3.

Thank you for taking the time and valuable info. I changed the cap to 2pf for now and I’ll run a test tomorrow. I’ll use it in a couple of sessions first to see how it behaves before I try more stuff. It’s funny but every time I increase the low end response in a mic, although it sounds more impressive, I end up taking out in the mix haha.
When you say remove R3 do you just leave it out or you jump the pads with a wire?
Thanks again.

 

[Delta Sigma]

Leave it open. If you shorted that you'd have no gain from the amp.

 

[Purplenoise]

Leave it open. If you shorted that you'd have no gain from the amp.

Great, thank you so much again for your help.

 

[Purplenoise]

Leave it open. If you shorted that you'd have no gain from the amp.

Hey Delta Sigma...unrelated question but since I will be experimenting with some options...would it be safe to use a 150v coupling cap instead of the 250? I have a few wet tantalums that I’d like to try if possible. Have you experimented with coupling caps? Thanks.

 

[Delta Sigma]

Hey Delta Sigma...unrelated question but since I will be experimenting with some options...would it be safe to use a 150v coupling cap instead of the 250? I have a few wet tantalums that I’d like to try if possible. Have you experimented with coupling caps? Thanks.

Sure, your B+ is 116V so you'll have 116V across the cap while the tube is warming. I'm more cautious with NOS caps and their voltage ratings. Don't get too close to 116 (ie, 150V is probably OK, 125V is questionable).

Maybe someone with more failed cap experience might have a better opinion. Especially with wet tants because I think they could fail short instead of open.

 

[Purplenoise]

Sure, your B+ is 116V so you'll have 116V across the cap while the tube is warming. I'm more cautious with NOS caps and their voltage ratings. Don't get too close to 116 (ie, 150V is probably OK, 125V is questionable).

Maybe someone with more failed cap experience might have a better opinion. Especially with wet tants because I think they could fail short instead of open.

Great, thank you so much for your help and valuable info.

 

[Purplenoise]

Mic is finished and sounds fantastic...quiet and smooth. I ended up with a clarity caps coupling cap but I would like to play around with this. I am thinking of trying a PIO but it’s not easy to find one that fits. I ordered a couple of nos Cornell-D 1uf 200v that looks like it will fit...or I could go 0.47uf and use a k42. Anyone tried a PIO in that position? Any suggestions? Thanks in advance.

 

[Bowie]

Mic is finished and sounds fantastic...quiet and smooth. I ended up with a clarity caps coupling cap but I would like to play around with this. I am thinking of trying a PIO but it’s not easy to find one that fits. I found that stage to be hugely influential. I ordered a couple of nos Cornell-D 1uf 200v that looks like it will fit...or I could go 0.47uf and use a k42. Anyone tried a PIO in that position? Any suggestions? Thanks in advance.

I've used a few different caps in the output, including PIO, and will just recommend trying different caps to see what fits your personal taste. I don't recommend using older caps unless you have a way to test for leaks and such. Even the best old PIOs usually have some degradation.
Most sellers of modern film caps will have the measurements published so you'll know in advance if it should fit. I can't advise because my 49s are P2P.

 

[Purplenoise]

I've used a few different caps in the output, including PIO, and will just recommend trying different caps to see what fits your personal taste. I don't recommend using older caps unless you have a way to test for leaks and such. Even the best old PIOs usually have some degradation.
Most sellers of modern film caps will have the measurements published so you'll know in advance if it should fit. I can't advise because my 49s are P2P.

Hey Bowie, thanks for chiming in. The tube you sent me sounds fantastic by the way, as always. I ordered some NOS caps, hydra mp, a Siemens mp ( old silver square one) and a Cornell-dubilier paper in wax. Sellers report good measurements as far as Vloss and esr. Hopefully they will be ok. They are coming from Europe so I would say they should be here in about a month.