M49 Alternate schematic for cardioid only

[oongbac]

I built one with @elskardio ’s schematic.

Body is a bit small so layout is not that neat, but it works really well.

Thanks @elskardio for sharing schematic and your build! Really appreciate it.

 

[elskardio]

View attachment 133702

I built one with @elskardio ’s schematic.

Body is a bit small so layout is not that neat, but it works really well.

Thanks @elskardio for sharing schematic and your build! Really appreciate it.

True DIY! Congrats!

 

[garp]

I am currently on a M49 point to point but missing the two 150M at R1 and R2 on original Neumann schematic, can i use 100m or 200M instead ? What is best choice ? more or less ohms ?

 

[OneRoomStudio]

I am currently on a M49 point to point but missing the two 150M at R1 and R2 on original Neumann schematic, can i use 100m or 200M instead ? What is best choice ? more or less ohms ?

I used 100M in mine, with no issues.

 

[Migs 31]

I am currently on a M49 point to point but missing the two 150M at R1 and R2 on original Neumann schematic, can i use 100m or 200M instead ? What is best choice ? more or less ohms ?

I second what OneRoom said: I also used 100M on two prototypes, and it sounds good.

On thé next build, I will try 200M (found them on the RS site) & will report.

M

 

[LucaN]

View attachment 133702

I built one with @elskardio ’s schematic.

Body is a bit small so layout is not that neat, but it works really well.

Thanks @elskardio for sharing schematic and your build! Really appreciate it.

That yellow board looks very practical for p2p. What material is it/where did you get it? Same for those turrets. Not that they seem special but the ones I got are either too big or too small, wondering if you have any specs on that. Beautiful build!! Would love to see the back

 

[LucaN]

In his schematic, Oliver omitted the C4 (8pf) plate to grid capacitor. Here's what I found so far

With no capacitor I find the mic sounding "harsh". I've tested different values and I ended up with 5pF.

You said you preferred the sound after adding C4 plate to grid capacitor...

Then you posted this,

Here's the schematic I ended up with and I'm satisfied with the sound of the microphone.

and I don't see C4. Did you change your preference or just forgot to put it in the final schematic?
I know I can try and judge for myself, but I think I ran out of capacitors around those values so I'm wondering if it's worth purchasing. What voltage rating should I look for?

 

[Khron]

What voltage rating should I look for?

160V bare minimum, 250V or more preferably. Film or NP0/C0G ceramic, and it's likely cheaper to stick to E6/E12-series standard values.

https://en.wikipedia.org/wiki/E_series_of_preferred_numbers

 

[OneRoomStudio]

You said you preferred the sound after adding C4 plate to grid capacitor...

Then you posted this,

and I don't see C4. Did you change your preference or just forgot to put it in the final schematic?
I know I can try and judge for myself, but I think I ran out of capacitors around those values so I'm wondering if it's worth purchasing. What voltage rating should I look for?

I wonder if @elskardio meant C1 (plate to ground). Oliver also omitted that, and as I have shared, I thought it made a positive difference to add it back. I think the description of the mic sounding “harsh” without it is accurate.

Also, C4 would affect the overall level, not the treble/bass.

 

[elskardio]

My first build was using 3U's GZT-87 transformer.

Without the 5pF C4 (to lower the output level) the transformer was saturating and the mic sounded "harsh".

I later switched to the UTM-0549 (bigger core) and removed C4.

So if you're planning to use a small core transformer, I would suggest adding C4.

I always use Silver Mica capacitor for that task with great results.
(https://mou.sr/3NgBnNA)