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)

 

[oongbac]

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

The board is bakelite made from fabric. I bought it from domestic supplier in S. Korea.

Turrets are https://www.mouser.kr/ProductDetail/534-11218 this one and https://www.mouser.kr/ProductDetail/534-1402-3 this one.

I'll upload backside later.

Edit. Pictures are attached.

 

[LucaN]

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)

Makes sense, thank you!

 

[LucaN]

View attachment 138015
View attachment 138016
View attachment 138017
View attachment 138018

The board is bakelite made from fabric. I bought it from domestic supplier in S. Korea.

Turrets are https://www.mouser.kr/ProductDetail/534-11218 this one and https://www.mouser.kr/ProductDetail/534-1402-3 this one.

I'll upload backside later.

Edit. Pictures are attached.

Thank you! Love looking at the details