Ela-M 251 Body from Aliexpress

[ubxf]

Darn I was thinking of using it for my hydrophone project

 

[garp]

Maybe but it is also much easy to work with (acrylic is brittle), totally heat proof when soldering, helps to maintain things clean of flux, and the most important a much better dielectric.
edit : Can i use / modify a chinese tube mic power supply with pattern switch for this project or am i forced to build Poctop's PSU ?

 

[Migs 31]

Can i use / modify a chinese tube mic power supply with pattern switch for this project or am i forced to build Poctop's PSU ?

Of course you can. This is a DIY site. Nobody FORCES anybody here (at least I hope). And I have done it (modding PSU).

You can either use a smaller Chineese PSU at 120V. I ordered one just this morning. Add pattern switch, easy.

Or modify one of Thomann’s - T.bone power supplies. You will need to lower voltage (two parts to change) maybe filter better the output voltage & ground it better. Fellow GDIY members went on at length on how to achieve that.

M

 

[garp]

You have a link ? or a schematic ? I already have two T bone retro II PSU from thomann

 

[Migs 31]

Link here - 30 bucks a piece for 120V PSU - Chinese made with prire.
http://www.ssyelectronics.com/product/15

GDIY members dissecting tiny micro-organisms & eating their internal organs, ad vitam aeternam:
https://groupdiy.com/threads/heater-voltage-filtering.80421/

Schematics below. Red circle/oval (change parts) and red arrow (polar patt).

Anything else... would you like some sugar and milk with your coffee Sir?

M

 

[garp]

No milk thank you ! Le service est impeccable j'en ferai part à la direction

 

[Buttercup1]

Hey Garp!
Cool build but how did you do the black rear grille?

 

[garp]

Spray paint Satin black for bike exhaust, masking tape bake in the oven et voilà !

 

[geekmacdaddy]

Got mine done. Such an impressive sound, look and feel of this microphone. I'm going to record something with long phrased vocals and acoustic guitar ASAP to demo for real, but wow. Is this self biasing? Did I read that, in a thread? If not, where do you measure from? Did a fast spoken demo late last night, no vari-mu compression this time. Straight into the hardware, no eq, just mic.
https://www.dropbox.com/scl/fi/nhvv...st-2.wav?rlkey=9vn830o2j3qgj4be3qcxeln31&dl=0
This was a scary build for me to get started, with it's point to point section. HerbertR is wonderful with his documentation which I followed (3U Tx, Beesneez Capsule) but I have the 250M grid to ground and a 1uf PIO in there. Herbert, I'm listening closely to see if it's too bassy, but my C12 def has more, and I'm happy in those frequencies, but does it have the sweet mids you referred to? I have no basis for comparison, only youtube.

 

[thomasdf]

Nice ! Did it come with the E on it ? What circuit did you use, and on what support ? Where did you get the shock mount ? Lots of questions

 

[geekmacdaddy]

Nice ! Did it come with the E on it ? What circuit did you use, and on what support ? Where did you get the shock mount ? Lots of questions

Yes, body came as is (heavy as hell too). Both body and shock mount from Ali Express. Dany's D251 boards but make sure you read through this thread. Lots of modifications needed to make this fit. Not a lot of direction with the power supply, but it's damn close to Dany's C12 P/S and photos got me the rest of the way there.

 

[thomasdf]

Do you have a link to the shock mount ? The ones I found were slightly too large iirc
I will probably go ptp / turret for mine.
It’s funny because my bodies came without the markings. Prob an older version.
Cheers !

 

[geekmacdaddy]

Sure. Know that it just about gets in there, but does fit. https://www.aliexpress.us/item/3256...t_main.30.3f561802wMWc4s&gatewayAdapt=glo2usa
Greetings from NY

 

[thomasdf]

Thanks !

 

[garp]

Same seller has bodies with markings ...

 

[HerbertR]

Got mine done. Such an impressive sound, look and feel of this microphone. I'm going to record something with long phrased vocals and acoustic guitar ASAP to demo for real, but wow. Is this self biasing? Did I read that, in a thread? If not, where do you measure from? Did a fast spoken demo late last night, no vari-mu compression this time. Straight into the hardware, no eq, just mic.
https://www.dropbox.com/scl/fi/nhvv...st-2.wav?rlkey=9vn830o2j3qgj4be3qcxeln31&dl=0
This was a scary build for me to get started, with it's point to point section. HerbertR is wonderful with his documentation which I followed (3U Tx, Beesneez Capsule) but I have the 250M grid to ground and a 1uf PIO in there. Herbert, I'm listening closely to see if it's too bassy, but my C12 def has more, and I'm happy in those frequencies, but does it have the sweet mids you referred to? I have no basis for comparison, only youtube.

Hi, I think it sounds very good. Crystal clear. Well done.

Now I would make adjustments until the sound meets your expectations and taste.

- Try reducing the 250M R4 grid to ground resistor to 30M, 60M or ....100M by putting the 250M in parallel with a 100M... "piggyback". Fast and easy to check, without any desoldering. This will give you an "on the face" immediately and also more noise, like the original.

-test different cathode capacitors C3 instead of the standard 20uF...like 10uF or up to 100uF, you can immediately hear the change in warmth, FR...... Find your sweet spot. This component is more difficult to replace

-and at least after these adjustments I would play with the DC decoupler capacitor C1 and eliminate all unwanted "low frequency dirt" by reducing these capacitors from 3uF to 100nF and adding the nuance of the capacitor used, Styro, PP, Pio, Wet Tantalum like in the original 251....

This mic is a playground...

 

[Khron]

test different cathode capacitors C3 instead of the standard 20uF...like 10uF or up to 100uF, you can immediately hear the change in warmth, FR.

Well, 20uF & 1.8k "already" gives you a 4.4Hz corner (-3dB) frequency, so i don't know just how (realistically) audible changing that is...

the DC decoupler capacitor C1 and eliminate all unwanted "low frequency dirt" by reducing these capacitors from 3uF to 100nF

Well, reducing that does indeed cut the low-lows, but also introduces a resonant peak, so...

https://sound-au.com/articles/audio-xfmrs.htm

 

[geekmacdaddy]

I've been listening to comparison vids on youtube. Now I understand that my first sample is a bit bottom heavy, but in fairness, I was right up on the mic. There is a 1uf PIO in there now. I'll try again a bit off mic, but if I want to get some of that bottom out, can I achieve it by going with a .68uf? I have a PIO coming in, but only have a 100v film (for marshall amps) to try. Is that too low voltage? Thanks for the help and ears.

 

[HerbertR]

Well, 20uF & 1.8k "already" gives you a 4.4Hz corner (-3dB) frequency, so i don't know just how (realistically) audible changing that is...



Well, reducing that does indeed cut the low-lows, but also introduces a resonant peak, so...

https://sound-au.com/articles/audio-xfmrs.htm

Test, test, test... Capsule, tube, TX, everything interacts. The UTM C12 TX, for example, sounds noticeably bassier than its much smaller 3U counterpart. I prefer the 3U here... It's a really great mic to try out different values on. Many engineers use 47uF, 100uF ...as the cathode capacitor on original GE6072 tubes instead of 20uF. The presence of the mic changes. That's the benefit of building two "exact" mics in parallel. Same goes for the DC block 3uF capacitor. It's too high in my opinion, too much bass boom comes through. Depends on each component for sure, Beesneez capsules vs. others... These are typical 251 values used by the mic gurus and most work pretty well.

But first I'd play around with the grid-to-ground resistor on Geeks Mic. It changes the character. It forms a HP with the capacitance of the capsule and sets the corner frequency lower with a higher resistance value. Capacitance of capsules varies a lot, from different manufacturers to the CK12 style capsule itself, I have measured from 40pF to 70pF... that means corner frequency from 130Hz to 70Hz at 30Mohm g-to-g, it's like night and day... Mids, treble, presence of the signal, everything changes. You need to adjust this....

Personally I wouldn't go below 160V or at least 120V for testing with the blocking capacitor. Heatup, tube conductivity, ...

 

[geekmacdaddy]

HerbertR, once again. Thank you.