Telefunken ELA M 251 Clone Tube Microphone Build Thread (D-Ela M 251E)

[doggy6812]

Can someone tell me the pin out from the seven pin connector to the pcb? Particularly the f8 and Omni.

 

[joshk34]

Probably a newbie question, but I picked up the kit and am having trouble sourcing the 251 capsule that I would like. Is there anything preventing me from using a D7 or K47 style capsule making a hybrid mic? Are they swappable or is there something circuit-wise preventing this, thanks!

 

[rock soderstrom]

Probably a newbie question, but I picked up the kit and am having trouble sourcing the 251 capsule that I would like. Is there anything preventing me from using a D7 or K47 style capsule making a hybrid mic? Are they swappable or is there something circuit-wise preventing this, thanks!

Go ahead, I see no reason why this shouldn't work. Maybe you have to adjust the 100pF capacitor (anode to ground) or even leave it out, otherwise this circuit has no frequency adjustment for a certain type of capsule, like the U67.

 

[doqmemory]

Probably a newbie question, but I picked up the kit and am having trouble sourcing the 251 capsule that I would like. Is there anything preventing me from using a D7 or K47 style capsule making a hybrid mic? Are they swappable or is there something circuit-wise preventing this, thanks!

The patterns require isolated backplates, so D7/K47/M7 will not work.

 

[Recording Engineer]

The patterns require isolated backplates, so D7/K47/M7 will not work.

Good call - I wasn’t thinking about that.

 

[rock soderstrom]

The patterns require isolated backplates, so D7/K47/M7 will not work.

That's true, as long as you don't adapt it to the capsule you're using. Corresponding microphones with the capsules mentioned give you an idea of what is possible and how it was implemented there.

My statement referred to the amp circuit itself, but since we are talking about a kit, doqmemory's statement is correct.

 

[doqmemory]

That's true, as long as you don't adapt it to the capsule you're using. Corresponding microphones with the capsules mentioned give you an idea of what is possible and how it was implemented there.

My statement referred to the amp circuit itself, but since we are talking about a kit, doqmemory's statement is correct.

You could rewire the relays to switch from cardioid to omni, but not figure 8.

Member @dmp has used this circuit with K47-style capsules, as shown here.

 

[paulcheeba]

Hello, is there such a thing as an accurate 251 body now the market is flooded with 1:1 replicas? All I can see online are the c12 hybrid cheap bodies. I have heard some good clones but I want them to look authentic. Thank you.

 

[Roxxy]

I’d also be interested in that….

 

[johnsonic]

I got the Beesneez body - not an accurate replica whatsoever but a damn fine body.

 

[paulcheeba]

I got the Chinese bodies from Aliexpress which look good and feel good. There is a thread about them from King Korg,

 

[ElSmurf]

I got the Chinese bodies from Aliexpress which look good and feel good. There is a thread about them from King Korg,

Just looked up the thread you mentioned, that body does look really good.

 

[neowalla]

Has anyone ever tried an M7 capsule in this circuit? Or a flat 47 from Arieanne?

 

[paulcheeba]

Just looked up the thread you mentioned, that body does look really good.

They're too short for any of the PCB's so I'm not sure what to do. Such a shame as they are lovely quality.

 

[victorr_sun]

Hey guys,

I’m just now finally getting around to building these. On the PSU not sure if I’m missing something or if I maybe received the wrong fuse holder from mouser?

Do I just need to lock this down with a small screw / nut (didn’t come with one).

Or is it supposed to be a different type that solders to the pcb solder pads below?

 

[johnsonic]

I had the same scenario - just found a screw to hold to the board and soldered the leads to the lugs.

 

[cfanzalone]

Howdy all,

I wasn't sure if I should post this for fear of backlash...

I purchased a Micparts V251 circuit kit 5 years ago and put it in an Avantone CV12 body with a TC capsule and am super pleased.

Just recently I got the new 251 body from Ali express and with just a few minor modifications it fits perfectly.

KNOW that this is clearly most like a 251E, NOT a 251, and I was NOT going to start all over with the more authentic 251 build with the relays for pattern change, sub miniture tube, etc......For some of us it's $$$.

The simple fact is that there will be nothing like the 251/E, U47, M49, M50...the best we can do is approximate it within our budget to be as close as possible. Either way, one can't go wrong in trying...

Capsules:...yes, a nightmare...I am fortunate to have Tim's capsule, purchased 3+ years ago. I've used Maiku capsules with a large degree of success for other project mics...

The tranny???...I've tried many, small core AND large core. I settled on a Cinemag 13114 that was designed specifically, with input from Bock, to help with the low end. Large cores, even tho used on the earliest C12s...I find the replicas too muddy.

My personal experience is I like the capsule, circuit and tube to shape the tone...the transformer to do it's work with a minimum of coloration....and, again, I've tried several trannies and always came back to the Cinemag...very musical transformers.

Please don't start this into a pissing contest...I don't need it...I'm just sharing my experience.

Blessings

 

[cfanzalone]

Ali express 251 body...Brass body? The inside looks so, but I'm not a metallurgist... It is thick, built like a tank and weighs like a tank. (Tiger, not Sherman)...LOL

I'm betting it's Brass...

 

[paulcheeba]

Probably a newbie question, but I picked up the kit and am having trouble sourcing the 251 capsule that I would like. Is there anything preventing me from using a D7 or K47 style capsule making a hybrid mic? Are they swappable or is there something circuit-wise preventing this, thanks!

The Beesneez BCK12 sounds just like the 1960’s CK12. I have vintage pairs and a C24 and my Beesneez BCK12 sound as good if not better. I was amazed.

 

[HerbertR]

Dany, my Mics are funished. It was a long road to complete my pair. I had way too much noise at the output. So I replaced some components to reduce the noise level. First I replaced the orange Matsushita DS2Y relays with these directly matching black Omron relays / they have higher insulation resistance. The second change was to increase the "very" low original grid resistor value from 30M ohms to 100M ohms (or even more possible, but over 400M Ohm it sounds boring in my circuit). This was a recommendation from Andreas Stenzel for my problem – great man, you are a true hero . However, in my opinion, it takes the known "heart" of the original M 251 circuit a little bit away as the typical "ready equalized cutoff frequency" of the 251 sound drops to 20-40 Hz / depending on the capacity of the used capsule for sure ... But the noise level decreases drastic. I think the relay-controlled pattern switch is really awesome but this original 251 circuit is known as one of the noisiest circuits among all tube microphone circuits. So these relays are located directly in the high impedance circuit can -or I think they will- induce a little bit of additional noise into this as well as already rather slightly higher noisy microphone. If I were to build a 251 again, I would play it safe and would use a classic 9-position variable pattern rotary switch and skip the relays.
In my opinion, 3.3uF for the block cap is also a bit high and it emphasizes the lower range too much in my ears. I went with 1uF PP Caps.

I also test 3U C12 TX and UTMs larger C12 output TX. I preferred the 3U because the UTM showed a bit too much low end in this 251 circuit - and I want to compensate for the opposite... The Inductances and DC Resistances compared with a simple LCR Meter showed also slight different Measurements as I can remind.
I can recommend to work through the whole thread to understand the Mic and play a little bit around till you find the perfect balance for you.

The rest is classic - great Beesneez C12 capsules, matched NOS GE6072 5Star Mica Tubes, rare NOS Styros from Philips, RFT..., and these "new" well-known 251 Micbodies from Aliex - made of heavy Brass, so pretty...

Strong sound - on the face, open, clear, brilliant highs and excellent mids... Btw, a big thank you to Kingkorg and his great knowledge / skills - or these Babies would not run yet....