Nady TCM 1050 mods

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Icantthinkofaname

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So I didn't get the Apex, seller didn't want to ship, so I ordered an EM T5001 which should be near identical to the Nady TCM 1050. What mods are recommended if I'm putting a CK12 capsule in it?

Stock tube is a 12AX7, not sure about the capsule though (I'm assuming it's a Chinese K67, I'll be pleasantly surprised if it's a CK12 or K47 style capsule). Asked the seller about the capsule, they just told me what the tube was, so even though the listing said "kit" I'm guessing they didn't build the mic, and instead meant that it came with a case and cable and stuff (which seems pretty typical for tube mics, which is why I thought they built it).
 
Bumping because I just saw the Nady SCM 960 on recording hacks, and it looks like it could be a cool little donor mic ($60 USD, 3 way pad, and cardioid/omni patterns) with an AKG C3000 style body, and I'm interested in what peoples take on them would be.
 
Icantthinkofaname said:
So I didn't get the Apex, seller didn't want to ship, so I ordered an EM T5001 which should be near identical to the Nady TCM 1050. What mods are recommended if I'm putting a CK12 capsule in it?

Stock tube is a 12AX7, not sure about the capsule though (I'm assuming it's a Chinese K67, I'll be pleasantly surprised if it's a CK12 or K47 style capsule). Asked the seller about the capsule, they just told me what the tube was, so even though the listing said "kit" I'm guessing they didn't build the mic, and instead meant that it came with a case and cable and stuff (which seems pretty typical for tube mics, which is why I thought they built it).

12AX7 nothing to write home about as a condenser mic tube... (high mu (100), noisy, microphonic, etc.)  Better off with a 12AY7 (6072), EF86, or other low noise tubes discussed in these pages...
 
rmburrow said:
12AX7 nothing to write home about as a condenser mic tube... (high mu (100), noisy, microphonic, etc.)  Better off with a 12AY7 (6072), EF86, or other low noise tubes discussed in these pages...
Yeah I'm already thinking I'm gonna swap tubes, I just don't know what sound I want sonically. I don't know if I want to put in a CK12 capsule, a K47, or have HF de-emphasis added into the circuit to get a really neutral U67 sound (I'm aware I'll probably need a sloped grille for that one as well).
 
12AX7 is the typical choice of many Chinese microphone manufacturers.
Personally, I never obtained good results with this tube.
All 12AX7's I have tested were all noisy.
I got much better results with the EF806S (EF86)
 
Icantthinkofaname said:
Yeah I'm already thinking I'm gonna swap tubes, I just don't know what sound I want sonically. I don't know if I want to put in a CK12 capsule, a K47, or have HF de-emphasis added into the circuit to get a really neutral U67 sound (I'm aware I'll probably need a sloped grille for that one as well).

If you are talking about mechanism of HF attenuation in u67 you might investigate that in advance, it's a very tricky thing because of transformer interraction with the rest of the circuit. But if you are talking about simple HF filter circuit with a cap, it's quite simple. And sounds just fine.

All the Apex mods available on the web are applicable to your mic. You can always switch in and out different tubes. And don't forget about russian ones, they are awesome!
 
Just ordered a 6072a from Mic Parts, they're cheap enough and are supposed to be tested. Are the stock K67s in these mics any good (with the proper HF de-emphasis), or should I replace it with iSK's K67?  If I do replace it, will the PSU zener diode mod be necessary?
 
No psu zener mod needed for that capsule. That k67 it's a hit or miss. Try how different sides work, one might be better than the other. And yes it does need some high end filtering, unless you are going for c800 kind of sound.

This article says a lot about the circuit. You should at least get rid of that nasty electrolytic as output cap(c8). If the circuits are the same.

http://advancedaudio-europe.com/forum/viewtopic.php?p=72#.XLaqTD_RYXM


 
And yes, i wouldn't "upgrade" the transformer, as I, several people here and Brian Fox found it to be cleaner, and flatter than most "upgrades". Unless you are going for some really expensive stuff leave the stock one alone.
 
kingkorg said:
No psu zener mod needed for that capsule. That k67 it's a hit or miss. Try how different sides work, one might be better than the other. And yes it does need some high end filtering, unless you are going for c800 kind of sound.

This article says a lot about the circuit. You should at least get rid of that nasty electrolytic as output cap(c8). If the circuits are the same.

http://advancedaudio-europe.com/forum/viewtopic.php?p=72#.XLaqTD_RYXM
I'm definitely going to have filtering added, since I'm trying to go for the same sort of mod as the FAR 67, which has a 1000 pF cap for the de-emphasis circuit . I think I'm just gonna take the capsule out of my BM-600 since I messed up that project.

I'll actually get a picture of the transformer once I get home from work, just to make sure it's one of the good ones. The actual model of the mic is EM T5001, but it appears to be identical to the Nady.
 
Just tested the stock mic and my god is it ever harsh. It's actually not too noisy, but I definitely want a flatter sound.

I'm probably gonna send it to someone to be modded since I've never worked with tube gear. I'd love to send it out to Brian Fox (since he did the Apex 460 to U67 mod I'm inspired by) but it seems that Fox Audio Research isn't doing orders right now.

I can't get to the transformer without desoldering the 7 pin connector from the PCB either, so I'll just assume it's fine for now. I'm waiting on a reply from Advanced Audio on whether or not they can install a tube socket and HF de-emphasis circuit.

If there's anyone in Canada or the US (Canada preferred) who can do the mods I'm interested in (I'll supply the tube and capsule), PM me with how much you charge.
 
Hey, that's cheating! This is GroupDIY, not Group-have-someone-else-do-it ;D

Jokes aside though, just the other day i was messing around in LTspice with the circuit in my CAD Trion 8000, and at least to my ignorant eye, a capacitor (or a series RC) across the plate resistor should be perfectly fine as a high-cut / high-shelf attenuator.
 
kingkorg said:
And yes, i wouldn't "upgrade" the transformer, as I, several people here and Brian Fox found it to be cleaner, and flatter than most "upgrades". Unless you are going for some really expensive stuff leave the stock one alone.
Do you know what the ratio of that transformer is?
 
Stupid question, but how would I go about adding a capacitor to an existing finished PCB? Do you need to add holes for the capacitor (this seems like a bad idea), or can you just put flux where you're adding the capacitor and solder it that way? I've only replaced capacitors that were already there in mics.

Khron said:
Hey, that's cheating! This is GroupDIY, not Group-have-someone-else-do-it ;D

Jokes aside though, just the other day i was messing around in LTspice with the circuit in my CAD Trion 8000, and at least to my ignorant eye, a capacitor (or a series RC) across the plate resistor should be perfectly fine as a high-cut / high-shelf attenuator.
Yeah, that seems right from a quick Google search.
 
Especially since you don't need a uF-range motor-start capacitor, tacking it on, say, on the back of the circuit board is perfectly fine.

See attached photo for an example.

To be double-safe, if you have any, you could add a small piece of double-sided tape between the board or the added part. Or a dab of non-acid-curing silicone / RTV.
 

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I think I might just opt for a simpler mod and make it a U47 clone. The 67 project would require a different tube, probably a different PCB since the stock one is for a triode, but the 67 project I was looking at uses a pentode. So I'm thinking: if I go for a 47 style mic I'd only be using iSK's K47 capsule, and I'd need a recommendation for a transformer to use in it. I'm also thinking about finally putting that Maiku CK12 capsule I have sitting around to use in the mic if I decide I want a C12 style sound.

I know I don't have anything in the style of a 47, but I do have something sort of in the C414 style (both airy/brass inspired, and flat/teflon inspires), so I don't know if putting the CK12 capsule in will give me anything I don't already have.

I'm looking into having Advanced Audio do the component replacement (regardless of which route) and PSU mod because I have zero experience with tube gear (I could probably do some basic soldering, but I wouldn't want to work on the PSU).
 
What're the odds the 67 circuit uses a pentode wired as a triode?

https://en.wikipedia.org/wiki/Pentode#Triode-strapped_pentode_circuits
 
I know AA mods might sound confusing, but if you invest just a little bit of time into what should be changed, you'll realize it's 15min job. And you don't have to change the transformer which might be the most complicated part.
 

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