Any Suggestion on Upgrade and Mod on the NADY TCM1050??

[Gus]

My microphone is modded, not CF, single gain stage no feedback. The circuit is a plate out, tube is running at about .9 ma and is using a 100 plate (I don't want to post the tube used).

Marik and I are fairly sure it the 32mm 3 micron capsule is the cause of the missing lows(sounds OK untill you place it next to a real microphone). The grid and pattern Rs are not the stock values. I am going to play with the output cap value some, right now it is 2.2uf polypro.

I would not design or build a microphone like the stock 1050. This is a mod experiment for tring to make the Nady TCM1050 usefull.

I need to hear a JP reskinned? capsule I am finding it hard to believe a 32mm can sound WORLD CLASS or even different than a stock china capsule.

 

[SonsOfThunder]

[quote author="Gus"]Both modded 1050 microphones seem to be missing some of the bass the highs are OK. The stock transformer does not sound good and is mising the lows as well.

The 1050 has a 32mm 3 micron china type capsule again a 32mm limiting the sound. I did not get around to removing one or more layers of mesh.[/quote] Thanks much for the update Gus! I guess this means I'll be stuffing the capsule from my SCM1000 (34mm?) into my TCM1050 after getting a new trafo!

Peace!
Charlie

 

[Gus]

Tried something in one of the nady 1050s today. I change the plate R to a 150K and the cathode R to 2.2k The bass did pickup some. I was thinking about xvlk post above. Maybe the 100K plate and 2.7K I had in the gain stage before caused the circuit to damp it to much.

AHH the u67 type circuit

 

[SonsOfThunder]

Thanks for the update, Gus. I'll certainly give that a try.

I have swapped the capsules but have not had opportunity to try it out yet. :sad:

Peace!

 

[Gus]

Some news. I am going to change some more parts of the 1050 microphone. The power supply at the microphone is 195VDC. The pattern voltages are to high stock at the cardiod setting in one of my 1050s the voltage is 96VDC IMO.

I am going to change a resistor and add one to the pattern control to get the voltages to 0VDC,60VDC and 120VDC. Maybe the combo of 3 micron PET and high DCV on the capsule cause the thin bottom.

I might even change it to the brauner style pattern control.

Has anyone found small 3 gig resistors with a good voltage rating?

 

[zebra50]

[quote author="Gus"]Has anyone found small 3 gig resistors with a good voltage rating?[/quote]

No. But I found 1,2 and 5 gig at Radio Spares. Here are the numbers, for the record.

523-1G  220-5279  £7.62 
523-2G  220-5285  £7.62 
523-5G  220-5308  £11.18 

OK Up to 5 kV! But not cheap.

Stewart

 

[maxwall]

Can someone post pictures of there stock and modified Nady TCM 1050 microphone. I'd like to compare them the the Nady TCM 1150 microphone.

 

[Guest]

[quote author="Gus"]Some news. I am going to change some more parts of the 1050 microphone. The power supply at the microphone is 195VDC. The pattern voltages are to high stock at the cardiod setting in one of my 1050s the voltage is 96VDC IMO.

I am going to change a resistor and add one to the pattern control to get the voltages to 0VDC,60VDC and 120VDC. Maybe the combo of 3 micron PET and high DCV on the capsule cause the thin bottom.

I might even change it to the brauner style pattern control.
[/quote]

I am just in the middle of converting Nady TCM1050 into ELAM251 type. I found that with the help of your schematic it would be very simple to convert it into ELAM251 type of microphone. I will change transformer with original Haufe T14/1, original tube to GE 6072A and I will keep original PCB. I will replace stock capsule with CEK12 from Peluso and for test plastic CK12 from AKG.

In the power supply I found, that without connected zener diodes the DC voltage is 286V. Stock resistors are 3x6,8k and 2x20K. I changed resistors to 3x10K and 2x33K but the voltages are same. Could someone explain me why is that so ? So I replace one zener which original was 99V with 30V and leave other (89V) in PCB and get approx 120V instead of 189V before. The pattern control is a little bit lower approx. 107 V. Duka send me schematic of APEX 450 both PSU and microphone, I don't know if I will violate copyrights (Duka kako je sa time ?) if I will publish it here, but I found that schematic is nearly the same (in the microphone there is no CF stage) regarding PSU.
The PSU is similar of old Neumann type, four diodes, five resistors in series and between them electrolitic cap to the ground (47uF/400V).
In the heater part is and "old" 7806 regulator.

 

[scott_humphrey]

[quote author="xvlk"][quote author="Gus"] The stock transformer does not sound good and is mising the lows as well.
[/quote]

10:1 is not intelligent to cathode follower output transformer,
use 1:1 - 4:1.
xvlk[/quote]

Isn't that why these companies are using a cathode follower circuit--to make up for the cheap, low ratio output transformer? If you have a good 10:1 transformer, you might try disconnecting the cathode follower part of the circuit (the second half of the tube). Run a wire directly from the first half of the tube at the plate (pin 1) to the output capacitor (c8). This makes the circuit very similar to a ela m251.

 

[scott_humphrey]

Did the original transformer in the ela m251 have a 14:1 ratio? I know that it was named T14/1, and I'm assuming that the name referred to the ratio, but I don't know that as fact.

If so, you could substitute the Jensen transformer that is used in the Royer mod (15:1 ratio). Disconnect the cathode follower circuit as described in my last post, swap the transformer for the Jensen or other higher ratio quality transformer, and you'd probably be in the ballpark.

 

[Gus]

I used a jensen 12:1 with a submini tube using the stock voltages in one. It is a cathode biased signal gain stage like the 251.

lampas the 107 volts is good. The stock 1050 has to much voltage at the capsule 0V-100V-200V.

You are using an AKG style capsule(no center treminal) the 0V-53.5V-107V pattern control will be very good with the power supply reduced to 107VDC

If I understand the history of the AKG correctly, the two ratios used were 10:1 and 11:1

Maybe you should study the AKG C24 schematic at
http://www.geocities.com/SiliconValley/Peaks/5212/start.htm
This is more the style of the TCM1050
just use one side of the tube.

 

[scott_humphrey]

[quote author="Gus"]I used a jensen 12:1 with a submini tube using the stock voltages in one. It is a cathode biased signal gain stage like the 251.

lampas the 107 volts is good. The stock 1050 has to much voltage at the capsule 0V-100V-200V.

You are using an AKG style capsule(no center treminal) the 0V-53.5V-107V pattern control will be very good with the power supply reduced to 107VDC

If I understand the history of the AKG correctly, the two ratios used were 10:1 and 11:1

Maybe you should study the AKG C24 schematic at
http://www.geocities.com/SiliconValley/Peaks/5212/start.htm
This is more the style of the TCM1050
just use one side of the tube.[/quote]

Good stuff, Gus! Yes, the TCM1050 is very close to the C12/24 if you were to leave off the cathode follower. That should be an easy conversion. The C12 circuit is very similar to the Gyraf G7 (but based around a different tube, of course).

 

[Guest]

[quote author="scott_humphrey"]Did the original transformer in the ela m251 have a 14:1 ratio? I know that it was named T14/1, and I'm assuming that the name referred to the ratio, but I don't know that as fact.
[/quote]

T14/1 have 11:1 ratio. Here is technical data:
http://www.cankar.net/duka/t14-1.pdf

 

[Gus]

just got done with a capsule voltage mod. I dropped the total voltage from 200VDC at the pattern control and 270K 270K resistors in the body to 125V. Tha sound is a little better still missing bass. I think I will drop the voltage some more.

I have two other microphones powered up for testing against it right now a modded Rode K2 and my 800 type with a real K67 capsule. Both the 800 type and rode have more bass and better balence highs to lows: however the 800 type has more balence and sounds more like what it is hearing. There is something very nice about real k67s.

The modded Rode sounds OK. The stock tube is a big ? to me why it was picked. Change a couple caps a different tube number and it is a nice microphone.

 

[SUPERMAGOO]

Im cloned 2 ela m251 .one w/ ck12 teflon .2 w/peluso capsules.
http://groupdiy.twin-x.com/displayimage.php?album=40&pos=29

 

[skipwave]

Hi all,

I'm reviving this thread because I'm trying to select a replacement transformer for my GT-2. What I've gathered from the discussion is that if I keep the CF in the circuit I should use a 1:4 ratio TX. How about one of these Cinemags, the CM-24110 or the CM-2461NiCo?

http://cinemag.biz/mic_output/mic_output.html

Thanks in advance.

Brian

 

[Gus]

Brian

If you use a 4:1 with the CF your output level will be hotter than with a higher ratio. What pres will you be using with the microphone? That might be a better way to pick a ratio. The CM-2461NiCo are kind of big will they fit in the body of the microphone?

What is a GT-2?

 

[skipwave]

[quote author="Gus"]Brian

If you use a 4:1 with the CF your output level will be hotter than with a higher ratio. What pres will you be using with the microphone? That might be a better way to pick a ratio. The CM-2461NiCo are kind of big will they fit in the body of the microphone?

What is a GT-2?[/quote]

ADK tube mike. We were discussing it in this thread, where I posted pics:

http://www.groupdiy.com/index.php?topic=9503

As for preamps, I have a grab bag of heavily modified cheap-o pres and completely DIY boxes. Most of them have transformer balanced inputs. Using the CF and 4:1 trafo, am I likely to need pads to avoid distortion?

Thanks so much for sharing your knowledge! I'm convinced that the GT-2 is the same off-the-shelf China special as the TCM-1050, except for the 6 micron Tenlux capsule, so I'm going to use the mods you and Marik did as a guide.

 

[skipwave]

A better look at the capsule.

 

[skipwave]

[quote author="Gus"]The CM-2461NiCo are kind of big will they fit in the body of the microphone?[/quote]

Gus - You're absolutely right, the CM-2461NiCo is too big for the transformer shield. The 24110 (4:1) or the 2480 (10.5:1) will fit. Now I just have to make the decision whether to keep the CF or not.

By the way, there is only one thin layer of mesh inside the grille. Someone mentioned removing several layers of mesh from inside the Nady and hearing a big improvement in it's sound.