nady 1050 mod

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nady 1050 mod

Postby sevin12385 » Thu Jan 16, 2014 5:53 pm

Whats up guys im new to modding somewhat. Can u please post a detailed description on the u47 mod for the nady 1050. Well..atleast installation of the the ak47 capsule and bv8 transformer. Thanks in advanced. Pictures would be even better
sevin12385
 
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Re: nady 1050 mod

Postby Dave Thomas » Fri Jan 17, 2014 11:52 am

Hi Sevin, upgrading a tcm 1050 to our CM47ve microphone is a fairly simple procedure.
Now, some of the very early 1050 microphones had the 12AX7 tube soldered into the circuit board and replacement of the tube in this version is much more difficult and requires a bit of "extreme" electronic techniques.

It is impossible to heat all 9 pins at once without setting the circuit board on fire. The only way to remove the 12AX7 is to don eye protection, put a rag on the tube and smash it with a hammer over the dust bin. Then cut away all the pieces and unsolder each of the pins one at a time. Then clean out the 9 pin holes with a solder sucker and solder wick. Then you can solder back in a PRE-TESTED 6072a tube. Make sure it is thoroughly tested before soldering it back in!!!!

The later tcm1050 microphones all have a tube socket which makes the tube replacement much easier.

The following changes should be made to the 1050 circuit.

1) C9 & C10 should be removed. They can be cut out and are not required into today's modern world. C9 & C10 where meant as RF filter from the days of Taxi cab's operating their 2-way radios on the upper AM radio frequencies.
These capacitor values were spec'd to low in the 1050. So, C9 & C10 in parallel to ground causes the distortion at 11khz to increase 4 times because of the inherent resonance between these capacitors and the low buget output transformer.
SIMPLY REMOVE THESE CAPACITORS...DO NOT...STRAP THEM WITH A WIRE JUMPER AS THIS WILL SHORT THE OUTPUT OF THE TRANSFORMER TO GROUND.

2) C6 & C7 should be removed. These bypass the cathode resistor in the 1st stage. However, they are not necessary in the 1050 circuit and only necessary in a single stage C12 type circuit.
Once properly modified the 1050 circuit is superior to any single plate output circuit. With C6&C7 removed the circuit is more linear without any LF roll-off. The gain drops 4db but this increases the headroom and signal to noise ratio by 4db.
AGAIN SIMPLY REMOVE THESE CAPACITORS...DO NOT... STRAP THEM WITH WIRE JUMPERS AS YOU WILL SHORT OUT THE CATHODE BIAS RESISTOR.

3) Replace C8 the 1ufd outut electrolytic coupling capacitor with a 2.2ufd metal film. This will place any resonance between C8 and the output transformer down into the sub-sonics where it will not negatively effect the audio signal.

4) Replace the 12AX7 with a 6072a this lowers the gain another 2db but the output impedance on the first plate is much lower. A new Sovtek 6072a selling for around the $20 is more than adequate in this clever CCDA type circuit.

Now, you will have optimized the 1050 circuit which is a 2-stage CCDA (constant current draw amplifier) with an output impedance 10 times lower than the venerable original U47 circuit.

5) Replace the stock economy transformer which has a 10.5:1 turns ratio with our BV8 having a 6.5:1 ratio. The green wire goes to pin 6 and the black wire to pin 5 on the 7 pin connector. The white wire goes to pin 4&7 on the 7 pin.
The red wire is attached to the red wire that goes to the output of C8. Remember, the gain has dropped by nearly 6db in the front end but the BV8 has 5db less loss than the economy 10.5:1 transformer.

6) The economy 32mm (k67) type capsule with its 3-5 micron thick diaphragms is replaced by our AK47 capsule which is a single back-plate w/dual 6 micron diaphragms having identical specs to the original K47 used in the U47 & M49.
The K47 will fit onto the existing saddle but will mount either 2mm closer to the front or the rear. I prefer to move it back 2mm.

7) Next replace Z5 & Z6 sometimes noted D5 & D6 inside the power supply with two 62v Zener diodes. This will drop the power supply B+ voltage to 124v dc + and - 2%. These supplies are usually set for 144v dc and this will place about 70v dc on the capsule. The AK47 and the original K47 capsule seem to give optimum results when they are polarized between 55 and 60v which is what you will get from a 124v dc supply. These are located behind the pattern switch on the board.

That's it!!! If this is all done correctly then the microphone should fire up and sound like a WORLD CLASS MICROPHONE.

I will try and take some pictures of the next 1050 we get in for upgrade.

Cheers, Dave




sevin12385 wrote:Whats up guys im new to modding somewhat. Can u please post a detailed description on the u47 mod for the nady 1050. Well..atleast installation of the the ak47 capsule and bv8 transformer. Thanks in advanced. Pictures would be even better
Dave Thomas
 
Posts: 172
Joined: Mon Dec 30, 2013 2:46 pm

Re: nady 1050 mod

Postby sevin12385 » Mon Jan 20, 2014 9:03 pm

Thanks dave awesome customer service. I was just informed that my 2.2 ufd capacitor didn't come with my Order. can you please tell me the exact 2.2ufd to order online. I see many but all different voltages.
sevin12385
 
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Joined: Thu Jan 16, 2014 11:36 am

Re: nady 1050 mod

Postby MBsounds » Fri May 26, 2017 7:48 pm

When I opened the power supply to replace D5 & D6, the secondary white wire (one end soldered to the W on the pcb) became detached from it's original position due to a bad joint. I am not sure where to reattach the other end and I can't find a schematic. Any help is appeciated.
MBsounds
 
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Joined: Tue May 23, 2017 7:18 pm

Re: nady 1050 mod

Postby Dave Thomas » Sun Nov 19, 2017 2:00 pm

Hello, just found your post.

Here is the schematic for the power supply it is exactly the same as the 460 power supply.


[quote="MBsounds"]When I opened the power supply to replace D5 & D6, the secondary white wire (one end soldered to the W on the pcb) became detached from it's original position due to a bad joint. I am not sure where to reattach the other end and I can't find a schematic. Any help is appeciated.

460 power supply.jpg
460 power supply.jpg (78.37 KiB) Viewed 44174 times


Cheers, Dave
Dave Thomas
 
Posts: 172
Joined: Mon Dec 30, 2013 2:46 pm


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