PCB hole spacing of Alctron GT2B / Nady TCM1050 / other rebrands?

[Khron]

Hey everyone,

I'm giving moderately serious thought to putting together some alternate circuit / upgrade boards for some tube mics.

I have a couple of t.bone SCT2000's, which may or may not be related to the Alctron GT2B and/or Nady TCM1050, but it would be nice to have some confirmation of the spacing of the mounting holes of similar / related mics. Perhaps also t.bone's SCT700?

Any volunteers?

 

[Khron]

Really? Noone?..

 

[Wordsushi]

Hey everyone,

I'm giving moderately serious thought to putting together some alternate circuit / upgrade boards for some tube mics.

I have a couple of t.bone SCT2000's, which may or may not be related to the Alctron GT2B and/or Nady TCM1050, but it would be nice to have some confirmation of the spacing of the mounting holes of similar / related mics. Perhaps also t.bone's SCT700?

Any volunteers?

I got ya. Spacing is 39mm hole to hole according to the one I have here.

 

[Khron]

Is that 39mm along the rails?

What about side-to-side? And distance between lowest edge of the headbasket, and the center of the upper mounting hole?

I can doodle up a diagram if that's terribly unclear.

 

[McIrish]

I have the Nady 1050. I have not had it apart in a while but next chance I get, I can make some measurements. Note: The 1050 I have is the shorter fatter version. It's not like the Apex 460, which is taller and skinnier.

 

[micolas]

I'm giving moderately serious thought to putting together some alternate circuit / upgrade boards for some tube mics.
Perhaps also t.bone's SCT700?

T.bone SCT-700
Only 2 screws secure the PCB
The distance between the centers of the holes is 39mm

 

[Khron]

I have the Nady 1050. I have not had it apart in a while but next chance I get, I can make some measurements. Note: The 1050 I have is the shorter fatter version. It's not like the Apex 460, which is taller and skinnier.

I'm fully aware i'm not asking about the Apex 460 / Alctron HST11A, but about the stubbier Alctron GT2B. I would've clearly mentioned "Apex 460", if i meant that (Not sure what the Apex rebrand of that might be, or whether they even have one at all.)

The distance between the centers of the holes is 39mm

And distance between the top edge of the main PCB, and the center of the mounting hole? An approximate value is plenty...

 

[micolas]

@Khron

Unfortunately, there is little room inside the SCT-700
That's why the tube is soldered directly to the head pcb
I soldered wires and an outer socket to select tubes. He won a Czechoslovak Tesla that is several decades old. Beat Mullard, Telefunken in tests. The microphone with the stock capsule, (I have met several t.bone capsules that sound good, it is possible that they were manufactured by Feilo?), but with the changed tube it sounded warm, transparent with low noise. You can even hear the pleasant, rich harmonics, of the transformer (which really sounds good, there are no reasons to replace it with another more expensive one)
It's been a few years since then, but I think I'll modify it a bit more. I think a flat K47 capsule would do wonders.

 

[Khron]

Unfortunately, there is little room inside the SCT-700

O...kay? In your 2nd photo there's ~45mm between the lower edge of the headbasket, and the top of the transformer enclosure, but that would mean the whole PCB is... 50mm long or so?

 

[micolas]

And the distance between the top edge of the main PCB, and the center of the mounting hole? An approximate value is plenty...

I'm an engineer, I like to work with exact data.
We have a proverb:
"You give a friend a finger and he takes your whole hand"
We're still joking!
I'll help you with everything I can.
I think that is also the purpose of diygroup

 

[Khron]

I'm an engineer, I like to work with exact data.

Much appreciated!

 

[micolas]

O...kay? In your 2nd photo there's ~45mm between the lower edge of the headbasket, and the top of the transformer enclosure, but that would mean the whole PCB is... 50mm long or so?

The whole main pcb
(longitudinal) has the length
of 47mm but the cylindrical metal bell that shields the transformer can be removed and a 73mm long pcb will fit.

 

[micolas]

@Khron
I think that for this money it's the best deal if you want a tube microphone,
built like a tank, with a power supply, good accessories, solid shockmount, hard-case
With a little imagination, ingenuity,
creativity and a moderate financial effort one can mod or build an exceptional microphone.
(I bought it used for 40 euros)

 

[McIrish]

Is there any other measurements you need? I have a micrometer and the 1050. Happy to check anything you need.

 

[Khron]

Is there any other measurements you need? I have a micrometer and the 1050. Happy to check anything you need.

As mentioned, the spacing between the mounting holes (in both directions, assuming 4 screws), as well as the distance between the bottom edge of the headbasket, and the topmost pair of mounting holes

 

[Horizoneer]

@Khron

Unfortunately, there is little room inside the SCT-700
That's why the tube is soldered directly to the head pcb
I soldered wires and an outer socket to select tubes. He won a Czechoslovak Tesla that is several decades old. Beat Mullard, Telefunken in tests. The microphone with the stock capsule, (I have met several t.bone capsules that sound good, it is possible that they were manufactured by Feilo?), but with the changed tube it sounded warm, transparent with low noise. You can even hear the pleasant, rich harmonics, of the transformer (which really sounds good, there are no reasons to replace it with another more expensive one)
It's been a few years since then, but I think I'll modify it a bit more. I think a flat K47 capsule would do wonders.

I tried the flat k47 capsule I got last week in an otherwise stock SCT-700 for 20 minutes, and yeah, quite pleasant! I didn't check the capsule polarity voltage before I put it all together though, so I didn't want to leave it on too long in case it was way high.

Stock SCT700
With Flat K47

 

[Khron]

I tried the flat k47 capsule I got last week in an otherwise stock SCT-700 for 20 minutes

Good for you..?

Not quite sure what that has to do with my initial questions, though...

 

[Horizoneer]

Good for you..?

Not quite sure what that has to do with my initial questions, though...

My post was pertinent to something Micolas said. He thought a flat K47 might work well in that mic, and I had experience of exactly that. What's the problem? Do we need the sarcasm?

 

[Khron]

Am i really so out of line for suggesting that your first reply might've been more appropriate in the flat k47 thread, perhaps?

As opposed to here, where (i thought) i had quite clearly asked for mounting hole spacing measurements (as opposed to capsule reviews or build ideas). Or there's always the private messaging system in place, as well...

 

[micolas]

I tried the flat k47 capsule I got last week in an otherwise stock SCT-700 for 20 minutes, and yeah, quite pleasant! I didn't check the capsule polarity voltage before I put it all together though, so I didn't want to leave it on too long in case it was way high.

Stock SCT700
With Flat K47

Thanks a lot for the samples.
The stock capsule in the SCT-700 is of the K67 type, which in my opinion favors the acoustic guitar over the K47 (especially in the mid-high/treble section, it offers a richer, more complex sound). It can be heard according to the mod that the sound is darker exactly as it is normally.
I was referring to the Voice that it will sound much better with K47 flat, without sibilants, warmer, smoother.
If you want to open another thread about the SCT-700 (if there isn't already one on the group) or in the K47 flat thread, it would be interesting to hear voice tests, singing, speaking and we would be very grateful.
Thank you once again for your good intentions, your work and willingness to help.