t-bone sct2000/Nady TCM1050 with new K47 capsule, 6072a and BV8 with SOUNDS

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manulaudic

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Nov 7, 2011
Messages
297
Location
Finland
Hello,

I've had this T-bone sct2000 for a very lond time now and i have been using it on many records.
Though i liked its sound i wanted to see if i could improve or somehow make it sound less harsh.


I was in touch with Dave Thomas and i ordered from him his RK47 capsule, BV8 Transformer and 6072a tube.

I've been upgrading the circuit like followed around and i thought it would be good to put this here with some sound samples so that someone else could attempt this.

It costed about 150 euros to mod.

Here is the BV8 (in Yellow) next to the stock transformer... Almost twice smaller and somehow the stock one seemed pretty decent built quality.

IMG_5095copy.jpg


Here is the circuit where i removed C6, C7, C9 and C10 from the circuit.

IMG_5099copy.jpg


Putting the transformer together was pretty hard with my small knowledge in dealing with small cables :)

IMG_5104copy.jpg


Best way to remember how to solder everything back :)

IMG_5106copy.jpg


The BV8 is too tall to fit in the Bell housing so i decided to remove the top part and for now will keep in place however i can. whenever i feel like this is the right circuit i will hotglue it.

IMG_5108copy.jpg


C8 was updated with a more Audio-like Capacitor but the value changed from 1uF to 2,2uF

IMG_5113copy.jpg


Change the Zener diode to get around 120V on the B+... I updated the zener D6 so that it would be around 121V at the output but i haven't checked it yet...

IMG_5114copy.jpg


T-bone stock 34mm K67 style capsule...
IMG_5116.jpg


The Final step. K47 style capsule 32mm in place. It fits on the stock Capsule holder.

IMG_5117.jpg


That's it for the build, nothing really hard...

As for the sound, well it is another mic, better i don't know. i like it more that way.
It is much more flat and not so bright. Though with a touch of EQ it is perfect and for my voice gives more body to it...


I am big fan of the SM7 mic and i feel like this mod got the t-bone closer to it in a way. I like that. Though it is really nice on bright source like bouzouki or Female vocal. Very nice.

I have tried through a DMP3 so i could hear only how the mic reacts but i will hook it up to my Golden age PRe-73 and will post some sounds via soundcloud in the week-end. Some guitar and vocals and maybe a piano straight into mbox2 pro to hear that too.

Thank you Groupdiy for all the help and Dave Thomas for the kind words and parts :)

I think i have a great mic :) now maybe a 1176 .. :)
 

Maliq

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Joined
Apr 23, 2012
Messages
65
looks good, i'm working on the same mic, but it takes me a while cause i'm to bussy with mixing and producing, anyway i ordered the Rk-47 Capsule and i can't wait to install it.. I hope it all works out. I've removed the inner mesh of the Grill..give it a lil bit more open sound.. but yes, i agree, its way to bright with the stock Capsule, I always cut about 4dB at around 10 Khz when tracking to smooth the sound a lil bit.. i hope that I don't need to do this anymore when i've installed the 47 Capsule.

I put in a Mullard 12At7u Capsule, very nice mids. Keep us posted and updated..  :)
 

manulaudic

Well-known member
Joined
Nov 7, 2011
Messages
297
Location
Finland
Yes it's a nice build.
Is the RK-47 fro Microphone parts?

I like the mic, it's much darker. Which is something you have to like. I like to boost highs rather than cut them.
So far it's a very nice mic, very quiet.

I have also been very busy working on music stuff. will post a song recorded with the mic. Guitar and Vocals.

Manu
 

Maliq

Well-known member
Joined
Apr 23, 2012
Messages
65
yes, the RK-47 is from microphone-parts, i've nor ordered it yet but i should have it in aminute i'll keep u updated as well :)
 

manulaudic

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Joined
Nov 7, 2011
Messages
297
Location
Finland
I was doing some recordings yesterday and it's funny how different the mic sounds on different patterns. Much Brighter, almost compressed sound on cardioid but pretty open and neutral on Omni.

Also, straight into a mbox2pro it's not the best, but with the Golden Age Project pre-73 then it really sings. The preamp really adds that tight medium low end and balances a bit the overall sound.

Through a Frequency analyzer though i realized there is lots going on in the very low under 60 hz. Could it be the microphone itself ?
The transformer? or something...

Manu
 

HellfireStudios

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Joined
Oct 17, 2011
Messages
513
Location
The Sunshine State
Basically, all the metal structural components of the mic act as a carrier for the ground. The PCB ground, tube ground, headbasket, body sleeve, end cap, metal railngs, headbasket baseplate, transformer housing, and xlr chassis pin should all show continuity (0 ohms) on your DMM. If not, then 60 cycle hum could result. Is the mic fully assembled before testing?

-James-
 

manulaudic

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Joined
Nov 7, 2011
Messages
297
Location
Finland
the mic is fully assembled. The only change esthetically is that i had to remove the housing for the transformer and the transformer is not properly attached. Though it's a dual bobbin BV8 style.

I should open it and see what to look for. Could be the power here too...

There isn't any hum you can hear though, but on the frequency analyst plugin i can see there is below 60hz a lot going on.

Manu
 

manulaudic

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Joined
Nov 7, 2011
Messages
297
Location
Finland
Hi Guys,

I went to the studio this morning and checked the T-bone out.

First off i like it, i mean it's not a t-bone anymore, it's much better but there is still something missing. The sound was really clean and very nice, no hum, i guess it sort of disappeared.
the one thing that i don't like about it is the lack of clarity in the midrange, aroun 700hz - 1500hz. Something is strange in there, makes the mic sound a bit like a bottle, and i think it could be due to the headbasket and some frequencies ringing.

I decided to compare it to the Neumann TLM 170 which in my opinion is an awesome mic. Just raise the EQ on the top end and voila. :)

Let me tell you the rig :

T-bone / Neumann -> Neve Portico 5012 -> Pro tools HDX card 44.1 khz 24bits.
both mics are in Cardiod

There is a small vocal track recorded on both mics next to each other :

T-bone
http://dl.dropbox.com/u/680387/T-Bone%20Stars.mp3

Neumann
http://dl.dropbox.com/u/680387/Neumann%20TLM170%20Stars.mp3

And to get a better idea of the sound i like with the t-bone.
Same setup but with a compressor.

T-bone Cardiod with Compressor (No pop Filter)
http://dl.dropbox.com/u/680387/T-bone%20Cardioid%20Compressor.mp3

Let me know what you think of it :)

Manu
 

Rishisv

New member
Joined
Oct 31, 2017
Messages
3
Hi Manu
I just found your thread about the SCT-2000 which has the same problem of a obvious harshness in the treble. Unfortunately all your photos are not available anymore. Do you still have them somewhere and could post them or send them directly to me? That would be of great help, specially with all the details about the circuit

Thanks in advance

Rishi
 

manulaudic

Well-known member
Joined
Nov 7, 2011
Messages
297
Location
Finland
Hi ! sorry i don't have the pictures anymore, not even sure where the Sct2000 is  ;D haha

Good luck with the project, you should be fine locating values from the pcb

Manu
 

mhelin

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Joined
Mar 12, 2005
Messages
562
Location
Tampere, Finland
Been modding a SCT2000 microphone for a friend, put a K47 (unknown origin) there and replaced the tube with 6N23P-EV (NOS Russian 6922, Reflektor brand but a cheap one). It sounds now better but there is still some distortion, mainly in midrange. Is the tube bad? Voltages are 1.8V on the cathode (fixed biased), 50V on ehe anode, 52V capsule and 120V B+ from the PSU. Replaced the grid bias resistor with 1G (was 200M), that improved the sound a little bit. There aren't that many microphones with 6922 tube, Rode NTK and K2 only I know. They use 3G resistor on grid. Should be fine, how about the stock 10.5:1 transformer?
 

mhelin

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Joined
Mar 12, 2005
Messages
562
Location
Tampere, Finland
Went back to 6N23P-EV after changing the anode resistor from 100k to 44k (close to what Rode uses in NTK), apparently there were issues with the grid current. Now there is 54V on the plate but the current has been increased to 1.25mA. Much cleaner now, the 6S6B-V was almost too clean and sterile (like a FET).
 
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