line to mic level using Neutrik NTE10/3 transformer
« on: May 18, 2020, 02:19:16 AM »
Hi there,

i would like to convert Line level audio to mic level using a transformer to protect my camera. witch is battery powered in contrast to the audio gear.

i found some schematics and would like to know how it's done correctly using the Neutric NTE10/3, witch i have bought in an impulse.

https://www.soundcardpacket.org/7cablerx.aspx


it's the first time i'm using a transformer in the audio biznis, don't know much about it.
did someone tried this?

kind regards and thanks in advance.

« Last Edit: May 18, 2020, 03:23:41 AM by Natural »


abbey road d enfer

Re: line to mic level using Neutrik NTE10/3 transformer
« Reply #1 on: May 18, 2020, 05:50:22 AM »
i found some schematics and would like to know how it's done correctly using the Neutric NTE10/3, witch i have bought in an impulse.
You could have done worse... :)

Quote

did someone tried this?
Yes.

That should work; the only risk is, if the line level is excessive, saturating the transformer. You may need an attenuator, such as this
https://www.thomann.de/fr/jts_ma_123.htm?glp=1&gclid=CjwKCAjw5Ij2BRBdEiwA0Frc9ebx97n9gPRNZ_m1sg2HgKS11ZTzAiUVHvcitLsMfan9EOBkcjmiWxoC8TkQAvD_BwE
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

Re: line to mic level using Neutrik NTE10/3 transformer
« Reply #2 on: May 18, 2020, 03:43:39 PM »
Hey thnx for your reply.

how about this?

taken from:
https://www.soundcardpacket.org/7cabletx.aspx

well the line level input is no problem, i can use opamps and reduce the gain.
as my gear is 10 v.p.p., but i can't have opamp or any parts powered by my gear on the secondary side.
i wanna protect the camera witch is battery powered.

i bought that Neutrik transformer in an impulse and i wanted to know if that type/model does the job.
https://www.neutrik.com/en/product/nte10-3

it's center tapped, being 10K on 1 side and 50K on the other.
witch should i use?

i don't know anything or little about transformers in the audio world.

kind regards

analogguru


Re: line to mic level using Neutrik NTE10/3 transformer
« Reply #4 on: May 18, 2020, 05:48:39 PM »
well, i'm building a DIY modular synthesizer.

i have reduced the gain from 10 v.p.p. to line level using 3.5 mm jacks, i don't have anything with XLR jacks, yet.

https://befaco.org/docs/Out/Output_V3_Schematic.pdf

now i'm trying to build a "thing" to convert line level to mic level ... so my camera can record the audio as it has a mic input and doesn't get destroyed. the producer of the camera tries you to sell a 650€ adapter.


Sony ECM-DS70P - Portable Stereo Condenser Microphone.
Electret Condenser Technology.

witch should be the same as ...

https://www.conrad.nl/p/microfoonkapsel-1-10-vdc-frequentiebereik100-hz-8000-hz-c9767ed423lf-302155?WT.mc_id=gshop&gclid=CjwKCAjw5Ij2BRBdEiwA0Frc9QG4L6VRnjbCIQI5TLXPBFctiBUPlSYmsu0aNbjS0lF3P-dzMEDWUhoCQ8oQAvD_BwE&gclsrc=aw.ds&tid=1578107505_66447429024_pla-356257857727_pla-302155&WT.srch=1&vat=true&insert_kz=8J

i haven't done any tests with a 3.5 mm jack into the camera and scope it.

the camera records fine, but you have to be quiet.
now i'm exploring a new area and i don't know much about impedance of the mic input .. and the neutric NTE10/3 transformer is on it way.





 



abbey road d enfer

Re: line to mic level using Neutrik NTE10/3 transformer
« Reply #5 on: May 18, 2020, 07:42:07 PM »
how about this?

taken from:
https://www.soundcardpacket.org/7cabletx.aspx
This can work, yes, but since you have the Neutrik xfmr, you should use it, as it is a better solution..

Quote

i wanna protect the camera witch is battery powered.
Don't worry about it.

Quote
i bought that Neutrik transformer in an impulse and i wanted to know if that type/model does the job.
Yes it does.

Quote
it's center tapped, being 10K on 1 side and 50K on the other.
Not exactly center-tapped. If it was, it would be 50k and 12.5k.

Quote
witch should i use?
Use the 50k connection.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

Re: line to mic level using Neutrik NTE10/3 transformer
« Reply #6 on: June 18, 2020, 06:33:19 AM »
Hi, there.

this is what i have soldered on prototype board.

but i seem to have distortion or noise, not that much on my camera, but a whole lot on my pc ... but i do need to make a new cable for the pc.

it looks like the transformer steps up between Black and Red, that why i soldered a 4m7.

also on the primary side it seams to pull hard and bug down the audio level a bit.

i also used the Black & blue + 3M3 resistor.

maybe it's the 10nF  ( C2 ) ... even if i unplug the synth from the jack, you see 1 bar in the audio meter.
i use WIMA capacitor.

the cable is mono core & shielded, but cheap 3.5 mm connectors.

in general, it works ok ... when producing sound, but ...

mt file size is 14KB ... it wont allow me to upload the file and it says the folder is full.

abbey road d enfer

Re: line to mic level using Neutrik NTE10/3 transformer
« Reply #7 on: June 18, 2020, 06:42:26 AM »
also on the primary side it seams to pull hard and bug down the audio level a bit.
That's because you're using teh xfmr the wrong way. the audio signal should be connected to the high impedance side and the low impedance side to the sound card.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

Re: line to mic level using Neutrik NTE10/3 transformer
« Reply #8 on: June 18, 2020, 06:57:46 AM »
i can't upload a schematic, file size!

 i have send you a pm, did you check you box?

Re: line to mic level using Neutrik NTE10/3 transformer
« Reply #9 on: June 18, 2020, 08:48:48 AM »
That's because you're using teh xfmr the wrong way. the audio signal should be connected to the high impedance side and the low impedance side to the sound card.

indeed, it was turned around.
 :)
thanks alot

i removed the 4M7 and soldered the White wire directly to pin 3 of the 100K pot, the Yellow wire to pin 1 of the same pot and the wiper to the output jack.

as ...

Black = ground on the synthesizer side.
Red = from the + of input jack.

i connected Black & White via a 10nF capacitor and 10K resistor.  (i think, i saw some schematic do that ... when i started this thread)

what should i do with the blue wire?
i can't have that floating in the air!
if you touch it ... you can see it on the scope.

i still have lots of noise on the pc, but i used a stereo jack instead of mono jack, but work fine in the camera now.



abbey road d enfer

Re: line to mic level using Neutrik NTE10/3 transformer
« Reply #10 on: June 18, 2020, 11:08:05 AM »
what should i do with the blue wire?
Isolate it with a piece of tape or heatshrink and let it dangle. Once your contraption is in a metallic box, you're fine.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

Re: line to mic level using Neutrik NTE10/3 transformer
« Reply #11 on: June 18, 2020, 11:13:06 AM »
i told Sony about it.

now my warranty is void!
i could cause dangerous situations.
: )


 

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