OPEN SOURCE DIY Mic Project - ORS 87 - Stripped Down u87

[Khron]

sort like star GND?

Sort of, but like the complete opposite. But I'd rather let the designer himself explain.

 

[homero.leal]

Direct quote from LNPrimer.doc, by @ricardo The doc can be found on the MicBuilders forum.

"PCB layout is critical for low noise. The first rule is to be very clear what your earths are doing. I always define 3 earths; Clean, Dirty and Chassis. I won’t talk about evil Digital earths but see the above link on www.planetanalog.com Consider carefully what you are doing when you connect anything to an earth. If you connect supply decoupling capacitors to an earth line, you make it Dirty. In our simple circuit, Clean earth is used ONLY for input / output earths and feedback components. The 10k input resistor is taken to BP so this line must be treated like Clean earth. BP is joined to Clean earth via a single 47u right at the input sockets. Dirty earth carries our supply decoupling currents. The 3 earths are joined ONLY at one point, at the output in our simple circuit. Output current does not upset the Clean input and feedback paths; a common source of instability. Some of you will recognise this as similar to "Star Point" earthing in power amplifiers."

 

[Khron]

That may very well apply to line-level circuits powered from the mains grid, that interact with other equipment powered from the mains grid. Some appropriate context for that quote would have helped..?

Found @ricardo 's quote on this forum as well, but as expected from the wording, it refers to preamplifiers, NOT microphone impedance converters...

https://groupdiy.com/threads/ina134-and-drv134-supply-bypassing.56079/post-715735

Unless you have special mic cables that have a separate shield that connects ONLY to the mic chassis, and the circuit ground of the circuitry connects ONLY to XLR pin 1.

As far as I'm concerned, a phantom-powered microphone might as well be a "floating" system, since it ONLY connects to the preamp you plug it into (tube mics could have a ground-lift on the output XLR, but that's a different issue).

Really no idea how and what "ground loops" you can achieve inside a mic, but i haven't managed that yet, despite my "careless" and "unwise" use of ground planes

PS. I would also slightly object to there being multiple "earths" there - i've been taught "earth" is (strictly) mains earth; anything else is a (circuit) ground. If only to try to avoid confusion...

 

[Juan Vargas]

hi guys at the moment I got this layout that will fit into this cheapo Temu mic that please don't laugh at the tiny PCB , ok so I add an opening for the NTE10-3 transformer that can be secure with zip ties the PCB size will fit only on this type of body that looks like those real Telefunken microphones body style I want it to add this data here so the screws mounting for the frame top PCB fastening are about 28.5 mm wide the next screws down are about 28 mm and from this screw mounts down is about 52 mm PCB size is 37 mm x 90 mm I'm gonna continue checking the layout to make sure that there are no bugs I've been doing this for many years but there is always one "oh no I forgot to..." you know what I mean the only thing different that I add to the layout is another R* so to combine different value resistors after FET is adjusted and get the trim pot resistance value to R* final value good day guys

​

 

[Korablev]

hi guys at the moment I got this layout that will fit into this cheapo Temu mic that please don't laugh at the tiny PCB , ok so I add an opening for the NTE10-3 transformer that can be secure with zip ties the PCB size will fit only on this type of body that looks like those real Telefunken microphones body style I want it to add this data here so the screws mounting for the frame top PCB fastening are about 28.5 mm wide the next screws down are about 28 mm and from this screw mounts down is about 52 mm PCB size is 37 mm x 90 mm I'm gonna continue checking the layout to make sure that there are no bugs I've been doing this for many years but there is always one "oh no I forgot to..." you know what I mean the only thing different that I add to the layout is another R* so to combine different value resistors after FET is adjusted and get the trim pot resistance value to R* final value good day guys

​

Dear Juan Vargas.
Are you planning to make the gerber file available for free use or sell it so that I can order a PCB of your version on Aliexpress?
The thing is that the bolt pattern of your board version is ideal for my case, which I recently purchased on Aliexpress.
https://aliexpress.ru/item/10050064...l.0.0.20204aa6XU8jLw&sku_id=12000037309239239
I would like to take this opportunity to say a big thank you to everyone who actively worked on this project. This is simply a wonderful opportunity to try to assemble a clone of the U87.

 

[Khron]

Are you planning to make the gerber file available for free use or sell it so that I can order a PCB of your version on Aliexpress?

Do none of the mounting holes on the ORS87-Plus on PCBway fit your intended mic body?

 

[Juan Vargas]

I just check the link and I don't think this mic body will fit the ORS 87 the V1.1 that they do have the link to order on PCBWay


oh by the way I don't sell things I just do for personal use and learning new things, OK, so if you have that mic body then measure with the vernier caliper you have top screws distance in millimeters then the metal frame width then front top screws to the last screw mounting also how long the PCB can be with that frame there are other option to fastening the tiny transformer PCB openings but for the mic body I have only I can use the NTE10-3 from Mouser the Ali one will not fit the mic body I have not sure about your mic body you got that one look like a really nice heavy duty mic shell

 

[Khron]

I just check the link and I don't think this mic body will fit the ORS 87 the V1.1 that they do have the link to order on PCBWay

Do none of the mounting holes on the ORS87-Plus on PCBway fit your intended mic body?

It helps if you read (all of) what is actually written, not what you might imagine is written...

 

[Korablev]

Do none of the mounting holes on the ORS87-Plus on PCBway fit your intended mic body?

Suitable. Can be secured with ties, but. PCBway services are unfortunately not available in my country.

 

[Korablev]

I just check the link and I don't think this mic body will fit the ORS 87 the V1.1 that they do have the link to order on PCBWay


oh by the way I don't sell things I just do for personal use and learning new things, OK, so if you have that mic body then measure with the vernier caliper you have top screws distance in millimeters then the metal frame width then front top screws to the last screw mounting also how long the PCB can be with that frame there are other option to fastening the tiny transformer PCB openings but for the mic body I have only I can use the NTE10-3 from Mouser the Ali one will not fit the mic body I have not sure about your mic body you got that one look like a really nice heavy duty mic shell

The dimensions between the holes are 28mm x 80mm. And I will order the same transformer as you: NTE10/3, Audio Transformers / Signal Transformers 1:3:10 MIC. https://www.chipdip.ru/product0/8004895384
I can redraw the board according to your drawing, but my main specialty is 3D modeling, I work in Rnino 3D, and I do not really understand the programs for developing printed circuit boards. But if necessary, I will figure it out. Just why, if you have a 1 in 1 layout suitable for my case. In other words, I would be grateful.

 

[homero.leal]

hi guys at the moment I got this layout that will fit into this cheapo Temu mic that please don't laugh at the tiny PCB , ok so I add an opening for the NTE10-3 transformer that can be secure with zip ties the PCB size will fit only on this type of body that looks like those real Telefunken microphones body style I want it to add this data here so the screws mounting for the frame top PCB fastening are about 28.5 mm wide the next screws down are about 28 mm and from this screw mounts down is about 52 mm PCB size is 37 mm x 90 mm I'm gonna continue checking the layout to make sure that there are no bugs I've been doing this for many years but there is always one "oh no I forgot to..." you know what I mean the only thing different that I add to the layout is another R* so to combine different value resistors after FET is adjusted and get the trim pot resistance value to R* final value good day guys

​

Congrats Juan, great work!!!

Quick question: Is the capsule of the TF22 a real LDC? From the pictures, it seems to be an electret.

Just wondering...

Cheers! Keep up the good work!

HL

 

[Juan Vargas]

Congrats Juan, great work!!!

Quick question: Is the capsule of the TF22 a real LDC? From the pictures, it seems to be an electret.

Just wondering...

Cheers! Keep up the good work!

HL

hi homero I think it is electret , oh thank you

 

[Juan Vargas]

The dimensions between the holes are 28mm x 80mm. And I will order the same transformer as you: NTE10/3, Audio Transformers / Signal Transformers 1:3:10 MIC. https://www.chipdip.ru/product0/8004895384
I can redraw the board according to your drawing, but my main specialty is 3D modeling, I work in Rnino 3D, and I do not really understand the programs for developing printed circuit boards. But if necessary, I will figure it out. Just why, if you have a 1 in 1 layout suitable for my case. In other words, I would be grateful.

oh ok ok so 28 mm top then bottom 80 mm for screw mountings, I can then adjusted to fit that, how much PCB length you can have on this mic body you got there or better say how long it can be? the width and the length take your time that is what I'm doing making sure all is correct you can do JLCPCB? I order from them many times

 

[Korablev]

oh ok ok so 28 mm top then bottom 80 mm for screw mountings, I can then adjusted to fit that, how much PCB length you can have on this mic body you got there or better say how long it can be? the width and the length take your time that is what I'm doing making sure all is correct you can do JLCPCB? I order from them many times

Thank you for your help. I measured more precisely. And quickly drew a 3D model of the HL-95 microphone. If someone is going to buy this case, it is sold here: https://aliexpress.ru/item/10050064...l.0.0.16244aa6VfUE5X&sku_id=12000037309239239

The thing is that the most convenient board manufacturing for me would be the NextPCB service https://aliexpress.ru/item/10050075...st.14.15c44aa6ARFKy8&sku_id=12000041381203745

But the Chinese manufacturer asks for a Gerber file.

JLCPCB is available to me through intermediaries with a headache, and I think it will take a very long time.

Could you share your gerber file? It doesn't even require any changes, our landing places and free space inside the cases coincided amazingly.

 

[Juan Vargas]

I'm glad that I brainstormed this a bit more if the transformer is installed with zip ties then how the other two wires will find a path? on the image "middle one" of the transformer has the zip ties and the example of the 3 wires what I did is to add more holes so the wire can then find it place

 

[Juan Vargas]

Thank you for your help. I measured more precisely. And quickly drew a 3D model of the HL-95 microphone. If someone is going to buy this case, it is sold here: https://aliexpress.ru/item/10050064...l.0.0.16244aa6VfUE5X&sku_id=12000037309239239

The thing is that the most convenient board manufacturing for me would be the NextPCB service https://aliexpress.ru/item/10050075...st.14.15c44aa6ARFKy8&sku_id=12000041381203745

But the Chinese manufacturer asks for a Gerber file.

JLCPCB is available to me through intermediaries with a headache, and I think it will take a very long time.

Could you share your gerber file? It doesn't even require any changes, our landing places and free space inside the cases coincided amazingly.

this is really value information you put here nice I can share the gerbers then you can use Sprint Layout 6 to modified if you need to I'm not sure if I'm allow to share links here, ok so top 28.5 mm x 80 mm I see that you can use maybe M3 screws with nuts for fastening, the hole size of the PCB now are 3.00 mm in diameter you notice that I post about the transformer other wire they are 5 of them and I didn't notice the other two or 3 on the other size need to find it patch for the TX? connections so I add more holes so wire can you know be connected

 

[Korablev]

this is really value information you put here nice I can share the gerbers then you can use Sprint Layout 6 to modified if you need to I'm not sure if I'm allow to share links here, ok so top 28.5 mm x 80 mm I see that you can use maybe M3 screws with nuts for fastening, the hole size of the PCB now are 3.00 mm in diameter you notice that I post about the transformer other wire they are 5 of them and I didn't notice the other two or 3 on the other size need to find it patch for the TX? connections so I add more holes so wire can you know be connected

Yes, I have Sprint Layout 6. I think I can figure out how to work with it. Here are my thoughts on NTE10/3, audio converters. Please note that there is a large gap of 2mm around the entire perimeter between the printed circuit board and the transformer. It is possible that additional holes are not needed. Well, as an option, the two lower wires can be soldered from the bottom of the printed circuit board. If you can't post files here, could you send me your project for Sprint Layout 6 to my email? tv-6 dog mail.ru

 

[Juan Vargas]

oh ok you right I will send you the files to your e-mail, ok so the holes are not really need it then?, oh yes you right there is a large gap and wire can be solder under the PCB, I think in my case my mic frame doesn't have not enough space at the bottom, you made the transformer way too tick I think lol I saw a video of a gentlemen that was using this NTE-3 former see image, also if you can check the layout to be sure all is correct I check it many times but a second pair of eyes can also help too let me know if all is in order.

 

[Korablev]

oh ok you right I will send you the files to your e-mail, ok so the holes are not really need it then?, oh yes you right there is a large gap and wire can be solder under the PCB, I think in my case my mic frame doesn't have not enough space at the bottom, you made the transformer way too tick I think lol I saw a video of a gentlemen that was using this NTE-3 former see image, also if you can check the layout to be sure all is correct I check it many times but a second pair of eyes can also help too let me know if all is in order.

Thank you! I'm sure there will be plenty of space in your case, but only if you remove this board.

And here is information on the transformer: https://static.chipdip.ru/lib/759/DOC029759077.pdf

 

[Juan Vargas]

Yes, I have Sprint Layout 6. I think I can figure out how to work with it. Here are my thoughts on NTE10/3, audio converters. Please note that there is a large gap of 2mm around the entire perimeter between the printed circuit board and the transformer. It is possible that additional holes are not needed. Well, as an option, the two lower wires can be soldered from the bottom of the printed circuit board. If you can't post files here, could you send me your project for Sprint Layout 6 to my email? tv-6 dog mail.ru

hi I try to send the file to your e-mail and is not working ? no worries , here are the gerber files please check from schematic to layout to see if all is in order and for what I read here the NTE-3 transformer connections are like this:

TXI- red wire
TXI+ black wire
TX0- yellow wire
TX0+ white wire
on the NTE-3 tiny transformer the blue wire is not in use

the PTFE insulator part number is 534-11154 Mouser the hole diameter is 3.20 mm you can change this one they are other ones,
the orientation of the transformer would be with the 3 wire down and the good thing is that they will align just fine, the gerber files can be imported to Sprint Layout 6 software if you need to do some adjustments to fit the microphone frame you have if need it.

Today adding more information on C7 1uF capacitor the pitch distances are 34.5 mm, 22.5 mm, 10 mm, 5 mm, and the last one 2.54 mm, I add and extra R* so in series you can get the value you need after Q1 FET final adjustment. The electrolytic caps C8,10,12 are 5 mm in diameter size and PD 2.54 mm, the top insulators have two options of part number Mouser# 534-11154 3.18 mm diameter on the PCB the hole is 3.20 mm the other one Mouser# 534-11150 1.90 mm diameter and hole diameter on the PCB are 2.00 mm "I'm not sure how tight they need to be" Korablev there it is