Some question from noob about capsule rk-12

[Андрій Чубака]

You absolutely can by ordering from something like Mouser. Also you can check quiescent current to be sure, and drive capabilities. You are wasting your time with TL072, if nothing else noise will be terrible, THD, and drive capabilities. Have you checked current and operating voltages with the TL072? If your component source is sketchy, you can't be even sure it's TL072.

If you interested about this topic read last messages I can`t write one more time wich is alredy wrote.

 

[kingkorg]

If you interested about this topic read last messages I can`t write one more time wich is alredy wrote.

Good luck.

 

[Андрій Чубака]

Well, that totally depends where you get your chips from...

Here I don`t have any choise because all local shops buying chips from china. I don`t know how it is working in europe but here only like this, chips from china also working but never can be sure about pure quality. /:

Who try help me anyway thanks. Sometime it was very helpfully. I don`t sure about next updates in this topic. Because all important things look like is done. About new chip I thinking now but as I say before until placing it I must do many tests only after this I can try put something more expencive in this mic then this tl072 wich is also working pretty good.

 

[Андрій Чубака]

One more final test without cliping on cutting of sound. Looks like now chip working without broking down. Most of all it was problem of old pcb it was dirty and maybe was with some problems. So if no updates to this topic in closer future then all working nornally. If I will have new better chip in future maybe I will upload some new test of recording.

 

[Андрій Чубака]

this is one more test with tl082 instead tl072 and without additional inductance

 

[Андрій Чубака]

Also here some compere of starting chip with turn on of phantom power. One with additional inductance other with out it. About quality of recording it is don`t make any difference. I will cut it from circuit and don't use this inductance any more.

 

[Андрій Чубака]

This is my last perfectly placed tl072 chip if it is will broke later i will give up with it. Previous one was broken this is new one more time. Possible it was problem of my soldering technology. I used pasta for soldering and i found some balls under chip.

 

[Khron]

SOIC8's are still very much doable with manual soldering, no need to reflow them (imho). Even with a fat tip (arguably, it's even better with a fat tip - more thermal mass / capacity).

 

[Андрій Чубака]

Maybe you are right but I was try with soldering iron first time and it was hard for me. Now here is more important will this all working on next day or not. I bit tired with all it. but this is life and everything is possible.

 

[Андрій Чубака]

Today I am all day testing this mic maybe like 8 hours I keep it turned on with some time turning off. and it is still working

I made some test with music. Hope now all problem is fixed and maybe later i will replace this tl072 on something esle. now this mic catch very many low frequnces I just almost turn off my subwoofer for recording this.

 

[Андрій Чубака]

I am forgot to say i have enough accurate multimeter so i check capacitance of this capsule and it is 63 pf as i am remind. This is one side capsule, so only for cardioid pattern.

 

[Андрій Чубака]

I made some additional test of this tl072 for compare with some opa1642 from china. And can say tl072 has more rich low frequency responses. But total quality of sound feels bit more low like. Opa1642 more accurate deliver the quality of sound. But level of grain is still bit more low on opa. Maybe some days later i will do some clear tests of comparing different chips for sound quality and will share it.

This tl072 looks like absolutely amazing for me compere to china products and price is more low than 3$ for a 10 piece.

About small level of hgh frequency noise on tl072 it is can be from inductance. I already removed it from board. But i can check later final results. Now there is opa and it is working without this noise.

About level of grain i know now how it is can be changed in good way. But now i want do some test with other chips and after i will decide need i am this changes in circuit or not. Also it is risky for burning chips.

In my opinion i will drop voltage of polarization on capsule for opa1642 chips maybe this is one of more better way for solve a problem with my capsule for this chip. I will check later how it is really works. So now without this dropping level of grain is bit low and level if high frequency is bit more high on opa1642, but on tl072 is good like now.

 

[Андрій Чубака]

OPIC LDC

So about ada4627-1 wich I wrote before like about possible for replacing. I bought 1 of this and later I check in datasheet it is not a dual op amp. and possible to try it only in circuits like in message before. I read about this op amp on some forum like possible for replasing tl072, but something was wrong in it, and in this case I just wasted my money because I don`t check datasheet carfully before I ordered it. What is interesting even in this op1642 circuit this ada4627 is worked some how but with very low sound output. Now I don`t know or this chip is still alive after my tests but most like is not. So bad expirience to me, but this is life and some time is possible made some one but big mistake. Also datasheet on this ada in not very clear for undestandig beause I miss about it not a dual amp. I bought only one piece of this ada for testing, but anyway it is expencive

Correct choise for opa-alice circuit from analog devices chips will be ada4625-2. But i won't buy one more high cost chip. So maybe in some future i will test it. Also this chip is maybe not like solution of all problems of mic. Even regular opa1642 already needed some low pass filter in circuit with my capsule as my opinion. So before i can go to this more expensive chip i must do many tests about how all this circuit is really working for me. Because here is high performance chips is not like solution of all problems of mic. Looks like circuit also need some changes for placing more high performance chips. Now i think about some additional inductance in this circuit, but i will check later how it is really working. Here is needed inductance without core i guess, but with small size so i not sure about final results.

 

[Khron]

Impedance-balanced output should work just fine, even with a single opamp - you don't necessarily need to actively drive both lines of a mic connection. Works well enough for Rode, anyway

 

[kingkorg]

I read about this op amp on some forum like possible for replasing tl072

TLC072! With "C". Very different to TL072

 

[Андрій Чубака]

I not a big pro in this. But in this part of world usualy it is call tl072. Even google know it.

I don`t using russian language but on russian version of TI site it is called like tl072 TL072 data sheet, product information and support | TI.com

 

[kingkorg]

I not a big pro in this. But in this part of world usualy it is call tl072. Even google know it.


there on photo it is also marked like tl072, but in english versions more like tlc072

I don`t using russian language but on russian version of TI site it is called like tl072 TL072 data sheet, product information and support | TI.com

TlC072 can be used for this circuit with some adjustment, but not TL072. They are two different chips, and will perform differently. Opamps have different current consumption, speed, voltage ranges, rail to rail specs, noise, driving capability, topology... Phantom voltage and current availability limits the opamps you can use. Depending on circuit, opamps current consumption determines operating voltages. What i am trying to say, without knowing exactly what you are doing you can not just blindly exchange the opamps. You could even have oscillation without realizing it, and that would throw off the whole thing.


There is a very specific reason why 1642 is used. By now, i have a feeling it would have been easier and cheaper if you just found the original 1642. It is available at LCSC, and it should be original and possible to deliver tou your region.

https://www.lcsc.com/mobile/product-detail/Audio-OpAmps_TI_OPA1642AID_OPA1642AID_C201728.html
Good fet for microphone use has about 1.5nV/√Hz noise, opa1642 has 5nV/√Hz, TL072 has 15nV/√Hz! That is simply too much.

 

[Андрій Чубака]

Opamps have different current consumption, speed, voltage ranges, rail to rail specs, noise, topology

Yes I can check all this in sound, I feel like tl072c not same smooth as opa because tl is 3 mhz and opa is 11 mhz, and I don`t talk like opa in everythig is better. Bass responce of tl is more rich, but opa deliver more quality of sound when I compare it head to head. I don`t need here any big lab where I will test many different thing for creating some new neumann mic. I searching my way and here is something is work and something is not.

JUst for you here is sound from opa1642 is same circuit, and you can compere it with sound of tl072c wich is already there is this topic.

I no need here many smart words and 0 results. I just trying for my own interest.



here is not big microphone factory. And I not a guy who must create best mic ever from chinese parts. I don`t wasting any products from shops and factorys I just want try some different ways with this circuits.

Later I want test some chips with different architecture not only jfet. But no need arter this write to me like I broking your pasta and you pure italian for who it is all is very important. yes sound is different and not more for me in this case.

PS: I am just waisting time on this mic building. Maybe later if I will have some fine results on my opinion I will try sale some mic, but now here is war and I don`t sure about I can sale this mic in this case. So all other I do just for myself and my own interest.

Also now as I understand in this simple circuit all op amp is working if power suply around 36 volts as in opa1642. Just it is have no sence almost change this opa on something else. For example I don`t expect from chips with different architecture nothing many here, in mostly case it is just hiding a bass and I know it is not in using here because it is contain some problems. But when I will check it I will know for sure how it is working.

I am noob in mic building but i am not a total *****.

 

[Андрій Чубака]

Good fet for microphone use has about 1.5nV/√Hz noise, opa1642 has 5nV/√Hz, TL072 has 15nV/√Hz! That is simply too much.

I will do additional tests later about small amount of high freq noise on tl072, now i think it was from additional inductance in circiut. I not absolutely sure about it but most look like this. Now i am not near this mic and i can't check anything at this moment. About other i think in all this circuit is capsule give most amount of noise totally. So you can calculate noise from fets very carefully but most like you can't improve total quality of sound from mic because capsule is not give for you possibly for using maximum low level of noise from fets, chips etc...

I think now i will close this topic. Now i thinking about some tests and some ways how possible increase total quality of sound with my Chinese capsule 34mm and this opa alice circuit. I must check all how it is working on practice and maybe some days later i will open new topic about what solutions i have and how it is really working with my capsule. I won't write anything now until i didn't check how different kind of solutions working in this circuit. As my opinion for different capsules and chips this circuit need some changes for a best performance. Maybe this is not big changes but anyway. And to me now looks like for broadcasting mic tl072 is a best solution for this circuit without any changes and capsule like i using now. For opa1642 looks like need change frequencys balance on bit more low and maybe increase gain level bit with some additional resistor or so. There also for example if you increase gain level with resistors with it you also have more distortion from some formulas to this chips but on practice this difference is not a noticeable on this kind of circuit and sound quality. Possible all this change with equalizer after recording and got almost same good result but i am anyway want try build mic with good sound directly from mic.