True, attenuation is required. I dont believe my brief has changed and the title to the thread remains true - Im just finding the right language to describe it whilst also trying to understand the many varying replies.
No. Not this version anyway
The output is Mic Level as the thread title suggests.
No. Bo Deadly's Simple DI is NOT for a console mic input. Most people don't have consoles. And even if they do, there would be an inclination to just run into an audio interface or some other line-level gear. Phantom / attenuation + amplification is not necessary.
I'm not trying to have a semantic debate and I wasn't really trying to directly answer the OP question. I posted the circuit because it shows how simple it can be to get directly from an instrument to a destination and that using a transformer to step down only to amplify again is simple unnecessary these days. Even in a live environment there are line level inputs. Having a passive box with galvanic isolation is good in some scenarios. But not so much in a studio (home or otherwise). A transformer is not ideal for a guitar. The impedance is not really high enough for some cases, the primary will have significant capacitance and you could easily get LF distortion if you're not careful or the transformer is a cheap one. Bo Deadly's Simple DI will capture a completely transparent signal with a through connection to an amp so that you can re-amp.
If you really want to get pedantic about CMRR then add the cap to pin 3. But that's really not necessary IMO. The purpose of the impedance balanced output is not so much about CMRR and more about ground noise cancellation which, if the other end is properly balanced, should be very effective.
True. But for a "simple" DI I don't think it would make enough of a difference to justify adding the 22uF (and drain resistor) to pin 3.
Same thing, ground noise is common mode noise.
Én is így gondolom, 40 év hangmérnöki (és elektrotechnikai) gyakorlattal! Nincs is jobb egy (Jó) transzformátornál! (És még a CMRR is tökéletes!) Az egyetlen gondom a FET bemenettel rendelkező opampok használata! Tapasztalataim szerint a hangzás nem valósághű (persze a rockzenénél nem fontos) De dolgoztam rockzenekaroknál és különböző műfajú zenei fesztiválokon is. Saját, jól felszerelt laborom van, emellett stúdióberendezéseket fejlesztek és javítok. Tapasztalataim szerint a vibrációs zaj rontja a hangot, ezért kerülöm a FET-eket. 20 évig fejlesztettem a magyar színházak hangtechnikáját is. Ott kritikus a zaj. Sok sikert a munkádhoz, sajnos már 67 éves vagyok. Egy akkreditált laboratórium mérései szerint a 10 GBit sebességű Cat 6 kábel is közel 10-szeresére javul,
I think the same, with 40 years of sound engineering (and electrical engineering) practice! There is nothing better than a (Good) transformer! (And even the CMRR is perfect!) My only concern is the use of opamps with FET inputs! According to my experience, the sound is not realistic (of course it is not important for rock music) But I have worked for rock bands and also at music festivals of various genres. I have my own well-equipped lab, and I also develop and repair studio equipment. In my experience, flicker noise makes the sound worse, so I avoid FETs. I also improved the sound technology of Hungarian theaters for 20 years. Noise is critical there. Good luck with your work, unfortunately I am already 67 years old. According to the measurements of an accredited laboratory, even the 10 GBit speed Cat 6 cable improves almost 10 times, even though it is no longer a sound spectrum!
So you think a transformer connected to a passive electric guitar is "realistic"?
Yes. But I think the differentiation is between "Ground Noise" due to varying "Ground" voltages between units and common mode interference from external sources eg H-field from a mains transformer. The former is generally dominant in a studio environment.
Same thing, ground noise is common mode noise.
I'm very suspicious about the noise performance of this arrangement with high impedance sources.
