| 10 Nov 2023 |
 positionhigh | I assume their ohm is much lower than that. | 21:51:14 |
 .thunderbold | Yes most headsets are like 16 or 32 ohms | 21:52:15 |
| positionhigh | mobile applications: 16 – 50 ohms
studio and Hi-Fi use: 60 ohms or more
DJ: 60 ohms or more
in-ear monitoring: 16 – 50 ohms | 21:52:26 |
| positionhigh | not sure, how accurate this list is. | 21:52:33 |
| .thunderbold | Seems fairly ok, I have a Custom Pro One Studio which is 80 ohm | 21:53:19 |
| positionhigh | i placed the resistors to be big and easy to exchange. hopefully most cases can be fixed by changing their value. The Amp has it's own SMD resistors but i prefer to not challange our users to change these very tiny parts. | 21:54:40 |
| .thunderbold | But actually because you have a 250 ohm, I dont the the amplifier IC itself is the issue but rather decoupling or power architecture | 21:54:55 |
| .thunderbold | Agreed, but the TDA seems to be just two opamps in one package so you could also consider rolling your own headphone amp | 21:55:39 |
 m.c.gentry_31770 | Wowee wow wow, great news on the new board! | 21:55:51 |
| .thunderbold | (makes it at least easier to adjust the amplifier circuit itself) | 21:56:02 |
| .thunderbold | But it's better to first try easy changes before going down that road | 21:57:42 |
| positionhigh | mdt is thought to be done by soldering novices, so avoiding all too complicated parts. I added the amp only because that was one of the most asked "features". The previous line out was very well and without any distortion or digital noise.. I put some jumpers in to make sure you could get the same output as before, but also some room for experimentation about the amplifier. My electronics knowledge is more on the very low side :_) | 21:59:18 |
| .thunderbold | https://codeberg.org/positionhigh/MicroDexed-touch/wiki/Wiring | 22:01:28 |
| .thunderbold | Is the schematic here still up-to-date or have there been changed? | 22:01:48 |
| .thunderbold | *changes | 22:01:51 |
| positionhigh | thats how it currently is | 22:02:51 |
| positionhigh | ..with the 27k resisors as only "modification" to it. | 22:03:57 |
| .thunderbold | What do you use to power your board? A smartphone charger or a PC? | 22:31:07 |
| positionhigh | currently pc. but i know that introduces all kind of noise issues. | 22:31:41 |
| .thunderbold | I'm definitely leaning towards power filtering being the issue. The amp is powered directly from the USB port and seeing that the Teensy has 2.2uF (and close to the usb, not the amplifier) and the headphone has an unidentified (but seemingly small) capacitance | 22:33:47 |
| .thunderbold | Do you have electrolytic capacitors around? Try soldering a 100uF on the power input of the amp and see if that makes a difference | 22:38:37 |
| .thunderbold | I can explain in more detail after I get some sleep 😉 | 22:39:21 |
| positionhigh | i do have. will try that tomorrow | 22:39:25 |
| positionhigh | i am looking at this behringer stuff. i think it is fake braids. | 22:39:48 |
| 11 Nov 2023 |
 lummsmusik | This week I received two new Teensy 4.1 for a reasonable price and will continue building my mdt. At last attempt month ago I destroyed the Teensy. Hopefully this time I will be more carefully in soldering and testing the electronics. | 12:09:40 |
| lummsmusik changed their display name from LummsMusik to lummsmusik. | 12:09:40 |
| positionhigh | If you had so much trouble, it is most likely that your tools or materials are not ideal. This is a hobby project aimed at musicals with some basic soldering skill, this is the reason i try to avoid incorporating overly small or complicated parts to solder in by the user. For some features, unfortunately this can not be avoided but for a basic mdt, just take your time to do it and if you have doubts about soldering, i think you will find a lot of tutorials on youtube etc. | 18:57:52 |
| positionhigh | made a quick test with the electrolytic capacitor but are not sure if i hear any difference. Would have to make some actual recordings to find out. However, when not powering by a PC USB port, but a USB Power bank or a different wall USB plug, i do not hear any digital noises or humming. | 19:36:22 |
| positionhigh | So that might be the easiest solution, just to not use a PC USB port for power. | 19:37:06 |
| positionhigh | * made a quick test with the electrolytic capacitor but not sure if i hear any difference. Would have to make some actual recordings to find out. However, when not powering by a PC USB port, but a USB Power bank or a different wall USB plug, i do not hear any digital noises or humming. | 19:37:32 |
