On Sat, Apr 10, 2021 at 08:42:10AM +0000, Rodolfo Medina wrote: Just use the four in the center, either the RCA connectors (red/white) or the TRS (black). It's just two types of connector, they have the same signals. You don't need the others. -- FA

On 2021-04-10 07:25, Rodolfo Medina wrote: You need an adapter such as this which converts phantom power 48V to the proper voltage for the microphones you have: https://www.amazon.com/Movo-Mini-Jack-Microphone-Connector-Integrated/dp/B0… or https://www.bhphotovideo.com/c/product/1540722-REG/saramonic_c_xlr_3_5mm_tr… The adapter must convert the 48V phantom power to the appropriate lower voltage for your microphones, it cannot just be connectors and wiring. -- Chris Caudle

David Kastrup <dak(a)gnu.org> writes: Just to stress: the plus sign in Røde VXLR+ is not optional. There is also an adapter called just VXLR and it does not convert the phantom power to plugin power, working only with microphones containing their own batteries. -- David Kastrup

Alf Haakon Pietruszka Lund <alf(a)mellomrommet.no> writes: Sure, but that still leaves you without plugin power. -- David Kastrup

Alf Haakon Pietruszka Lund <alf(a)mellomrommet.no> writes: Yes and no: electret condenser. They don't need phantom power for polarising the capacitor capsule as it comes prepolarised. But they do need some power (typically 3V–6V) as plugin-power to power the built-in FET preamplifier without which the weak capsule signal would not make it through the microphone cable. The infamous Neewer BM800 can convert phantom power to plugin power and thus can be run on either depending on the cable type (while providing S/N ratios that are not impressive for either application). But a lot more typically, devices only work with one kind of power. The kind of soundcard/computer providing 3.5mm TRS (or TS) microphone inputs tend to carry plugin power (sometimes switchable by software), XLR inputs tend to have an option for phantom power (almost always +48V these days), sometimes switchable in groups. -- David Kastrup

Edgar Aichinger <edogawa(a)aon.at> writes: Cheap compact microphones invariably are electret condenser and invariably need a power source: plugin power, 1.5V battery or something else. Laptop headset jacks invariably provide plugin power. USB soundcards can also power actual phantom power since the actual current requirements are low, so a stepup converter will make for +48V if you manage to design it in a manner not contributing converter whine into the sound experience. Invariably using plugin power unless they require their own batteries. -- David Kastrup

Fons Adriaensen <fons(a)linuxaudio.org> writes: In particular, using omnidirectional microphones for 4-channel audio is not likely to lead to a lot of differentiation unless you work with some clever arrangement of baffles. -- David Kastrup

Rodolfo Medina <rodolfo.medina(a)gmail.com> writes: Have you looked at the 2 channels to check whether there are actually two significantly different significantly non-zero channels? It is not usual that the sound card detects how many sources are open or actually connected, and it would be entirely unusual that the recording software would act on such information rather than recording at least 2 channels by default. There is a high probability of muddy trebles, a significant noise floor and an overemphasis on the 1k–4k frequency range: the main application of cheap microphones like that is improving voice chat. Since they have less size limitations than a microphone built into a laptop and are not in contact with the case that also holds hard disks (though those are often SSDs these days) and cooling fans as well as various voltage converters including for LCD backlight, they have a reasonable chance to offer significant improvement there. But it's a decidedly lower bar to cross than picking up piano sound. For piano, a good bet for close pickup are small-diaphragm but silent condensor mics with omnidirectional characteristic. You don't want to use too many mics because of comb filtering problems. For basically any ensemble placement, you want comparatively directional microphones, cardioid or hypercardioid (the latter tends to make it a bit easier to mask other players in an ensemble arrangement at the cost of being more finicky in placement). I am going to go out on a limb here and state that I've seen surprising value from Behringer B5 microphones (comes with omni and cardioid capsules) for use with virtual rehearsals of an accordion ensemble. Certainly to the degree where I could not justify getting the Oktava small diaphragm condenser mics for everyone that I use myself. Accordion is comparatively tricky in sound quality and easily sounds too harsh and disharmonious in recordings (also tends to self-destruct under lossy audio compression at surprisingly high bit rates). Of course, close-captioning an accordion does not really require a low noise floor, but the Behringer B5 should rarely be a dealbreaker in that regard either, at least when considering the typical small diaphragm condenser use case (you'd use large diaphragm for room/distance recordings anyway). One channel sounds different from another. Of course, if you are placing your microphones per-instrument (rather than as a recording group), that's not going to be an issue. -- David Kastrup

Fons Adriaensen <fons(a)linuxaudio.org> writes: I'm interested in recording different, say e.g. 4, mono channels. So it's not important to me that a certain microphone be stereo, I'm using it as mono anyway. So no, I don't exactly know and it does not matter to what I'm looking for. The above microphone produces a 2-channel record. I've used that microphone just once to record my voice speaking. Listening back to that record, well, no, I couldn't say if it's stereo or mono. Thanks Rodolfo

Fons Adriaensen <fons(a)linuxaudio.org> writes: I don't. I don't want to do audio engineering. I am learning the basics and don't mean t waste other people's time. Cheers Rodolfo

Alf Haakon Pietruszka Lund <alf(a)mellomrommet.no> writes: Its words don't matter at all to me... ;-) But thanks...! In fact I know my lack of knowledge and that's why I'm here to ask questions to expert people. It's been very useful, I've learning a lot. Thanks to the precious help you all provided I'm now planning to buy the Behringer UMC404HD audio interface and also one of those Behringer B5 microphones as suggested, and test it. Then with the UMC404HD I'm going to do do some home-made multichannel records and also that sort of strange experiment of playing more than 2 different channels simultaneously out of a multichannel audio file. Ciao, Rodolfo

Fons Adriaensen <fons(a)linuxaudio.org> writes: You could print the grill but not actually make any holes :) -- David Kastrup

On 2021-04-29 09:27, Jeanette C. wrote: speaker-test helped me when I experimented with some home built hardware a few years back. I liked the voice feedback that comes with -twav For continuous 2 channel test I use: speaker-test -c2 -twav end with ctrl-c For single shot 2 channel: speaker-test -c2 -twav -l1 For 5 it would be: speaker-test -c5 -twav For a single shot on channel 3 id use: speaker-test -c5 -s3 -twav -- /bengan

Rodolfo Medina <rodolfo.medina(a)gmail.com> writes: It works...!!! That's what I did: 1) I plugged the Behringer into the mains; 2) I connected the Behringer to the PC via Behringer's USB cable; 3) I plugged 3 amplified loudspeaker (could also be not amplified but then sound is low) into 3 of the 4 black holes (the TRS ones, but it could be ok also with the RCA ones, I didn't try yet) of the `PLAYBACK OUTPUTS' system on the back of the Behringer; 4) from my Linux box I did: $ ecasound -f:16,3,44100 -i:sndfile,3canali.wav -o alsaplugin,2,0 where `3canali.wav' is a 3-channels file. And voilà: each of the 3 loudspeakers play a different channel of the 3 channels composing `3canali.wav'. There don't seem to be any issue with Behringer's controls: the `MAIN OUT' and `MIX' knobs can be whatever, such as the `STEREO/MONO' switch (so it seems). Thanks to each and all that helped...! Cheers Rodolfo