Would you care to elaborate? I don't see anything gross in here. Maybe I'm not concentrating on the right part of the circuit...Unfortunately I don't have a schematic of that mixer but I have one from his younger brother (402VLZ3) and here's what grounding looks like. This one was obviously designed by some novice engineer.
I thought the 402 was an old model from last century... rebranding it with extra letters after the numbers does not make it a scratch design.The mixer I commented on was designed in 2007. Greg left Mackie in 2006. So surely some novice engineer designed this one .
Would you care to elaborate? I don't see anything gross in here. Maybe I'm not concentrating on the right part of the circuit...
Of course I wouldn't extend this to a large mixer.
The TRS connectors on Mackie mixers (and Behringer, etc.) do not have an insulated sleeve contact so the audio ground is connected to the front panel / housing at many points. Additionally, the electrical integrity of the housing is increased by using bolts that are typically made of brass that can be electrically connected to the audio ground on a PCB. That is why it is quite difficult to distinguish between audio ground and chassis 0V reference, and this design cannot be used as a school example of how best to perform ground wiring.
Is it?.... And then they changed it to isolating the chassis from 0V and using the chassis for phantom return. The VLZ3 and presumably VLZ4 do in fact isolate the chassis from 0V and so your statement is simply false...
You're right, but can you tell me what is audio 0V reference for a connected compressor to an insert point? Does he "see" the difference between mixer chassis reference and audio 0V? That's why I said "That's why it's quite difficult to distinguish between audio ground and chassis 0V reference, and this design cannot be used as a school example of how best to perform ground wiring."..The sleeves are NOT connected to 0V and there's a very prominent comment about GROUND "SWEET SPOT" where all the grounds are connected together...
Myself and Atomic use the MeanWell supplies, they are very well made.So again, the details are in the implementation. Don't roll your own. Use some MeanWell modules with CMs and input filters. It can be done. Whoever did that supply just whiffed. It happens. One data point is not conclusive.
No. The only remotely possible soluttion would be using two IRM-01 24V in series, for a max current of 42mA. If you add an LED that draws 10mA, you still have enough for 3 P48 mics.Do you know of any MeanWell module suitable for a couple of mic channels (ie very light load)?
Maybe. For a "very light load" you are going to run into a problem because you have to load an SMPS enough to stop it from modulating the output. I think I've already posted my Rules for SMPS in Audio about 50 times here but look at #2. So just about the smallest you'll find is something like APC-16-350 which I have used before and works very well. But it puts out 350mA which is enough for about 30+ phantom supplies. If you only have say 2 or 3, that means you have to basically burn 100mA just to keep the output from modulating. You could just slap a resistor across the output but 48V * 0.1A = 4.8W which means you probably need one of those aluminum cased resistors which, altogether, starts to make for a pretty chunky and clumsy solution. So it's not really right but it could be made to work if this is just for fun or a bench sort of project. The smaller ones like IRM-01 24V that Abbey mentioned might work but I have found that the output voltage of the smaller DC/DC converters can droop a bit under load.Do you know of any MeanWell module suitable for a couple of mic channels (ie very light load)?
In any case, you need additional filters, usually LC in addition to the capacitor at the output (see datasheet for value).Hi!
Meanwell 15w 48v dc output, 200mv P-P ripple at full load. max current 313ma. I suppose it needs some output filtering,
All smps need a minimum load to operate within specs, typically 20% of nominal load; that would be about 60mA. Since it largely exceeds the needs of most P48 mics, you'll gave to dissipate that in a power resistor (at least 3W). Now, the datasheet indicates no minimum current, so maybe they have improved the design as to lower the limit and dissipate it internally.or i can use it as is for just one preamp?.
Underload modulation doesn't stop it from working at all (not to be confused with "hiccup mode" which is when the output is switched off / on very slowly to handle an overload or too much capacitance which would stop it from working). I'm sure this SMPS works just fine with a 10mA load. But the noise floor will have a low frequency whistle (like 2kHz or so) from the output being modulated. That's a problem for audio but for just about anything else it is not a problem at all.Now, the datasheet indicates no minimum current, so maybe they have improved the design as to lower the limit and dissipate it internally.
Some experimentation is needed.