Those are rated 15VA, it’s been years since I was into this stuff but please correct me if wrong; that means 2A for the 7,5V trans and a little more than 1A for the 12V one, right?
Yes, 2A for 7,5V but just 0,625A for the 12V rails. The same transformer is used for both + and - 12V.
I will provide some pictures. THe base board is not fitted in the box. The synth is in a P-10 enclosure. The 1U box contains PSU and expansion stuff. It is very crowded…
I have been thinking about a switcher as well, but am hestitant because I also want to use AOUT and SSM boards. Toroid trafo’s still are the way to go in audioland AFAIK…
I doubt this tired old debate of “to switchmode or not to switchmode” will ever cease, but every-time it comes up, I learn something.
I will say I am running a switching DC power supply on my sammichSID at the moment since I just haven’t run into an extra AC power brick nor have I gone out and grabbed one up from Goodwill. It sounds great - I’ve even used it for recording, though that was because I forgot I was using a switching supply. If I had remembered, I would have swapped it out before that.
I would imagine that using certain filtering caps can mitigate the noise, if not totally eliminate it. Maybe this is a place where tantalum (another fun debate) might be useful since I recall it handles HF noise fairly well. I wonder if the HF noise from these guys can be picked up on an oscope?
I myself prefer a linear supply because they are fun to build; but I’ll admit, having something that is “good enough” if not perfect would be good initially, particularly if it has some of the built in protection we have been discussing here. That way I can go about working on the other parts of my synthesizer.
But back to the world of linear, I just found this from Allied Electronics in my inbox. First e-mail from them that might actually prove to be useful:
I haven’t looked at the spec sheet yet but perhaps this might be something to look at.
The Meanwell SMPS are very popular for powering DIY audio amplifiers.
Modern SM power supplies also have a much higher switching frequency than in the past.. waaaay above the audio spectrum.. Plenty of people are using em for racking up vintage channel strips from old consoles etc, including some serious racking specialists that I know. I figured, that if it’s it good enough for them, it’ll be good enough for a noisy as F@#k SID synth.
Something definitely worth looking into. I’d save some space for my MB-SID rack. That said, I still like linear supplies just 'cause I guess. As far as SIDs being noisy, that’s sort of true (they aren’t THAT noisy). I find that any noise you do get from the SID is part of the character of it. I don’t want to introduce noise that isn’t there for sure.
I’m waiting for the linear PSU peeps to voice their opinion but, yeah, it sounds like a good solution, particularly if it has built-in protection (that’s a biggie because, if not, I can just as easily make a linear PSU).
EDIT: Looks like it has current limiting protection according to the Spec Sheet. This could be a contender!
. As far as SIDs being noisy, that’s sort of true (they aren’t THAT noisy).
Well, they are easily the noisiest bit of kit I own… yep, not offensive.. a nice soothing 8 bit noise, but you sure can hear it when it’s switched on and nothing else is playing.
Also, regarding the price, when I check the mouser link it shows me $62.. not $46, unless you get different price breaks in the US etc.
I find Mouser is rather expensive her in Australia, sure, convenient and a vast catalogue, but expensive.
Yeah it’s definitely $46 here (checked again just to be sure). Usually I use Allied Electronics as they are the next city over and so shipping is (usually) super fast. Didn’t find these PSUs there though, and, speaking of expensive, they tend to be There’s DigiKey as an alternative - perhaps they might have a few.
For cost savings, the only thing I can think of is trying to see if people want to rock a bulk order. I was thinking of offering that for my LED matrix board I’m working on; but I don’t think I’m quite ready to manage one of those things yet Otherwise, the prices on eBay seemed pretty reasonable so that might be an avenue as well?
EDIT: One thing I did notice, though - there’s no 9VDC so that will have to be regulated. I wonder, do the protection features of the PSU make having to make a simple 9VDC power supply (or using the MB6582 mainboard perhaps) negate some of the benefits of the switchmode supply?
Regarding the 9vDC.. yea, I suppose you could use the 12v and regulate it down.. You probably don’t need any other components apart from a regulator.
I had height & room constraints for the inside of my 6582 synth, so the SM PS was a nice tidy solution. It also runs very very cool, which was important, considering the SID’s get warm enough on their own.
If you are using 8580 or 6582A SIDs, you need to supply them with 9V so either have to figure out how to use the regulation found on the MB-6582 or build your own. I haven’t looked at that part of the MB-6582 schematic in a while to know how easy that would be. Wilba made the PSU options fairly configurable though this particular setup is not one of the documented PSU options.
I would like to keep heat away from the MB-6582 baseboard so if I go with this PSU option, I will likely just use a simple circuit off the PSU to supply 9VDC. Since the 12VDC supply is already a stable output, I don’t need to do most of the tricks talked about in this thread (though may want the regulator protection diode. You can check out some of the spec sheets that have been passed around in this thread for what that looks like. If you go this route, you can also look at the spec sheet of the regulator you buy just to match capacitance values and such.
Even when having to regulate 9V on your own, it will still end up being quite a bit less heat than going with a linear option (at least when using one transformer) - plus you get a supply that has a good amount of built in protection. Anyways hope that helps!
I feed 12V DC into my MB6582 where it’s supposed to have 9V AC. The voltage goes through the rectifying bridge (loose some voltage) smoothing caps (no change) and finally through regulator (regulated down to 9V). It works fine and doesn’t seem to generate much neat (actually I think it generates less heat than the standard 9V AC way). One thing I am thinking about though is if the dc cable is more prone to pick up noise than an ac ditto.
I feed 12V dc into my MB6582 where it’s supposed to have 9V dc. The voltage goes through the rectifying bridge (loose some voltage) smoothing caps (no change) and finally through regulator (regulated down to 9V). It works fine and doesn’t seem to generate much neat (actually I think it generates less heat than the standard 9V ac way). One thing I am thinking about though is if the dc cable is more prone to pick up noise than an ac dito.
I was thinking about doing exactly that. Just to clarify: you mean your MB-6582 is set up for the C64 power supply option, and you feed 12VDC into your MB6582 where it’s supposed to get 9VAC, right?
I’ve been thinking about this all morning Are filtering caps and/or inductors not sufficient for filtering out the HF noise from these types of PSUs? Is if the frequency that’s the issue? Because I know ceramics and tantalums are typically good at HF filtering. Curious if just using some of those could help filter out the noise from the DC outputs of switchmode supplies?
I have been talking to someone with experience on using switching PSUs in audio applications. He suggested putting coils in the path for filtering, if the HF noise would be within the audible spectrum. I have no idea if and how that would help, maybe someone who is into this matter could explain further?
That’s what I read as well, though the Wikipedia page on inductors indicates that they can actually bring in noise from other sources as well. I have read that inductors (and capacitors) are suitable for filtering HF noise so I think there is some truth to that. I don’t know much about inductors to really say where to go from here, though I’ve seen inductors in PC PSU (I think anyway) so perhaps the Mean Wells already have them *shrug*
EDIT: Here is a PDF that measures filtering capabilities of tantalums up to 10kHz. The document really talks about it from an audio pipeline perspective it looks like, but there was some pretty decent information on there.
I was thinking about doing exactly that. Just to clarify: you mean your MB-6582 is set up for the C64 power supply option, and you feed 12VDC into your MB6582 where it’s supposed to get 9VAC, right?
I wonder if you could do the same with a C64.
Thats right.
Just like capacitors act like hp-filters when connected in series with something, coils act like lp-filters when connected in series, so it makes sense.
I feed 12V dc into my MB6582 where it’s supposed to have 9V dc. The voltage goes through the rectifying bridge (loose some voltage) smoothing caps (no change) and finally through regulator (regulated down to 9V). It works fine and doesn’t seem to generate much neat (actually I think it generates less heat than the standard 9V ac way).
There’s DigiKey as an alternative - perhaps they might have a few.