SMPS for diy audio amps and multi-channel diy amps (and their power supplies)

[tlparker]

So I've decided to check out some of these audio amps. I'm going to try Peter Daniels design/kit, and probably Brian's gainclone design/kit. Then, since there's such a lack of published technical audio data on most of these kits (THD, S/N ratio, etc), do some subjective (*blech*) A/B testing.

What I'm a little freaked about is the power supply. These huge coils just bother me for some reason (I'm used to PC electronics at best). One of the big reasons is that my eventual goal is to create a multi-channel (around 12-maybe 20 channels!) amp. The weight of the coil-based power supply(ies) would be enormous (I'm hoping for at least 100W per channel). Just as an FYI, this is all eventually heading towards an active crossover system I can use with multiple speaker builds to test/try as I build them (using something like the Behringer 2496 as the very flexible external xover). I'm even hoping to add capabilites like those provided by let's say the Speakercraft 1265 (12 channels by 65W each, whcih I use for external zones outside my main listening area) like channel bridging, allowing up to 3-4 "virtual channels" via switching individual channels to a particular "mega channel".

Now, I've read a lot of stuff about linear power supplies providing significantly better sound quality and even to the point that SMPS would create such junk sound output that they aren't even considered in the "audiophile" world (which I'm always suspect of).

So now I start seeing (here and/or elsewhere) talk about using SMPS for audio amps. Anyone done any A/B testing on whether or not they affect the typical sound parameters like THD, S/N ratio, etc? I know this type of information is very hard to come by in the (particular amp) diy world, but I have hope.

Or, do I need to just do it all on my own and do some subjective listening with my personal "reference" stuff (7.1 setup using Paradigm 100's for front/center/right and Polk di/bipoles for sides and rears, oh and a decent 300W subwoofer)?

If this is the case (in lieu of "published specs" based on a given smps power supply and using it with various diy amps), can somebody recommend smps kit(s) that I might look at (I'm not comfortable building any of this stuff from scratch) to consider using and if any of them may or may not be better suited for use as audio power supplies?

Or am I just nuts and I won't be saving anything (weight, space) by using the big ol' coils?

Thanks,

terry parker
terryparker@myself.com

[janneman]

Hi terry,

I have had good experiences with Vicor smps modules ( www.vicr.com ). Interesting note: the founder of Vicor had the same concerns as you and started to develop modules for his private audio projects. Now his company is one of the largests in the world in smps business...

Just for kicks, I built an LM3886 gain clone with a pair of 150W Vicor modules that sounds great, but is really over the top. Those two modules could easily power a couple or more of those amps.

Jan Didden

[traw]

i've used one off ebay, several of them actually... done several experiments using the sellers recommended mods. on unit i used, voltage rails higher, but works excellent. had sold off experiments to friends and they all commented about the quickness and cleanness out the sound. another liked the toroid implementation i'd made him more - but it was also a bridge config rather than single chip implementation (gainclones) that suits his speakers differently.

from diy building side... i liked the ease of grounding, no touchy 60hz hum to battle with.

i personally like them for given applications. have only tried with clones so far, but may try some to drive some greg ball ska amp boards.

i'd like to learn more about actually building them and stronger, more current, smps modules.

[tlparker]

Funny you should mention that, it wasn't on my previous list, but I think it's a contender for my project as well. Currently, because of the lack of published specs on diy amps, it looks like going to have to build a few, then try them out with difference power supplies, find the best combination, then start the Motherload Project (multi-channel diy amp).

Anyone happen to know of any existing multi-channel (5 or more) diy amp projects / kits?

[tlparker]

I went to their site and it is impressive and certainly daunting. Can you recommend particular models "blocks" as they call them, that work well with a particular diy amp? Problem is, I'm having some trouble converting the diy-amp project/kits requirements defined by toroidal transformers vs. the specs used to described smp's. Usually seems like apples and oranges when comparing values, so makes it hard to pick smps to substitute for a coil transformer main/secondary specs. Any help?

Originally posted by janneman
Hi terry,

I have had good experiences with Vicor smps modules ( www.vicr.com ). Interesting note: the founder of Vicor had the same concerns as you and started to develop modules for his private audio projects. Now his company is one of the largests in the world in smps business...

Just for kicks, I built an LM3886 gain clone with a pair of 150W Vicor modules that sounds great, but is really over the top. Those two modules could easily power a couple or more of those amps.

Jan Didden

[thomaseliot]

Originally posted by janneman
Hi terry,

I have had good experiences with Vicor smps modules ( www.vicr.com ).
Jan Didden

I just made a 300W configuration in Vicor's site. It costs 800$. Possible?

Ciao

Giovanni

[tlparker]

Yeah, I've been over at their site a lot trying to figure out a way to make it work. They have a lot of very neat stuff. Very small configurations with low heat dissipation and emi filtering modules. The problem is, as you've just indicated, they aren't cheap at all, from what I can see.

My "ballpark" number for quality amperage wattage is $1 per watt (cheap) to $1.5 per watt (good average). That's for used quality or diy quality. New, you can double those figures. But $800 for 300W of diy is way out of what I would consider acceptable. Dangit, 'cause I do like their stuff, it'd be perfect for a multi-channel amp config. (I do this same kind of thing with RAM and hard drive storage, almost treat it like a commodity -- see where the $ per MB is and use that as a barometer for "deals").

Don't know if a group buy would lower costs or if anyone else is interested. I'm surprised nobody is looking at taking something like Peter Daniel's stuff and making a multi-channel amp out of it (like a speakercraft, allowing you to bridge to different output sets, etc.). I wish I had the electronics background to bring it all together, but I'm working on it.

[nikwal]

I also used vicor modules in my amp.. the only thing was that i had to screen the modules with a metal sheet because the amplifier circuitboard was too close.. (the amp is really small)
But i think they're really really good.. i have four 100watt 28volt modules, that works pretty well for me..

[janneman]

Originally posted by thomaseliot


I just made a 300W configuration in Vicor's site. It costs 800$. Possible?

Ciao

Giovanni

That's too much! A pair of 150W 2nd generation DC-DC converters run just above 100$ each (I think in Europe they are 112$ for 1-24 pieces). That means you add a rectifier bridge directly off the mains and a hold-up capacitor (a few 100uF at the rectified line voltage, 450V in Europe) and a few 1000uF at the output and you're done.

Jan Didden

[tlparker]

Like I said, sure seemed expensive. Though, I was looking for "end to end" or "turnkey" vicor solution (AC to DC-DC), which they can provide/configure. Perhaps that's where his added cost was coming from.