Why a linear power supply?

[Superdad]

Hahahaha! Sounds like better engineering and parts spec in Hovland than Krell... Who would have thunk it.

 

Yeah, no kidding. You would not believe just how much we spent on parts for our gear. The RADIA had $1,900 in parts and 25 hours of labor (plus custom chassis supplier headaches) in our West L.A. offices. Wholesale to distributors was $5,250. Just one factor in what became a broken business model. But the stuff sounds great and will still challenge all comers…

 

BTW, we used the Dennis Morecroft designed, BHC/Aerovox slit-foil electrolytics (10,000uF/63V) in all our gear.

 

 

P.S. Please excuse my hairy foot.

[RichB]

Oh gosh, that's not it at all Jakov. We want this supply to be as flexible as possible so it can be used with a wide range of gear (or at least with gear only needing a positive DC voltage since we are not doing a bipolar, +/- supply). This is a supply that will sound great with CAPS, small DACs, hard drives/SSDs, headphone amps, etc.

 

Also, for some 5V DAC users, I'd like to find a source for something like this cable:

[ATTACH=CONFIG]10590[/ATTACH]

It passes through the data yet interrupts the computer's 5V to feed from cable "T"ed into it. Does anyone know where to get these cheaply?

.

 

Jeez a inexpensive (external USB power) adapter like that would be brilliant! I did some searching and I don't think anyone makes anything like it.

 

Have read through this whole thread and it has been a great combination of refresher course taking me back to my undergrad EE classes and expanding on all the stuff I learned back then and learning some new things too. My thanks to the contributors.

 

I am wondering what benefits or not there are when it comes to things like high speed recovery diodes in the rectification circuit and what folks like JJJ and John think about that.

 

Alex - when you start making the power supplies - do drop me a line. I'd love to get one to use to power my 2009 mini and external FW drive.

[JJJ]

Yikes - let me first state that I am a newbie to this stuff. I've just been learning as I go along. So re rectification diodes I understand that one desires something that switches fast or ultrafast but, importantly, which has soft recovery to minimise transformer ringing. So you get people seeking the benefits of HEXFRED and other diodes. I had asked a very knowledgeable guy on DIYAudio what he thought of CREE C3D08060A silicon carbide Schottky diodes which Alex here and recommended. He responded in a sensible manner:

 

"I myself certainly would not select or pay for Cree's Silicon Carbide diodes; instead I'd probably choose something like the Fairchild FFPF30UP20S. It's rated for 30 amps, 200 volts, and most importantly, it's an honest to goodness soft recovery diode with the softness parameters (ta, tb) measured and specified on the datasheet. Non repetitive peak surge current is 300 amps. It's way cheaper than the Cree diode too."

 

So I think this is an area where different people have different opinions. Also, I've come to the conclusion that a CRC snubber across the transformer secondaries is also very important.

 

John Swenson expressed views on rectifier diodes in this other thread (posts 302 and 304)

 

http://www.computeraudiophile.com/f10-music-servers/good-linear-power-supply-unit-s-computer-audiophile-pocket-server-music-player-wont-break-bank-17336/index13.html#post280723

[sandyk]

Steve

The Cree diodes were a little too expensive for me. I was only passing on a report from a member of another forum who had tried them in the PSUs of a Class A power amp project that I had posted.

 

Regards

Alex

[JJJ]

Yes, sorry - indeed you were passing on the suggestion of another. But I think the point is still correct, one will likely get different opinions re diodes depending on who is asked.

[jtwrace]

So is there any update on the power supply? When will it be complete and ready for purchase? Kit?

 

Voltages and current ratings?

[Superdad]

So is there any update on the power supply? When will it be complete and ready for purchase? Kit?

 

Voltages and current ratings?

 

Hi Jason: I assume you are asking me with regards to the forthcoming UpTone Audio/Swenson JS-2, 2-rail adjustable PS.

 

Everything is coming together well, thanks. I'd like to begin shipping first units in May. Lead time for chassis customization will be the determining factor. I should know that in a week or two. PCBs layout and test is all done--fabrication of those is just a couple week turnaround.

 

It won't be a kit. Classy finished product in a box. 5 amps per output depending upon user-set output voltage. Each output can be independently set to 5,7,9, or 12VDC; One of the outputs (the one with the option to switch on the remote voltage-set/sense line) can be for any voltage from 1.25V up to about 14V, based on resistors set at the end of the sense line.

 

I'll post pictures of the preproduction unit as soon as I have the chassis back.

Thanks for everyone's patience. I already have a nice list of interested parties, so the first run (25-50 units) should go pretty well this summer. We designed them for easy assembly (and are using a board stuffing house), so once all the parts are here I should be able to fill orders quickly.

I won't announce the price until I have the chassis punching/tapping/printing from Japan.

 

Regards,

 

--Alex C.

[jtwrace]

Thanks. Keep me/us posted!

[Paul R]

Great news - but UpTone Audio/Swenson JS-2, 2-rail adjustable PS? Yikes...

 

how about UTA JS2?

 

Hi Jason: I assume you are asking me with regards to the forthcoming UpTone Audio/Swenson JS-2, 2-rail adjustable PS.

 

Everything is coming together well, thanks. I'd like to begin shipping first units in May. Lead time for chassis customization will be the determining factor. I should know that in a week or two. PCBs layout and test is all done--fabrication of those is just a couple week turnaround.

 

It won't be a kit. Classy finished product in a box. 5 amps per output depending upon user-set output voltage. Each output can be independently set to 5,7,9, or 12VDC; One of the outputs (the one with the option to switch on the remote voltage-set/sense line) can be for any voltage from 1.25V up to about 14V, based on resistors set at the end of the sense line.

 

I'll post pictures of the preproduction unit as soon as I have the chassis back.

Thanks for everyone's patience. I already have a nice list of interested parties, so the first run (25-50 units) should go pretty well this summer. We designed them for easy assembly (and are using a board stuffing house), so once all the parts are here I should be able to fill orders quickly.

I won't announce the price until I have the chassis punching/tapping/printing from Japan.

 

Regards,

 

--Alex C.

[Superdad]

Great news - but UpTone Audio/Swenson JS-2, 2-rail adjustable PS? Yikes...

 

how about UTA JS2?

 

Thanks Paul. Yeah, it is just the "JS-2"--from UpTone Audio.

[tranz]

Thanks Paul. Yeah, it is just the "JS-2"--from UpTone Audio.

 

Hi Alex,

Do you have ripple measurements for both rails in use of the new baby? Will both rails be completely isolated?

Cheers

[jtwrace]

Hi Alex,

Do you have ripple measurements for both rails in use of the new baby? Will both rails be completely isolated?

Cheers

I was going to wait (for once) until it was officially released. Thanks for asking though! :-)

[Superdad]

Hi Alex,

Do you have ripple measurements for both rails in use of the new baby? Will both rails be completely isolated?

Cheers

 

Not yet. Ripple will be suitably low, but the key thing is that it will be a very quiet supply with none of the high megahertz noise that other supplies (standard cap/regulator style) let through. The inductor and John's careful choice of pre and post-choke caps are the key to making this an exceptional unit. Specs will be published I promise.

 

As to the rail isolation: There are two LDO regulators, but behind them there is only one set of everything (caps, inductor, transformer). To do a true, fully isolated 2-rail supply would require a second big inductor, a second set of caps and resistors, and a custom, muti-secondary power transformer. That's not going to happen in my little 9" x 9" x 3" case. But I will ask John to do some measurements regarding rail isolation.

 

I've simultaneously powered both a computer (my Mac mini) and a DAC at the same time and it sounded great. Mostly I am using the second rail for an external hard drive.

 

Here is a sketch of the back panel (this is NOT the final artwork, just what I gave to my architect friend doing the CAD work for the case and printing files). Gives you a sense of it though:

[AlainGr]

Hi Alex,

 

I am also eager to give my order

 

Regards,

[Superdad]

Hi Alex,

 

I am also eager to give my order

 

Regards,

 

Thanks Alain, I've now added you to the list. I'll send out info via PM to everyone as I have it. While I am allowed to answer direct questions and share some information here on the forum, I am also trying to be careful not to appear to be using it for commercial promotion. That would not be cool.

I need to get my web site up soon.

 

Best,

AJC

[AlainGr]

Thanks Alex It is funny... Recently I changed my external SSD and suddenly the iFi iUSB that I used to power that drive can't start the one I put in. It is quite probable that the power required for that SSD is too much for the iFi, but all seems to fall in place now

[Paul R]

Thanks Alain, I've now added you to the list. I'll send out info via PM to everyone as I have it. While I am allowed to answer direct questions and share some information here on the forum, I am also trying to be careful not to appear to be using it for commercial promotion. That would not be cool.

I need to get my web site up soon.

 

Best,

AJC

 

Can it be used to power one of the new Minis, the ones withou the power brick?

[Superdad]

Can it be used to power one of the new Minis, the ones withou the power brick?

 

Hi Paul: I guess this thread has gotten pretty long. So long that I have to paste a link back to a post with pics on the first page to show you the YES answer. http://www.computeraudiophile.com/f10-music-servers/why-linear-power-supply-18929/#post288005

 

The production mini-PCB for the Mac mini will a custom cut affair with the jacks on it. The pic you see is just me cabling in the proto board. The adapter board for the Mac mini will in fact be the first shipping pseudo-Kelvin-sense remote module for the JS-2. After it and the first PSUs go out the door we will start on the "Sense-cubes" as I describe them up-thread.

 

Ciao,

ALEX

[Kuro]

I just found this thread and what is so interesting is that I've already got the PCB made and the circuit is an improved version of John's power supply. It has two independent 5v outputs, each powered by an ultra low noise super regulator (4uV RMS). I have another version that is using a R-core transformer, and it does sound significantly better than the Triad transformer John has specified (much richer and deeper low bass). Here are some pics of my supply:

 

[Michele Mirenda]

Interesting project, regulators seem belleson, you may post the wiring diagram and possibly the design of the printed?

Thank you.

[Kuro]

It is the same circuit as the John Swenson LPS. Regulator is the Belleson SPJ (new generation with lower noise output and san SMD ceramic caps - i.e.: no microphonic effects).

[jmm007]

Hi

I am new to the list and have read all the above posts in this tread. I want to do a mac mini LPS upgrade and most of the LPS units I have seen on the web I have not been impressed with. Are there any updates or photos on the LPS (I think it was SuperDad) unit previous described here?

Thanks

Joe

[Superdad]

Hi

I am new to the list and have read all the above posts in this tread. I want to do a mac mini LPS upgrade and most of the LPS units I have seen on the web I have not been impressed with. Are there any updates or photos on the LPS (I think it was SuperDad) unit previous described here?

Thanks

Joe

 

Hi Joe:

Thanks for your interest. I now have a good size list of people awaiting the production of the supply. Everything is on track and, barring supply delays, first units should ship at the end of May. Here are a couple of renderings. I'll have actual photos of the pre-production/fit-check unit in about three weeks.

Best,

Alex C.

 

[jtwrace]

Is there pricing and info in one spot so I don't have to go back through this thread. I thought interested people were getting a PM or email.

[Superdad]

Is there pricing and info in one spot so I don't have to go back through this thread. I thought interested people were getting a PM or email.

 

Hi Jason: I am really sorry, but:

a) I have not yet announced the price (just waiting for printing/machining quote from my Japanese chassis supplier);

 

b) Other than you see from the back panel (2 independent, voltage selectable rails, one with option for remote voltage-sense feedback), and that each rail will be good for 5 amps, I do not yet have measurements to publish. That will happen when I get the pre-production unit back to John Swenson for torture and measurement. That will be the first unit with the regulators and diodes bolted to the real heat-sinks with everything in the actual box, so we can quote true noise and ripple and load specs.;

 

c) I need to get a basic web site up as I am already treading on thin ice by discussing a product here in the forum. So I just answer direct questions. Since CA members are my prime market, I look forward to supporting the site further by advertising here. But that's useless until I have a web site up.

 

d) You have been on the list since early on, I just have not sent any e-mails to the "listers" as I am waiting to do so with a price and more accurate dates.

 

So hang in there everyone. I promise it will be worth the wait (the chassis is lovely and I am deciding on some subtle front-panel graphics today).