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-   -   The SLB (Smooth Like Butter) Active Rect/CRC/Cap Mx Class A Power Supply GB (https://www.diyaudio.com/forums/group-buys/336479-slb-smooth-butter-active-rect-crc-cap-mx-class-power-supply-gb.html)

s610adam 4th May 2019 01:14 PM

Hello - if it's not too late I'd like to add 4 boards to the list


Thanks!
Adam

xrk971 4th May 2019 02:38 PM

Not too late at all.

Quote:

baswamin - 2 boards - Paid
meanie - 2 boards - Paid
jwjarch - 2 boards - Paid
gary s - 2 boards - Paid
nautibuoy - 2 boards - Paid
antoniopf1972 - 2 boards - Paid
ravid - 2 boards - Paid, Simple PSU Paid, ship at same time
Gricko - 2 boards - Paid
poseidonsvoice - 2 boards - Paid
Bkdog - 2 boards - Paid
Jazzfan - 4 boards - invoice sent
van of monks - 2 boards - need PayPal address
Wtl - 4 boards - invoice sent
cerole - 2 boards - Paid
s610adam - 4 boards - need PayPal address

yoaudio 4th May 2019 02:42 PM

Quote:

Originally Posted by xrk971 (https://www.diyaudio.com/forums/group-buys/336479-slb-smooth-butter-active-rect-crc-cap-mx-class-power-supply-gb-post5780370.html#post5780370)
GB status update:


Please let me know if I made a mistake with this list.


yoaudio - 2 boards - Paid

Pbergstrom 4th May 2019 04:27 PM

I'd like 2 boards as well.

ferret 4th May 2019 07:38 PM

SLB board
 
Hi XRK,

Put me down for two please. Also, is it possible to add on 2 of the LT4320IN8#PBF, as I can only seem to find the SMD one here?

Many thanks, Kevin

Roundtoit 4th May 2019 09:36 PM

Wondering about verification build mentioned in post #62. I'd like to see pics if you have had time to build it. I would also like to know the dimensions of the build and where the heat will be. Low profile would be nice.

xrk971 4th May 2019 09:54 PM

SLB Verification Build Testing
 
6 Attachment(s)
I built up the verification build PCB and managed to do some testing today using a pair of big 100w 8ohm resistors (8 ohms single and 16 ohms in series). The trafo was an Antek AN 3232 (300VA 32v) and first thing I noticed is that the active rectifier MOSFETs are barely warm (40C) under 4.3A load and not even noticeable at 2.15A load. So the LT4320 and the selected MOSFETs are working out very well. It is so refreshing not to have heat or huge heatsinks for the rectifier of a big Class A PSU.

Under 4.3A load and 35V out with a 3.5V dropout, I measure about 7mVpp ripple. Under 2.15A load and 37V out, I measure under 1mV ripple - it is hard to see because the radiated noise pickup in the lab with the PSU turned of is about 4 to 5mVpp.

Here is the setup:
https://www.diyaudio.com/forums/atta...1&d=1557006846

Here is a closeup of the verification build:
https://www.diyaudio.com/forums/atta...0&d=1557006846

Here is the O-scope shot of the noise pickup in the lab with PSU turned off:
https://www.diyaudio.com/forums/atta...2&d=1557006846

For 2.15A load using a 16ohm resistor, here is the ripple upstream of the cap Mx at the output of the CRC we get about 287mVpp for 37v at the load:
https://www.diyaudio.com/forums/atta...3&d=1557006846

Here is the output of the SLB at the load resistor or downstream of the cap Mx, we barely get any visible ripple - probably under 1mV. Compare this to 287mVpp from just the CRC. Typical 25w Class A amp CRC's are using maybe 33,000mF and about 0.11R so probably half this for circa 120mV to 140mVpp ripple. With the SLB in place, there should be absolute silence in the black background - no more 60Hz hum:
https://www.diyaudio.com/forums/atta...4&d=1557006846

For the 4.3A load case, the temperature of the 0.1R KOA BPR resistors was measured to be about 73C. I was able to touch it for a few seconds but without applying heavy squeeze pressure. It's not a burn hazard as you can easily retract your fingers in time. At the typical 2.15A to 2.5A load that folks will be using this as a PSU for a Pass 25w Class A amp, the temp is much lower and it should not be a problem at all:
https://www.diyaudio.com/forums/atta...5&d=1557006846

The SLB is now verified to work, but I did notice that the current 200ohm pot does not give much of an adjustment range. So I will work with Hugh and Jhofland on that - probably a few minor changes to some resistors should do the trick. For the production unit, I have asked Jfoland to add more output spade terminals so that one SLB can power a stereo amp and also have returns for the speakers. Having a built in GLB with an NTC and 22nF cap on board is nice to reduce the amount of ancilliary stuff that needs to be done.

xrk971 4th May 2019 10:03 PM

1 Attachment(s)
Quote:

I would also like to know the dimensions of the build and where the heat will be.

The heat is confined to the pass transistor mounted on the convenient AMP connector with flying leads. You can mount it anywhere convenient, like the chassis floor or the main side heatsink. On the board itself, the KOA resistors can get to 73C if you are runninng a huge load like 4.3A. But for 1.25A or 2.5A loads, it's not even an issue.

Size of the final board is a bit larger to accommodate more spade terminals on the output. Here is the outline and parts. It is 150mm x 100mm in size. Height will be the height of the 15,000uF caps (about 42mm to 45mm tall).

https://www.diyaudio.com/forums/atta...1&d=1557007684

xrk971 4th May 2019 10:20 PM

GB Status Update:
Quote:

baswamin - 2 boards - Paid
meanie - 2 boards - Paid
jwjarch - 2 boards - Paid
gary s - 2 boards - Paid
nautibuoy - 2 boards - Paid
antoniopf1972 - 2 boards - Paid
ravid - 2 boards - Paid, Simple PSU Paid, ship at same time
Gricko - 2 boards - Paid
poseidonsvoice - 2 boards - Paid
Bkdog - 2 boards - Paid
Jazzfan - 4 boards - invoice sent
yoaudio - 2 boards - Paid
van of monks - 2 boards - need PayPal address
Wtl - 4 boards - invoice sent
cerole - 2 boards - Paid
s610adam - 4 boards - need PayPal address
pbergstrom - 2 boards - need PayPal address
ferret - 2 boards - need PayPal address
Sorry, I don't really have spares of the LT4320 to include in the order. They are available on Mouser here:
LT4320IN8#PBF Analog Devices | Mouser

antoniopf1972 5th May 2019 12:06 AM

Very good work. It looks all very neat and beautiful. And it also works as expected. Congratulations. I already have to try to see how it goes. I have all the components ordered in Mouser. And I have two symmetrical 30v transformers in alternating. I hope not of too much tension at the exit, once rectified


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