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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)

Vunce 5th May 2019 12:28 PM

Fantastic work X, Hugh and jhofland!!
The SLB will be an excellent building block for the ultimate Class A amplifier projects.
The SLB-SR would also be a welcomed addition for my MoFo and other single rail powered projects, Bring It On!!:D

nautibuoy 5th May 2019 12:55 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-post5781230.html#post5781230)
Hi NB,
Sure, we can start thinking about the single rail version of the SLB now that we know the layout is good. Itís basically the top half of the SLB board. We will have to wait for Jhofland to make the layout.

Letís call it the SLB-SR, and simply specify SLB or SLB-SR in the GB list. Pricing will be $17ea for the SLB-SR. Note that cost of boards is mostly based on the single maximum dimension, and not the surface area.


Thanks x. I did thnk about buying a couple more dual rail boards and simply removing the negative half but a single rail board will be a much more elegant solution.


Count me in for two SLB-SR boards and invoice when you're ready to go. Happy to wait for delivery so all four boards ship together - I assume it'll save on shipping costs.

tubesguy 5th May 2019 02:14 PM

Hi x -

The original list appears to be out of date now, but could you count me in?

I've gotten a little confused (probably just my age) but I have both two 200VA 22v transformers and one 300VA 22v transformer, and want to build one of those "typical class A" amps calling for 24v rails in a store 4U Deluxe chassis. Suggestions from the crowd on how to proceed, and therefore how many boards? TIA - Pat

s610adam 5th May 2019 02:20 PM

I was thinking about just using the single rail on the dual board as well, but using just the rectifier portion of the other rail to create a separate positive rail (not using the cap multiplier on that rail.) It would be for the DC filament heater of the preamp tube, which has its own CCS for ripple.

See any issues as to pulling the output off that 2nd rectifier for other uses like this?

Mark Johnson 5th May 2019 02:38 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-post5780993.html#post5780993)
After some discussions we decided to remove the 10R resistor at R17 and R18 to buy back some gain that should squash the ripple even more.

I think you'll have a few Eureka moments if you select the emitter degeneration resistor values in a Complementary Feedback Pair, to be integer multiples of the effective emitter resistance (1/gm).

Step RdegenNPN = (1/gmNPN), (2/gmNPN), (3/gmNPN), ... etc

and also

Step RdegenPNP = (1/gmPNP), (2/gmPNP), (3/gmPNP), ... etc

Since gm is inversely proportional to absolute temperature, you'll want to calculate gm at the forecasted operating temperature.

Plot "gain" (the quantity you wish to "buy back", through changing resistors) versus these integers. Eureka! There exists a wide spectrum of design choices. Many many possibilities besides Max and TooLittle.

xrk971 5th May 2019 03:08 PM

Quote:

Originally Posted by s610adam (https://www.diyaudio.com/forums/group-buys/336479-slb-smooth-butter-active-rect-crc-cap-mx-class-power-supply-gb-post5781350.html#post5781350)
I was thinking about just using the single rail on the dual board as well, but using just the rectifier portion of the other rail to create a separate positive rail (not using the cap multiplier on that rail.) It would be for the DC filament heater of the preamp tube, which has its own CCS for ripple.

See any issues as to pulling the output off that 2nd rectifier for other uses like this?

That would work fine and you could use smaller bulk caps and perhaps a linear regulator like 78xx.

nautibuoy 5th May 2019 03:37 PM

Quote:

Originally Posted by s610adam (https://www.diyaudio.com/forums/group-buys/336479-slb-smooth-butter-active-rect-crc-cap-mx-class-power-supply-gb-post5781350.html#post5781350)
I was thinking about just using the single rail on the dual board as well, but using just the rectifier portion of the other rail to create a separate positive rail (not using the cap multiplier on that rail.) It would be for the DC filament heater of the preamp tube, which has its own CCS for ripple.

See any issues as to pulling the output off that 2nd rectifier for other uses like this?


Yes, I had similar thoughts but the second rail I would need (for a gyrator loaded 4P1L driver stage for my MoFo project) needs to be up towards +200V, however, I'm not sure the active rectifier on the negative section could be used anyway as it I believe the pinout of the mosfets means it isn't as simple as reversing them on the board? My observation is based on the picture of the PCB in the first post which shows the board has a connection between the grounds lines of the two sections.

C37 5th May 2019 04:01 PM

I have often wondered what such psu could bring to class A/B. there are some hints on Eliott projects page but it stays generic. What would you advice if used foi A/B? Is it a waste of resources?

xrk971 5th May 2019 04:12 PM

I have used a cap Mx before on a Class AB, and personally really liked the sound - much deeper blacks in the background. I added a 22,000uF cap array consisting of 22 x 1000uF caps in parallel to give a very low ESR charge reservoir after the cap Mx and that increases the bass authority on very deep excursions. I found no detriment - it made the amp sound much better. I talk about it on the CFH7 thread. The only downside is the circa 3v drop so you need to size your trafo voltage one notch higher.

CFH7 Amp

You can see that cap Mx in the middle
https://www.diyaudio.com/forums/atta...tereo-vert.jpg

xrk971 5th May 2019 04:37 PM

Quote:

Originally Posted by tubesguy (https://www.diyaudio.com/forums/group-buys/336479-slb-smooth-butter-active-rect-crc-cap-mx-class-power-supply-gb-post5781340.html#post5781340)
Hi x -

The original list appears to be out of date now, but could you count me in?

I've gotten a little confused (probably just my age) but I have both two 200VA 22v transformers and one 300VA 22v transformer, and want to build one of those "typical class A" amps calling for 24v rails in a store 4U Deluxe chassis. Suggestions from the crowd on how to proceed, and therefore how many boards? TIA - Pat

You have lots of choices. Two SLBs and two 200VA 22v trafos for dual monoblocks is good. Or one SLB and one 300VA 22v trafo works too. I would do the dual mono lock personally. The stereo separation and imaging is better. Plus the ground loops possibility is reduced. I will add you to list when I get a chance.

Both will get you circa 24v after the SLB.


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