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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)

evanc 7th October 2019 11:58 AM

Option 2 for 115 volt mains.

Dadbeh 7th October 2019 12:03 PM

Quote:

Originally Posted by evanc (https://www.diyaudio.com/forums/group-buys/336479-slb-smooth-butter-active-rect-crc-cap-mx-class-power-supply-gb-post5936794.html#post5936794)
Option 2 for 115 volt mains.

thank you.
Quote:

Originally Posted by Vunce (https://www.diyaudio.com/forums/group-buys/336479-slb-smooth-butter-active-rect-crc-cap-mx-class-power-supply-gb-post5929761.html#post5929761)
Hmm....
Something doesn’t sound right, if hooked up correctly I don’t think you should see any smoke with a 36vac trafo and 50vdc capacitors. Could there be a short somewhere?

i havent been able to find any other mistakes. but i intend to double and then triple check everything before firing it up again.

meanie 11th October 2019 12:37 PM

Having built up 2 sets of SLB and had bench tested it at 3A resistor dummy load, it performed so well on the oscilloscope with very little ripples.

However, when I hook the amp up with the SLB, I got slight hums and noise on my F6 and USSA5, on M2X its worst. Having reached my wit's end, I seek help from Xrk. He shares with me this diagram of his wiring setup.

I followed his method and Voila!
All 3 amps are very quiet, M2X surprises me the most, it used to be the worst hum among all and now so quiet.

SLB is awesome for ClassA applications. Thanks, X!

https://i.ibb.co/BLvPFhf/Amp-Wiring-Setup.jpg

xrk971 11th October 2019 01:15 PM

Great to hear the good news, Meanie!
Nice debugging!
:cheers:

Vunce 11th October 2019 01:27 PM

Fantastic Meanie!!
Now enjoy the music :D

:cheers:

aljordan 17th October 2019 06:29 PM

Hi,

Is the BOM project labeled "Smooth_Like_Butter_BOM_V1.2" the correct BOM for the dual rail SLB boards on Etsy? There are two choices for dual rail boards on Etsy, one labeled V1 and one with no version label. I ordered the boards that did not have a V1 label, and want to make sure this is the correct BOM for the board I ordered.

Thanks

xrk971 17th October 2019 06:47 PM

V2 is just the production board with more Faston connectors for star ground. Other components are the same. V1 are the verification build boards 1.6mm thick, 1oz copper, no ENIG. They work well though.

baswamin 18th October 2019 06:53 AM

Hello Meanie,


Can you post the wiring diagram for benefit of other folks?



Thanks
Balaji



Quote:

Originally Posted by meanie (https://www.diyaudio.com/forums/group-buys/336479-slb-smooth-butter-active-rect-crc-cap-mx-class-power-supply-gb-post5941020.html#post5941020)
Having built up 2 sets of SLB and had bench tested it at 3A resistor dummy load, it performed so well on the oscilloscope with very little ripples.

However, when I hook the amp up with the SLB, I got slight hums and noise on my F6 and USSA5, on M2X its worst. Having reached my wit's end, I seek help from Xrk. He shares with me this diagram of his wiring setup.

I followed his method and Voila!
All 3 amps are very quiet, M2X surprises me the most, it used to be the worst hum among all and now so quiet.

SLB is awesome for ClassA applications. Thanks, X!

https://i.ibb.co/BLvPFhf/Amp-Wiring-Setup.jpg


TungstenAudio 27th October 2019 08:21 PM

Fun with the SLB
 
Since I've already found the LT4320-based rectifier to be worthwhile, and have been contemplating CFP style capacitance multipliers in my power supplies for some time, it seemed natural to try the SLB power supply for an F6 clone build that is currently in progress. I was fortunate to get in at just the right time, and shipping was very prompt.
This is not my first rodeo with CFP-based capacitance multipliers. I have designed them into professional medical imaging (Ultrasound) equipment, as well as used a variation in two of my old Class A/B favorites, the Hafler DH-200 and DH-220. So if it looks like I'm taking a couple small liberties with the design, yes I am, but informed by previous experience.
I purchased two of the SLB boards to be used in a dual-mono F6. I have built one so far, to check out the design with my tweaks applied. Here is a list of the changes that were made, referenced to the SLB-APRIL-11-2019 schematic:
R1, R2: 18 Ohm
Q1 – Q8: IPP029N06N
C7, C8, C13, C14: SLPX183M050H9P3 (18,000 uF, 50V)
Q9, Q11: KSC2690AYSTU, KSA1220AYS
Q10, Q12: MJW1302AG, MJW3281A
R17, R18: 1.8 Ohm

I've been using the IPP029N06N Mosfets for my other ideal rectifier builds and they seem to work well. The FOM values look good on paper, and the devices worked favorably in my M2x. I haven't tried other parts yet, and the specified STP110N8F6 should be very comparable. I prefer to provide adequate supply filtration prior to a capacitance multiplier. Though the pass transistor(s) appear to multiply the capacitance at their base, it works better if they have some real capacitance to back them up. Hence the substitution of 18 mF caps for the 15 mF caps.
Besides having high gain, the pass devices need to have low Vce Saturation performance. This helps to maintain gain at the low voltage dropout which we prefer to use for this implementation of the CFP. The KSC2660 and KSA1220 are superior in this respect to the BD139 and BD140. Likewise the MJW1302 and MJW3281 are higher performance in this area. It may also be worthwhile trying the newer Toshiba replacements, TTA1943 and TTC5200. Finally, I prefer to keep emitter degeneration of the controlling transistors (Q9, Q11) to a minimum, thus reducing the 10Ω values to 1.8Ω. There are other means of controlling oscillation or other instability in the CFP, but they don't seem to be necessary here.

On my test bench, I hooked up the SLP to an Antek AS-3222 and used it to drive a 15 Ohm load on each of the outputs (PVout & NVout). The transformer performed as specified driving the inputs of the ideal rectifier with a solid 22.2 Vac. Given the 1.7 Amp load, the CFP section exhibited a dropout of 2.1 Volts for a final Vout of 26 Volts with 2 mV ripple indicated on my DMM. A scope with AC coupling on Vout showed nothing remarkable, and supported the 2 mV ripple reading.

If there is any surprise here, it was that the rectifier + filter section only managed to produce about 28 Volts at the input of the CFP. I might have expected higher, but am still somewhat new to the LT4320-based rectifiers. Overall, I am pleased with the performance of the SLB, and plan to build the second board the same way as the first. What remains to be determined is whether additional bulk capacitance on the outputs of the SLB is beneficial or not. This needs to be tested by ear.

xrk971 27th October 2019 08:49 PM

Hi Tungsten,

Thanks for the detailed account of your build. Sounds fun indeed. R17 and R18 sometimes depends on the amp you are driving. I have heard a screeching sound on certain Pass Class A amps with the SLB when the degeneration is too low. But sounds like you tried it on an M2? Anyhow, 1.7A AF 26v and 2mV ripple is super performance. Nice!

I was able to get 1mV ripple at 37v and 4A. So it may actually work better at higher currents? Although I was running a 3v drop across the pass transistor.

Cheers,
X


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