The SLB (Smooth Like Butter) Active Rect/CRC/Cap Mx Class A Power Supply GB

[Mark Johnson]

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?

The Akitika GT102 is a class AB chipamp. It's got a regulated power supply, which is equivalent to the highest possible performance capacitance multiplier (you can imagine it as a Mx with Cap=infinity). This drops an even larger number of volts than a capacitance multiplier, but the result is ultra low impedance, super clean supply.

How does it sound? Fantastic. What does it cost? More than a Cap Mx. Photo below. Notice that the voltage regulator PCB is bigger than an amp channel PCB, and the voltage regulator heatsink is bigger than a (class AB) amp channel heatsink.

_

 

[Roundtoit]

I've watched this thread hoping to find a candidate for a discrete power-pcb/tranfo build to move between Class A projects while building and testing. SLB is the one to start with! Wow and Thanks to X, Hugh and jhofland! I think more about using a refined modular power supply component approach to simplify build layout and to reduce amp chassis size (not sink size) and make a long, narrow footprint. Makes it easy to A/B compare different PSUs.

Roundtoit - 2 SLB boards - 2 SLB-SR boards

Watch out MOFO!

(Hot, elegant, and delivery on difficult details; These are qualities of items to keep close to home...

 

[tubesguy]

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.

Thanks x -

I'll do the single SLB and do stereo in the 4U chassis. Dual monoblocks would be cool, but there's going to be some belt tightening going on around here soon (no, really) and I don't want to invest in another chassis. - Pat

 

[xrk971]

GB Status Update:

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 - invoice sent
Wtl - 4 boards - Paid
cerole - 2 boards - Paid
s610adam - 4 boards - Paid
pbergstrom - 2 boards - *need PayPal address*
ferret - 2 boards - Invoice sent
Jimk04 - 2 SLB boards, 2 SLB-SR boards - invoice sent
Roundtoit - 2 SLB boards, 2 SLB-SR boards - Invoice sent
Tubesguy - 1 SLB board - Invoice sent

 

[jwjarch]

This is really an exciting PSU design. Can’t wait to try it out. Thanks Jhofland, X and Hugh!

I know it was discussed early in the thread that too much capacitance in the bulk caps may not be a good thing. Is 15mF the limit here? I have a stash of 22mF caps I’d like to use.

 

[nautibuoy]

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 - Paid
cerole - 2 boards - Paid
s610adam - 4 boards - Paid
pbergstrom - 2 boards - *need PayPal address*
ferret - 2 boards - Invoice sent
Jimk04 - 2 SLB boards, 2 SLB-SR boards - invoice sent
Roundtoit - 2 SLB boards, 2 SLB-SR boards - Need PayPal address
Tubesguy - 1 SLB board - need PayPal address
nautibuoy - 2 SLB-SR boards - Awaiting invoice (dual rail boards already paid for)

 

[xrk971]

Hi Jwjarch,
If your current draw is not too high, the 22,000uF can work. If the ripple current of the system exceeds the ripple current rating of the cap, its lifetime is decreased. I think you are going to be ok if you use for 25W Class A amp.

 

[xrk971]

Some close up photos of the SLB verification build (v1). Note that the production v2 will be a bit longer to accommodate extra output FASTOn spade connectors for use as a stereo PSU.

With output slave BJT's (2SA1943N and 2SC5200N) mounted on a cheap $5 aluminum heatsink. The chassis floor plate or the actual side finned hetasink of an amp enclosure will be fine. I love the AMP quick disconnect cables (I use 18ga silicone super soft and flexible wire from RC model cars) - it makes removing the PSU board literally a snap. You also have the choice of mounting the transistors directly to the board in an underhung fashion:

Another view:

End view of the Cap Mx part with the CFP master on the small local heatsinks and the NTC and 22nF ground loop breaker for connection to chassis GND and mains earth GND:

Closeup of the LT4320 active bridge and MOSFETs:

Input AC snubbers are also provided.

 

[jhofland]

use of 22,000 caps

Hi jwjarch,

X's comments on the ripple current are on the mark. The other piece of information that may be of use to you is the pc board is set for a 35mm diameter cap, 10 mm lead spacing.

 

[jwjarch]

Thanks for the info guys. Sounds like it’s not really worth the risk. May as well order some 15mF caps. I’m sure the 22’s will get used for something else anyway.

 

[xrk971]

Get the 50v 15,000uF caps and you have a PSU that can handle almost anything amp wise under 50v rails.

 

[xrk971]

GB Status Update:

baswamin - 2 boards - Paid
meanie - 2 boards - Paid
jwjarch - 2 boards - Paid
gary s - 2 boards - Paid
nautibuoy - 2 SLB boards - 2 SLB-SR boards - both Paid, ship together
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 - *Invoice sent*
Wtl - 4 boards - Paid
cerole - 2 boards - Paid
s610adam - 4 boards - Paid
pbergstrom - 2 boards - *need PayPal address*
ferret - 2 boards - Paid
Roundtoit - 2 SLB boards, 2 SLB-SR boards - Need PayPal address
Tubesguy - 1 SLB board - Paid
Kokanee - 8 boards - Please send PayPal address
Arthur - 10 boards - Please send Paypal address

 

[gary s]

Mouser has 12,000 of the CDE SLPX 15,000uF 50VDC rated snap in caps in stock for a good price of $5.13 USD each or $4.62 USD each for a qty of 10+. These have a ripple rating of 6.56 amps, and are 35mm dia x 45mm high - Mouser part number is: 598-SLPX153M050H4P3

 

[SanjeevM]

Hi X,

I am planning to use these boards for a 30W Jean Hiraga class A monoblocks, working at +/- 30V supply. Will it be OK if I add 150 mf capacitor's per rail, after the board? Assume that the capacitors will have an adequate ripple rating, and that I will be using a soft start circuit with a 5 second delay.

Sanjeev

 

[xrk971]

SLB v2 (May 3, 2019) Production Board Top View:

BOM (txt and csv format) and pdf schematic are below.

 

[xrk971]

Hi X,

I am planning to use these boards for a 30W Jean Hiraga class A monoblocks, working at +/- 30V supply. Will it be OK if I add 150 mf capacitor's per rail, after the board? Assume that the capacitors will have an adequate ripple rating, and that I will be using a soft start circuit with a 5 second delay.

Sanjeev

You could do that, but since it is a Class A amp that draws a steady current, it would be a waste of caps as I am not sure it would add anything. The whole point of the SLB is to eliminate the need for huge amounts of bulk capacitance. You mean 150 milli Farad right? That's 150,000uF right? It would be a dreadful excess of caps and a waste of money as the SLB gets you 1mVrms ripple with only 30milliFarad (30mF).

 

[SanjeevM]

You could do that, but since it is a Class A amp that draws a steady current, it would be a waste of caps as I am not sure it would add anything. The whole point of the SLB is to eliminate the need for huge amounts of bulk capacitance. You mean 150 milli Farad right? That's 150,000uF right? It would be a dreadful excess of caps and a waste of money as the SLB gets you 1mVrms ripple with only 30milliFarad (30mF).

The purpose was to provide an energy store for improving bass response.

 

[xrk971]

Ok, I guess if the amp can go into Class AB mode and draw more current than the quiescent then it can use some charge storage, but probably 10,000uF cap would be enough for this purpose.

 

[SanjeevM]

Ok, I guess if the amp can go into Class AB mode and draw more current than the quiescent then it can use some charge storage, but probably 10,000uF cap would be enough for this purpose.

Thanks.

 

[SanjeevM]

Thanks !