Best SMPS for Gainclone

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Hi.

I am looking to find a ready built switch mode PSU for a gainclone. I think i need the following spec:

+/-20V with 6A on both positive and negative legs.

Can anyone let me know if I am correct in these requirements and if so, where I can buy one? I would hope to go to 2 PSU's in the future.

Thanks.
 
jackinnj said:
you can buy a 48V switching supply -- always for sale on EBay -- then configure the GC as single-supply as National Semi describes. The performance isn't much different vis a vis a bipolar supply.


I guess that if someone thought that they had to have dual supplies, they could always split the 48v into +/-24v, using another chipamp to make a power supply "splitter", with a circuit something like what is shown in the LM675 datasheet (The LM675 is almost identical to the LM1875. But something very similar should work with almost any amp chip.).

- Tom Gootee

http://www.fullnet.com/~tomg/index.html

-
 
Complete PN: Cosel PBA150F-24

Datasheet: (page 13~14)
http://www.cosel.co.jp/en/products/pdf/SFE_PBA10-150.pdf

Manual:
http://www.cosel.co.jp/en/products/pdf/CME_PBA-PBW.pdf

Test Data:
http://www.cosel.co.jp/dl/dl.php3?f=pba150f-24.pdf&k2=D1&ext=.pdf&d=PBA&s=PBA150F

Spec Highlights:
Efficiency(%): 85typ
Power Factor(%): 99 typ
LINE REGULATION[mV]: 96max
LOAD REGULATION[mV]: 150max
RIPPLE[mVp-p] 0 to +50C: 120max
RIPPLE NOISE[mVp-p] 0 to +50C: 150max
DRIFT[mV]: 96max
OUTPUT VOLTAGE ADJUSTMENT RANGE[V]: 19.2 - 27.0vdc


Just ordered two, shipping, USPS Priority: $12.93 to Silicon Valley, Calif
 
additional info:

From Manual, page 8:
4.1 Series Operation
- You can use a power supply in series operation. The output current
in series operation should be lower than the rated current of a
power supply with the lowest rated current among power supplies
that are serially connected. Please make sure that no current exceeding the rated current flows into a power supply.

4.2 Parallel Operation/Master-slave Operation
PBA10F, PBA15F, PBW15F, PBA30F, PBW30F, PBA50F, PBW50F, PBA75F, PBA100F and PBA150F
- Parallel operation is not possible.
- Redundancy operation is available by wiring as shown below.
 
Totally new here but...

Isn't this SMPS outputting 2 x 24v? The pics for terminal option -T and molex connector option -J seem to show 2 pair of +/-V rails. The molex connector H-OU-21 shows 3 pair of black/red wires?!?! Am I wrong in reading the pdfs from Cosel?

I just ordered 2 of these to build Peter Daniel's 4780 dual monoblock kit. I just can't afford toroids and components for the PS boards on my fixed income.

I sure hope I am not wrong about the voltage on these or I will have to return em or ebay em. Probably won't hurt since they are usally retailing for over 120 bucks everywhere but bgmicro.

Oh, and HI first post!
 
Re: Totally new here but...

sixtoe said:
Isn't this SMPS outputting 2 x 24v? The pics for terminal option -T and molex connector option -J seem to show 2 pair of +/-V rails. The molex connector H-OU-21 shows 3 pair of black/red wires?!?! Am I wrong in reading the pdfs from Cosel?

It's just two sets of connections to the same single supply, not two independent supplies.
 
I don't know what I was thinking. Two of these supplies even at only one 24v rail should work fine for Peter's 4780 kit in the bridged configuration. One supply per channel. The schematic for the psu on that kit shows a single toroid with 2 x 22v secondaries. These supplies could be used for 4 ohm speakers because they have a potentiometer that allows output adjustment. Maybe even down to 18v perhaps.
 
I am learning be kind. :/ Ok, 2 of these supplies in series will provide 1 +/- 24v for a single bridged 4780 using a single amp PCB board from Peter's kit. I would need 4 of them to provide dual +/- 24v for 2 4780 bridged chips using both boards from Peter's 4780 kit. Right?
 
Received two (2) BGMicro Cosel PBA150F, 24vdc @ 6.5amp switching supplies:

BAD NEWS:
- appears to be a modified model, configured for an equipment manufacturer.
- output is NOT floating, with (-) minus internally connected to ground.
- attached quick drawing shows shorts when configured for series, bi-polar +/- 24vdc output.

GOOD NEWS:
- easy to modify, by clipping single wire-link inside the supply. (not a hack, but configuring an option)
- made in Japan, with 105c Nippon Chemicon KZE capacitors.
- forward converter, 120kHz switching freqency with 60~550kHz active filter.
- quick measurements:
PSU 1: Adj Range: 16.36~29.64vdc
PSU 2: Adj Range: 15.83~29.56vdc

NOISE: (+/- 24vdc series configuration 48vdc)
C515:
Jumpered: RMS: 104mV PP: 928mV
2.2nF: RMS: 22mV PP: 120mV
150nF: RMS: 4mV PP: 34mV

Will post detailed procedure, with pictures, on how to isolate (-)minus output from ground, later tonight...
 

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BGMicro, Cosel, PBA150F configuration change from grounded (-)minus to "isolated/floating" output:

- remove cover, careful not to force, cover bends easily.
- a bit of jiggling, with "slide catches" releasing with bias away from output side.
- remove single wire jumper, at position C515.

- optional: cut jumper in the middle, leaving "stubs," to solder-in film capacitor.
- 150nF installed, calc'ed from core 125mHz switching frequency. (metalized poly film @ 200vdc, only because I had them)

!Standard lethal voltage caution when working with switching power supplies!

Picture:
 

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For the more technically inclined, replace jumper with capacitor to ground. (board removal from frame)
- 150nF installed, calc'ed from core 125mHz switching frequency. (metalized poly film @ 200vdc, only because I had them)
- remove heatsink clips carefully, keeping "clip-lip" from dragging across silicon-rubber thermal cover. Easily torn.

Series of five annotated pictures below...


Other Notes:
- source: modified XFI Elite Pro, diddled low-pass filter values, with Intersil EL2227 opamp.
- speakers: Beovox MC120.2's with reworked crossovers, vents and woofers.
- previous power supply: single 320va torroid, 2 x 20vac secondaries, powering 2 BrianGT LM3886's.
- supply caps: RIFA PEH532JCD5100M2 10kuF @ 35vdc, one each rail.
- supply snubber: 150nf + 1ohm.
- PBA150F's adjusted for 25vdc each, sagging to 24.92vdc @ 25W, (stereo,50w total), 8ohm resistive loads, white-noise input.

Only 2 hours of listening time:
- highs clean and "tinkle" free.
- mids clean and more forward.
- very tight low and mid-bass.
- seems to have much less siblients and wider/imaging soundstage...
- overall, satisfied with this cheap experiment...

Picture(s):
 

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