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Gb - Power Amp Power Supplies

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I'd like to offer pre-built power supplies to the DIY market at cost plus a small assembly charge

Here are the components:

(1) PCB with 2.5 oz copper traces
(2) International Rectifier bridge rectifiers
(2) Rectifier heatsinks
(8) Wima .01uF polypropylene film and foil snubber caps
(4) Nichicon KG 8200uF 50v filter capacitors (good stuff)
(1) Dale dropper resistor

The PS will work great with 1 or 2 channel chipamps and the Hypex 90/180 modules using a max 30-0-30 transformer.
The inductors will hadle 10 amps, which is > 300 watts.
I'd recommend the inductors to be used with any amp.

As the rectifiers are heatsinked, the PS will work great with Class A amps. If additional filtering is needed, omit the inductors and tie the two capacitor banks together with some big Erse inductors.

I've used the power supplies for over two years with no issues. They are guaranteed to work great.

All parts are currently stocked. Please provide feedback if you are interested, and I will adjust order quantities accordingly.

Please respond to this post, or e-mail me at:
mhbaustin@att.net

Base price assembled and tested :
$69 USD + $8 shipping

Options:


Highly recommended Vishay/Dale 100uH inductors connecting capacitor banks (great for chipamps)
Add $20.00

Faston connectors
Add $2.50


12000 (x4) Panasonic 105 deg TSHA filter caps
N/C

Blue power LED with 10" leads and chassis mount hardware
Add $10
 
why the 100uH inductors ? -- this just adds another problematic dollop of inductance to the "tank circuit" formed by the transformer's leakage inductance, the interwinding and diode capacitances -- this could be a very nasty problem as the resonance in the hundreds of kHz will propagate back up the a.c. line and onto connecting cables -- consider instead a bifilar wound choke of some tens of milli-Henries to the filter bank.

Consider further the C||RC||D snubber described by Hagerman, well worth recommending to eliminate diode ringing. (Illustrated below).

why not a bifilar choke with X and Y caps on the input --

in days gone by, when switch-mode power supplies and 900 Megahertz phones weren't the norm, you could get away with a simpler approach to the power supply. nowadays even your 'fridge and toaster will have an 8-bit microprocessor.

fwiw, 8,200 uf doesn't do the trick with power amps.
 

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That's 4x8200uF caps per power supply which is more than sufficient for feeding one or two channels. My old Rotel power amp had 4x6800uF caps for both channels, and BrianGT's power supplies only use 2 filter caps.

I have an oscilloscope and can verify there are no HF nasties when using the inductors. The inductors have very low ESR (.03 ohms) which is little more than that of a link.

IMO, the inductors improve the sound quality of chipamps. There is a slight reduction in ripple and noise on the supply rails when using the inductors rather than links. I've designed the PCBs so that the inductors may be omitted or substituted with any choke you can fit in your chassis. Also note the blue panel LED option.

The rectifiers are the standard high current type with heatsinks.

These are the same power supplies I have used in my chipamps that I've been building as monitor amps for pro audio folks in my area. You can get a general idea of the layout here:


Sierra Fidelity

I'll post pictures after the holiday.


I'd be happy to sell folks bits and pieces as long as they total >= $10. Just ask...

Hope this helps, and happy T'giving to all.

mhb
 
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