[serengetiplains]

Paul, can you make a regulator for this amplifier?

http://www.diyaudio.com/forums/diyaudio-com-articles/202480-l-amp-simple-sit-amp-part-deux.html

The amp as shown in the above link operates with a supply voltage at 35VDC, and at a quiescent operating point of 2A.  I'm planning on doubling the output into class-A push-pull with transformer loading, and will bump up the supply voltage to, say, 40-45VDC.  Power supply duty will be performed by two Vicor switchers.

4 to 5A quiescent, that's a lot of current!

[Paul Hynes]

I sure can, Tom.

However the regulator would have to be a shunt regulator type to handle reverse current flow, due to the inductive nature of the load, whilst still maintaining regulation. The amplifier is essentially as solid-state SET amplifier. Series regulators do not work well with this type of amplifier.

The current source section will have to dissipate around 60 watts but the shunt regulator output stage can be set to around 6 amps and will only be passing about an amp while the load is connected so this will dissipate around 35 watts making a total of 95 watts per amplifier. The heat sink for the CCS and regulator section will need to be rated at around 0.3 degrees C per watt. This should keep the heat sink operating temperature to around 30 degrees C above ambient temperature.

If you are OK with the heavy thermal engineering, I will work out what is necessary for your project.

Some detail about the proposed Vicor switchers for the 45 volt rail would be helpful.

You can use the amplifier and power supply to keep the listening room warm in winter.

Regards
Paul

[steve2701]

You can use the amplifier and power supply to keep the listening room warm in winter.

& listen to music in your swimwear in the summer - or aircon springs to mind 

That looks a serious bit of amp - very interesting .

[serengetiplains]

Paul and Steve, the amp is, yes, essentially a SET.  I love its simplicity.  I once patched together a single-stage PP SET amp using 6C45P triodes.  It was wonderful sounding.  Single stage---amplification of stage-inherent PSU and signal distortion minimized.

The Vicor switchers are here:

http://www.vicorpower.com/cms/home/products/brick/FlatPAC

I have purchased two 48VDC/600W units from eBay (model # VI-NU4-EM).  Each switcher essentially comprises three paralleled 200W DC-DC converters packaged into a single-output unit.  That output, for the NU4 model, is rated at 12.6A per switcher, 48VDC (configurable at ∓ 10% of rated voltage).  There is enough room in the chassis and sufficient heat sinking to provide the required cooling.  On that note, I was thinking a largish, copper interface between the sink and supply would aid cooling.

Btw, Paul, what capacitance can the shunt reg handle on its output, or perhaps better, what would the optimal capacitance be?  I want to use as much film capacitance as possible to diminish sonic effects of electrolytics, and in any event have some large 10,000uF Black Gates for possible use.

The amplifier chassis is this:

[Paul Hynes]

Hi Tom,

I have not yet found a load capacitance combination that upsets the shunt reg. You should be fine with the black gates and film caps.

One thing I should mention for constructors considering using shunt regulators in their projects is that the current source will set the maximum current that can be delivered to the load. I say this for the benefit of anyone considering shunt regulators for their projects because it has come to my attention that a certain company selling regulator upgrades has posted tests of one of my low power shunt regulators against his higher power regulator. He has subjected the shunt regulator to a load exceeding the regulator current setting and shown the resultant regulation dropout. This is normal for shunt regulators but does highlight the need to set the shunt regulator up properly for the application. For a fairer test he should have used an SR1M set up for a load current that exceeds the test current. Incidentally the regulator used in this test is a five year old design, and it has been revised several times since this earlier design to improve the performance.