John Curl's Blowtorch preamplifier part II

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Richard, maybe you can tray the one from Hypex. Hypex Electronics webshop
I did not try it (to expensive for me) but could be good one, look for specification, protection included (even possible to add external DC offset loudspeaker protection)
BR Damir

THx -- I have asked where it was bought -- make and model. Will get back on this when I have a reply. But it looks very much the same as the Hypex SMPS 1200A400.


-Richard
 
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PFC regulations only stipulates that the current drawn follows the mains VAC envelope within certain limits, rule of thumb is less than 5% THD of the mains supply, ie. 50/60Hz sinus, it has virtually nothing to do with switching noise.

There are mainly 2 types of PFC, passive which is essentially a huge inductor and some larger capacitor between mains and SMPS, and active which is maintained by the switcher controller itself.

Some PFC trivia: Many cheap PC PSU stating having PFC are passive else if the manufacturer explicitly states "active PFC", I make ascertain that I really get an active PFC PSU for my PC for the only simple reason, a passive have often a couple of % lower efficiency which translates into more heat and a noisier fan. 🙂
 
The only reason I see to use an smps over linear is efficiency. So since it is such PITA to control noise and who cares about efficiency in most audiophile designs why use an smps? Unless one just wants to flex the engineering muscle.

I said --- weight. If suitable performance.... the shipping weight of transformer/rect of high power amp is very high. Shipping charges add a lot to price. But if smps is so much higher cost... then shipping cost pales in comparison. Size of smps doesnt reduce package size due to heat sink size needed ... large enclosure/heatsink needed.
Balancing costs and checking to see what they can do.


THx-RNMarsh
 
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Richard, one way to get weight down considerably is to build a Class-D (acting as rails voltage supply modulated by the audio signal + an offset) + Class-whatever-you-want (A, AB, ...) hybrid, the question is, is it "audiophile" enough as these types of amps have existed for a long time for PA use and may come with a certain association, but let's break the frontier! 🙂

Radical innovation built upon proven technologies - Lab.gruppen
 
Richard, one way to get weight down considerably is to build a Class-D (acting as rails voltage supply modulated by the audio signal + an offset) + Class-whatever-you-want (A, AB, ...) hybrid, the question is, is it "audiophile" enough as these types of amps have existed for a long time for PA use and may come with a certain association, but let's break the frontier! 🙂

Radical innovation built upon proven technologies - Lab.gruppen

Like this one? 200W Class A amp with high efficency
 
Hi Robert,
The beauty of using an SMPS is that the internal voltages are regulated over input voltage ranges and load demands. For many amplifiers, this represents a performance increase. On top of that, lower amounts of heat and a lighter chassis. This will reduce the cost to the customer as the amplifier is now much cheaper to ship.

Even a coarse regulated supply design like the Carver "magnetic field amplifier" had enormous benefits for everyone. It also shut down faster under fault conditions, which reduces damage to the amplifier and connected loads. So aside from demanding real engineering skill to design, there are no down sides to a switching design power supply.

I still service this equipment, many folks have devised modifications (including me) to enhance the performance over what they had. Even switching transients have been reduced over the years. So an M-1.5t today after modifications will perform far better than a lot of new equipment does. Even the dreaded triac switched noise is generally no longer a problem.

I think that switching power supplies are the technology of the future. No point in fighting it as long as you can hire the chops to properly design with them.

-Chris
 
You have multi-stage, additional rails filtering, right?

Here is simulated PSRR without rail caps and with caps.
 

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The only reason I see to use an smps over linear is efficiency. So since it is such PITA to control noise and who cares about efficiency in most audiophile designs why use an smps? Unless one just wants to flex the engineering muscle.

Except controlling noise at 100+ kHz passively is a bit easier, see Mark Johnson's talk of a RLC 2nd order filter on the SMPS output to bat down any hash. A decent purchased unit shouldn't be radiating too much (as has been stated), as there's a ton of market forces to make better and better SMPS. Might as well ride the wave!
 
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