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Old 30th June 2007, 10:50 AM   #1
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Question SMPS For Valve amplifiers??

Has anybody got any schematics they're willing to share.

I'd like to design one later this year...
learning heaps at my course but still a long way away lol.

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Old 1st July 2007, 03:33 AM   #2
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Oh yeah the supply I want would be around 500v suitable for a 100 watt power amp. Enough filament current to run 4 6l6gc's and a few pre amp tubes would do the job nicely and be usable
for an aux supply if i wired the tubes in series (eg 12.6v for 2 6l6 tubes in series. all 12**7 tubes have 12.6 series filaments too.)

I've built small boost converters for pre amps but they we're unsuitable for scaling up for power amps because they were battery powered.

I've seen the silicon chip article on modifying pc power supplies for valve amps but i'd rather build my own board lol.

I'm interested in building the off line type supply using the TL494 because it is very common and the teacher at my school just ordered a ton of surface mount 494's.
If anyone could point me in the direction to find a spice model to simulate this controller in multisim it would be awesome!

I've been reading the power supply cookbook from marty brown and i'm getting quite familiar with the circuits and the jargon in this area of electronics.
After building a very more low power smps's i think i might tackle the big off line one. Any advice?
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Old 2nd July 2007, 12:19 AM   #3
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An active PFC circuit is a good point to start. They operate with output voltages at about 370v, so it's not too far off from 500v. A little modification of the design should get 500v easily.
For the filaments, just use a standard power supply module.
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Old 2nd July 2007, 01:39 PM   #4
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Yeah doesn't sound like a bad idea. But i definately want to integrate the filament supply into this design.

I'm guessing 300 w is around the right area for a 100 watt output stage for a guitar valve amp.
I know that sounds a bit much but my marshall says it takes around 375w!
Guess it must be losses in output transformer, power transformer etc..
Filament windings will be good for 4 6l6gc or more power hungry tubes like kt88.

This supply is intended to be built so it is safe and other people could build it. I'll have a look at active pfc as a future project, i'm sure it's an improvent i could add on later....
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Old 10th July 2007, 11:54 PM   #5
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Default smps design

Switch mode power supplies are very complicated to design. SMPS requires skills in magnetics, components, control loops/ compensation, thermal management, and circuit board layout. The PFC circuit is not the way to go. Their main purpose is to make a capacitive load look like a resistive load to satisfy mostly European agencies. If you want to learn how to do smps, start small! Try a 12V to 5v non-isolated buck converter. This would help get you learn magnetics design (output inductor), gate drive, output capacitor selection, diodes, emi filters, and, one of the biggies, control loop design/compensation. Then you move on to thermal and layout. Layout of a properly designed smps is about 50% of the design effort. Once you have done that, try an isolated 12v to 5v design using the forward tiopology.

My advice is to stay away from the high voltage stuff untill you know what you are doing. You can get serioulsy burned and possibly kill yourself if you are not carefull!
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Old 12th July 2007, 02:41 PM   #6
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Yeah that doesnt sound like a bad idea at all. I'd probably be most happy working with a half-bridge at low voltage.

I've done a few boosts and bucks etc and a push pull but they were all projects that were already prototyped.
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Old 17th October 2013, 07:16 PM   #7
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Question Are there any SMPS for tube amplifiers for sale somewhere?

I found this thread because I was searching for existing SMPS suitable for tube amplifiers. Are there some manufacturers that produce them?

Company names, links, anyone?
High-order harmonics are more offensive than low.
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