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High Power Regulate Power Supply for Audio Amplifier

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Dr. Dark Current

Mon Dec 22 2008, 10:14PM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

Mestre Racerxdl wrote ...

Steve: I run it at 55V (that is the caps charge), I think the transistors only see the supply that is attached, because its +55 for the TIP142 that goes through it and goes to the speaker, and -55 goes through TIP147 and to the speaker.

With full amplitude to one polarity, one transistor will theoretically see 110V and the other one 0V. Practically it will be a little less but still it can easily shoot over 100V.

MRacerxdl

Tue Dec 23 2008, 12:08AM

Registered Member #989 Joined: Sat Sept 08 2007, 02:15AM
Location: SÃ£o Paulo, Brazil
Posts: 476

Hmm, I never had any problems here, and the amplifier is running about one year without any problems. Is there any other good Darlington to use at my amplifier (with high voltage)? I never see a darlingon with more than 100V.

Arcstarter

Tue Dec 23 2008, 04:21AM

Registered Member #1225 Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253

Mestre Racerxdl wrote ...

Hmm, I never had any problems here, and the amplifier is running about one year without any problems. Is there any other good Darlington to use at my amplifier (with high voltage)? I never see a darlingon with more than 100V.

I have some darlingtons that are 9 amps and i think 200 volts, so i am sure they make some alright voltage ones. I actually got a circuit board out of a large rear projection screen television, and it has 9 of the pnp and 9 of the npn, each set with their own heatsink.

Steve Conner

Tue Dec 23 2008, 01:09PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Darlingtons are a poor choice for audio anyway, you can get better results with two stages of ordinary transistors. There are some really nice audio BJTs like the MJL3281/MJL1302 (now obsolete I think, replaced by even better ones)

The transistors do indeed see the sum of the rail voltages, but only when the amp is putting out full signal voltage. With +/-55V rails, there will be times when there's 0V across one transistor and 110V across the other.

MRacerxdl

Tue Dec 23 2008, 04:16PM

Registered Member #989 Joined: Sat Sept 08 2007, 02:15AM
Location: SÃ£o Paulo, Brazil
Posts: 476

Why darlingtons are a poor choice? They reduce one power stage to the ouput stage, less consumition from base.

Maybe the current bias at the the trasistors drop the voltage to something safe, I didnt measure here, I will try it someday.

I am seeing here, I think about making a new amp with MJ15003/15004, it is 20A for 140V, the hfe is about 25 to 100, considering 25, 1A base current, not too much. But they are TO-3, heatdissipation cap to 250W. They are good but very expensive, about US$5 each here :P

Carbon_Rod

Tue Dec 23 2008, 07:13PM

Registered Member #65 Joined: Thu Feb 09 2006, 06:43AM
Location:
Posts: 1155

These chips may be of interest:

It would be interesting seeing these in a split regulated power supply.
=)
Cheers,

MRacerxdl

Wed Dec 24 2008, 01:22AM

Registered Member #989 Joined: Sat Sept 08 2007, 02:15AM
Location: SÃ£o Paulo, Brazil
Posts: 476

Hmm, that is interessting, I was thinking about making an SMPS for my Audio Amplifier, but why no one uses Switch Mode at Audio Amplifier Power Supply? I never seen anything like that, and that will be reduce much of the transformer size.

Dr. Dark Current

Wed Dec 24 2008, 11:07AM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

Mestre Racerxdl wrote ...

Hmm, that is interessting, I was thinking about making an SMPS for my Audio Amplifier, but why no one uses Switch Mode at Audio Amplifier Power Supply? I never seen anything like that, and that will be reduce much of the transformer size.

It's perfectly fine to use a SMPS for an audio amp. Just make sure it does not produce excessive noise (fixed frequency SMPS is the best), runs at >>20kHz and there's not a lot of ripple on the output.

Steve Conner

Wed Dec 24 2008, 11:36AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Mestre Racerxdl wrote ...

why no one uses Switch Mode at Audio Amplifier Power Supply? I never seen anything like that

You obviously never looked very hard. They are popular in high-powered PA amps. Small domestic hi-fi amps still use an iron core transformer, though, because it's so small that it's hardly worth eliminating.

MRacerxdl

Wed Dec 24 2008, 05:11PM

Registered Member #989 Joined: Sat Sept 08 2007, 02:15AM
Location: SÃ£o Paulo, Brazil
Posts: 476

Hmm, I think I will go to SMPS, that I will get very nice regulated PSU, and with a small transformer. I will run at normal SMPS frequency, that is 50kHz (Ideal for a core that I have here).

I once, made a SMPS for testing at my audio amp, it worked when I soft started the amplifier (increasing the voltage at variac not too fast), but when I powered on direct, it blowed one of the mosfets :'( it was one 800V 45A minibrick mosfet. I will try later with a TL494 and a good driver.

What is the best thing to the powersupply? a Half/Full-bridge or a "Dual-Flyback" (I think its that name) like that :

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