Transformer advice needed.

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Completely wrong on all counts AG.

The modules are fairly expensive because it's a high quality and very highly regarded design.

Plus it's NOT class A, it doesn't run hot, and it doesn't have particularly massive heatsinks.

There's a link above that goes to a page that has a link to the original article about the current dumping technology (feed forward), and how it uses a low power class A (cool running) amplifier, with the high power added in class B.
 
What nobody has explicitly pointed out that these amp modules require bipolar 30VDC – 50VDC; you need a positive supply AND a negative supply. So you need something like a 30–40 volt centertapped transformer. TWO windings of 30 – 40 volts.

Someone posted a schematic of a bipolar supply earlier.
 
Thanks have looked at one similar to this. 2 x 30v this is where I get confused, the multiple secondary outputs. Connect these together to get 60v x 0.7 which will give me 42 volts AFTER it has passed through the rectifier? I was expecting the voltage to increase not decrease when goes through the rectifier.

Can anyone recommend a respectable publication so I can actually learn this stuff for myself.
 
The amp modules require a bipolar supply. That means 30 - 50 volts between common and V-positive, and 30 - 50 volts between V-negative and common. The sketch here shows what this would look like with two DC supplies (battery symbol represents the D supply).



Starting with a transformer, you'll need a center-tapped winding of about 80 volts (each winding providing 40 volts). Rjenkins showed how to do this in this post:

Transformer advice needed.

I need some help understanding transformers. I need a transformer for an audio project, preferably a toroidal transformer. I want to out 240v UK mains into it and get 18 volts out if it. All the various ones I see to buy online have multiple secondary outputs. I wish to understand if I can buy a...
www.electro-tech-online.com
 
The amplifier needs ±30 V to ±50 V. That means that it needs a negative supply that is between -30 V and -50V, as well as a positive supply that is between +30V and +50V. The total voltage, measured between the -ve supply and the +ve supply will be 60 to 100 V.

Your 2 x 30 V transformer will give 60 V ac between the ends of the secondary windings if they are in series. 60 V ac will give around 80 V dc when rectified, which is what you want.

Having the windings as 2 x 30 V in series instead of 1 x 60 V makes no difference to the overall voltage. However it does give you a mid-point so that the supply 80 V will be evenly split, with the positive and negative ends about equally far from ground.
 
Aaaaaah that is quite clear. Thank you very much. I've been reading up on this, all more complicated than I thought it would be, but logical. Thank you.
 
I copied a review that talked about Class-A and did not describe "current-dumping". Now I saw the article about current dumping and it is what I used to eliminate crossover distortion in Korean speakerphones.
Sure the Quad 405 amplifier uses little modules that the Chinese copied but the original amplifier mounted their modules on a massive heatsink.
 

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I wouldn't have called that 'massive', and it's as much a cosmetic feature as heat sinking, with only short fins.

The older 33/303 Quad (45W per channel) had more substantial heat sinks, but they were class AB.
 
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