What 'class' is this Hill Audio DX3000 Amplifier?

[dicky96]

Hi guys, this is general query really

So I have a Hill DX3000 3KW audio amplifier here.

It has a topology/design like a class A/B but all the banks of output transistors (10 transistors in each 'side' of the channel) are NPN.

I was wondering what class this is. It doesn't fit the description of class A.
It also doesn't match class A/B or B amplifiers as all the examples I see have a complimentary output stage desigs (NPN/PNP) and clearly is not G, H or D

I looked for 'class A push pull' but that didn't tell me anything either

Here is the schematic. So what is it?


OOPS WRONG PIC - On moment

thanks
rich

[dicky96]

Re: What 'class' is this Hill Audio DX3000 Amplifier?

Try this pic

[eccerr0r]

Re: What 'class' is this Hill Audio DX3000 Amplifier?

Without looking at the schematic, likely Class AB.
AB can also be all NPN or all PNP power transistors.

---

Now after looking at the schematic, it indeed has a quite unusual design, but seems to fit just as well - still has all the characteristics of an AB design.

[dicky96]

Re: What 'class' is this Hill Audio DX3000 Amplifier?

Thanks eccerr0r

[Erico1]

Re: What 'class' is this Hill Audio DX3000 Amplifier?

@eccerOr
The manual you provided describes it on page 5 as a "Super A" sliding bias configuration. See the first paragraph in the Operation section.

[eccerr0r]

Re: What 'class' is this Hill Audio DX3000 Amplifier?

The main characteristic of class B is evident in the design however - since only half of the transistors are on during a specific half of the waveform. Yes this design leaks like a class A but not as much as so due to the half waveform design, so it's tough to classify these.
I don't see any advantage of this over a traditional AB design, just costs more with ugly transformer coupling...

[Erico1]

Re: What 'class' is this Hill Audio DX3000 Amplifier?

I read an article that described it as an A+B type. The design is derived from Technics.