EEEngine

[lumanauw]

I think this one is the patent of EEEngine. Patent #5,347,230.
It's interesting, because classD principal is used for efficiency of rails, while the main amp still can be classAB or even classA.
The important component is in L1. The right side of L1 (150uH) is classD/square full voltage, and at the left side of L1 it is a voltage follower, following Qb to feed the output transistors Qa. Output transistors Qa is cascoded by Qb emitor voltage at low voltage, so the dissipation in Qa is small (compared to rail that is +/-90V)
If Qb's emitors are sitting at +5V, the from +5V to +90 (85V) is given by L1 from classD mechanism, efficient.

But is this schematic selfoscilating at constant frequency like UCD or not? Is this good or not?

[bikehorn]

i played a yamaha bass amp with an EEEngine class D output stage....sounded great so i guess it's at least good for something?

[lumanauw]

If your amp is EEEngine, then the audio amp is classAB, the rail is classD.

[soongsc]

How long has this been out on the market? Any specific products?

[lumanauw]

EEEngine has been in the market long enough. The patent is from 1994.
Example of current product : Yamaha PC9501 : 3000W in 8ohm bridged. And it is classAB that making 3000W with 1rack size.

Is this EEEngine do-able as a DIY project?

Anyone has schematic/service manual of Yamaha amp that uses this EEEngine?

[kartino]

Hi David,

I am in perth now so i lost all chance for diy class-D. I didn't find glodok's like shop here.

OK, from the description on pages:

http://www.yamahaproaudio.com/topics..._eeengine.html

the technic looked similar to tracking power supply isn't?

[kartino]

this is one of implemented EEEngine tech of Yamaha manual with circuits:

http://www.eserviceinfo.com/download...YST-SW800.html

a sub amp.

[lumanauw]

Halo, Mas,

Sedang sibuk di Perth?

That's right, it's a tracking power supply system. The idea is similiar with the one from Labgruppen.
I've looked that subamp. Do you have the schematic for full range amp (up to 20khz)? Maybe the values different for sub amp and for full range amp?

[soongsc]

I doubt we can see any Hi Fi full range performance with this kind of design. All devices have optimum performance voltage ranges. If you move the voltage out of this range, you sacrifice, performance to save power. In the low frequency region, we are not as sensitive to such amount of degradation and the power saving is probably dominating the design.

[kartino]

of course it is not for hi fi arena. this kind of amp is used for pro (read: thousands watts amps). There is no benefit using this kind of amps for your home amps since the tech is more complex than class-d.

btw some pages offer service manuals but not free, you can try googling as "eeengine service manuals". if you lucky maybe you will find full range ones. But I doubt it is worth for you who want to build by your own, too bloody, better than open ebay and you will find second hand EEEngines for 500usd.

have you ever see QSC's schematic?

quite hot in perth right now....