Bash

Hi,

http://www.bashaudio.com/technologies.htm

First time I heard of it, thanks for bringing it around.

From the little I can tell it's a class AB output stage with class D modulation of the power rails in order to help out efficiency...

Pro:
Extra efficiency Over a class AB due to the power rail modulation


That's all I can tell with the given info.

I'd imagine it would still have all the disadvantages of class AB, less efficient and less linear than a pure class D..

I smell fish when I notice all they speak of is power output /efficiency, for which it couldn't possibly match a pure class d topology (which I'm glad is a point they don't try to hide) and at the same time not a single graph regarding linearity, THD.. or even a claim as to what it could possibly be, anywhere.

In conclusion, I think they likely have an amp that's more efficient than class AB, less efficient than class d, and has the worst of both worlds mixed in.

Incedently, unless I'm mistaken, this seems to be an example of class G topology, which I don't see them state anywhere at all.

Incedently, unless I'm mistaken, this seems to be an example of class G topology, which I don't see them state anywhere at all.

Click to expand...

This is not a bad description. They actually use a class-d downconverter to feed the amp, like Carver does. The main difference is that BASH uses a bridge topology and Carver's is single ended.

There is also a more modern incarnation of this topology around:

http://www.audiophysic.de/produkte/mono/aufbau_e.html

And it seems to be based in this patent:

http://l2.espacenet.com/espacenet/viewer?PN=DE19822814&CY=ch&LG=de&DB=EPD

It had a lot of good reviwes, even Jonathan Carr was raving about it.

Regards

Charles

The other thing about BASH is that it is commercially very successful. It is found powering a lot of active subwoofers in mid-end audio, as well as private labelled car amplifiers.

There is also potentially some linearity gains by having voltage rails track the audio signal that could offset other issues.

BASH doesn't pretend to be really high end, but deliver a commercially viable good quality product.

The original Carver cube (M400) was a tracking downconverter design, but Bob had troubles with production units so he went to the multi-rail design instead.

His Amazing subwoofer is a singlesupply, line operated, tracking downconverter design feeding a class AB amplifier rated at 2.7KW

BASH is great technology however the benefits, compared to Class D, are almost wasted in a low frequency limited bandwidth application. The "bad" characteristics (such as interaction of the output filter with the driver) of Class D design don't really apply to a subwoofer. I'd use an amp with the highest efficiency possible (Class D)...it will be less expensive and provide you with more power.


BASH is actually an implementation of a Class H amplifier. Class G refers to multi-step rail voltages whereas Class H is defined as an amp with rail voltages that is modulated by the input signal.

That Carver sub is rated at 2.7KW peak dynamic power. That's 1350 Watts RMS dynamic and likely around 1000W RMS continuous but not FTC...still impressive though.