Yamaha AST-A90M 0 ohms with electrical current able to run infinitely?

Can anyone explain what this means, other than this amplifier is a 0 ohm superconductive power supply with the right speaker? :scratch2:

"The Yamaha AST-A9OM, unlike any existing amplifier, is an amplifier that can have a negative resistance figure in its output impedance.

The voice coil impedance of a conventional speaker is approximately 6 ohms, and the AST-A9OM can apply a negative resistance to eliminate this voice coil resistance portion.

As a result, with the combination of the AST-A901M and the AST System exclusive speakers (AST-SV90 etc), the resistance between the amplifier and speakers will become approximately 0 ohms and the electrical current will be able to run infinitely (condition close to superconductivity).

In other words, the amplifier output voltage will directly drive the speakers, hence making it possible to provide a powerful driving force and damping power of steady speed operation.

Because an element possessing a negative resistance figure does not exist in nature, we have developed this by way of electrical circuits in the AST-A90M.

If the type of speakers varies, the negative resistance figure will be different. Accordingly, we have developed the negative resistance producing circuit into a cartridge form to apply to various AST speakers.

In addition, with the utilization of the Air Woofer system in which the air in the port functions as a diaphragm, the distortion is considerably retained in the low range to enable high-quality enjoyment of bass."

The above is quoted from the owners manual per Hifi Engine. Since negative resistance does not exist in nature, is this amplifier intended for unnatural acts of amplification?

If they do not specify 6 guag speaker wires they are "talking out their ass" and it is a bunch of hype. I just got the owner's manual, and there are no sense wires to the speakers.

Therefore it is all bullshit. Might be a good amp, but that shit is shit. It may sound better but you cannot be sure until the square wave test.

JURB kind of what I wondered, but had to smile at the marketing creativity. Akin to a car maker saying "this car's drive train will generate negative speed which will allow infinite miles per gallon at a perceived 0 mph".

The cartridge is interesting and impractical. It sure looks like Yamaha is manipulating DF to reduce speaker distortion.

I've seen company after company go from high quality to hype quality.

There was a discussion on damping factor not too long ago. Comes down to that you can increase it by using remote sensing, but that voice coil resistance will always be there.

Yamaha might have nulled it out somehow, but it simply is not what they claim unless it has remote sensing.

There are no police for stuff like this. They can claim damnear anything they want anymore.

JURB and SoCal I think the police as always are our ears. All hype ends in the listening room. The sad part for many is that they can't even find a listening room let alone one they can get to in less than a days drive.

We feel very fortunate that our stereo shop is an hours drive away and their philosophy has always been let the customer listen until they hear what they want (although they will listen too and bring in new and used gear they think will fit with your listening preferences).

The latter, used gear, is also a wonderful thing as that is how we started. Our first system was a mix of new Creek 5350SE integrated amplifier and Naim CD5 CD player with a pair of used NHT 2.7 speakers, which we selected in the course of a mornings listening through each component type. It's why we do all our business with them in hopes they will always be there.

JURB said:

I've seen company after company go from high quality to hype quality.

There was a discussion on damping factor not too long ago. Comes down to that you can increase it by using remote sensing, but that voice coil resistance will always be there.

Yamaha might have nulled it out somehow, but it simply is not what they claim unless it has remote sensing.

There are no police for stuff like this. They can claim damnear anything they want anymore.

Click to expand...

Kenwood Sigma Drive does this. The closest I have heard is the Accuphase E-202 which has selectable DF that does not rely on feedback or some signal sensing like the others. I really like this feature in the E-202, the sound is noticeably different on the different settings.

I heard of that.

Actually, it seems to me that if you are not using the maximum damping, remote sensing is a waste of time.