The company's full name is Infigo Audio Inc. in Canada. CEO is Hans Looman. Their amp is called Method 3 ...So I searched USPTO for patent/applications but found none.
https://infigoaudio.com/page/method-3/
In my third reading of the sales pitch. I never see the word “pure” uttered. Just that the amp presumably stays in class A.
It suggests to me, that it may be class A/B and controlled such that it never leaves class A. Perhaps with control of bias. Maybe a look ahead PWM scheme of some sort with hard limiting?
I find it sort of bizarre that the length of the connection to the speaker is critical to it working optimally.
Fortunately, we’re ecstatically happy to have our ACA’s and some really efficient speakers. That is some pure class A!
In my third reading of the sales pitch. I never see the word “pure” uttered. Just that the amp presumably stays in class A.
It suggests to me, that it may be class A/B and controlled such that it never leaves class A. Perhaps with control of bias. Maybe a look ahead PWM scheme of some sort with hard limiting?
I find it sort of bizarre that the length of the connection to the speaker is critical to it working optimally.
Fortunately, we’re ecstatically happy to have our ACA’s and some really efficient speakers. That is some pure class A!
Similar to what I was wondering. Can you do AB and then figure some way to keep either half from turning off, and then call that A?
I guess in a sense it can be twisted around to make it come out that way. What it says is that it keeps the amplifier “operating in class A at all times”. So let’s say the amp has enough devices strung together that it doesn’t transition to AB until it reaches 260 watts and you begin hard peak limiting by whatever means at a few tenths of a volt below the point it produces 250 watts.
If the driving signal is never allowed to exceed the point that the output current is twice the bias value. Then yes it would be operating in class A. It would probably be really distorted at that level. In its simplest form you could do that with a clipper diode on the input signal. The same kind they used in the past on telephone handsets to protect your ear if the person at the other end started yelling. Anything past 1.3 volts was sawed off.
Like it is pointed out in another response. The devil is in the details. It just says something keeps it operating in class A. But doesn’t say it is strictly class A topology.
Just my take on it! Clever marketing. Not really deceptive because a class AB is class A until it isn’t anymore. Unless you were trying to fill a stadium with audio. The only thing you’d be is deaf if you ever actually ran it at that much power.
Bob Cordell and I agree that it's Class A when both halves of a push pull circuit make a significant contribution to the output.
This leaves out circuits which remain conducting small amounts of current which are better described as "non switching".
Perhaps arbitrarily I would regard a 5 or 10 percent minimum contribution as adequate to be regarded as Class A.
This leaves out circuits which remain conducting small amounts of current which are better described as "non switching".
Perhaps arbitrarily I would regard a 5 or 10 percent minimum contribution as adequate to be regarded as Class A.
"The amps only consume 35Wpc in idle."
Maybe therein lies the answer...Class A for the first 10W or about a third of that value.
Maybe therein lies the answer...Class A for the first 10W or about a third of that value.
But thats not what they claim on webpage...classA all the time. It never leaves classA to AB.
That's exactly what they claim. Hence the speculation about sliding bias.
But its all just speculation without the schematics.
That's exactly what they claim. Hence the speculation about sliding bias.
But its all just speculation without the schematics.
Another member of this forum and I did simulations on a topology which consisted of an asymmetrical output stage that tried to achieve something like that about 10 years ago. One output device is within the feedback loop controlling the output voltage. The second output device was part of a control loop that is keeping the amount of bias current to an absolute minimum all the time.
The simulations looked very promising from a THD point of view but it wasn't easy to achieve stability.
Regards
Charles
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imho, you can use class h topology with idle current in class a . but 35w to 250w is too much difference .
We would have to see some sort of schematic.
I did get a later patent on a cascoded push pull follower That biased the outputs into "pure" class A, but the cascodes were not, and even then the 35 / 250 watt ratio is not realistic...
I did get a later patent on a cascoded push pull follower That biased the outputs into "pure" class A, but the cascodes were not, and even then the 35 / 250 watt ratio is not realistic...
Off topic, but electric vehicles tow great. They're very efficient, though, so towing increases the load in a logical manner such that energy equivalent MPG drops from something on the order of 100 to something closer to 50MPG. That's still amazing, but when the battery size is only something like 3-4 gallons of gas equivalence (in kWh), the resulting range drop doesn't make towing worthwhile for most.
Gas/diesel vehicles are so inefficient and their fuel so energy dense, towing doesn't seem to cause much penalty.
(EDIT: I did find a Lightning review that said torque felt poor in passing ranges, so that particular vehicle may have other (gearing) issues. But towing a heavy Airstream with a Tesla Model 3, which is not rated to tow at all, can work pretty well.)
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From the Infigo website:
"Our special design keeps the amplifier operating in class A at all times, without cooking the room."
"at all times" seems like pure class A to me.
"Our special design keeps the amplifier operating in class A at all times, without cooking the room."
"at all times" seems like pure class A to me.
F150 lightning did ridiculously bad. Could pull beans, and mileage range went nothing not so great.
"Cool class A" sounds like "cold fusion"
Oxymorons...like the F150 lightning.
Battery tech has a long way to go before those make sense. And if it gets that far, electric vehicles will become as ubiquitous as the grid ( and supplementary power sources ) will allow.
"Coal powered environmentally friendly vehicles"
😉
Oxymorons...like the F150 lightning.
Battery tech has a long way to go before those make sense. And if it gets that far, electric vehicles will become as ubiquitous as the grid ( and supplementary power sources ) will allow.
"Coal powered environmentally friendly vehicles"
😉