As @amirm said:
Probably because he saw early on it wasn’t a stellar performer, so wanted to save time.
That was one of the biggest "marketing vs reality" scandals this site has seen.moreover this F2 amp is reminiscent of the Starke Sound AD4.320 which uses the same PSU and almost same design
ASR measurments :
I reviewed and measured the Starke Sound AD4.320 multichannel amplifier a few months ago. This is the measurements of a second sample kindly sent in by a member.
The first sample missed its power by a factor of two. Company disputed this and promised their own measurements that would show otherwise. This did not materialize. We did find out that the review sample received by Audioholics had similar power shortfall to my (new) sample. Explanation given through Audioholics was that a few samples had miswired power supplies rated for 240 instead of 120. This was puzzling...
Complex load vs pure resistive one... Seems to make sense though difficult to raise a standard...
There is no problem at 4 ohm, flat frequency response, only 8 ohm causes trouble.
My question was re: "another question is do we still need 8 ohm passive speakers as standard nominal impedance?
It is a very common issue with class D amplifiers, though some offer now blameless performance.
I gave it a “not terrible” rating. The measurements are nowhere near SOTA, but they aren’t THAT bad. They aren’t particularly good, and are not a good value for the money, but are “not terrible.” They are most probably below the limit of audibility, but if your speakers are highly inefficient, then at certain points when the amp starts to run out of gas, it might have audible consequences (ie, clipping due to not having enough headroom). But that holds true for any 100wpc amp.
Yes, if you call a whole lot from 300 moneys upwards "some", and 20 years ago (Hypex UcD release) "now" or "recently".
The electrical impedance of a speaker or speaker system can be represented as magnitude and phase or as a real and imaginary part. The real and imaginary representation is the most useful. The real part of the impedance is what you call "true impedance" and represents the load into which the amplifier delivers real power. The imaginary part determines the reactive power exchanged between the load and the amplifier and not transferred to the load. The Dayton measurement system should be able to represent the impedance as a real and imaginary part (DATS V2 and V3 do). This saves you from calculating the real part (multiplying the magnitude by the cosine of the phase angle). Now, suppose a system has a minimum of 2 Ohms at 100 Hz and the amplifier does not have enough current. The amplifier clips, but not only at 100 Hz: it becomes "blind" to anything presented to its input (until linear operation is re-established). This is one of the reasons why multi-amplified systems are superior to passive systems. If one amplifier clips, the others continue to function, and distortion, even if present, is much less noticeable.
