Reminder: how to tell current from an amp's specs?


I have a sinking feeling that I've been here before but, as the subject line says, how can I tell an amp's current from its published specs? 

Thanks!

northman

@atmasphere 

If I can point something else out: Just because your amplifier can drive to 2 Ohms and is able to double power as it does so does not mean its sounding its best when doing so. All amplifiers make higher distortion when driving lower impedances! If you think that distortion is inaudible think again- the increased distortion is audible as increased brightness, harshness and a reduction of detail (distortion obscures detail) because most of that added distortion is unmasked higher ordered harmonics.

Hi Ralph 

I appreciate you pointing this out. It’s very often overlooked in these types of discussions. I have always failed to find the wisdom in designing low impedance/high phase angle (Difficult load) speakers that then require/demand massive amplifiers to drive them. An environment for the appearance of high odd order harmonic distortion. 
Charles

@atmasphere

“…

The REGA Osiris integrated amp is one of these exceptions. While it is a beefy hi-current and high WPC amp that doesn’t fully double down, it still has LOTS of current because of its high-end build and design. This is provided by those four Sanken output transistors per channel, that insure that no speaker is too hard to drive.

This statement is incorrect. The extra transistors make sure the output section can support the current without damage but if the power transformer lacks the current capacity it really won’t make any difference.

 

I’m no engineer but it’s still a beefy beast, It’s power supplies are big muthas,

it’s a no compromise, super high performance, 162 W into 8 Ω (250 W, 4 Ω), dual mono amplifier housed in a custom Rega CNC machined aluminium case. It weighs over 54lb.that provides more than enough current to drive the hardest of loads.

The Osiris uses two low noise, purpose designed 400 VA toroidal transformers using high-grade, fully bonded core material. Eight Sanken 200 W output transistors are used in a “triple” high current output stage enabling the Osiris to drive even the most awkward of speaker systems with ease.

@8th-note   how do you know the Thiel's will sound anemic in the bass with tube amps, have you ever tried a high powered tube amp with them? There is a guy running tube research labs gt800 tube amps with apogee full range and he said the bass was way better than any solid state amp that he had tried with them, and the list is long.

I asked Wendell at Magnepan that same question and he said:

 

"If the amp doubles its power between 8 and 4 ohms you will be fine."  In my experience, the Maggie .7 sounds best with class-A solid-state or a good push-pull tube amp. 

 

herb