What does Current mean in a power amp???

refere to ohm's law:
P = U*I = U*U/R.
where P is power, U is voltage and I is current.

If you have 8Ohm speakers than the current passed during the maximum power transfer of 100W/ch amp will be approximately 3.7A basing on above relationships.

Research 8th grade physics.

Nikki...,

Let me be straight forward on how good watts are different from bad ones...

If you for example take a look on professional power amps such as Carver highly regarded by DJs available at RadioShack stores, you can see and feel that it has a plenty of boost and the power(~300W/side) to any impedance load and pretty darn cheap(aka $250).

The Ohm's law mentioned up above states that ALL watts are "created" equal. The double wattage of the good amps into the lower impedance loads cannot be rated as a CONTINUES power and needs lots of lines to explain. Shortly I can say that price of an amp is not an explaination why one has a reserve power and the other one hasn't.

To increase the power you either have to increase the current or the voltage.

The main problem in this issue is our 110V wall outlet power that realy limits engineers to work on high-power-quality amps where designing a proper power supply is the most essential issue.

So to correct you in both threads I must state that the main design difference between "bad watts" and "good watts" is that the power supply is OK to handle the large current.

The quality of sonics (I must say here that it's completely different issue from wattage) is the quality of an active amplification elements(tubes, transistors, diodes) and also passive elements. The working area of an amplification elements in high quality equipment is selected so that it covers the widest-possible freequency bandwidth rather than working in the peak values. Thus more transistors or tubes is required to deliver the signal to desirable level with good output characteristics.

BTW the most successful setup with SA100 I heard with Genesis 5, Sonic Frontiers SFL2, Basis 2000/Plinius Jarrah/Dynavector 20XH/; Analysis+ 9 speaker wire, AudioQuest Diamondblack interconnects almost everywhere.

Listening to "Stabat Mater" by unfamous and forgotten italian composer Pergolesi, despite being so skeptical auditioning classical music, the voices were so real and 50y.o. vinyl made me forget about clicks and pops and dive into the music everything else simply dissapeared.

...now we're speaking in full engineer terms but let me clarify further:

First, we need to understand further the concept of IMPEDANCE rather than RESISTANCE. In case with DC we call it RESISTANCE. In case with AC we call it IMPEDANCE since it has a reactive components such as capacitance and inductance. The resulting complex value of impedance consists from active resistance R and reactance which is a complex value:

Z = R + i/2*pi*f*C + j*2*pi*f*L

where R is active resistance C is capacitance L is inductance i, j are directional vectors since capacitive reactance with inductive reactance is out of phase by 90degrees, f is the freequency and pi is the famous constant. The sum of members with directional vectors in the formula is called reactance which is the value excluding the active resistance. Please note that reactance consists of vectors and doesn't follow the arithmetic adding and certainly the Impedance is a vector value and has a direction.

So the Ohm's law for the alternated current will yeald: U = Z*I where U is voltage(volts) Z is IMPEDANCE(Ohms) and I is current (amperes)

As to the Bryston discussion it realy has not enough current for continues power and clips! Their professional models don't clip but sound pathetic. If you have Bryston amp you'd better not use low-impedance speakers, it will clip.

Bryston 4b-st for instance is not even capable to deliver 200W into 8Ohms as specified. Plinius SA100 rated 100W/8Ohms will rock much faster and easier and even louder with the speakers of the same sencitivity and impedance no $hit!

To finalize this situation I believe that 80% of that issue is depending on power supply and the rest is to electronics capability to deliver the current.

Sean, the equation I've mentioned is not as simple and yes, this equation is being used to specify the speaker impedance curve in responce to any particular freequency. The reactance is a directional part of an overall impedance and resulting vector of reactance can be negative and that's when the impedance falls can occur.

Indeed the music is a complex signal having lots of harmonics and subharmonics but it's more arithmetics still since the numbers we work here with is finite and can be calculated. The theory states that the signal of any arbitrary form or complexity can be represented by the sum of sine waves of different order(Fourier theorem) which means that the freequency(to be more precise a sinusoidal freequency components) of an arbitrary form signal can be defined using Fourier theorem.

As to your statement about the differences in sound with relatively same capabilities amps and the speakers first of all they're assume will be not too much audiable, second there is a specific formula but truly it doesn't make a sence to excersise it untill you find the family of infinitessimal values specifying these nano-ohms and nano-volts once again using a Fourier theorem along with Ohm's law.

As to the good amp formula so not to be so exhausted calculating limits using a complexed engineering formulas(certainly applied in more sophisticated amplifiers than audio) you're completely right and I believe that Plinius SA100 falls in this category.

Nikki, Brystons arn't bad at all as a budget amps having a huge 20Yr transferable warranty but I heard from many people that they can't drive the speakers that have impedance falls lower than 4Ohms -- they start to clip.

Plinius SA100 IMO is a champ.

Sean, Indeed Plinius gear(listened in several setups) is worm and musical. The situation you're describing I heard with Merylin speakers but than again I've never heard Merylins soft or musical.
SA-100 has a large range of operating in class A(upto 25W/ch) and has a closes to the tubes midrange. I assume that it will do the best with low-impedance speakers such as JM Lab 921, Thiel 3.6 and might be bright and hard driving high impedance speakers such as Coinsident.