As per the above lines one can see that how low output impedance allows nearly doubling (or even quadrupling in some accuphase amps in 1/4 th impedance ) of power when halving the speaker impedance.ok then let's start from scratch. you have speakers of 8ohm nominal impedance and amp with output impedance of say 0.1ohm. your normal listening level requires say 18w at speakers. so for 18w into 8ohm makes required voltage at speakers as 12v ( P=V^2/R) and corresponding current = 1.5A (i=V/R). for 1.5A current in the circuit, the voltage for internals of amp= 1.5x0.1=0.15V ( where 0.1ohm is output impedance of amp ). now lets find the power available for the frequencies where the load impedance drops to say 2ohm, assuming that amp is still providing overall voltage as 12+0.15=12.15V. now 12.15=i*(0.1+2) ( 0.1ohm is output impedance and 2 ohm is load impedance for frequencies for which impedance dips low ) so i here comes out to be 5.79 A. so power available in those frequencies is i^2*R=5.79^2*2=67.04w ( obviously this will be for momentarily music passages )
now we have an amp having 1.5ohm output impedance and we are still using those same speakers and listening for same 18w output at speakers ( here obviously 18w are as per average listening levels ). now voltage for internals of amp will be 1.5x1.5=2.25V (1.5A is current in circuit as calculated earlier corresponding to 18w in 8 ohm speakers and 1.5ohm is output impedance of amp ). so overall voltage by amp will be 12V+2.25V=14.25V ( you see with higher output impedance of amp the available voltage is less so you may need to crank up the volume to still get those 12v and 18w at speakers ) . now again current available for passages when load impedance dips to 2ohm, 14.25/(1.5+2)=4.07A ( 1.5ohm is output impedance and 2ohm is load impedance for passages when impedance dips low). now power available to those frequencies when impedance dips to low is 4.07^2*2=33.13w which is less than half of what when output impedance was 0.1ohm only. hope now it is clear how the higher output impedance is the culprit in not driving the difficult loads properly. higher impedance almost always thus colors the frequency response and is main reason for softer, slower and mushy sound of tube amps along with the usual harmonic distortion.
The amp's output impedance and the speaker impedance form a voltage divider in the simplest sense of the stuff. Do I need to explain a voltage divider?
Are you talking tube power amps? (as opposed to headphone amps) Don't most of them have output (voltage) transformer which would have an open circuit as an output impedance? I am no expert in amps with output transformers but the power transfer work differently than typical amps with feedback no? I may be wrong.
and... then this comment I made.>
Agreed
I refer you to:Agreed
"Buhu, it has a Volume control!", "The Volume Control is the wrong color", "I hate Volume control". And to top it all off, Mr Clueless chimes in with: "Does it have Volume Control?"
This is Chi-fi so most likely you can just rip the knob right out and throw it away if you have such grave issues with it.
I´m kidding of course... But my heart goes out to the designers of consumer electronics trying to satisfy all thesemoronspeople.
www.audiosciencereview.com
Point taken, I revised my post ever so slightly...I refer you to:
Has civility on ASR declined recently?
I have noticed an increase in combative and insulting posts on ASR over the last couple of months--mostly, but not always, by new members. The posters definitely have not seemed to heed the message at the top of every forum page to Come here to have fun, be ready to be teased and not take online...
Point taken, I revised my post ever so slightly...
Exactly I also never required to go to even medium gain on ahb2. Modern dacs have high enough clean output for low gain of ahb2. What more the beauty of ahb2 is that it is rated 100w RMS at it's minimum distortion figures not at 10% thd or not even 1% thd. So ahb2 is lot more powerful than many other high end amps.
