Pass labs xa25 amp and BW 804 d3?
The X250 isn’t even a class A amp. It’s a high bias class AB amp with a single ended bias of 20 watts. Contrast that with the XA25 with it’s 50 watt class A envelope. That’s a plenty of amp for most people. https://www.passdiy.com/project/articles/leaving-class-a |
Macguy said his meter indicates the amplifier remains in "class A operation". So the first 20 watts of the x250 is bias in class A (bias set at 0.8 for this model per the Nelson Pass article). At his listening levels the Vandersteen speakers aren’t demanding of more than these first 20 watts. I suspect that very often not more than a few watts are utilized at easonable listening levels. Charles |
Exactly. That's my point. Folks really don't seem to have a grip on the scale of power they're really using, then go buy massive triple digit amps because they heard somebody talking about "headroom". As one reviewer of the F5 put it, if you're speakers need more power than the F5 puts out, they're just poorly designed speakers. |
I do understand the desire/concern of many listeners in regard to "headroom" availability for demanding musical peaks and the fear of having insufficient ’juice ’ on hand. This is a common topic in audio forums. I do think that to some extend it gets blown out of proportion. I do not agree with the popular audiophile axioms, "the more power the better" or "enough power is never enough". I’ve read (more than a few) testimonials on various forums from those who drive their 100 db> horn speakers with 200- 300 watt amplifiers so that they "never run out of headroom" regardless of volume or music genre demands. So without any doubt there are those who have different perspectives and experiences. Speakers of this type can provide reasonable SPLs (65- 75 db C weighted) with only 1/20- 1/100 (0.05 to 0.01) of 1 watt Charles |
A minor point but one that should probably be mentioned is that the Vandersteen 5 has a built-in amplifier handling the deep bass. And it is designed to be used with a passive high pass filter inserted between the preamp and the power amp, which rolls off low frequencies by 3 db at 100 Hz and at 6 db/octave below that frequency. (The built-in sub amp provides a complementary frequency response which restores overall flatness). So the power that is demanded of Macguy’s X250 is significantly reduced relative to what be required if it were driving a comparably efficient speaker full range. In any event, it appears that the Vandersteen 5, like the currently produced 5a Carbon, is rated at 87 db/2.83 volts/1 meter, but apparently has an 8 ohm nominal impedance rather than the 5a Carbon’s 6 ohms. Assuming those specs are accurate it can be calculated that at a typical listening distance of say 10 feet, and in a medium sized room, two such speakers will produce an SPL for a centered listener that is in the vicinity of 95 db when both are driven with 20 watts. Enough for many listeners on most or all of their recordings, but certainly not enough for some listeners, especially on recordings having wide dynamic range. I do not agree with the popular audiophile axioms, "the more power the better" or "enough power is never enough".I disagree with those axioms as well, Charles. A point that seems to often be overlooked by proponents of those axioms is that for a given level of amplifier quality more watts usually = more $, at least within a given amplifier topology and a given class of operation (A, AB, D, etc.). So if a given amount of money is to be invested in an amplifier of a given topology and class of operation, choosing an amp that has more power capability than necessary may very well mean that more of those dollars than necessary will be directed toward watts rather than toward quality. At least that’s how I see it. Best regards, -- Al |
