Arny Krueger wrote:
"Sander deWaal" wrote in message

" said:

Krell 350 Watt monoblocks @ $17,500.00 per pair
350 watts wpc @ 8 Ohms
700 wpc @4 Ohms
1400 wpc @ 2 Ohms
Signal to noise = 118db 95 db @ 2.83 V
THD = .05% 20 Hz - 20 kHz
Input Impedance = 100 K Ohms
Input Sensitivity = 2.6v RMS for max power
Voltage gain = 26.4 db

---------------------------------------------------------------------------------
QSC PLX 3402 Stereo amp $1200.00
700 wpc @ 8 Ohms
1100 wpc @ 4 ohms
1700 wpc @ 2 ohms
Signal to noise 107 db
THD = .03% 20 Hz - 20 kHz
Input Impedance = 6 K ohms
Input sensitivity = 1.9 Volts @ 8 ohms
Voltage gain = 32 db


One of the things that I noticed immediately is the
ability of the Krell to deliver twice the power (meaning
current) in half the load, up to 2 ohms.
I suspect that even in 1 ohm the figure would be close to
the required 2800W, be it for a brief period of time.
The QSC has only marginally more power into 2 ohms (not
that those insanely high wattages have any meaningful
use, you will note).
Also, the current doesn't double with half the load.
This means the Krell has a stiffer power supply, despite
the lower average wattage. It is a true constant voltage
source.

Just shows that Sander is easily snowed by raw specsmanship.

It's pretty well known in the industry that the Krell
ratings sheet has been juggled by Krell. The 8 ohm power
rating was backed off, to create the impression that it is
an ideal amp and puts out twice the power into 4 ohms. If
the Krell amp were rated more conventionally based on those
tests that Sander's buddy Middius hates, there would be a
different story.

The input impedance of the QSC amp is rather low,
something to keep in mind when driving it directly from
an opamp's output.

Most conventional audio-grade opamps have absolutely no
problem driving a 1K load to 5 volts rms,

What good is that if 1.7 V will drive the QSC to clipping
into a 4 ohm load?

let alone just 2.
Ditto for modern preamps, whether vacuum tube or SS.

But not all. I have a CD that didn't like it. As I said before
(and Arny snipped cuz he couldn't address it), that low input
impedance probably leaves the
passive attenuator pres out.


The input sensitivity should have nothing to do with the
output load impedance, is this a typo, a mistake or does
the amp use such a high amount of global feedback that
the load has influence on the input? In the latter case,
problems might arise with strongly reactive loads, and
this may make for a different sounding amplifier.
I also noticed the DF isn't specified.

Shows that Sander can't see that the amps input sensitivity
is scaled to its output ratings into various load
impedances.

BS... Sander's right and only cheap ass amps whose max output
voltage diminishes as a function of load need do this.

You say Krell underrates their 8 ohm capability...
I say QSC overrates theirs.

Which would you prefer.. an underrated amp or an overrated amp?

ScottW