Thule Audio PA350B Multi Channel Amplifier Review

[gene]

<P class=MsoBodyText style="MARGIN: 0in 0in 0pt"><FONT size=2><FONT face=Arial><SPAN style="mso-bidi-font-size: 10.0pt; mso-bidi-font-family: Arial"><A href="http://www.audioholics.com/productreviews/avhardware/ThuleAudioPA350Bp1.php"><IMG style="WIDTH: 125px; HEIGHT: 94px" alt=[IMGP2454001] hspace=10 src="http://www.audioholics.com/news/thumbs/IMGP2454001_th.jpg" align=left border=0></A>The Thule PA350B multi-channel amplifier left me with mixed recommendations.<SPAN style="mso-spacerun: yes">&nbsp; </SPAN>As a 2CH bridged amplifier, its power reserves&nbsp;and measurements were excellent -&nbsp;able to belt out over 500 low distortion watts into the 4 ohm new RBH Signature T30-LSE Super Speakers in our Showcase Reference System.<SPAN style="mso-spacerun: yes">&nbsp;&nbsp;The PA350B's</SPAN>&nbsp;sound quality&nbsp;was both smooth and dynamic!&nbsp;<SPAN style="mso-spacerun: yes">&nbsp;&nbsp;However, a</SPAN>s a 5CH amp, it fell short of its published power specifications though still performing above average. Thule’s fully complimentary circuit topology from input all the way to the speaker output is rarity in the audio industry but it pays dividends in achieving exemplary low distortion figures.<SPAN style="mso-spacerun: yes">&nbsp; </SPAN>Combine these virtues with its switching rail power topology, relatively high efficiency and compact chassis and its high price tag may seem a little less disheartening, especially for those with limited rack space.<?xml:namespace prefix = o /></SPAN></FONT></FONT></P>
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[Mobster]

Hi!

I just read the review and I noticed something that I had to check from Thule (I read again the Thules 'Virtual Class A' -documentation). I have looked at one Thule amp and had read their literature recently. And I started wondering...

In the review the following is stated:
"...most modern linear amps these days are of a Class A/B design where the amp operates in Class A for low power levels. Although Thule was able to achieve a higher bias into Class A while preventing excessive heat build up by rail switching at higher power levels."

As far as I understood this means Thule is just using higher bias current (100mA)? And when an A/B amp is switching from A into B with higher current the other transistor is switched off like normal A/B amps do?

But when reading Thules document:
"...a variable control voltage in tune with the musical signal, is used to set the idle current, so that the idle current is maintained through both output transistors regardless of the output current. This means that both output transistors stay active the entire time."

Doesn't this mean that the transistors are not switched off - no matter what level of current is output? So the reviewed Thule would actually differ from traditional A/B amplifiers and would not be just a high biased A/B? It would not make it a 'true' Class A-amp since those might have full current flowing through transistors instead of a low variable current.

Which one is right? Is it just anohter class A/B amp or do they actually have something more sophisticated inside?