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Old 18th February 2014, 10:00 AM   #11
tiefbassuebertr is offline tiefbassuebertr  Germany
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Location: D-55629 Schwarzerden
Any news concerning LEF?
I the attachment pdf schematic of an other power amp circuit approach from CEC:
Attached Files
File Type: pdf LEF CEC AMP3 power amp Section.pdf (52.2 KB, 231 views)
File Type: pdf LEF CEC AMP3 power amp Section-II.pdf (54.3 KB, 189 views)

Last edited by tiefbassuebertr; 18th February 2014 at 10:14 AM.
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Old 11th May 2015, 09:51 AM   #12
tiefbassuebertr is offline tiefbassuebertr  Germany
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Quote:
Originally Posted by Nelson Pass View Post
Actually sounds more like a single transistor driving a
complementary version of the Aleph current source. In
this design the N channel current source of say, the Penultimate
Zen, is complemented by a P channel current source and
together they form a push pull version of the current source.

If you set their current gain very high, they don't load the
single transistor very much, and so it works.

My experience with this circuit is that it can be made quite
good in performance, but as a practical matter the current
sources must be run pure Class A to avoid high distortion.

In the case of the CEC, this implies about a 900 watt idle.

Given the description I would be skeptical that you would
want to refer to the amp as Class A or single stage.
In this case I have found a description concerning LEF by the B.M.C. Amp C1 under
B.M.C. Audio Amplifier C1 integrated amplifier | Stereophile.com
Here I read follow:
The Unique Circuit
When we met following his visit, at the 2012 Consumer Electronics Show in January, Carlos Candeias told me that the Amplifier C1's circuit is neither class-A nor class-B; instead, he calls it Load Effect Free (LEF). He doesn't use energy-wasting class-A operation to eliminate crossover distortion and have transistors operate within a more or less linear range, because such designs still usually require some global feedback to further reduce distortion. If the distortion never happens in the first place, due to the choice of transistor operating characteristic, it doesn't need to be corrected.

Unfortunately the measuring results under
http://www.stereophile.com/content/b...r-measurements
indicates for me a harsh sound in the high frequency area above 2 KHz, and below 8 ohms load impedance (go to fig. 10). This is typical and usual at all class AB models with low idle current through the output stage.

Last edited by tiefbassuebertr; 11th May 2015 at 10:06 AM.
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Old 26th March 2020, 11:40 AM   #13
tiefbassuebertr is offline tiefbassuebertr  Germany
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any news ?
a friend of me, who use this model, want to remove the bad character of distortion in Fig. 10 unter
B.M.C. Audio Amplifier C1 integrated amplifier Measurements | Stereophile.com
and therefore a schematic diagram is necessary.

Last edited by tiefbassuebertr; 26th March 2020 at 11:43 AM.
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