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  ExtremeA Class A Amplifier by Sander Sassen 
 
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Michael Taplin Feb 26, 2007, 04:50am EST Reply - Quote - Report Abuse
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In the past using a class A amplification at high power levels for its low thd was a bit of a joke because every other component in the amplification stage was so noisy or distortion prone, particularly the highly reactive loudspeakers. I have not kept up with the technology of output devices. I know significant progress has been made. I would like to know what hardware the author would reccommend their Amplifier be used to drive? What the thd of the complete amplifier chain would have. Also given the logarithmic roll off of human hearing, whether we could distiguish between his class A of a good quality A B output design?


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Sander Sassen Feb 26, 2007, 06:51am EST Reply - Quote - Report Abuse
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>> Re: ExtremeA Class A Amplifier by Sander Sassen
Obviously you'd need a quality loudspeaker to fully appreciate the quality of this amplifier. Moreover, driving it from a single-ended, rather than the intended balanced source would negate many of the benefits. I can't really say how it compares to a run-of-the-mill class-AB, as theirs millions of them out there, with specs ranging from atrocious to mediocre for the majority of commercial designs by popular brands.

Best regards,

Sander Sassen
Editor in Chief - Hardware Analysis
ssassen@hardwareanalysis.com
Freddie Villanueva Apr 11, 2008, 11:48pm EDT Reply - Quote - Report Abuse
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>> Re: ExtremeA Class A Amplifier by Sander Sassen
I would like to try this amp. Where can I buy the kit if I decide. Is it possible to add more transistor in parallel to get more power? Let me know.

Thanks,

Freddie V

Sander Sassen Apr 12, 2008, 05:26am EDT Reply - Quote - Report Abuse
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>> Re: ExtremeA Class A Amplifier by Sander Sassen
Freddie,

Bare PCBs are available, as mentioned in the last page, contact me for details. Using more output devices would allow you to raise the idle current and hence achieve higher output power, the penalty however is you'll need an even larger heatsink.

Best regards,

Sander Sassen
Editor in Chief - Hardware Analysis
ssassen@hardwareanalysis.com
Derek Wilson Sep 19, 2008, 04:45pm EDT Reply - Quote - Report Abuse
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>> Re: ExtremeA Class A Amplifier by Sander Sassen
Further to my email earlier today (six monoblocks for an active tri-amped system) can you tell me would it be possible for me to buy the bare boards and then populate them as per your instructions but with a few selected component "upgrades" allowing for space on the board.
Have you any recomendations on which components you feel would give the best bang for the buck ( not literally !) if you were to do so.
Also what is the bandwidth of the finished design?
What is the minimum surface are of alloy heat sink you would safely recomend for the full 100 watt per channel?
What is the maximum current draw into 8 Ohm, 4 Ohm and 2 Ohm respectivley?
What is the price of boards and how long is delivery time for the boards, and also your power supply.
Lastly and most importantly...how does the finished design compare with the sound quality of a well built Hypex 400 watt set up..?

Many thanks in advance of your reply.

Derek Wilson.

Michael Taplin Sep 21, 2008, 05:46am EDT Reply - Quote - Report Abuse
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>> Re: ExtremeA Class A Amplifier by Sander Sassen
For the sake of the carbon footprint I should recommend AB because any low distortion AB is more efficient and indetectably different, except when measured by laboratory equipment, from class A circuits. Historically double blind listening tests by many manufacturers have proven this. Also we have the digital revolution where a reevaluation of all we held sacred comes under the modern microscope of further progress.

Derek Wilson Sep 24, 2008, 10:53am EDT Reply - Quote - Report Abuse
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>> Re: ExtremeA Class A Amplifier by Sander Sassen
If anyone has actually built this amplifier in the last 18 months please let me know as I would be greatly reasured to hear your opinions!
The amp looks on paper to be a true reference standard although it is horribly inefficient and therefore expensive as far as electricity bills go!
I am very tempted to buy a full tri amped set up and use it as my ultimate reference standard.
My utopia would be a Hypex based ultra efficient design that sounds as good but does not "cost the Earth" to run!!!
Once the true digital amps (not chip amps or class D or switching technology) based around Zetex and a few other developing technologies get going all our problems with power amps, pre amps, DAC's DSP crossovers and room correction / EQ all go away!!!

One box to rule them all really is only 18 months away or less (NAD / Zetex are launching a "half way house" market testing product in the next 6 months) but I need a true as good as gets reference to use as my reference when comparing all the new contenders.

Any feedback on the ExtremeA will be gratefully received.

Thanks
Derek.


Frans de Kok Apr 28, 2009, 10:32am EDT Reply - Quote - Report Abuse
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>> Re: ExtremeA Class A Amplifier by Sander Sassen
Hallo Sander,
I am interested in building this amp (2 mono blocks). Pls send me info with repeect to the prints.
Can you shere pictures, adresses to order parts, etc.

Regards

Frans de Kok

Sander Sassen Apr 28, 2009, 11:04am EDT Reply - Quote - Report Abuse
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>> Re: ExtremeA Class A Amplifier by Sander Sassen
Frank,

Please send me an email at ssassen[at]hardwareanalysis[dot]com and I'd be happy to send you all the relevant info, as well as a translated version of the article in Dutch.

Best regards,

Sander Sassen
Editor in Chief - Hardware Analysis
ssassen@hardwareanalysis.com

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