Why all this fuss about power consumption? No one seems to bother about the hundreds of watts consumed by computers,especially those with high performance Graphic Cards!
Just sit back and enjoy the superb sound of Class A !!!
Just sit back and enjoy the superb sound of Class A !!!
some of us have limited 'funds', and need money to build this stuff
personally I enjoy music 24/7
and I enjoy this hobby too
but just sitting there is not my game anymore
or maybe I simply dont have time for that
maybe because there are no other alternatives
QUOTE=Alan Frobisher;3531444]
Just sit back and enjoy the superb sound of Class A !!![/QUOTE]
yes, but also possible with other than classA
Hi, just bumped into this thread. Lots of concern about power consumption and rightly so - but how many of us sit down and watch a plasma TV for a few hours an evening that consumes 300+ watts compared to about 90watts for LCD. Me, I'm quite happy to pay the extra in electricity cost to have quality.
Alan
Alan
Because government said to save the energy.😀
Also in my experience Class A is no longer superb.😛 JLH, SE RF triodes, SE source follower hexfet, all vs future design of class B. Just like 100W bulb vs 11W philips energy saving lamp.
I personally fuss over it because I don't want to pay (in heatsinking, electricity, and occasionally AC) for a drop more of class A than I actually need to drive just the top end. Bass doesn't deserve class A...
the top end is indeed important, it is where good imaging coming from, it couldn't be acieved with old style class AB anyway. It need really different classAB. This incoming classAB may kill all inefficient classA, because sound characthers are easily adjusted to what it need to be.
I had a chance today to do some serious listening to my amps. The amps I compared were two KSA 50's, an Elliot P101, Leach Low TIM, Aleph-X and a Symasym. The winner in my book was the Symasym. Speaking of imaging? When I hooked up the Symasym, it was like I walked into the room where the band was playing. Better clarity and soundstage than any of the others. I'm not sold on the Class A superiority.
In all fairness to the Aleph-X, there were some decisions made during the build that probably changed the sound. I used the MTW32N20E/D devices and a 1200VA 12-0-12V transformer. I have only 16V rails. To be honest, it is the least favorite of all the amps I've built. I would love to hear one that lives up to the praises I hear from folks like yourself.
Right. Never heard that before. What _exactly_ is the incoming class AB?
How does it differ from the works done by Messrs. Self, Leach, Dean and Mooly?
These so called class A amplifiers should be abandonned ,
they are generaly far worse than AB class siblings caracteristics
wise and are inherently less reliable.
I suspect that they are appreciated not because of perfs ,
wich are almost always awfull , but because of non electronics
related psychology in that a warm body is perceived as being
alive while a cold one is seen as dead.....
they are generaly far worse than AB class siblings caracteristics
wise and are inherently less reliable.
I suspect that they are appreciated not because of perfs ,
wich are almost always awfull , but because of non electronics
related psychology in that a warm body is perceived as being
alive while a cold one is seen as dead.....
Wahab,
tell us why a 10pair EF output stage (To220 50MHz fT), with each pair biased to 125mA (Pq=3.1W), for a ClassA output of 2.5Apk will be
tell us why a 10pair EF output stage (To220 50MHz fT), with each pair biased to 125mA (Pq=3.1W), for a ClassA output of 2.5Apk will be
and why this will be
when it is an optimally biased BJT amplifier that is fully ClassA upto 25W into 8r0.
Most do not use 10 output pairs at low TDP , rather theses
are classic high power devices with huge heat amount to remove ,
but even in your exemple 62W/channel to dissipate permanently
will up the temp for all devices substancialy and transistors do not
like at all high temperatures , in fact the whole amplifier is less reliable ,
higher temp will reduce drasticaly the electrochemical caps life cycle
even if theses are 110°C rated.
On the bias , 125mA is not an optimum biasing , actualy
japanese audio transistors optimum is at way lower values ,
somewhere in the 30mA-70mA range , even with 0.22R emitter
resistors , wich i suppose you took as base so that the 125mA
yield 26mV voltage drop , as per D Self assumption that it yield
lower THD , wich is wrong since he didnt provide any mathematical
explanation to this number.
The weather say it is 25 degree Celsius outside. You may yelling, " It is hot!" No. It is not hot for Indonesia people like me.
People might tasted differently. So, subyectivisme is useless for engineering. If there are any taste that can not be measure, let find how to measure them.
People might tasted differently. So, subyectivisme is useless for engineering. If there are any taste that can not be measure, let find how to measure them.
you surmised correctly that I was aiming for 26mVre.
That figure has been confirmed by other Member amplifier Designers.
I do not think the optimally biased BJT is in doubt, even though you put little faith in D.Self's derivation of the values he quotes.
However, you may be referring to the transistor's internal re and the effect this would have on the crossover distortion vs Vre(apparent external value). Optimal biasing requires the the crossover distortion be minimised and the Vre measured on that actual amplifier for this crossover distortion minima.
Since I didn't state the Re value, I left the method of determining minimum distortion using Vre open.
A good Designer and/or Builder will design the operating temperature such that it is reliable. If that requires a bigger heatsink on which to mount the 22, or more, To220 devices then that is what is done.
If a ClassAB amplifier uses just one pair of To247/264 devices and works at a reliable temperature on a far smaller heatsink then so be it.
That is no reason to tar all ClassA amplifiers as unreliable.
So back to your assertions in post113.
Can you justify these criticisms?
Post115 shows prejudice rather than engineering.
Can you justify these criticisms?
Post115 shows prejudice rather than engineering.
Tinitus😀o I detect the voice of youth? Wait until you are my age,you will want to sit around!
Still4given:Horses for courses.Where high sound levels are required,a good Class AB fits the bill,but at low levels(and when sitting around(see above!) ),the ear tends to be far more critical of what it hears,hence Class A.
Still4given:Horses for courses.Where high sound levels are required,a good Class AB fits the bill,but at low levels(and when sitting around(see above!) ),the ear tends to be far more critical of what it hears,hence Class A.
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