Please read the article carefully again, my friend. Professor Leach did tried but failed in the attempt. He did not meant to critize MOSFET. He simply stated that with such a high slew-rate in his design, the MOSFET available to him at that time was not suitable for his application.
No one type of electronic devices is more superior than others. It is really depend on how you use it. IMHO, MOSFET is probably the best device for audio power amplification if the front end circuitry is carefully designed to get the most out of it.
Somtimes two good things put together does not always generates perfect result.
No one type of electronic devices is more superior than others. It is really depend on how you use it. IMHO, MOSFET is probably the best device for audio power amplification if the front end circuitry is carefully designed to get the most out of it.
Somtimes two good things put together does not always generates perfect result.
Workhorse said:
I guess that will depend on the application......
If you have a higher VAS rail voltage compared to the output stage I think it is possible to use the fet with some advantages - and If they sound good it looks like a win win situation for high power amps.
If however you have the same rail voltage to the VAS and output stage it is more difficult to fully use the advantages of the mosfet.
If you have a way to get around this problem please let me know as I would like to try my hands on some sort of fet output stage design...
Looking forward to your helpful input
\Jens
JensRasmussen said:
Hi Jens ,
This problem[Rail Loss] is not with FETS , but with the design criteria of designer.....and how well the designer succeed in mentoring his design
There many ways you could do it without higher VAS supply,,
1 . Bootstraping the Drivers[Simple Killer amp by Greg uses it]
2 . Using Floating Supplies for drivers[QSC uses it in PL6.0 Mosfet] amp
3 . String Differential Method with Bootstraping [Workhorse uses it ]
Whereas Second Breakdown Voltage is inherent with Bipolar Transistors and its their BIG FLAW.......
Mosfets were always a winner.......so we are!
regards & have a nice Diying
K a n w a r
Hi Jens,
...."If however you have the same rail voltage to the VAS and output stage it is more difficult to fully use the advantages of the mosfet.
If you have a way to get around this problem please let me know as I would like to try my hands on some sort of fet output stage design..."
I solved it most elegantly in the Simple Killer Amp topology, why can you not acknowledge this? It works a treat.
Cheers,
Greg
...."If however you have the same rail voltage to the VAS and output stage it is more difficult to fully use the advantages of the mosfet.
If you have a way to get around this problem please let me know as I would like to try my hands on some sort of fet output stage design..."
I solved it most elegantly in the Simple Killer Amp topology, why can you not acknowledge this? It works a treat.
Cheers,
Greg
amplifierguru said:Hi Jens,
...."If however you have the same rail voltage to the VAS and output stage it is more difficult to fully use the advantages of the mosfet.
If you have a way to get around this problem please let me know as I would like to try my hands on some sort of fet output stage design..."
I solved it most elegantly in the Simple Killer Amp topology, why can you not acknowledge this? It works a treat.
Cheers,
Greg
Greg,
Sorry I must have missed your schematics........
Please point me to where it can be found - thanks
\Jens
Hi Jens,
Do you have any answer for "My Answer For your Mosfet based Question in Previous Post" or it is your habit of ignoring something which doesnot suits you........
I think you haven't understand the schematic yet.......
K a n w a r
Do you have any answer for "My Answer For your Mosfet based Question in Previous Post" or it is your habit of ignoring something which doesnot suits you........
From where came the Bill Of Materials for the Simple Killer amp to help you, How is it associated with the designing, since the name already incorporates "Simple" as its first letter......
I think you haven't understand the schematic yet.......
K a n w a r
amplifierguru said:
Patent Pending ?
I would be interested to see how you differentiate your design from the "Lang" 20W class A mosfet amplifier which was published in 1985. Elrad Magazine & Audio Amateur "Power Amp Projects" book.
The topology is very similar.
( Can't show show circuit at present camera is lent out )
Unless you ARE Mr Lang, but I doubt that is case because he cascoded the driver stage and said is was a big contributor to the amps good sound.
mikelm said:Mmm.... OK now that I look at the circuits there are some fairly major differences...
I should say so.
Quite a number have built the Lang amplifier, easy but spectacular it is not. Overhere the design appeared in the November 1985 issue of Radio Bulletin, a regular A1A2A3 design with Vas as A2 in Guru Ball's lines. The Fig2 block-schematic in the article is even drawn as such.
Mr Ball's design seems to have a "five easy pieces" feel to it.
Bloody H. , i might even turn esoteric ecologist.
Thanks Jacco,
..."Mr Ball's design seems to have a "five easy pieces" feel to it.
Bloody H. , i might even turn esoteric ecologist. "
Hi mikelm,
My heart sank there for a moment when I read your post's - but there's little in common with that Lang amp except comp diffl's..
his following stages are very conventional and, I must say, wasteful and complex in the supply. The cascode Vas only swings +/- 18V so, with 3-5V output EF losses, output is only 13-15V or barely 12Wrms.
My S.K.A could get over 20W from this same +/- 20V supply and wouldnt need the 24V supplies at all. But, with +/-55V supplies
can do 150W!
Cheers,
Greg
..."Mr Ball's design seems to have a "five easy pieces" feel to it.
Bloody H. , i might even turn esoteric ecologist. "
Hi mikelm,
My heart sank there for a moment when I read your post's - but there's little in common with that Lang amp except comp diffl's..
his following stages are very conventional and, I must say, wasteful and complex in the supply. The cascode Vas only swings +/- 18V so, with 3-5V output EF losses, output is only 13-15V or barely 12Wrms.
My S.K.A could get over 20W from this same +/- 20V supply and wouldnt need the 24V supplies at all. But, with +/-55V supplies
can do 150W!
Cheers,
Greg
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