I'm not knowlegeable at all. Most of what is written here loses me. However there is something that generally puzzles me. So few posts about MOSFETs.
I always believed that : valves(tubes) won't work for big amp (500W) and are fragile. Transistors are a little ......cold. FETs give a warmer sound while handeling real power and being robust.
...................... very little talked about. Why?
I always believed that : valves(tubes) won't work for big amp (500W) and are fragile. Transistors are a little ......cold. FETs give a warmer sound while handeling real power and being robust.
...................... very little talked about. Why?
OK, get your point. One reason might be that most people don't
find the need for such immense power. Another thing worth noting
is that some designs are more or less easily scalable to higher
powers by paralleling output devices (and maybe drivers). Take
for instance Slones Optimos design, which is scalable up to 400W.
I think also Holtons amp can be configured for various power levels
up ot around 400W. I you need more, I am sure both of these could
be slightly modified to cater for that. Pick you choice of amplifier and
start a thread on how to modify it for higher output power.
find the need for such immense power. Another thing worth noting
is that some designs are more or less easily scalable to higher
powers by paralleling output devices (and maybe drivers). Take
for instance Slones Optimos design, which is scalable up to 400W.
I think also Holtons amp can be configured for various power levels
up ot around 400W. I you need more, I am sure both of these could
be slightly modified to cater for that. Pick you choice of amplifier and
start a thread on how to modify it for higher output power.
Why? I like mosfets and they are hard to destroy but I'm also fully aware of it's drawbacks. Sometimes BJT are much better.Pbassred said:
It's a matter of knowing the part and it's characteristics.
Hello, Mr. Ampman. You are fantastic.
Why don't you put a website with all your stuff. I wonder how your amps look like.
is 2kW really the limit!??
Commentable Thoughts
Hi P-e-r-a-n-d-e-r-s
ThanX for ur advice about Website, I will certainly Think about it!
As far fantasticity is concerened I think u r more fantastic than ampman, aren't u.
To be serious 2KW is not end of my limit.
Regards
Ampman
peranders said:
Hello, Mr. Ampman. You are fantastic.
Hi P-e-r-a-n-d-e-r-s
ThanX for ur advice about Website, I will certainly Think about it!
As far fantasticity is concerened I think u r more fantastic than ampman, aren't u.
To be serious 2KW is not end of my limit.
Regards
Ampman
Pbassred said:
Most of what is written here is about AB type amps with
reasonable idle dissipation, where Bipolars have the distortion
edge. Mosfets become more attractive in simple Class A
designs.
Also, I have noticed that some people are simply afraid of
Mosfets after they hear about the handling and matching
precautions, which are often overblown.
MOSFETs can sound very warm when applied correctly in a circuit--indeed they can sound quite nice in very simple circuits, incl single ended.
Discrete MOSFETs don't see a lot of play perhaps due to durability concerns. Remember that IRF MOSFETs are the reason why Counterpoint went out of business. This was probably due to a poor understanding of "thermal inertia".
It doesnt take much to kill that metal oxide layer. Something else people don't realize is that you can weaken or fatigue that layer and never know it until a later time when the MOSFET mysteriously craps the bed--either by itself or after making a minute and possibly unrelated change to the circuit. Thus, some MOSFETs have earned the reputation for being extremely sensitive (when really they are just subject to cumulative damage).
Note that Nelson's designs utilize HUGE heat sinks and many paralleled devices... In fact he even comments on his DIY site that the heat sinks really shouldn't exceed about 50C. When used in this manor, MOSFETs are likely very reliable.
Discrete MOSFETs don't see a lot of play perhaps due to durability concerns. Remember that IRF MOSFETs are the reason why Counterpoint went out of business. This was probably due to a poor understanding of "thermal inertia".
It doesnt take much to kill that metal oxide layer. Something else people don't realize is that you can weaken or fatigue that layer and never know it until a later time when the MOSFET mysteriously craps the bed--either by itself or after making a minute and possibly unrelated change to the circuit. Thus, some MOSFETs have earned the reputation for being extremely sensitive (when really they are just subject to cumulative damage).
Note that Nelson's designs utilize HUGE heat sinks and many paralleled devices... In fact he even comments on his DIY site that the heat sinks really shouldn't exceed about 50C. When used in this manor, MOSFETs are likely very reliable.
No.....................
"IRF MOSFETs are the reason why Counterpoint went out of business"
WRONG! The reason the mosfet amps blew up is because Mr. Elliot refused to use Source resistors. The last mosfet amp from Counterpoint that I worked on had Harris mosfets. Most of the Counterpoint stuff was pretty unreliable. Mr. Pass's amps with IRF mosfet outputs are extremly reliable as are a few others I know of with
source resistors. Get your facts straight before jumping to such mistaken conclusions.
http://www.altavistaaudio.com/100repair.html
For the alleged reason for Counterpoints demise.
http://www.altavistaaudio.com/Counterpoint_News.html
"Discrete MOSFETs don't see a lot of play"
There are many successful amplifiers with mosfet output devices. For over a decade! Where have you been?
"IRF MOSFETs are the reason why Counterpoint went out of business"
WRONG! The reason the mosfet amps blew up is because Mr. Elliot refused to use Source resistors. The last mosfet amp from Counterpoint that I worked on had Harris mosfets. Most of the Counterpoint stuff was pretty unreliable. Mr. Pass's amps with IRF mosfet outputs are extremly reliable as are a few others I know of with
source resistors. Get your facts straight before jumping to such mistaken conclusions.
http://www.altavistaaudio.com/100repair.html
For the alleged reason for Counterpoints demise.
http://www.altavistaaudio.com/Counterpoint_News.html
"Discrete MOSFETs don't see a lot of play"
There are many successful amplifiers with mosfet output devices. For over a decade! Where have you been?
Commentable Thoughts
Hey man all ur comments on IRF MOSFETS are not Logicable!
We are Professional Manufacturers Of Power Amplifiers and we exclusively used IRF N-Channel MOSFETS in output stages.
We have never encountered a single failure of device in 7 Years and regarding thermal runaway our amps use source resistors to proveide stability and we also never had any thermal runaway yet.
Regards
Ampman
JFETglare said:
Hey man all ur comments on IRF MOSFETS are not Logicable!
We are Professional Manufacturers Of Power Amplifiers and we exclusively used IRF N-Channel MOSFETS in output stages.
We have never encountered a single failure of device in 7 Years and regarding thermal runaway our amps use source resistors to proveide stability and we also never had any thermal runaway yet.
Regards
Ampman
Re: No.....................
the story doesn't make a whole lot of sense to me. it first talked about the company volunterily filing chapter 11, and then it followed up to say that the bank "took this action" to put the company in chapter 7, especially when the loan was "current". a bank cannot foreclose on a loan that's current.
so I suppose there are something else in the story that wasn't presented on that page.
Fred Dieckmann said:
the story doesn't make a whole lot of sense to me. it first talked about the company volunterily filing chapter 11, and then it followed up to say that the bank "took this action" to put the company in chapter 7, especially when the loan was "current". a bank cannot foreclose on a loan that's current.
so I suppose there are something else in the story that wasn't presented on that page.
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