Lm4702

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Re: Excuses excuses

glennb said:
You Hooking up a SAP-15N/P or SAP-16N/P pair of darlingtons is actually quite easy. I make no apologies for the blunders of people who don't actually know what they are doing, but learning by practical experience is a great tool.


The article from Elektor last summer points the way. ("Compact 200W Output Stage", Elektor, July-August 2005). If you don't subscribe to Elektor (you should) , you can purchase a PDF of the article from their website.
 
Rigid Engineering Topologies And Subjective Philosophy

Hi,

Just a simple minded idea. According to Peavey at

www.peavey.com/support/technotes/poweramps/classact.cfm

there is also design philosophy quoted from page 2 MOSFETS

"properly designed and used within design parameters, an amplifier will not have a characteristic sound -- the positive sound qualities attributed to vacuum tubes are actually artifacts of non-ideal preformance and musical sounding overload beyond electrical clipping".

With this design philosophy in mind

www.genzbenz.com/?fa=detail&mid=1839&sid=422&cid=95

states "with seperate FET and 12AX7 tube channels that can be selected independently or mixed togeather creating endless tonal possibilities".

So just the rigid topologies of A, B, AB et all and rigid electronics

theory and application, can still leave room for design philosophy

while investigating output stages, even odd FET and TUBE

parallel output stages philosophy.

Mark
 
LM4702 Audio Philosophy

Hi,

Written by Nelson Pass of Pass Labs

www.passlabs.com/downloads/articles/seclassa.pdf

We've heard Triodes, Pentodes, Bipolars, VFMET, MOSFET, IGBT ...

and appreciation of audio is a completely subjective human

experience ... we should no more let numbers define audio

quality than we would let chemical anaylsis be the arbiter of fine

wines ... why are we looking to reduce subjective experience to

objective criteria anyway?

Mark
 
LM4702 Output Stages And Amp Simulators

Hi,

With a GN X 3000 from www.digitech.com a musician can

simulate 40 amp models and 25 speaker cabinets and with a POD

X Live from www.line6.com a musician can simulate 36 amp

models and 24 speaker cabinets. So why should the LM4702

driver be limited to the subjective sound of 1 output stage,

expecially calling this 1 output stage the "best"? Some like TUBE

flavor. Some like BIPOLAR flavor. Some like MOSFET flavor. Some

like hybrid flavors. So why 1 "best" ouput stage for all subjective

human listening experience?

Mark
 
Lm 4702 Philosophy

Hi,

National Semiconductor writes some philosophy on LM4702:

"Sound quality can be a very heated and subjective debate.

However, some feel that there are differences that can be heard

between different pieces of equipment and that almost all of

these can be quantified ... a significant amount has been written

in the audiophile press about how different types of passive

components affect perceived sound quality ... [in our prototype]

all of the passive components used in the demo amplifier are

standard".

www.national.com/an/AN/AN-1490.pdf#page=7

at topical subdivisions sound quality and parts selection.


So I guess one philosopy of ouput design, is to start with the

stardard parts and then evolve into the more esoteric parts,

while always listening to the subjective sound output and then

double checking the subjective with the objective quantified.

Mark
 
National Semicondutor Output Philosophy

Hi,

NS has already made an output stage philosophy at the FAQ

question entitled "How do I get an ouput power of 300 watts or

more per channel for the LM4702".


NS's answer: The output stage will need to be composed of 3

NPN/PNP output pairs.


It is also possible to get 100 watts with 1 output pair and 100-

200 watts with 2 NPN/PNP output pairs.


This philosophy is 1 pair then 2 pair then 3 pair or 2 transistors

per channel then 4 transistors per channel then 6 transistors per

channel, which is a standard design philosophy.

http://search.national.com/iphrase/query?query=LM4702&render&1&categories=1phrase

Mark
 
Newer IGBT Application Note

Hi,

UNETTO minimal power amplifier uses class A driver (which

LM4702 is) and class AB push pull output stage.

Note says IGBTs are voltage sensitive devices and a small change

in the input voltage generates a large change in the output

current. This would be an odd mixture with LM4702 semi-constant

current (for low noise) with large voltage change to next drive

a low voltage sensitive IGBT output stage with a high current out

put swing. The "odd couple amp".

http://digilander.libero.it/essentialaudio/unetto_home.htm

Mark
 
Strict Moderators

Hi,

Just spent 4 hours with www.4hv.org HIGH POWER.

One poor guy peeped "I am wondering about the [IGBT] for audio

amplifier and joined the site on 02-09-06.


On 02-13-06 the moderator cut the thread off for no more

General Science And Electronics forum and transfered the thread

to the chat room by suggesting link a Las Vegas gambling

program design to predict Aces entitled: "How to ace caculate on

the street" from University of California, Davis, mathematics

department.


We are lucky for the open minded DIYaudio moderators, since

these pro engineer guys at the other HIGH POWER forum are

much sticter on the (1) forum rules and (2) topic rules.


Thanks for the free speech oppertunity,


Mark St. Denis
 
To Jackinnj

Hi,

Thank you for your reply.


I less than 2 months that I have been part time reading

DIYAUDIO, I have gone from just any amp that I could design was

a good beginners start -- into this amp worship egomanic design

guru philosophy.


I am presently questioning my own motives to prototype an amp

to begin with.


Maybe subconsciously I wanted to be another Nelson Pass with

world wide audience.


Anyway, if you have any fundamental must read IGBT data,

please let me know.


www.audia.it/pages/e/100.html


Thanks,

Mark
 
More Homework

Hi,

Best I can find so far is Elektor Electronics Magazine's book titled

"Build Your Own High End Audio Equipment" 1995 and 2002

Edition at Chapter 5 named 90 Watt IGBT Power Amplifier.


I am at a low level of basic homework right now, so I am not

ready for prototype yet.


www.audioxpress.com/bksprods/books/bkee38.htm


Hope this post helps another find faster one of the few DIY IGBT

amp design books.


Mark
 
National Needs New Trademark?

Hi,

When Intel finished a high priced legal transaction, the

intellectual property law judge ruled P5 is a genetic term.

Intel then spent $300,000 at a speciality company to replace P5

with the trademark-able name Pentium.


Why is LM4702 still generic name?


Why not name the circuit COOL HOT POWER (TM) so that OEMs

can say COOL HOT POWER INSIDE (TM).


It costs about $400 a year for a trademark.


How are OEMs supposed to market and sales the LM4702 with a

generic name?


Any suggestions on trademark name for LM4702, besides

somewhere in the so called Overture (TM) Serries including

complete chip amps as divided from class A drivers?


http://tess2.uspto.gov/bin/gate.exe?f=tes&state=9nrbe4.1.1



Mark
 
Re: National Needs New Trademark?

Mark St. Denis said:
Hi,

When Intel finished a high priced legal transaction, the

intellectual property law judge ruled P5 is a genetic term.

Intel then spent $300,000 at a speciality company to replace P5

with the trademark-able name Pentium.


Why is LM4702 still generic name?


Why not name the circuit COOL HOT POWER (TM) so that OEMs

can say COOL HOT POWER INSIDE (TM).


It costs about $400 a year for a trademark.


How are OEMs supposed to market and sales the LM4702 with a

generic name?


Any suggestions on trademark name for LM4702, besides

somewhere in the so called Overture (TM) Serries including

complete chip amps as divided from class A drivers?


http://tess2.uspto.gov/bin/gate.exe?f=tes&state=9nrbe4.1.1



Mark


Logo-rhea
 
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