for Nelson Pass or Mr Curl

[lt cdr data]

Hi seeing as you are the guru's gurus, I am pretty much a valve person myself, I understand valve amps reasonably.

I have read Randy Slone's amp book, and John Linsley Hoods'.

Anyway, to the point.

I was just wondering a few things about tranny amp designs.

1/ How long would it take a pro company to come up with a working design roughly?

2/ Do they work backwards...ie start with power required and select output transistors and configuration?

3/ now it gets interesting, having seen a few Japanese amp schematics, there are multitude of variations, why so many and so complex in the first 2 stages, i.e. once you have an ouptut stage, how does that determine the former stages?

4/ another important question, can you really tune the sound, ie the designs are done by maths on paper, so how does the 'sound' arise, ie. laidback say, punchy bass, you know, what you want it to have...is it just really an accident, or what areas can you play with within reason....just the feedback and caps.?

5/ some Japanese amps have elaborate compensation, ie lots of caps, how?? on earth do they hone in on the areas that need stabilising?


thanks look foward to an informative reply, best wishes.

[lt cdr data]

I can't seem to edit, couple more questions.

why so many capacitors in designs ie

an input cap for frequency
the miller cap
the cap in the feedback loop
the zobel cap

I mean, why an input cap if the others roll off frequency?

and..

is there a systematic guide to types of distortion, ie is it fair to say current driving output stage is lo. frequency and slew rate is current at high frequencies?

thanks again

[jam]

You need need the masters to answer a few questions.....................and teach you amplifier design?

The answers would probably take up a few books. I suggest you look up Pass DIY, Douglas Self and Horwitz and do some reading first.

Regards,
Jam

[darkfenriz]

guess not interested in my opinions

wouldn't it be easier to e-mail these two guys rather than starting a thread on forum?

[Variac]

Well, it makes sense that if they are going to take the time to answer, we should all benefit. OTOH I think that everyone's point is that these are not questions that can be answered in a few sentences.

[lt cdr data]

all are welcome to reply, but I was after the pro's ideas in particular, to see how things are done for manufacture.

not to cause consternation, but what is Mr Curl's background, I can see he is revered, but I am a bit in the dark concerning his history.

And I have also read Doug self, very good, too, trouble is, this is such a tough subject to get a good grasp of, and no book seems to be explain things properly, the ones I have mentioned go some way, but still fall short.

[janneman]

Originally posted by lt cdr data
all are welcome to reply, but I was after the pro's ideas in particular, to see how things are done for manufacture.

not to cause consternation, but what is Mr Curl's background, I can see he is revered, but I am a bit in the dark concerning his history.

And I have also read Doug self, very good, too, trouble is, this is such a tough subject to get a good grasp of, and no book seems to be explain things properly, the ones I have mentioned go some way, but still fall short.

I think Jam's advise is the best one. As you yourself say, these subjects are tough, so it would also be very, very tough to answer by whoever in just a few posts, and it would amount to some lengthy private tutoring, for which you normally would pay muchos $$$.

Your post # 2 shows that you need to study some basics first.
This is not to put you off; we've all been there one time or another. But unless you YOURSELF understand the issues, you won't get anywhere. Even for a hobby, serious effort is required to advance.

Pretend there is no internet, and get a book. You'll be amazed how fast you learn if you really want! Ask the forum for some good basic text, I'm sure you get lots of good advise.

Jan Didden

[bear]

Let me take a crack at some answers:

A pro company can take from minutes to years to make a new design. Crown, for example actually hires engineers and has developed essentially "new" designs for a substantial number of their amp products over the years. The ones that take minutes are simply taking "well understood" designs and packaging them for the application, with appropriate "glue".

Capacitors: they are needed to keep the amp stable. Amps like to become oscillators generally speaking. Judicious use of caps in the real world keeps your amp from becoming silicon fuses, or fused silicon!

Understanding all of the details of amp design is not an easy task unless you already have an engineering degree, in which case most of the math involved transfers very nicely - making the details much easier. To do the thing really well (design) you need college level math skills and optimally some computer skills to run SPICE (a circuit simulation program), plus the digestion of a number of texts on electronics.

I do suggest that the Horowitz and Hill book is a very excellent place to begin, as it is *readable* without special math or electronics background. (Why can't more people write texts this clearly??)

I'll say this, I am a complete moron and still have gaps in my knowledge and have forgotten as much or more than I could tell you right now today about amp design, electronics in general. Personally I am constantly amazed by people who can quote some obscure equation off the top of their head on cue after not having used it for 10 years... "it ain't me babe..."

There's no easy path... one way to go is to go to the library and read all the back issues of EW+W and Audio Express (Audio Amateur) and read all the web pages that talk about this stuff to start to see how it hangs together. This forum has some fabulous threads that get pretty deep into specific areas of amplifier design both for specific amps and for general amp ideas. You could read them for a few weeks and maybe come up with some things you want to learn more about, then go out and research them... that will lead you to other things, and so on...

_-_-bear

Oh, one of the best ways to learn is to build things yourself. If you have yet to build anything, start *very simple* and with a kit if possible, or a mod from a magazine or website that is known to work... then build something from scratch, etc... you'll learn that way. Most of the readers here are DIYers not professional audio/circuit engineers. I suspect most got started that way.

[Elso Kwak]

This may be nice reading too:
http://www.arraydesign.com/downloads/index.html

[janneman]

Originally posted by lt cdr data
[snip]why so many capacitors in designs ie

an input cap for frequency
[snip]

Just an example: if you depict a source going into an amp via a series C (that's your question, right?), what's so special about a cap, what a resistor or a coil couldn't do?


Jan Didden