John Curl's Blowtorch preamplifier part II

[syn08]

Originally Posted by gerhard

I don't like math.

Then never touch Class D with NFB. This is what it takes: http://eprints.nottingham.ac.uk/501/1/final.pdf

P.S. I have spend only 10 minutes reading this work, so I don't claim understanding more than the basic plot. I don't plan spending more time on it

[Wavebourn]

Originally Posted by syn08

Then never touch Class D with NFB. This is what it takes: http://eprints.nottingham.ac.uk/501/1/final.pdf

P.S. I have spend only 10 minutes reading this work, so I don't claim understanding more than the basic plot. I don't plan spending more time on it

It is a new can of worms advertised as a solution to all former problems.

But what it really brought, an energy saving in an output stage and better suitability for micro-miniaturization. Add here a SMPS, and you have small light cheap amp for a mass production to drive dragon tails on stadiums.

[stinius]

Originally Posted by Wavebourn

I started building one for you, but you've stopped answering e-mails as soon as I said that you have to share at least some expenses.

What do you mean?
My latest email to you was that I could send you some money and I asked you what I would get. After that I haven’t heard anything from you. If you have responded to that email, I’m sorry but I haven’t seen it. Please send the email one more time.

I’ve been aware of that the spam filter I used was a bit to clever so I have changed it.

If anybody else has sent me emails that I haven’t responded to please send them one more time, I usually answer emails.

[Wavebourn]

Originally Posted by stinius

What do you mean?

I mean I stopped getting answers from you.

Now it is too late, the amp is being made for my own specification. I still hope to get some SiC devices, but even without them the amp will be superb.

[stinius]

Originally Posted by syn08

Then never touch Class D with NFB. This is what it takes: http://eprints.nottingham.ac.uk/501/1/final.pdf

P.S. I have spend only 10 minutes reading this work, so I don't claim understanding more than the basic plot. I don't plan spending more time on it

Syn08

You told me that you didn’t like Class D amps when I asked you if we should do a Class D amp together.

What do you think about these figures?
Ah! Too much 7th, I have to work on that.



FREQUENCY COMPONENT
1 1.000E+03 1.000E+00
2 2.000E+03 4.338E-07
3 3.000E+03 1.565E-07
4 4.000E+03 7.605E-07
5 5.000E+03 5.121E-07
6 6.000E+03 7.621E-07
7 7.000E+03 9.802E-07
8 8.000E+03 4.249E-07


Cheers
Stinius

And why the heck doesn’t show up like the way I put it in?

[Wavebourn]

The best improvement from class D I ever experienced, was a recording amp in a tape recorder. I was going to combine a bias oscillator and an output stage, but as the result got much cleaner sound and unbelievably reduced tape noise. I was intended to use it with a pre-cleaned tape, but found that an erase head was not needed at all!

[syn08]

Originally Posted by stinius

Syn08

You told me that you didn’t like Class D amps when I asked you if we should do a Class D amp together.

What do you think about these figures?
Ah! Too much 7th, I have to work on that.



FREQUENCY COMPONENT
1 1.000E+03 1.000E+00
2 2.000E+03 4.338E-07
3 3.000E+03 1.565E-07
4 4.000E+03 7.605E-07
5 5.000E+03 5.121E-07
6 6.000E+03 7.621E-07
7 7.000E+03 9.802E-07
8 8.000E+03 4.249E-07


Cheers
Stinius

And why the heck doesn’t show up like the way I put it in?

What makes you think I give a rat's *** on class D amps simulations? Build it, measure it, listen to it, then we'll talk about. Be prepared, be very prepared for some very nasty surprises. Class D is much more difficult to build than any Class A/B amp.

It's not that I don't like them, I don't need them and can't afford to build from scratch something up to my standards. Without a 4-6 layers SMD board, iterated 3-4 times, it's unlikely the results are going to be spectacular.

And for mid-fi (like the stuff affordable to build from scratch or buy as a kit), the TI power chipsets are very good, no need to go further than that. They have some limitations (including zero PSRR :-) ) but still you can't beat them for the money.

[stinius]

Hi John

Sorry if I stopped the thread that was not my intention, it wasn't me that brought up the Class D stuff.

So back to you, why do you prefer video op amps?

Cheers

stinius

[john curl]

It never ceases to amaze me, as to why people bring their most fun topic of what they are doing to this thread.

Now, taking a deep breath, I will attempt to remind everyone as to why this thread has grown so 'popular' (in a sick sort of way) and my original intentions of contributing to this thread.
It all started, years ago, when someone, long lost in time, wondered about the CTC Blowtorch's schematics, mentioning that Bob Crump (when he was still alive) hinted to some people, that we might give to audiophiles after we stopped production. I tentatively agreed, at the time, but the situation changed when Bob unexpectedly died, without finishing about 6 units that we pre-sold. This put the burden on me to finish them, myself, and this took almost 1 year, after his death.
I came to this thread to put out some immature criticisms of the CTC design that came from a number of instant critics, most of whom, are not here, anymore. I then hoped to extend the topic of this thread to cover most areas of audio circuit design and promote what seems to work to a greater audience. I was told, by close friends and associates, that this was a serious waste of time, and that I should keep my design ideas to myself, since I needed to continue consulting. At the very least, this effort was a waste of my time, that could be engaged in more productive pursuits, such as producing new designs for ultimate sale in the audio marketplace.
So much, for why I came here. Now, I had hoped for some spirited discussion, but things tended to get out of hand, and if I had a lick of common sense, i would have dumped this project, long ago. Unfortunately, I am not completely appalled by vigorous discussion, in fact I kind of get a charge out of it, as it gets me, back to the textbooks and looking up obscure technical papers, long lying fallow, waiting for such a situation. This differs from people with real jobs, who find this sort of thing just takes their time and potentially loses them money. Being semi-retired, I have the time, and this reduces the boredom.
Now, where has this gone wrong? Well, this thread has had its ups and downs, but lately I can't seem to get a word in edgewise without a group of people, who could just ignore me, instead deciding that I am 'poisoning' the audio community with 'unproven' ideas and deviating designers from the 'true path' (whatever that is), you know something like: Good op amps are virtually perfect, and if you pay a little extra, you don't have to bother building your own electronics. Or, the human ear cannot detect such subtle factors, and this can be proven in a double-blind test, therefore audiophiles are imagining that they hear differences. Or, a number of opinions in that general type.
Yet, when I talk to audio friends, designers, and people in the audio industry, we have a completely different conversation, where we compare subtle factors, often independently discovered, that there is very little 'proof' of, as to why these factors make any difference at all. Still, we hear these differences, sometimes together, sometimes independently, and we feel sorry for those who ignore these details, as they will almost invariably make a 'mid-fi' quality design, rather than an 'audio quality' design. At least, that has been our experience, thus far.
Now, where to go from here? Back to discussing the subtleties of quality preamp design, or continue the aimless diversions that just confuse the issue?

[anatech]

Hi John,
What strikes me about your posts is that most of them involve putting people down in some way. Heck, you've handed out the highest variety of put downs I have ever seen anyone else even attempt! There isn't one single method you haven't used.

There are times when I guess you feel more cooperative and do contribute a little, then there is the moaning and crying about the original purpose of the thread being lost. John, you've kicked things off track more than anyone else here! Many times you can be seen crying that you are not believed, then typically a name drop where the "name" does agree with you. There is of course the never ending "you're wasting your time John", from people unseen. It's all just your word. No way of checking what you say ever pops up.

Next, I'll address some of your last comments.

-Chris