Explendid amplifier designed by Michael Bittner, our MikeB

Jump to Latest
#822
Hi all,

Can we get the "Marketing" and "Engineering" departments working together here?

We need both to have a successful DIY product and you can't sack one department half way through a project.

If we get rid of the marketing department we'll end up with a excellent engineering product that know one knows about, and visa versa, if we upset the engineering deaprtment, we end up with a product that hasn't reached its potential.

regards
 
#824
AKSA said:
But Greg,

This is normal, even when one man does both!!

Hugh
Click to expand...

Yes, I know. I been fortunate enough to work in lots of different positions in companies, cleaning, engineering departments, drawing office, IT, pre and post sales and have seen the same battles. IT is very interesting because you really work for ALL departments in an organisation nowadays.

I'd like to see your row of hats! 😀 Are they colour coded.

Regards
 
#825
Mike and Pavel,
I see you are working hard on the problem and I am really amazed to see people from different corners of the world working together with such devotion. I really think such efforts should bring people more close together, and not divide.
From what we have up to now, a builder has two options:
a) Don't use the combination 2SC5200/2SA1943 for output
b) If you use it change 22pF cap for 3.3pf

I built my first (breadboard version) with 2SC3281/2SA1943, which is not a complementary pair. This should be a mistake, but it sounded ok (note: I don't really know if it oscillated and judging by the sound is not a reliable way to find out! I also did not do many hours listening).

Perhaps (a) should be changed to something like "don't use 2SC5200 for output"? But could someone recommend transistors from different complementary pairs? I don't know.
Mike what do you mean by the term "step response"? You mean response to square wave input?

Keep up the good work!
 
#827
Greg Erskine said:
Hi all,

Can we get the "Marketing" and "Engineering" departments working together here?
Click to expand...

The trouble is that marketing always think they know what engineering should do. They come with 1000 nonsenses ("technical solutions" 😉) only mystifying people. If they kept their business, there would be no problem. We also do not suggest how to do marketing.

But this is about independent work, if it was about marketing/EE hierarchy, I would never took part in. This is about good feeling, which is very important.
 
#828
This amplifier

Hi Mike

Yes, that's your fault, you never told me anything after I sent
you an e-mail. Perhaps because you heard things that weren't
completely true, I don't know...

Anyway, yes I built the latest version of your amp[lifier and I am satisfied, completely no, but I am satisfied, your amplifier is in
fact a very good performer even using those Sanken you
remember from the first version. By the way, I gave it to my son,
he needed an amplifier for PA (imagine!).

You remember, it's incredible! But let me tell you, this time I used
2sa1493 and 2sc3857 which I think are better yet than those
you "remember"....

Anyway, it seems that you have not been affected by third party,
and this is good...

The only thing is, you told me long time ago, after I e-mailed you
that you would keep in touch, it never happened!
Regards
 
#829
PMA said:
The trouble is that marketing always think they know what engineering should do. They come with 1000 nonsenses ("technical solutions" 😉) only mystifying people. If they kept their business, there would be no problem. We also do not suggest how to do marketing.
Click to expand...

Yes Pavel, this is exactly the point and exactly the answer from all engineers. We need a balance.

I believe Carlos's only "issue" is the name of the Aymasym was being tarnished by discussion of some minor issue, although he didn't quite say that. He has spent months talking it up ("mystifying people") creating a desirable product (with help from many others, of course)

I am from an electrical engineering background (spent a lot more time at university than most because I am a little stupid 😀 ) but I still have these engineering traits. I get very very focused on the technical issues. I think, "Why doesn't everyone just leave me alone and I'll fix it". I have noticed that the only people engineers dislike more than marketing people are the accounting people. 😀 My change from engineering to IT has forced me to see what the other departments actually do and appreciate that without each other there isn't a product. I know this is getting a little deep for a DIY audio forum, and I apologise for that.

Anyway, I hope you don't take anything I've said personally or too seriously, I was just really pointing out a few things that seem universal in companies (or forums) around the world, and hopefully make a little difference.
 
#830
Or to maybe put it another way: There is a reason for sex and it's not what you might think. It's to enable diversity and rapid transformation. Diversity is necessary in natural populations in order to ensure maximum survivability, or that at least some will survive under difficult conditions. Humans, and some other social species, can go even farther than that. They can use diversity and collaboration to create a more capable society than is possible with a homogeneous one. We have an expression, "it takes all kinds".

It really does.

Sheldon
 
#831
Greg,

I understand perfectly, but I was thinking this is a non-commercial forum (or that the business is not the primary intent). Probably I was wrong? 😉

I was thinking it was for hobbyists and diyers, people, who relax here.

If this was a second regular job with all its rules I would probably not post here 😉.

Cheers,
Pavel
 
#832
I tried the combination 2SC3281/2SA1943 at Iq=105mA today. Sounds quite good. But when I lower bias to 10mA then it sounds even better ( best, I could say). So I think the above combination still oscillates (I have no other explanation for lowering bias off optimum operating point and getting better sound). And I could say also that the above combination sounds better than 2SC5200/2SA1943 at any Iq.
Cheers.
 
#834
PMA said:
Greg,

I understand perfectly, but I was thinking this is a non-commercial forum (or that the business is not the primary intent). Probably I was wrong? 😉

I was thinking it was for hobbyists and diyers, people, who relax here.

If this was a second regular job with all its rules I would probably not post here 😉.

Cheers,
Pavel
Click to expand...

Pavel,

You are right. We should just come here and relax. Have a chat about the pros and cons of various amps, and not take things too seriously. 😀

We all can make things more complicated than they need to be, human nature I guess.

regards
 
#835
Hugh is correct : global feedback compensation isn't good and lead to instability. All is caused by too fast VAS ( which is much faster than output circuits ). This amp is very similar to old Dynaco 400 ( designed by Erno Borbelly, as I remember ), where was compensation at VAS ( connected in CB ) and from C of VAS against ground. I had build many of these amp without any problems with instability...
 
#837
Excellent, excellent work, Herr Bittner !

Carlos, you can come back and open a bottle of Jamaica rum.

I just performed several distortion measurements. It looks excellent. My loop-back method shows 0.003%, which is the limit and I must bring special generator next week. The attached image is for low-level signal, not very good conditions for class B, but symasym surprised me. 0 dB = 1 Vrms.

The image confirms perfect PCB design. The highest PSU spuriae is -103 dB (related to 1V!!) at 150 Hz. And this line is again a limit of my measurement setup. Such a result is impossible with spider-nest or breadboard amateur construction (Mike, thick wire not used!)

Michael - try these Toshiba's. IMHO they are the best power BJTs in the world.


Cheers,
Pavel
 

Attachments

  • sym5_thd.gif
    sym5_thd.gif
    27.8 KB · Views: 845
You must log in or register to reply here.
Top Bottom