Explendid amplifier designed by Michael Bittner, our MikeB

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#2,801
Hi Al,
I have Eagle, but darned if I've learned it yet. I just need to figure out how to print on the photo paper. I also want to stick maybe 6 board patterns (to fit on an 8 X 11 sheet) so as not to waste on sheet per board. That way I can build some. Etching and drilling is no problem.

Mike, as soon as I figure out how to make boards I can help out. If you recall, we had discussed groundplanes earlier. I think the groundplane should be split between the output area and input area.

How about "Symasym- going further" for a new thread, also one for troubleshooting to help keep things on track?

Another request (as if you need this!). Cascode circuit. It can be jumpered past. I don't see the board size as terribly important right now. Less than 4" X 6" is fine. Then you can add another set of outputs for lower impedance loads if you want.

-Chris
 
#2,802
pinkmouse said:
Using Mike's Eagle files at the moment, but I'm going to redo the schematic with Protel to try and sort out the grounding, Eagle is just too limiting for that.
Click to expand...


I've just made a Protel schematic. Can I send it to you? I'm using a newer version of Protel so you'll need to associate parts on the schematic with footprints on the board.
 
#2,804
anatech said:
I also want to stick maybe 6 board patterns (to fit on an 8 X 11 sheet) so as not to waste on sheet per board.
Click to expand...

I use the CAM processor to output eps format files, then combine them in Photoshop. Do you have Photoshop?

How about "Symasym- going further" for a new thread, also one for troubleshooting to help keep things on track?
Click to expand...

Good idea, we are well over the 2000 post mark.

Another request (as if you need this!). Cascode circuit.
Click to expand...

Point me at a schematic. 😉
 
#2,805
Hi Al,
Man, you're a busy fella! 😉

I tried using Photoshop Elements 2.0 (That's all I have), but just got really frustrated. (what the heck are layers??) Mind you, Word frustrates me as well. I learned on a typewriter and I end up fighting with the program.

In short, not too successful so far.

-Chris
 
#2,806
Hi everybody,

I layed out a new board for Symasym with 4 AC filter caps on board measuring 5" x 3" double sided. So far everything is running great. I modified the design slighty so that it works with 50v rails. I'll post pics of the amp, waveforms, schematics , and THD measurements later today after I get home work. Mike, thanks for a great design!

Best regards,

Al
 
#2,807
Hi Al,
Using Mike's Eagle files at the moment, but I'm going to redo the schematic with Protel to try and sort out the grounding
Click to expand...
Yup. I really don't like the zobel ground and aux cap grounds where they are.
That's what happens with a small board.

As for a schematic, one could simply adopt the cascode from most amplifiers (Luxman, Marantz and tons more). I think I'd like to see Pavel or Mike guide this as they have a deeper understanding of this amplifier.

Mike, do you want to create the new threads or would you rather we do it? Just waiting for a title you like really.

-Chris
 
#2,808
anatech said:
Yup. I really don't like the zobel ground and aux cap grounds where they are.
That's what happens with a small board.
Click to expand...

These days, I actually start off on a layout with about a dozen separate ground nets added to the schematic, and route and combine them as I go along. It makes much more sense to me, but would probabaly confuse the hell out of anyone else. 😉
 
#2,809
Hi All,
I'm impatient sometimes. Mike, I opened a pair of new threads for you. The names can be changed to protect the guilty! 😉

The first is troubleshooting, here.
The second is for developement, located here.

I'll go back and link here ....

Hi Al,
What you are saying about ground nets makes sense to me anyway. Good idea.

-Chris
 
#2,814
Ooops, 2 Al's ?

Problem with dithering ? You need the dithering to supress harmonics generated by aliasing. The trade off is noise level at -130db, but completely acceptable, assuming a typical noise floor at -120db.

If you look at my fft-picture, the upper is without dithering, the lower with dithering. Obviously the dithering is mandatory for readable fft plots.

Mike
 
#2,820
PMA said:
Michael -

remember "horrible amplifier" (BTW - you were not happy 😀))
and "measurement that does not help" 😀

BTW - how is your 50Hz and its multiples now?

Cheers,
Pavel
Click to expand...

Yes, i remember "horrible"... 😉
I have to admit, have not heated up the soldering iron for days, was researching FFT and dithering and so on, my programmer side was stronger these days. 😀
At least, i would have all routines together to build up my own measuring software. Had to try dozens of FFT-windowing possibilities. Only 3 survived... (Kaiser,Hanning,Gauss)
I always need to know what's behind the scenes... :devilr:

Mike
 
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