Burning Amp 2016

[jrubins]

Originally Posted by Bob Cordell

Some folks expressed interest in seeing the slides from my Burning Amp 2016 presentation of the Hafler DH220C revamp using a full-complementary JFET input stage with a floating tail. It is a powerpoint file, and, unfortunately, it is over 7 MB, even zipped (zip compression of ppt files is negligible). I don't know of any easy way to post it here. Please email me if you would like a copy.



Cheers,

Bob

You should be able to "save as" or "print to" pdf, which is much more portable



Sent from my iPhone using Tapatalk

[delange]

Originally Posted by Bob Cordell

Some folks expressed interest in seeing the slides from my Burning Amp 2016 presentation of the Hafler DH220C revamp using a full-complementary JFET input stage with a floating tail. It is a powerpoint file, and, unfortunately, it is over 7 MB, even zipped (zip compression of ppt files is negligible). I don't know of any easy way to post it here. Please email me if you would like a copy.

Cheers,
Bob

Dropbox is an easy way to share files.

[amb]

I am interested, and agree with the Dropbox solution.

[Bob Cordell]

Hi guys,

Here is a PDF of the slides, thanks to Mark Johnson.

Cheers,
Bob

[linuxworks]

400k file and its perfectly fine.

good that export-to-pdf was the easy win

it goes to show: rarely is it a good idea to use microsoft file formats to share files to the world. pdf at the resolution you used was perfectly fine.

cheers

[dady]

Originally Posted by Bob Cordell

Hi guys,

Here is a PDF of the slides, thanks to Mark Johnson.

Cheers,
Bob

Thanks for share.
Happy new year for you.
Happy Christian new year for Dad and the rest of gentlemen of this fantastic community.

[amb]

Thanks Bob Cordell!

[AndrewT]

Originally Posted by Bob Cordell

Hi guys,

Here is a PDF of the slides, thanks to Mark Johnson.

Cheers,
Bob

Thank you for all your efforts to get these posted.
You used 489 and 689 dual jFETs.
Can k170/j74 be substituted? or k389/j109?
What performance would deteriorate with this substitution?

[Variac]

Was great fun to be there as Bob summed up the specs he'd gotten after following thorough the process! Not Bad!

[Bob Cordell]

Originally Posted by AndrewT

Thank you for all your efforts to get these posted.
You used 489 and 689 dual jFETs.
Can k170/j74 be substituted? or k389/j109?
What performance would deteriorate with this substitution?

In principal, these substitutions can be made in this architecture with appropriate changes to some passive component values, especially the tail resistor. However, there is little benefit unless you already have those parts hanging around (most are no longer available). A key issue is that you really want dual monolithic matched pairs for the P and N JFETs. The hassle of matching and changing component values is probably not worth it. Although the parts you mention have somewhat lower voltage noise, the net reduction in noise by use of these larger-area JFETs is not great, since there are other contributors to noise. Moreover, with the LSK489/LSJ689, the amplifier already achieves very low noise for a power amplifier. The larger-die JFETs, like the k389, also have much higher capacitance.

Cheers,
Bob