Preamp gain stages: how they sound and why

[EtherealWidow]

When opening the file "Some graphics about gain shape" in MS 2013, the first page has one graphic on the first page and it looks like it's labelled with 100k Rp and 1.5k Rk, but as I look again, I see 100k Rp and 820R Rk far over to the left. I think my MS program butchered the labelling of the graphs on the document. Haha.

[titser_marco]

This is great!

I'm currently referencing the "Graphics" file where you have the frequency curves of various combinations. At the moment, I was wondering if I could tweak these values to remove the harsh fizzy sound that I am getting from the OD channel of my D-style build.

I'm particularly interested in the 100K 1k5/4.7uF (Rg) combination as that is the closest to the circuit I am working on currently. That said, I am wondering whether the schematic I have needs to have that 220K inserted in both stages (either to replace 68K and 180K or ADD the 220K before the pots that lead to the two Rg; thoughts?) so I can get close to the frequency graph that was posted and hopefully remove the fizz.

I've attached the schematic for your reference. I'd appreciate your thoughts on this, thanks!

[sepulchre]

Man, I wish these were still there.

[ChopSauce]

In a loosely related matter, I could find no link to an ODS_Notes.pdf file (*) I have downloaded I do not even remember where.

The search engine of the forum (as Google also) was of no use there, but maybe a member here remembers something about it.

The document shows no author name, so the content can not be assessed, but its matter seems to be worth reading - pertaining with low & high plates settings in the OD, notably.

I can even make it available for download, if there is some interest for that
___

(*) not to be confused with Schematic Heaven's Dumble notes https://schematicheaven.net/dumbleamps/dumblenotes.pdf yet I haven't compared their respective contents, latter which might recover in some matter.

[pompeiisneaks]

I don't know if this is the right 'ods notes' file, but I ran across it on the server filesystem, and found that it wasn't accessible due to the system setup, I've fixed that, and it may make some of the other files that were 'lost' now accesible. Let me know if so.

http://ampgarage.com/forum/files/ods_notes_809.pdf

~Phil

[ChopSauce]

Yes, this is the one! You're definitely doing a great job here, Phil!



Now I'll be looking for comments & criticisms - if any

[roberto]

Man, I wish these were still there.

Let me in some old hard disks I have around.
I'm sure I still have those simulations somewhere.

[ChopSauce]

... and it may make some of the other files that were 'lost' now accesible. Let me know if so.

It does look like, yes

[roberto]

Some of the old cathode follower plots:

[roberto]

Some of the old gain stage plots:

[roberto]

Other gain stage plots: