Hafler T2 gut shots, schematics: mid/treble boost mods?

[roberto]

If you don't have the coupling trafo anymore, you can simply convert to a three stage plus cathode follower (split loaded to have a low amplitude signal for the rest of the preamp), and remove the two diodes between tubes and ICs.

Remove also the grid stopper to stage II.

[ryanpg]

If you don't have the coupling trafo anymore, you can simply convert to a three stage plus cathode follower (split loaded to have a low amplitude signal for the rest of the preamp), and remove the two diodes between tubes and ICs.

Remove also the grid stopper to stage II.

So, remove D9 and D10 completely? I think I did that when I lifted C49, and it had little effect.

And you're saying bridge or jumper R7 instead of the 0.001μF bypass cap I have parallel there now.

Correct? Thanks!

[roberto]

Not only that. Before you have to convert it to a three stages plus CF.

[roberto]

double post.

[Tone Lover]

roberto I see that he,s probably struggling with understanding what a 3 gain stage with CF is, Im at work or I would put a schematic up for referance.
Bill
ryanpg I would not use a 12at7 to cut down the gain get a 5751 or 12ay7 .I dont like the sound of 12at7 when it distorts. Just my personal preferance.

[ryanpg]

roberto I see that he,s probably struggling with understanding what a 3 gain stage with CF is, Im at work or I would put a schematic up for referance.
Bill
ryanpg I would not use a 12at7 to cut down the gain get a 5751 or 12ay7 .I dont like the sound of 12at7 when it distorts. Just my personal preferance.

You're right Bill, I will search around but would love to see a schematic if you get the chance later. This amp is two stage correct? TA1 -> TA2 -> TB1 & TB2. In a three stage there would be another stage TB1 -> TB2. Am I close? (-:

[roberto]

Here we are. This is a JCM800 preamp.
We can say the father of all three stages plus CF preamps.

http://www.tremolo.pl/Przedwzmacniacze/ ... 04prem.gif

[ryanpg]

Here we are. This is a JCM800 preamp.
We can say the father of all three stages plus CF preamps.

http://www.tremolo.pl/Przedwzmacniacze/ ... 04prem.gif

Thanks Roberto, I'll study that schematic and do some research. As far as my preamp goes, I think I've probably reached the limit of my ability, and/or the limit or what can be easily changed in the tube part of the circuit without venturing into the active Eq section.

(I'm interested in figuring out the design of the "pull- gain" circuit. Maybe there's some potential for fun there too.)