Ampeg PF20T Schematic

[TPJ]

I'd like to find out some info about using the Ampeg PF20T Preamp DI on Pre-EQ mode but don't understand block diagrams. I'd like to understand if in Pre-EQ, the signal goes through any of the preamp valves or if it's just Thru. The manual and diagrams get confusing as one section says in Pre-EQ it acts like a Thru but in another it states the Pre-EQ is after the first gain stage. The block diagram (to me) looks to show three preamp valves but there are only two. Hence my confusion.

 

Below are screen shots of the FAQ about the Preamp DI, and the block diagram. I've included a link to the owner's manual. https://ampeg.com/data/6/0a020a3f12c8b5e0b88f60b5ae/application/pdf/Owner’s Manual - English .pdf

 

Any help is appreciated.

[Hellzero]

In the pre-eq mode, the signal is taken just after the first (half of of the first) 12AX7.

 

A 12AX7 is a twin triode, so it has 2 halves.

[TPJ]

Thank you for the reply @Hellzero. I'm trying to determine whether using it as a live DI is viable. It's a lot of glass to carry around for 1/2 a valve . It does offer quite a clarity to the tone and I prefer the pre-eq over the post-eq. It sounds more open then my Stagebug too.