I've just rebuilt a little McGohan M102 PA head. The idea is that it will be used to drive the reverb send in my home studio (the reverb "chamber" is my hardwood-floored living room).
So rather than taking a balanced mic-level or unbalanced phono input (both of which it's set up to do), I'll be taking a balanced line-level signal out of my DAW and running it through the amp. I'm assuming that all I need is an input transformer rated at 600 ohms primary to 50k ohms secondary to drive a 6AU6A (the first preamp tube).
However, studying the schematic more closely, it might make more sense to skip the first gain stage and route the transformer output to the phono stage. After all, I'll be using a +10dbm signal, and I doubt I'll need that much gain.
The physical rerouting of the signal is easy; what I'd like to know is what the second gain stage (a 6EU7) wants to see in terms of impedance. I've searched for a reference for "typical" values but have come up short. Is there a guidebook, or at least a rule of thumb?
Many thanks,
Seth
[IMGDEAD]http://thegoldenbears.net/images/WebMcGohan.jpg[/IMGDEAD]
McGohan M102 Schematic
So rather than taking a balanced mic-level or unbalanced phono input (both of which it's set up to do), I'll be taking a balanced line-level signal out of my DAW and running it through the amp. I'm assuming that all I need is an input transformer rated at 600 ohms primary to 50k ohms secondary to drive a 6AU6A (the first preamp tube).
However, studying the schematic more closely, it might make more sense to skip the first gain stage and route the transformer output to the phono stage. After all, I'll be using a +10dbm signal, and I doubt I'll need that much gain.
The physical rerouting of the signal is easy; what I'd like to know is what the second gain stage (a 6EU7) wants to see in terms of impedance. I've searched for a reference for "typical" values but have come up short. Is there a guidebook, or at least a rule of thumb?
Many thanks,
Seth
[IMGDEAD]http://thegoldenbears.net/images/WebMcGohan.jpg[/IMGDEAD]
McGohan M102 Schematic