TAB V372-1D

[Bomper]

Hey guys

I'm working on a TAB V372_1D I recently got. Wanted to add a rotary switch to set gain and maybe a phase and pad switch. I was checking the schematic an some things weren't clear to me.
First, is there anybody who can tell me what component Dr1 is on page 8?
Second, if someone could explain to me how the feedback mechanism works on the secundairy of the input transformer? That would be great...

Thanks a lot, Thomas

 

[enginefire]

I think it's a trim pot...

How do you find this unit?  What do you use it for?  I have one sitting in a bin somewhere and ive often wondered about it...

 

[Bomper]

Hey, it's not a trimpot I think. If you check page 6 it's the big round device. In reality it looks more like some kind of inductive element.
I'm planning on using it as a mic preamp. It should be possible to get the gain up to 40 dB when playing with the resistance value between terminals 8 and 9. I have two U374a's (talkback preamps with built in limiter) which I use as room preamps sometimes and two V673's (headphone amps) which I use as insert effect on guitar and drums to color the sound a bit. I like them on high gain guitars.

 

[[silent:arts]]

Dr1 is a variable inductor

 

[opacheco]

Hey guys

I'm working on a TAB V372_1D I recently got. Wanted to add a rotary switch to set gain and maybe a phase and pad switch. I was checking the schematic an some things weren't clear to me.
First, is there anybody who can tell me what component Dr1 is on page 8?
Second, if someone could explain to me how the feedback mechanism works on the secundairy of the input transformer? That would be great...

Thanks a lot, Thomas

I think this is a Inductor with a ferrite (maybe!) core adjustable !!

Opacheco.